Tesi: "Biotic and abiotic stresss"

1

RICCI, SARA. "Study of biotic and abiotic stresses in Solanaceae by metabolic and proteomic approaches". Doctoral thesis, Università di Foggia, 2017. http://hdl.handle.net/11369/363315.

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2

Escalante, Pérez María. "Poplar responses to biotic and abiotic stress". kostenfrei, 2009. http://nbn-resolving.de/urn/resolver.pl?urn=nbn:de:bvb:20-opus-46893.

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3

Karim, Sazzad. "Exploring plant tolerance to biotic and abiotic stresses /". Uppsala : Dept. of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/200758.pdf.

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4

Jain, Ritu Shree. "Rice response to simultaneous biotic and abiotic stresses". Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/6415/.

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With the predicted climate change and an ever-growing population there is increasing pressure to develop crop plants with improved stress responses, increased yield and high nutritive value. We have explored transcriptomic changes in the leaves and roots of rice plants (Oryza sativa japonica cv Nipponbare) in response to drought and the root-knot nematode Meloidogyne graminicola. A glasshouse model was developed to mimic conditions experienced by rice plants in the field. The plant responses under simultaneous biotic and abiotic stress were dominated by the drought element accompanied by a unique set of genes that were only responsive to the simultaneous stress. Highlighted within this group were novel members of stress-responsive gene families for example cytochrome P450, wall-associated kinases, lipid transfer proteinlike proteins and new candidate genes that may play important roles in the response of rice to multiple stresses. The genes that were differentially regulated between the multiple and the drought stress treatment were explored using loss-of-function mutants. The loss-of-function mutant for peroxidase precursor gene (per) showed improved growth and yield compared to the wildtype Nipponbare plants. The experiments conducted in growth rooms were validated in a field study. Both Nipponbare rice plants, and the popular lowland indica rice cv IR64 were grown under prolonged vegetative drought stress accompanied by cyst nematode or root-knot nematode infection. Reduction of phytate, an anti-nutrient, has been adopted as a major strategy to improve the nutritional value of crop plants. Nematode susceptibility of low phytate Arabidopsis plants was studied to determine the effect of reduced phytate content on the plant’s defence response. The study has provided insight into the genome-wide transcriptional changes in rice under a combined biotic and abiotic stress. It has led to better understanding of the stress responses in plants that will be advantageous in developing crop varieties with improved yield and nutritive value.

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5

Madeo, M. "MEDICINAL PLANT RESPONSE TO ABIOTIC AND BIOTIC STRESS". Doctoral thesis, Università degli Studi di Milano, 2010. http://hdl.handle.net/2434/150114.

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Medicinal plants have always been considered a rich source of secondary metabolites that promote human health. Quality and property of medicinal plants strictly depend on secondary metabolites profile. They also play important roles in plant physiological processes and in ecological systems. The environment exerts a selective pressure on plants and these molecules actively participate to the plant response and adaptation. Amongst secondary metabolite, the phenolic compounds possess properties able to prevent oxidative stress. Therefore, an enhancement of the amount of phenolic compounds can be observed under different environmental factors. With this project we aimed to study the phenolic compounds of the medicinal plant Achillea collina Becker ex Rchb. cv “SPAK”, and their implication in physiological and biochemical response to abiotic and biotic stresses. We seek the possibility to increase the synthesis of phenolics with health properties or useful as potential control agents of insect pests. Abiotic stress. Hydroponic culture was used to evaluate the effect of long-term mineral, nitrogen starvation (abiotic stress) in A. collina. By means of HPLC-DAD-ESI/MS and NMR techniques, the content and the qualitative profile of A. collina methanol soluble phenolics, were evaluated. We concluded that the methanol extracts of A. collina leaves and roots are rich in hydroxycinnamic acids such as chlorogenic acid (2.33 ± 0.3 mg g-1 Dw), 3,5-di-O-caffeoylquinic acid (10.7 ± 4.2 mg g-1 Dw) and 4,5-di-O-caffeoylquinic acid (0.88 ± 0.24 mg g-1 Dw). The content of hydroxycinnamic acids significantly increased in plants growth under mineral nitrogen starvation, respect to the control plants. Chlorogenic acid increased by 2.5 and 3-fold and 3,5-di-O-caffeoylquinic acid increased by 8.5 and 35-fold in leaves and root, respectively. Biotic stress. A. collina plants cultivated in soil were infested with the phloem feeders aphids. We set up the system (e.g., age of plant, type of the cage, number of insects per plant, duration of infestation) to co-cultivated the plants with specialist (Macrosiphoniella millefolii) and generalist (Myzus persicae Sulzer) aphids. Plant growth, water and total protein content were evaluated. Based on a preliminary assessment of phenolic fingerprint, further extractions and separations were performed on A. collina leaves, to obtained soluble and cell wall-bound fractions and their sub-classes. Our results showed that A. collina plants were strongly affected by aphid infestation. Twenty days after infestation, the fresh weight was twenty-fold and seven-fold increased, in control and infested plants. Water and protein content, condensed tannins and methanol soluble phenolics content, were not affected by the aphid infestation. Cell wall-bound phenolics content increased in infested plants. The main phenolics were found to be chlorogenic acid and 3,5-di-O-caffeoylquinic in methanol soluble fraction, and caffeic acid in cell wall fraction. The chromatographic profiles showed that the main hydroxycinnamic acids were present in control and in both M. persicae and M. millefolli infested plants. The quantitative analysis indicated that the levels of chlorogenic acid and 3,5-di-O-caffeoylquinic acid, were 44% and 37% higher in M. persicae infested plants, respectively. The levels of chlorogenic acid and 3,5-di-O-caffeoylquinic acid, were 27% and 39% higher in M. millefolli infested plants, respectively. Twenty days after infestation the content of caffeic acid was resulted 43% and 34% higher in M. persicae and M. millefolli infested plants, respectively. These differences should indicate the different evolutionary interaction between plant and generalist/specialist aphid. We hypotheses that the increase of these molecules may represent a plant resistance mechanism against aphid attack. Finally, a chemometric approach, by means multivariate statistical analysis, was applied on chromatogram profiles to verify whether there is difference between methanol soluble fraction of infested and non infested A. collina plants. The discriminant analysis showed a significant effect of phloem feeders aphids on soluble phenolic compounds and indicated two peaks, not yet identified, that separate control from infested plants. In conclusion the model system developed to cultivate A. collina was useful to understand the metabolic basis of the environment interactions. The main hydroxycinnamic acids identified, were resulted increased in both abiotic and biotic stress, suggesting their implication in A. collina protection to environmental controversies.

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6

South, Kaylee. "Improving abiotic and biotic stress tolerance in floriculture crops". The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595499762154056.

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7

Chemayek, Bosco. "Studies on Resistance to Biotic and Abiotic Stresses in Wheat". Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15362.

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This investigation was focused on the assessment of genetic diversity for resistance to stem rust and stripe rust in an international wheat nursery, genetic characterisation of adult plant stripe rust resistance in Australian wheat cultivar Sentinel, understanding of genetic relationship between two stem rust resistance genes (Sr36 and Sr39) located on chromosome 2B and assessment of genetic diversity for physiological traits among a set of wheat landraces. Ten seedling stem rust resistance genes (Sr8a, Sr8b, Sr9b, Sr12, Sr17, Sr23, Sr24, Sr30, Sr31 and Sr38) and seven stripe rust resistance genes (Yr3, Yr4, Yr6, Yr9, Yr17, Yr27 and Yr34) were postulated either singly or in combinations in an international wheat nursery. Genotypes carrying uncharacterised resistance for stem rust and stripe rust against the Australian rust flora were identified for genetic analysis. Three consistent QTL (QYr.sun-1BL, QYr.sun-2AS and QYr.sun-3BS) were demonstrated to condition high level of adult plant stripe rust resistance in Sentinel. QYr.sun-1BL, QYr.sun-2AS and QYr.sun-3BS explained on an average 18.0%, 15.6% and 10.6% variation in stripe rust response, respectively. Additive nature of three QTL to condition high level of stripe rust resistance was demonstrated through comparison of recombinant inbred lines (RILs) carrying these QTL in all different combinations. Detailed characterisation of these loci will be performed. Stem rust tests on F3 populations involving Sr39 on a large and a shortened Aegilops speltoides translocation with Sr36 on a Triticum timopheevi segment showed complete repulsion linkage. The molecular cytogenetic analysis however indicated that these can be recombined using large F2 population. Significant variation for water-use efficiency related physiological traits was observed among wheat landraces. Genotypes with low and high mesophyll conductance, stomatal conductance and other physiological attributes will be useful in designing crosses to achieve high water-use efficiency in future wheat cultivars.

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8

Alzwiy, Ibrahim A. Mohamed. "The interaction between abiotic and biotic stress in Arabidopsis thaliana". Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/13946.

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Plants are continuously exposed to different abiotic and biotic stresses in their natural environment. Their capacity to survive depends on the capacity to perceive external signal and quality amount a defence response for protection from the stress perceived. The purpose of this project was to study the impact of combined abiotic stress and biotic stress on the outcome of the disease inducing Arabidopsis thaliana – Pseudomonas syringae interaction. This study included a focus on the role of ABA in these interactions and also whether 3´-O-β D- ribofuranosyl adenosine (hereafter it called ‘400’ compound), a novel adenosine derived compound induced during compatible interactions, was involved. The later involved the targetted disruption of a putative 400 biosynthetic pathway involving analysis of knockout mutants of enzymes; APD-ribose diphosphatase NAD binding / hydrolases of the NUDIX class, glucosyl transferases, ribosyltransferases, a ribose-phosphate pyrophosphokinase3 and galactosyltransferases. Unfortunately, none of these targeted interventions modified the host response to Pseudomonas infection, nor altered levels of 400 in challenged leaves. The primary research investigated the interaction between abiotic and biotic stresses in Arabidopsis plants focussing on the modulation of plant defence against multiple, and possibly antagonistic, stress responses and the role plant hormones play in this process. We showed that high light caused enhanced susceptibility to the already virulent Pseudomonas syringae DC3000pvsp61. The pathways contributing to this enhanced susceptibility were largely ABA independent. Subsequent characterization of transgenic lines expressing the soluble Arabidopsis abscisic acid receptors, PYRABACTIN RESISTANCE1-LIKE4-6 provided compelling evidence for a role for these receptors in DC3000 virulence strategies, but they contribute to a lesser extent to the enhanced susceptibility under high light. This was corroborated genetically by using mutants of the immediately downstream targets of PYLs, the type two protein phosphatase, specifically the triple mutant hab1-1/abi2-1/abi1-2. A number of epitope and fluorescent constructs were generated to facilitate future studies of the role of ABA signaling. Targetted profiling suggested that SA dynamics were altered under DC3000 challenged Arabidopsis grown under high light. Furthermore, differential accumulation of flavonoids suggested these may also play a role in attenuating host defences under high light. Finally we provide evidence based on comparative analysis of that the photoreceptors phytochrome double mutant phyA-211/phyB-9 and cry1/cry2 behave antagonistically in Arabidopsis response to DC3000. Overall our studies support the conclusion that plants abiotic stress (HL) response takes precedence over biotic stress (DC3000) responses and that abiotic stress is detrimental to plant immunity. The luciferase transgenic PYL lines showed high level of expression of ClucP::PYL5 plant tissues challenged 2hpi of DC3000 (OD600: 0.15) in comparison with C1lucP::PYL6. This result opposes to what RT-PCR reported; which was that three PYLs genes display similar expression level at 6hpi of hrpA or 18hpi of DC3000. The epitope tags of CaMV::HA transgenic plants showed HA-tagged signal with stunted phenotype in a range of PYL4, 5 and 6 plants but none of the plants displayed any differences in susceptibility to DC3000. Although, RT-PCR assay showed high levels of expression in the three PYLs, 6hpi of hrpA but no signal was detected in B8eGFP::PYL5 transgenic line either followed the DC3000 and hrpA infection or by examined plant seedlings at early stages under confocal microscopy.

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9

Pham, Jasmine. "The role of AHK5 in abiotic and biotic stress signalling". Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/8959.

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In Arabidopsis thaliana, eight histidine kinases (HKs) have been identified which function in hormone signalling, stimuli perception, and plant development. To better elucidate HK roles in signalling, the function of the least characterised HK, AHK5, in stress tolerance was investigated using a T-DNA insertion knockout line (ahk5-1). Reduced inhibition of seedling root growth was seen in ahk5-1 in response to salinity when compared to wild-type Col-0 in tissue culture assays. In mature plants, ahk5-1 showed greater fresh weight gain under either salinity or drought stress. Loss of AHK5 function did not alter cold stress tolerance, nor basal and acquired heat stress tolerance in terms of seedling root elongation. Infection with the biotrophic pathogen Pseudomonas syringae pv. tomato DC3000 revealed ahk5-1 is compromised in disease resistance, exhibiting increased chlorosis and in planta bacterial growth. Levels of the plant hormones salicylic acid, jasmonic acid, and abscisic acid, alongside the bacterial phytotoxin coronatine, were lower in pathogen challenged ahk5-1 mutants compared to wild-type plants. The ahk5-1 mutant was also more susceptible to the necrotrophic pathogen Botrytis cinerea, supporting more fungal growth and displaying accelerated symptom development. Hydrogen peroxide production has been linked with both resistance and susceptibility towards B. cinerea; in ahk5-1, 3,3-diaminobenzidene (DAB) staining suggested reduced hydrogen peroxide production in response to infection. Complementation and expression of AHK5 with either full-length genomic AHK5 under the 35S CaMV promoter or full-length AHK5 cDNA under the native promoter rescued the ahk5-1 mutant stress response phenotypes. In summary, AHK5 was found to negatively regulate abiotic stress tolerance whilst positively contributing towards resistance against pathogens employing different lifestyles. To begin to establish an AHK5 signalling network, tandem affinity purification coupled with LC-MS/MS was employed for identification of possible AHK5 interacting proteins. Suggestions for further optimisation of the purification method are presented. The role of AHK5 in regulation of plant stress responses through modulation of reactive oxygen species and hormone signalling and through protein-protein interactions are reviewed. Suggestions for further investigation are also discussed.

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10

Endeshaw, Solomon Tadesse. "Grape and olive: physiological responses to biotic and abiotic stress". Doctoral thesis, Università Politecnica delle Marche, 2013. http://hdl.handle.net/11566/242716.

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Le piante crescono in ambiente aperto in continuo cambiamento e sono sottoposte a stress. Gli stress possono essere classificati come interni e esterni. Lo stress interno porta a mutazioni o a abnormi divisioni cellulari e infine a una ripartizione anomala della crescita, dell’allocazione e della ripartizione del carbonio. Stress esterni possono essere abiotici o biotici. Siccità, freddo, caldo, alta salinità, fitotossine rilasciate da lettiere indecomposte o altri residui organici sono fra i fattori che più drasticamente riducono la crescita, lo sviluppo e la produzione delle piante. Fra gli stress biotici quelli da patogeni (batteri, funghi, fitoplasmi, virus) sono i più pericolosi per la produzione. Nei prossimi anni per consentire livelli elevati di produzione capaci di rispondere alla crescente domanda di olio e vino, ogni regione produttiva dovrà rispondere con un incremento delle superfici coltivate nelle zone agroecologiche in cui sono attualmente coltivate oppure dovrà espandersi in nuove zone. Questo richiederà in ogni caso un cambiamento di tecniche di coltivazione e di gestione degli impianti che dovranno di conseguenza fronteggiare maggiori stress biotici (nelle zone meno vocate) o stress dovuti al reimpianto (se impiantati negli stessi appezzamenti). Questo progetto ha lo scopo di valutare la risposta fisiologica della vite e dell’olivo a stress biotici e abiotici. In particolare sono oggetto stati di studio gli effetti del legno nero (fitoplasma) e del accartocciamento virale (GLRaV-3 virus) sugli scambi gassosi e sulla produzione di vite Chardonnay and Cabernet Franc, rispettivamente. Sono stati inoltre approfonditi gli effetti di residui colturali di olivo indecomposti e di sansa proveniente da un frantoio a due fasi su olivo cv. Arbequina and Frantoio. L’infezione con fitoplasmi e virus ha indotto una riduzione significativa della fotosintesi, della traspirazione e della conduttanza stomatica in entrambi i vitigni durante l’estate dopo l’allegagione. La riduzione degli scambi gassosi e del metabolismo ha indotto una riduzione della produzione, della crescita dei tralci e della loro lignificazione. In definitiva la riduzione della produzione è stata pari al 70 e 40% rispettivamente. L’applicazione di residui colturali di olivo e di sanse di olivo su piante in vaso ha ridotto la crescita radicale e dei germogli in funzione della dose applicata, mentre ha portato in proporzione ad un aumento del contenuto di sostanza organica nel substrato. In conclusione, nel caso di fitoplasmi e virus è necessaria un’attenta profilassi per evitare la diffusione attraverso il materiale di vivaio e una volta presenti in campo deve essere prevista una campagna di eradicazione delle piante infette che possono sopravvivere all’infezione e funzionare da inoculo. Nel caso dell’olivo si deve invece tenere conto che applicazioni localizzate di residui indecomposti e di sanse hanno un’azione temporanea fortemente tossica per le radici e quindi per poter sfruttare al meglio il miglioramento indotto del contenuto di sostanza organica e non avere ripercussioni negative sulle produzioni serve un’attenta programmazione delle dosi e del momento dell’intervento.
Plants grow and develop in an open field, with continuously changing weather condition that induces stress. Stress are broadly classified as external and internal. Internal stress is that drive from mutation or abnormal cell divisions and to unbalanced growth and carbon allocation and partitioning. External stress can have abiotic and biotic origin. Drought, cold, high-salinity, heat and phytotoxin released from undecomposed litter and manure are major abiotic stresses that severely reduce the plant growth, development and yield. Whereas, pathogen (bacteria, fungi, phytoplasma, virus) are the major biotic stress that severely reduce yield. To meet the current increase in global demand of agricultural good in general and olive oil and wine in particular, each growing region has to respond either by incorporating new olive and grape orchard in the existing agroecological zone and/or expanding to new agroecological zones or by changing mode of cultivation and orchard management, facing different biotic stress and external stress in replanting condition. This project aimed at evaluating the physiological responses of grape and olive to biotic and abiotic stress respectively. In particular, effect of Bios noir (BN, a phytoplama disease) and grapevine leafroll associated virus 3 (GLRaV-3, viral disease) on gas exchange and yield of Vitis vinifera cv. Chardonnay and Cabernet Franc respectively; and effect of undecomposed olive shoot residue (OSR, originated from pruning and leaf shedding) and fresh two-phase olive mill waste (TPOMW, coming from two-phase decanter) were studied on shoot growth, root proliferation and biomass partition of Olea eropaea L. cv. Arbequina and Frantoio. Biotic stress originated from BN and GLRAV-3 infection showed that Photosynthesis, stomatal conductance and transpiration were significantly reduced in the symptomatic Chardonnay and Cabernet Franc vines through the summer after the fruit set. The reduction in metabolism due to BN and GLRaV-3 infection in cv. Chardonnay and Cabernet Franc had a direct influence on the decrease in total berry production, vine size and cane lignifications of symptomativ vines. Indeed, they suffered a drastic decrease of about 70 and 40% in yield respectively. Whereas, application of OSR and TPOMW in the pot altered shoot and root growth, biomass partition and relative growth rate of fine root and shoot; while increasing soil total organic matter and carbon, total N and polyphenol content of the growing substrate. Hence there is no chemical spray develop to control the infection of BN and GLRaV-3 pathogens, planting phytoplasma and virus free root stocks during the vineyard establishment and uprooting the infected vine and replanting new to avoid spread during pruning and by insect vectors is the best way to minimize the adverse effect of BN and GLRaV-3 on quality and quantity yield. To avoid antagonistic effect of OSR and TPOMW on root and shoot growth and improve soil fertility knowing the exact quantity, for each types olive orchards, and when to apply in play major role.

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Gessese, Mesfin Kebede. "Characterization of wheat landraces for resistance to biotic and abiotic stresses". Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17198.

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This study covered genetic and molecular analyses of stripe rust and leaf rust resistance in common wheat landraces and investigation of response of drought and short term leaf temperature changes among a set of 20 durum wheat genotypes. Three all stage resistance genes (YrAW5 in Aus27430 and YrAW6 and YrAW7 in Aus27492) were identified. YrAW5 and YrAW7 were located on chromosomes 6AS and 5AL, respectively. The location of YrAW6 was inconclusive. While Aus27430 was concluded to carry Yr18, Aus27492 appears to carry an uncharacterized adult plant resistance gene. Four QTL for stripe rust resistance (QYr.sun-1BL, QYr.sun-2AL, QYr.sun-5AL and QYr.sun-3BS) were detected in Aus28166/AvS RIL population. QYr.sun-1BL and QYr.sun-5AL also conferred resistance to leaf rust in Aus28166. QYr.sun-1BL and QLr.sun-1BL corresponded to the pleiotropic locus Lr46/Yr29/Sr58/Pm39/Ltn. The co-located loci QYr.sun-5AL and QLr.sun-5AL appear to represent a new pleiotropic resistance locus. Durum wheat genotypes showed significant variation for mesophyll conductance in response to water stress and short-term variation of leaf temperature highlighting the potential for improving durum wheat for drought and heat stress.

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12

Dutta, Sampa. "Abiotic and biotic stress response of tea plants and their biochemical characterization". Thesis, University of North Bengal, 2000. http://hdl.handle.net/123456789/878.

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13

Condorelli, Giuseppe Emanuele <1987&gt. "Genetic dissection of resistance to abiotic and biotic stresses in durum wheat". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amsdottorato.unibo.it/9223/1/Condorelli_Giuseppe%20Emanuele_tesi.pdf.

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This thesis was aimed to investigate the genetic response to abiotic and biotic stresses in durum wheat (Triticum turgidum L. var. durum), a cultivated tetraploid subspecies used for the production of pasta, couscous and various types of bread. Two research areas were focused: i) the high-throughput phenotyping (HTP) to detect novel drought tolerance quantitative trait loci (QTL) clusters and ii) the Kompetitive Allele Specific Polymerase chain reaction (KASP) marker development for the genetic dissection of Furarium head blight (FHB) resistance. Concerning the first area, I investigated drought adaptive traits on durum wheat elite accessions at Maricopa Agricultural Center (University of Arizona, US) which provided the experimental field and the high-throughput phenotyping platforms. The genome-wide association study (GWAS) detected thirty-one QTL clusters for two or more drought adaptive traits unrelated to the major loci responsible for phenology and plant height. Twelve of them overlapped with the major QTL for grain yield and related traits previously reported in studies carried out across a broad range of soil moisture availability and field drought conditions in wheat. Concerning the second area, I investigated two plant materials: i) 130 durum wheat accessions artificially inoculated with Fusarium culmorum and F. graminearum species and evaluated for incidence (INC), severity (SEV), FHB index, Fusarium-damaged kernels (FDK) and deoxynivalenol (DON) content; ii) 165 F6 recombinant inbred lines (RILs) from the cross between the cultivars Simeto and Levante evaluated for SEV using FG as inoculum. The genetic dissection led to sixteen QTL clusters, in part unrelated to the phenology and unknown in bread wheat, from which specific loci significantly influenced DON content. The haplotype analysis allowed me to validate KASP Single Nucleotide Polymorphisms (SNPs) suitable for marker-assisted selection (MAS) programs and to select cultivars for resistance/tolerance to DON content and other FHB traits.

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Falkenberg, Nyland Ray. "Remote sensing for site-specific management of biotic and abiotic stress in cotton". Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/478.

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This study evaluated the applicability of remote sensing instrumentation for site- specific management of abiotic and biotic stress on cotton grown under a center pivot. Three different irrigation regimes (100%, 75%, and 50% ETc) were imposed on a cotton field to 1) monitor canopy temperatures of cotton with infrared thermometers (IRTs) in order to pinpoint areas of biotic and abiotic stress, 2) compare aerial infrared photography to IRTs mounted on center pivots to correlate areas of biotic and abiotic stress, and 3) relate yield to canopy temperatures. Pivot-mounted IRTs and IR camera were able to differentiate water stress between the irrigation regimes, however, only the IR camera was effectively able to distinguish between biotic (cotton root rot) and abiotic (drought) stress with the assistance of groundtruthing. The 50% ETc regime had significantly higher canopy temperatures, which were reflected in significantly lower lint yields when compared to the 75% and 100% ETc regimes. Deficit irrigation up to 75% ETc had no impact on yield, indicating that water savings were possible without yield depletion.

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15

Leitão, Susana T. "Unravelling the genetic control of combined biotic/abiotic stress resistance in Phaseolus vulgaris L". Doctoral thesis, Universidade Nova de Lisboa, Instituto de Tecnologia Química e Biológica António Xavier, 2020. http://hdl.handle.net/10362/95339.

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Dissertation presented to obtain the Ph.D degree in Plant Sciences
"Common bean (Phaseolus vulgaris L.) is among the most important grain legumes for human consumption worldwide. Portugal has a promising common bean germplasm that resulted from more than five centuries of natural adaptation and farmers’ selection. Nevertheless, limited characterization of this resource hampers its exploitation by breeding programs. To support a more efficient conservation of the national bean germplasm and promote its use in crop improvement, we performed, for the first time, a simultaneous molecular marker and seed and plant morphological characterization of 175 accessions collected from Portuguese mainland and islands traditional bean-growing regions. Most of the Portuguese accessions grouped with the race representatives and wild relatives from the Andean region."
N/A

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SEVESO, DAVIDE. "Assessing the expression of HsP60 in scleractinian corals subjected to biotic and abiotic stresses". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2013. http://hdl.handle.net/10281/41879.

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The reef health worldwide is seriously threatened by a multitude of factors such as abnormally elevated and low ocean temperatures, high UV radiations, changes in salinity, pollution and increasing incidence of diseases. Under adverse circumstances the equilibrium between the partners of the coral holobiont may be compromised and can lead to coral bleaching events. Bleaching refers to the loss in the coloration of the coral colony induced by the dissociation of the symbiosis between corals and their symbiotic algae. The extreme or unexpected environmental fluctuations could be very stressful for sessile marine organisms such as corals, causing important cell damage since corals lack any developed physiological regulatory system. One mechanism of reaction to deleterious conditions is the rapid increase of the induction of a set of stress proteins called Heat shock proteins (Hsps). Under normal cellular physiological conditions the Hsps mainly function as molecular chaperones and they are involved in a multitude of proteome-maintenance functions that regulate protein homeostasis in directing the folding and assembly of other proteins. They also are involved in the intracellular protein transport and in the degradation of damaged proteins. An up-regulation of the expression of Hsps constitutes an emergency response and confers tolerance to harsh conditions. This study highlights the modulation of the expression of a vital but scarcely investigated group of Hsps, the mitochondrial Hsp60 which are essential for the vitality of the cell and whose induction represent one of the first reaction to stress. The overall objective of my dissertation is to elucidate the major aspects of Hsp60 modulation in various taxa of corals as a result of their exposure to different abiotic and biotic stress factors. In the first study we investigated for the first time the effectiveness of the Hsp60 as indicator of biotic stress and competitive interaction in the coral Acropora muricata, focusing on two biological interactions such as a coral disease, the Skeleton eroding band (SEB) caused by the protozoan Halofolliculina corallasia and the algal overgrowth. The two different biological stresses trigger diverse responses on Hsp60 level. No detectable effect on Hsp60 modulation appeared in colonies subjected to algal overgrowth. On the contrary, corals displayed a robust up-regulation of Hsp60 in the fragments sampled just above the SEB dark band indicating that the aggressive behavior of the protozoan causes cellular damage also in coral portions neighboring and along the advancing front of the infection. Portions of coral sampled distant to the SEB band showed a Hsp60 level comparable to that observed in healthy colonies. We propose Hsp60 expression as a promising tool to evaluate physiological stress caused by coral disease in reef corals. In the second study we examined the different modulation of Hsp60 in the coral Seriatopora caliendrum subjected to salinity stress, since that corals are generally considered stenohaline and osmoconformers. We analyzed the Hsp60 expression profiles of the coral polyps under three salinity scenarios (hypersalinity of 45 ppt, hyposalinity of 27 ppt and extreme hyposalinity of 15 ppt) during the time course of a 2 days period. Experiments were conducted at the Civic Aquarium of Milan using a flow-through aquaria system. S. caliendrum responds differently to hyper- and hyposaline conditions at morphological and cellular levels and the response of corals to osmotic stress reflects the severity and duration of the disturbance. The Western blot analysis showed for each salinity a similar strong up-regulation of Hsp60 after the first 6 h of stress, but subsequently Hsp60 exhibited for each salinity treatment specific patterns of expression. In hypersalinity condition a negative trend of Hsp60 expression was observed, but the colonies showed a morphological appearance similar to healthy control colonies, suggesting a possible metabolic acclimation of corals to the stress. In S. caliendrum exposed to moderate hyposalinity, Hsp60 exhibited marked oscillation and the level of Hsp60 generally remained high over time indicating that cellular damages in the animal host were in progress. In extreme hyposalinity condition, a considerable gradual down-regulation of Hsp60 was detected until the end of the experiment. This was accompanied by extreme degradation and necrosis of coral tissues. Finally, we focused on the responses of Hsp60 to thermal stresses, initially analyzing the susceptibility of three coral genera (Montipora, Acropora and Seriatopora) to a severe heat stress of 36°C for 12 h. Despite the Hsp60 trend appeared similar, each genus displayed a different persistence of the Hsp60 signal, and so a different threshold of tolerance and resistance. Secondly, the sensitive S. caliendrum was subjected to a cold shock of 21°C, a moderate heat shock of 29°C and a severe heat shock of 34°C. The modulation of the Hsp60 at lowered temperatures are similar to those involved in very elevated temperature stress with an up-regulation after 6 h followed by a down-regulation when the cellular damage become irreparable. This is accompanied by the appearance of bleaching events. The mild heat shock of 29°C did not significantly affect the normal Hsp60 oscillatory pattern. With this study we proposed the application of the mitochondrial Hsp60 and the analysis of its modulation as an useful and accurate biomarker, to assess the effect of several types of stress in scleractinian corals, and to diagnose coral health prior that the coral bleaching occurred.

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17

Burcher, Chris L. "Biotic and abiotic responses to rural development and legacy agriculture by southern Appalachain streams". Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/27438.

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Streams are integrative systems spanning multiple spatial and temporal scales. Stream researchers, land-use managers, and policy decision makers must consider the downstream displacement of streams when approaching questions about stream ecosystems. The study of how anthropogenic land-use influences streams demands an ecosystem perspective, and this dissertation is an example of applying large scale analyses of stream reach responses, and linking the activity of humans in the landscape to stream structure and function. I investigate whether rural development and agriculture land-cover types influence abiotic and biotic stream responses. I establish a method for considering land-cover as an independent variable at multiple scales throughout a streamsâ watershed using hydraulic modeling. The travel time required for water to drain from the watershed to a stream reach provided a continuous index to delimit watershed sub portions along a spatial continuum. Within travel time zones (TTZs), I consider land-use at increasingly larger scales relative to a stream reach within which biotic responses are typically measured. By partitioning land-cover in TTZs, I was able to determine the spatial scale at which land-cover was most likely to influence in-stream responses. I quantified a suite of physical and biotic responses typical to the aquatic ecology literature, and found that streams did not respond much to rural development. Rural development influenced suspended and depositional sediments, and likely altered watershed hydrology though I was unable to find significant evidence supporting a hydrologic effect. Subtle differences in assemblages suggest that differences in sediment dynamics influenced macroinvertebrates and fish. Using the Land Cover Cascade (LCC) design, I link the influence of land-cover to biotic responses through a suite of multivariate models, focusing on sediment dynamics in an attempt to capture the subtle influence of hydrology and sediment dynamics. My dissertation provides future researchers with improved methods for considering land-cover as an independent variable, as well as introduces multivariate models that link land-cover to sediment dynamics and biota. My dissertation will assist future research projects in identifying specific mechanisms associated with stream responses to disturbance.
Ph. D.

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18

Muthevhuli, Mpho. "Investigation of the role of AtNOGC1, a guanylyl cyclase protein in response to abiotic and biotic stress". University of the Western Cape, 2018. http://hdl.handle.net/11394/6763.

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>Magister Scientiae - MSc
Agricultural production is one of the most important sectors which provide food for the growing world population which is estimated to reach 9.7 billion by 2050, thus there is a need to produce more food. Climate change, on the other hand, is negatively affecting major global crops such as maize, sorghum, wheat and barley. Environmental factors such as salinity, drought, high temperatures and pathogens affect plant production by oxidatively damaging the physiological processes in plants, leading to plant death. Poor irrigation used to combat drought result in salinasation, which is estimated to affect 50% of arable land by 2050. Plants have developed several mechanisms that protect them against stress and these include overexpression of stress responsive genes and altered signal transduction to change the expression of stress responsive genes, among others. Cyclic 3’5’ guanosine monophosphate (cGMP), a second messenger that is synthesised by guanylyl cyclase (GC), transmit signals to various cellular functions in plants during plant development, growth and response to abiotic and biotic stresses. Arabidopsis thaliana nitric oxide guanylyl cyclase 1 (AtNOGC1) is a guanylyl cyclase which upon activation by nitric oxide (NO) leads to the production of more cGMP. Cyclic GMP further activates protein kinases, ion gated channels and phosphodiesterase which mediate response to various stresses. In this project the role of AtNOGC1 was investigated in response to abiotic and biotic stresses through analysis of its evolutionary relationships, promoter, gene expression and functional analysis via the viability assays in Escherichia coli (E.coli). Phylogenetic tree, exon-intron structure and conserved motifs were analysed using the Molecular Evolutionary Genetics Analysis (MEGA V.7), Gene Structure Display Server 2.0 (GSDS 2.0), and Multiple Expectation Maximisation for Motif Elicitation (MEME) tools respectively. AtNOGC1’s gene expression was analysed by the Real-Time Quantitative Reverse Transcription Polymerase Reaction (qRT-PCR), whereas functional analysis was carried out using the cell viability (liquid and spot) assays to determine its ability to confer stress tolerance to E. coli.

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19

REGGENTE, MELISSA AMANDA LJUBICA V. "Assessing the expression of different biochemical indicators in scleractinian corals subjected to biotic and abiotic stresses". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2016. http://hdl.handle.net/10281/101829.

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In the last few decades about the 27% of coral reefs have been destroyed worldwide caused by different environmental stressors, both abiotic and biotic. Moreover one of the main causes of coral reef destruction has been the dramatic increase in coral disease. In reef building corals, as well as in other organisms, several components of the cellular stress response can be used as diagnostic indicators of stress, in order to assess their cellular physiological condition, expressing them with significant different patterns in relation to different stressors. In this study the diagnostic indicators used were: Heat shock protein 60-kDa (Hsp60), Heat shock protein 70-kDa (Hsp70), Heme-oxygenase (HO-1), and Manganese Superoxide Dismutase (MnSod), all involved in cellular response to stress. Two of the most studied diseases responsible for ongoing coral losses on Indo-Pacific reefs were chosen as the biotic stressors: the Brown Band Disease (BrB) and Black Band Disease (BBD). BrB is a virulent coral disease characterized by a dense concentration of ciliates ingesting coral tissue. In order to investigate the effect of the ciliate presence in the coral physiology, the level of the mitochondrial Hsp60 was analyzed in colonies of Acropora muricata affected by BrB in a Maldivian reef. Samples in the apparently healthy coral polyps located at different distances along the advancing front of the infection were analyzed. The BBD is characterized by a thick microbial mat, dominated by phototrophic cyanobacteria, which is responsible of the disease virulence and create the characteristic necrotic dark band. It is known to be persistent in reef, contributing to the long term mortality of the infected coral. In Maldives waters one of the highest prevalence was observed in Goniopora columna, which show a very slow progression rate. Due to its high persistence in infected corals, colonies of Goniopora were analyzed in two time periods, space out by three years. Samples in the apparently healthy coral polyps were collected at three different fixed distances along the advancing front of the infection from the black band of necrotic tissue, in order to analyze how the disease’s progression affect the expression of Hsp60 and Hsp70, HO-1, and MnSod. Finally Hsp60, Hsp70 and HO-1 were analyzed in relation to nictemeral and seasonal variations of temperature and light, in three different taxa of reef building corals living in the Maldivian waters: Acropora, Echinopora and Porites. These three taxa were chosen for their different growing morphology and susceptibility to stress. Samples were taken in November for the wet season and March for the dry season in order to made a comparison between the two seasons. During each selected month, in a day, corals were sampled in six time intervals while temperature and light intensity were measured by data-loggers attached to the colonies. Results show the biochemical indicators used being modulate in different ways in relation to species and stressors.

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20

Khan, Thana Khalid. "Transcriptional and physiological responses of wheat Triticum aestivum to a combination of abiotic and biotic stress". Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/3511.

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Plant responses to simultaneous biotic and abiotic stresses involve the activation of multiple signalling pathways that often interact in a synergistic or an antagonistic manner. Recent studies have shown that the plant response to a combination of stresses differ to those that occur when exposed to a single stress. The aim of the present study is to investigate the response of wheat (Triticum aestivum) to both salinity and aphid Sitobion avenae infestation, applied singly and in combination, at the physiological and transcriptional levels, to provide a better understanding of the impact of abiotic and biotic interactions and cross tolerance in wheat. These two forms of stress were selected since they are known to have a major impact on crop productivity. Wheat genotype 122-1 was shown to be tolerant to salt (160 mM NaCl) on the basis of biomass; accumulating high levels of Na+ in the shoots and was partially resistant to aphids in terms of fecundity. Pretreatment of this genotype with salt significantly (p < 0.001) reduced aphid fecundity (by 37%) relative to its control, indicating enhanced resistance to aphids. This positive interaction between salt and aphid stress was investigated at 6h and 24h post aphid infestation on the wheat transcriptome. Microarray analysis indicated common and specific gene expression patterns of the 61.290 transcripts differentially regulated in response to salt stress alone, aphid infestation alone and dual stress compared to the controls. Dual stress specifically and strongly increased the transcription level of the following genes assigned to jasmonate synthesis encoding lipoxygenase (LOX), abiotic stress (heat), miscellaneous enzyme families (acid and other phosphatases) at 6h, and secondary metabolism (phenylpropanoids) at 24h. Furthermore, based on functional classification analysis, several categories which were shown to be significantly activated by dual stress such as cytokinin hormone synthesis and MAP kinases signalling were not, however, significantly changed under either salt stress or aphid infestation alone. The current study demonstrated that jasmonate hormone signalling pathways antagonized those of salicylic acid under dual stress and aphid infestation at 6 h. Results suggests that the interaction between combined salinity and aphids stresses caused distinct alteration in gene expression patterns that could not be detected under either of the two stresses when applied individually. This study proposes that the activation of specific genes involved in the acquisition of defence/tolerance, such as those encoding cytochrome P450 and MYB domain transcription factor families, due to prior exposure to salt may enhance subsequent tolerance to aphids. The present study sheds light on candidate genes with putative functions in the crosstalk and the acquisition of cross tolerance and provides new insights on wheat response to multiple stress conditions. Such information is a prerequisite for enhancing crop tolerance to a broad-spectrum of stress.

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21

Lo, Cicero Luca. "Generation of CsGSTUs over-expressing tobacco plants and their role in abiotic and biotic stress tolerance". Doctoral thesis, Università di Catania, 2014. http://hdl.handle.net/10761/1574.

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Xenobiotics are toxic chemicals that are normally not the natural substrates for enzymes or transporters involved in plant resistance. Plants have developed a three phases detoxification system from toxic compounds. Xenobiotic are firstly activated so that certain functional groups can be exposed to the successive action of several modifying enzymes. Among them, the glutathione transferases (GSTs) catalyze the nucleophilic addition of glutathione (GSH) to the electrophilic groups of a large variety of hydrophobic toxic molecules. Previously, two gstu genes have been isolated from sweet orange leaves [(Citrus sinensis) L. Osbeck)] namely GSTU1 and GSTU2. The encoded proteins differ in three amino acids, all of them included in the C-terminal domain of the enzymes (R89P, E117K, I172V). In order to evaluate the contribution of the mismatched amino acids on the catalytic activity of enzymes, several cross-mutant genes were produced by site-directed mutagenesis followed by the biochemical characterization of the in vitro expressed enzymes. In this work, transgenic tobacco plants via Agrobacterium tumefaciens mediated transformation over-expressing both the wild type and mutant CsGSTU genes were generated. Along with the molecular characterization of transformed plants, an in planta study to assess their ability in detoxifying herbicides was also performed. Therefore, transgenic plants were subjected to the action of fluorodifen, a diphenyl ether herbicide that cause photooxidative stress by inhibition of the plastid protoporphyrinogen oxidase and alachlor a chloroacetanilide herbicide which is used to control the growth of broad-leafed weeds and grasses in many crops. The electrolytic leakage assay was carried out to test the damage caused by fluorodifen treatment upon transformed and untransformed tobacco plants. The data revealed that the transgenic lines show a sharp reduction of membrane damage compared with the wild type tobacco plants. To study the tolerance towards alachlor in planta, we assayed the growth inhibition of untrasformed wild type and transgenic tobacco seedlings in the presence of 7.5 mg/l of alachlor. Alachlor negatively influences the growth of roots and stems of untransformed an transformed tobacco seedlings with the exception of the transgenic plants over-expressing CsGSTU2 which are clearly unaffected by herbicide treatment considering either stem or root lenght. Consequently, the herbicide-tolerant transgenic tobacco plants, which are described in the present study, can be utilized for phytoremediation of residual xenobiotics in the environment. Drought and salinity stress tolerance was also assessed. When exposed to 200 mM NaCl both the wild type and transgenic seedlings exhibit a reduction of root lenght, with the exception of the CsGSTU2 over-expressing tobacco line whose root length is as long as untreated control roots indicating a high level of tolerance to NaCl. The effect of drought stress upon root elongation was measured by growing seedlings in the presence of 8% mannitol. In this case all treated tobacco seedlings disclose a sharp decrease of root length, although transgenic lines appear to better tolerate drought stress conditions as the mean root length is significantly higher than that of treated tobacco wild type seedlings. In order to understand the response of tobacco plants over-expressing the CsGSTU genes to biotic stress, untransformed and transformed tobacco leaves were infiltrated with a bacterial suspension of the P. syringae pv. tabaci Tox+ DAPPG-PG 676 strain. The differences observed in symptomatology indicate that the over-expression of CsGSTU1 and CsGSTU2 in tobacco plant bestow the capability to avoid active toxin diffusion in plant tissues blocking chlorotic halos formation probably because tabtoxin is head towards a modification pathway in which CsGSTs could be involved in. This result was confirmed when tobacco leaves was treated with culture filtrates.

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22

Pagani, V. "INTEGRATION OF COMPONENTS FOR THE SIMULATION OF BIOTIC AND ABIOTIC STRESSES IN MODEL-BASED YIELD FORECASTING SYSTEMS". Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/487500.

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The raising global demand for agricultural products and the exacerbated inter-annual fluctuations of food productions due to climate change are increasing world food price volatility and threatening food security in developing countries. In this context, the availability of reliable operational yield forecasting systems would allow policy makers to regulate agricultural markets. However, the reliability of the current approaches (the most sophisticated being based on crop models) is undermined by different sources of uncertainty. In particular, large area simulations can be affected by errors deriving from the uncertainty in input data (e.g., sowing dates, information on cultivar/hybrid grown, management practices) and upscaling assumptions, as well as from the incomplete adequacy of crop models to reproduce the effects of key factors affecting inter-annual yield fluctuations (e.g., extreme weather events, pests, diseases). The aim of this Ph.D. project was to reduce the uncertainty affecting the existing model-based forecasting systems through: (i) the implementation of approaches for the estimation of the impact of biotic and abiotic stressors on crop yields (based on dynamic models and on dedicated agro-climatic indicators), and (ii) the integration of remote sensing information within crop models. Concerning the first objective, the approaches for the simulation of transplanting shock and cold-induced spikelet sterility in rice included in Oryza2000 and WARM models, respectively, were improved, by increasing the model adherence to the underlying systems. Moreover, generic approaches for the simulation of the impacts of extreme weather events on crop yields were developed and evaluated, as well as approaches specific for sugarcane. For the second objective, remote sensing information was used to derive rice-cropped areas and sowing dates varying with time and space, as well as for the assimilation of exogenous leaf area index data using both recalibration and updating techniques (to account for factors not explicitly reproduced by the model within large-area applications). The application of the improved forecasting systems to different crops and agro-climatic contexts worldwide led to marked improvements compared to existing approaches. This was achieved through an increase in the percentage of inter-annual yield variability explained. On the one hand, the simulation of the impact of weather extremes (cold shocks, heat waves, water stress and frost) allowed to reduce the tendency of CGMS (the monitoring and forecasting system of the European Commission) to overestimate cereal yields in case of unfavorable seasons. Moreover, the integration of dynamic crop models and of agro-climatic indicators led to enhance the predicting capacity of available approaches. On the other hand, the integration of remote-sensing information within high resolution simulation chains allowed to decidedly reduce the uncertainty of the standard CGMS-WARM system when applied to the main European rice districts.

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23

Duzan, Haifa. "Nod factor recognition and response by soybean (Glycine max [L.] Merr) under abiotic and biotic stress conditions". Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84236.

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Plants possess highly sensitive perception systems by which they recognize signal compounds originating from microbes. These molecular cues play an important role in both symbiotic and pathogenic relationships. Establishment of the soybean (Glycine max)-Bradyrhizobium symbiosis is orchestrated by specific signal molecules exchanged between appropriate plant and microbe partners: flavonoids as plant-to-bacteria signals, and Nod factor as bacteria-to-plant signals. How this signaling process interacts with stress conditions (abiotic and biotic) is the subject of this thesis. The abiotic stresses were suboptimal growth temperature, low pH, and salinity. Suboptimal growth temperatures affected the ability of the microsymbiont, Bradyrhizobim japonicum, to perceive nod gene inducers (genistein) and produce Nod factor. Nod Bj-V (C18:1, MeFuc) production by B. japonicum strains 523C and USDA110 was strongly affected by suboptimal growth temperature. Nod factor production declined with temperature, from 28 to 15°C. Strain USDA110 was more affected by decreased temperature than strain 532C. Decreased Nod factor production at low temperature was due to both decreased bacterial growth and lower production efficiency (Nod factor per cell). When a 1:1 mixture of Nod factor Nod Bj-V (C18:1, MeFuc) and Nod Bj-V (Ac, C16:0, MeFuc) was applied to soybean roots, root hair deformation increased as Nod factor concentration increased under stressfully low temperature and low pH conditions. High salinity stress strongly reduced the root hair deformation caused by Nod factor, and increasing the concentrations of added Nod factor did not over come this. Exogenous application of Nod Bj-V (C18:1, MeFuc), from strain 532C, to soybean root systems under two root zone temperatures (RZTs---17 and 25°C) reduced the progression of disease (powdery mildew---Microsphaera difussa) development on soybean leaves; this effect increased with Nod factor concentration and was gr

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24

Hou, Shiji [Verfasser], Paul [Gutachter] Schulze-Lefert e Ute [Gutachter] Höcker. "Root microbiota functions in mitigating abiotic and biotic stresses in Arabidopsis / Shiji Hou ; Gutachter: Paul Schulze-Lefert, Ute Höcker". Köln : Universitäts- und Stadtbibliothek Köln, 2021. http://d-nb.info/1231992778/34.

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25

Reddy, Latha J. "Investigations in wheat (Triticum aestivum L. em Thell) using molecular and conventional breeding techniques for abiotic and biotic stress". Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/Spring2006/l%5Freddy%5F042106.pdf.

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26

Tank, Jennifer Leah. "Microbial activity on wood in streams : exploring abiotic and biotic factors affecting the structure and function of wood biofilms /". Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-06062008-144954/.

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27

Leufen, Georg [Verfasser]. "Sensing the response of sugar beet and spring barley to abiotic and biotic stresses with proximal fluorescence techniques / Georg Leufen". Bonn : Universitäts- und Landesbibliothek Bonn, 2016. http://d-nb.info/1095099078/34.

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28

Brosi, Glade Blythe. "THE RESPONSE OF TALL FESCUE AND ITS FUNGAL ENDOPHYTE TO CLIMATE CHANGE". UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_theses/126.

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Tall fescue is the most common cool-season grass in the eastern USA, with broad economic and ecological importance to the region. Tall fescue is known to associate with a fungal endophyte, Neotyphodium coenophialum, whose presence can decrease biotic and abiotic stress experienced by the plant. This thesis evaluates the response of tall fescue and the fungal endophyte symbiosis to predicted climate change. I participated in two multi-factor climate change projects where I investigated the response of tall fescue tissue chemistry and growth to various climate change factors. Endophyte-infected (E+) tall fescue had decreased alkaloid production under elevated CO2 but increased alkaloid production under elevated temperatures. Significant differences between E+ and E- (endophyte-free) tall fescue tissue chemistry were also found, suggesting the endophyte interacts with the plant response to abiotic stress. Although several studies have reported benefits of endophyte infection for tall fescue growing under drought stress, my research found no differences between E+ and E- total growth and surprisingly showed increased mortality of E+ individuals under elevated temperature. Taken together, my research indicates that this grass-fungal relationship will respond to climate change, and may produce dramatic and unforeseen results that question the widely believed mutualistic nature of the symbiosis.

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29

MASACHCHIGE, C. N. N. NANAYAKKARAWASAM. "STUDY OF THE EFFECT OF ABIOTIC AND BIOTIC STRESS ON THE GROWTH DEVELOPMENT AND SECONDARY METABOLISM OF MEDICINAL PLANT SPECIES". Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/168729.

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Achillea collina Becker ex Rchb., a medicinal plant rich in volatile compounds, was used to study the effects of biotic and abiotic stresses over plant growth and secondary metabolism. Biotic stress was induced by Myzus persiceae Sulzer and Macrosiphoniella millefolii (De Geer ), a generalist and specialist aphid species respectively. Abiotic stress was caused by mechanical damages provoked by a pin and a specially built equipment which apply a controlled and extended pressure to the plants. Plant growth and volatile compounds emissions were evaluated in the different experimental conditions analyzed. The effect of jasmonic acid on the plant volatile fingerprint was also evaluated. The volatile emission patterns obtained in the different conditions were compared in order to have suggestions regarding the metabolic pathways activated in each situation. Furthermore pea (Pisum sativum L.) and peach (Prunus persica L. Batsch) volatile fingerprints due to M. persicae infestation were analyzed and compared to those obtained from A. collina. The comparison of the results lead to the identification of volatile compounds induced only by the aphids in all the plant species studied, suggesting the activation of a common metabolic pathway due to infestation. Preliminary molecular approach seems to confirm pytochemical data.

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30

Chang, Christine Chi-Chen. "Mechanisms and genes controlling the signalling network for biotic and abiotic stress defences in Arabidopsis thaliana (L.) Heyhn : Functional cross-talk between photo-produced reactive oxygen species, photosynthesis and plant disease defence responses". Doctoral thesis, Stockholm : Department of Botany, Stockholm University, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-418.

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31

Fantaye, Chalie Assefa Verfasser], Jonathan [Akademischer Betreuer] [Gershenzon, Ralf [Akademischer Betreuer] Oelmüller e Ted [Akademischer Betreuer] Turlings. "The roles of plant sesquiterpenes in defense against biotic and abiotic stresses / Chalie Assefa Fantaye. Gutachter: Jonathan Gershenzon ; Ralf Oelmüller ; Ted Turlings". Jena : Thüringer Universitäts- und Landesbibliothek Jena, 2014. http://d-nb.info/1062536177/34.

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32

Fantaye, Chalie Assefa [Verfasser], Jonathan [Akademischer Betreuer] Gershenzon, Ralf [Akademischer Betreuer] Oelmüller e Ted [Akademischer Betreuer] Turlings. "The roles of plant sesquiterpenes in defense against biotic and abiotic stresses / Chalie Assefa Fantaye. Gutachter: Jonathan Gershenzon ; Ralf Oelmüller ; Ted Turlings". Jena : Thüringer Universitäts- und Landesbibliothek Jena, 2014. http://d-nb.info/1062536177/34.

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33

Unver, Turgay. "Detection And Characterization Of Plant Genes Involved In Various Biotic And Abiotic Stress Conditions Using Ddrt-pcr And Isolation Of Interacting Proteins". Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609805/index.pdf.

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The main objective of this thesis dissertation is functionally characterizing the genes involved in biotic and abiotic stresses of plants at molecular level. Previously, upon pathogen attack Rad6 gene expression was found to be changed in wheat and barley plants. To functionally characterize the Rad6 gene, VIGS (Virus induced gene silencing) system was used. HR (Hypersensitive response) like symptoms was detected in every silenced barley and wheat plants. To figure out, transcriptomes and proteomes of Rad6 silenced plants were analyzed. 2-D PAGE analysis was also performed on silenced and control wheat plants. No pathogen growth was observed in Rad6 silenced barley lines. Additionally, the susceptible wild type Arabidopsis plants showed resistant phenotype when any of the Rad6 gene copies is mutated. This suggests that Rad6 gene has a negative regulatory role in plant disease resistance which was proved for the first time. Yeast two hybrid protein interaction study suggests that RAD6 carrying out its function by interacting with SGT1 protein and regulating resistance related genes. It has been first time reported in this thesis that E2 (Ubiquitin conjugating enzyme) takes role in plant disease resistance. Boron which is the other consideration in the scope of thesis as an abiotic stress factor at a very limited amount is necessary for the normal development of plants. This study is conducted on highly boron tolerant Gypsophila perfoliata L. collected from a location in the boron mining area. The plant samples were tested in the presence of high boron (35 mg/kg) concentrations. The transcriptomes of the plant samples treated with the excess levels of boron to that of the samples grown under normal concentration were compared using differential display PCR method. Thirty bands showing differential expression levels at varying time points were analyzed. 18 of them were confirmed via qRT-PCR.

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34

Jacobson, Douglas Keith. "Deficient, Adequate and Excess Nitrogen, Phosphorus, and Potassium Growth Curves Established in Hydroponics for Biotic and Abiotic Stress-Interaction Studies in Lettuce". BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/5986.

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Mineral nutrients have marked effects on plant health by providing the building blocks for plant growth, as well as for mitigating abiotic and biotic stress factors, particularly disease development. Even if mineral nutrition field studies are conducted to study pest management, they are at the mercy of complex soil, water, and climatic conditions not amenable to strict experimental control. Therefore, a hydroponic method of growing lettuce was developed and growth curves were established for the macronutrients nitrogen (N), phosphorus (P), and potassium (K). Lettuce plants were grown at varying levels of each nutrient: 2.5, 5, 10, 20, 40, 80, 160, and 320 mg N/L; 0.5, 1, 2, 4, 8, 16, 32 and 64 mg P/L; and 0, 2.5, 5, 10, 20, 40, 80 and 160 mg K/L. Due to inadequate results lettuce was grown again at 0, 10, 20, 40, 80, 160, 320 and 640 mg L K. Optimal levels of N, P, and K were 160 mg/L, 4.0 mg/L, and 80 mg/L respectively. C:N ratios were also looked at for the N experiment. The overall result was consistent with results from similar studies. Unlike similar hydroponic studies done with other plants, micronutrient levels did not become deficient at high phosphorus levels suggesting phosphorus toxicity. These growth curves can be used to test lettuce resilience to various biotic and abiotic stresses.

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35

Paleari, L. "IN SILICO IDEOTYPING: DEFINITION AND EVALUATION OF RICE IDEOTYPES IMPROVED FOR RESISTANCE/TOLERANCE TRAITS TO BIOTIC AND ABIOTIC STRESSORS UNDER CLIMATE CHANGE SCENARIOS". Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/483333.

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The development of new cultivars better adapted to specific growing conditions is a key strategy to meet an ever-increasing growing global food demand and search for more sustainable cropping systems. This is even more crucial in the context of a changing climate. Ecophysiological models and advanced computational techniques (e.g., sensitivity analysis, SA) represent powerful tools to analyze genotype (G) by environment (E) interactions, thus supporting breeders in identifying key traits for specific agro-environmental contexts. However, limits for the effective use of mathematical models within breeding programs are represented by the uncertainty in the distribution of plant trait values, the lack of processes dealing with resistance/tolerance traits in most ideotyping studies, the partial suitability of current crop models for ideotyping purposes, and the absence of modelling tools directly usable by breeders. The aim of this research was to address these issues improving methodologies already in use, proposing new paradigms for the development of crop models explicitly targeting ideotyping applications and developing tools that would encourage a deep interaction of the modelling and breeding communities. The focus was on rice, for its role as staple food for more than a half of world’s population, and on resistance/tolerance traits to biotic/abiotic stressors, for their central role in increasing crop adaptation. Moreover, current conditions and climate change projections were considered, to support the definition of strategies for breeding in the medium-long term. A standard procedure to quantify − and manage − the impact of the uncertainty in the distribution of plant trait values was developed, using the WARM rice model and the Sobol’ method as case study. The approach is based on a SA (generating sample of parameter distributions) of a SA (generating samples of parameters for each generated distribution) using distributions of jackknife statistics calculated on literature values to reproduce the uncertainty in defining parameters distributions. As a practical implication, the procedure developed allows identifying plant traits whose uncertainty in distribution can alter ideotyping results, i.e., traits whose distributions could need to be refined. Global SA was then used to identify rice traits putatively producing the largest yield benefits in five contrasting districts in the Philippines, India, China, Japan and Italy. The analysis involved phenotypic traits dealing with light interception, photosynthetic efficiency, tolerance to abiotic stressors, resistance to fungal pathogens and grain quality. Results suggested that breeding for traits involved with disease resistance and tolerance to cold- and heat-induced spikelet sterility could provide benefits similar to those obtained from improving traits affecting potential yield. Instead, advantages resulting from varying traits involved with grain quality were markedly frustrated by inter-annual weather variability. Since results highlighted strong G×E interactions, a new index to derive district-specific ideotypes was developed. Given the key role of biotic/abiotic stressors in determining actual yield and the deep impact of related G×E interactions, a study was carried out by explicitly focusing on the definition of rice ideotypes improved for their resistance to fungal pathogens and tolerance to abiotic constraints (temperature shocks inducing sterility). The analysis was carried out at district level with a high spatial resolution (5 km × 5 km elementary simulation unit), targeting the improvement of the most representative 34 varieties in six Italian rice districts. Genetic improvement was simulated via the introgression of traits from donor varieties. Results clearly showed that breeders should focus on increasing resistance to blast disease, as this appears as a factor markedly limiting rice yields in Italy, regardless of the districts and climate scenarios, whereas benefits deriving from improving tolerance to cold-induced sterility could be markedly affected by G×E interactions. To reduce the risk of discrepancies between in silico ideotypes and their in vivo realizations, both studies involved only model parameters with a close relationship with phenotypic traits breeders are working on. However, a long-term strategy to overcome limitations related with the partial suitability of available models would be building new ideotyping-specific models explicitly around traits involved in breeding programs. This proposal for a paradigm shift in model development was illustrated taking salt stress tolerance and rice as a case study. Dedicated growth chamber experiments were conducted to develop a new model explicitly accounting for tolerance traits modulating Na+ uptake and distribution in plant tissues, as well as the impact of the accumulated Na+ on photosynthesis, senescence and spikelet sterility. An ideotyping study was conducted at two sites (in Greece and California) characterized by different seasonal dynamics of salinity in field water. Results showed how, under different scenarios, traits assuring the largest contribution to the overall tolerance could refer to completely different physiological mechanisms: tissue tolerance in one case, sodium exclusion in the other. This encourages the development of explicit trait-based approaches to increase the integration of crop models within breeding programs. A parallel path to achieve this goal is the development of modelling platforms targeting breeders as final users, who does not have necessarily in-depth skills in crop modelling and IT. The platform ISIde, derived from a close collaboration between target users, biophysical modelers and IT specialists, represents the first prototype of a platform specifically developed for being used directly by breeders to evaluate in silico improved varieties at district level. This thesis demonstrated the usefulness of simulation models for the definition of ideotypes for specific agro-environmental conditions. Targeting ideotyping applications, new methodologies, paradigms for model development and modelling tools were developed, thus contributing to improve the potential of crop modelling to support breeding programs. Future developments will target researches aimed at overcoming the limits behind this study, i.e., (i) absence of explicit interactions between traits, (ii) no adaptation strategies considered, and (iii) lack of approaches for the simulation of the evolutionary potential of pathogens in response to long-term climate variations and increased host resistance.

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36

Paull, Rachel May. "Evaluating the Role of Biotic and Abiotic Ecosystem Components on the Retention and Removal of Ditch Nutrients in Ditches of Different Construction". Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1594220539737151.

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37

Fernández, Crespo Emma. "Estudio integral de los mecanismos de resistencia inducida. Inductores frente a estrés biótico y abiótico". Doctoral thesis, Universitat Jaume I, 2016. http://hdl.handle.net/10803/398704.

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En este trabajo se ha demostrado que el NH4+ actúa como inductor de resistencia frente a estrés salino en cítricos, observándose acumulación de ABA, poliaminas (PAs), H2O2 y prolina. También se ha demostrado que plantas de tomate crecidas con NH4+ muestran una reducción de los síntomas de la enfermedad producida por Pst. El estudio del modo de acción de la NH4+-IR reveló que los mecanismos inducidos en las plantas en respuesta a NH4+, tales como la acumulación de ABA, PAs y H2O2 son clave para la inducción de aclimatación sistémica adquirida (SAA) que confiere a las plantas de tomate resistencia frente a Pst. Por último, se ha demostrado que el virus MNSV induce en plantas de melón una compleja red hormonal de respuesta, así como la acumulación de calosa y ROS. El Hx resultó ser efectivo como inductor de resistencia frente a virus evitando el paso del virus al floema.
In this work, we reveal that NH4+ nutrition in citrange Carrizo plants acts as an inducer of resistance against salinity conditions. We investigated its mode of action and provide evidence that NH4+ confers resistance by priming abscisic acid and polyamines, just as enhancing H2O2 and proline basal content. Moreover, we demonstrated the NH4+ nutrition induces-resistance (NH4+-IR) against Pseudomonas syringae pv tomato DC3000 (Pst) in tomato plants. N-NH4+ plants displayed basal H2O2, abscisic acid (ABA) and putrescine (Put) accumulation. H2O2 accumulation acted as a signal to induce ABA-dependent signalling pathways required to prevent NH4+ toxicity. This acclimatory event provoked an increase of resistance against later pathogen infection. We studied the basal response of melon (Cucumis melo) to Melon necrotic spot virus (MNSV) and demonstrated the efficacy of the hexanoic acid priming that blocks the virus systemic spread. We analyzed callose deposition and ROS production, as well as the hormonal profile and gene expression at the whole-plant level.

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38

Kerner, René [Verfasser], Gerhard [Akademischer Betreuer] Müller-Starck e Rainer [Akademischer Betreuer] Matyssek. "Analysis of protein abundances in Fagus sylvatica L. and Cenococcum geophilum Fr. following biotic and abiotic stresses / René Kerner. Gutachter: Rainer Matyssek. Betreuer: Gerhard Müller-Starck". München : Universitätsbibliothek der TU München, 2012. http://d-nb.info/1020706554/34.

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39

Perrineau, Francois Clement [Verfasser], e Sabine [Akademischer Betreuer] Lüthje. "Regulation of class III peroxidases and respiratory burst oxidase homologs by biotic and abiotic stress in maize (Zea mays L.) / Francois Clement Perrineau ; Betreuer: Sabine Lüthje". Hamburg : Staats- und Universitätsbibliothek Hamburg, 2019. http://d-nb.info/119081899X/34.

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40

Perrineau, Francois Clement Verfasser], e Sabine [Akademischer Betreuer] [Lüthje. "Regulation of class III peroxidases and respiratory burst oxidase homologs by biotic and abiotic stress in maize (Zea mays L.) / Francois Clement Perrineau ; Betreuer: Sabine Lüthje". Hamburg : Staats- und Universitätsbibliothek Hamburg, 2019. http://d-nb.info/119081899X/34.

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41

Chiteri, Kevin Oyale. "Functional & Phylogenetic Analysis of Arabidopsis thaliana Organic Cation Transporters (OCT5 & OCT1) Genes in Polyamine Transport in Plants". Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1563038129138996.

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42

Castro-Alves, Victor Costa. "O efeito da proximidade do fragmento florestal de Mata Atlântica sobre a área de cultivo no amadurecimento de bananas (Musa acuminata AAA cv. Nanicão) e nos compostos fenólicos das folhas de bananeiras". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/9/9131/tde-20032014-151022/.

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Considerando (1) a importância da bananicultura no Vale do Ribeira, (2) o destaque da Mata Atlântica no contexto da conservação da fauna e flora mundial, (3) a necessidade da adoção de práticas agrícolas alternativas mais eficientes do ponto de vista ambiental e econômico, (4) o papel dos hormônios etileno, acido indol-3-acético (AIA) e ácido abscísico (ABA) no contexto das respostas dos vegetais a diferentes condições ambientais e nos atributos de qualidade da banana, (5) a falta de metodologias otimizadas para a extração de compostos fenólicos solúveis totais (CFST) em bananeiras e (6) a importância do estudo da relação entre os CFST e fatores de estresse, o presente trabalho teve como objetivo avaliar a influência da proximidade do fragmento florestal de Mata Atlântica com a área de cultivo da banana (Musa acuminata AAA cv. Nanicão) sobre o amadurecimento da fruta e os CFST em folhas de bananeiras, além de otimizar uma técnica para a extração destes últimos. Foi observado que bananas colhidas próxima ao fragmento florestal apresentam vida-verde (período compreendido entre a colheita do fruto e o início do seu amadurecimento) maior quando comparados a frutos com a mesma idade fisiológica, porém colhidos em áreas sem a influência da floresta nativa. Este fato pode ser explicado, pelo menos em parte, pela diferença nos perfis de etileno, ABA e AIA ao longo do amadurecimento das bananas provenientes das diferentes áreas, que também influenciam no metabolismo amido-sacarose. Quanto aos CFST nas folhas, foi observado que a utilização de acetona 80% em água (v/v) e posterior emprego de hexano para a remoção do excesso de clorofilas é capaz de obter um bom rendimento de extração de CFST, sem extrair compostos que interferem significativamente no método de Folin-Ciocalteu. Além disso, a utilização da metodologia otimizada mostrou que bananeiras podem apresentar diferenças na sua composição de fenólicos quando influenciadas ou não pela presença de biodiversidade. Assim, a avaliação dos CFST em folhas pode fornecer informações importantes sobre as condições ambientais da planta.
Considering (1) the importance of banana production in Ribeira Valley, (2) the Atlantic Rainforest in the context of fauna and flora conservation, (3) the need for the adoption of more sustainable agricultural practices, (4) the ethylene, indole 3-acetic acid and abscisic acid responses in acclimation mechanisms of plants and in the quality attributes of the banana, (5) the lack of methodologies optimized for the extraction of total soluble phenolics compounds (TSPC) in banana leaves and (6) the importance of the relationship between the TSPC content and stress factors, the present work aimed to evaluate the influence of the Atlantic Forest fragments proximity in the banana (Musa acuminata AAA cv. Nanicão) crop area on fruit ripening and leaves TSPC levels, using a optimized methodology. It was observed that bananas harvested near to the forest fragment presented a longest greenlife (period between the harvest and the climacteric) when compared with the fruits with the same phisiologycal age, but without the influence of the native forest. This fact can be explained, at least partly, by the difference on ethylene, ABA and IAA profiles in the ripening of bananas from the different areas, which also influence the starch-sucrose metabolism. Moreover, it was observed that the extraction with acetone (80% v/v in water) and posterior hexane cycle to remove chlorophylls excess was able to obtain a good TSPC extraction yield in leaves, without extracting compounds that interfere significantly with Folin-Ciocalteu method. In additional, the use of optimized methodology showed that bananas leaves can present different TSPC amount when influenced by the presence of native forest. Thus, the evaluation of leaves TSPC profile can provide important information about the environmental conditions of the plant.

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43

Bürling, Kathrin [Verfasser]. "Potential of fluorescence techniques with special reference to fluorescence lifetime determination for sensing and differentiating biotic and abiotic stresses in Triticum aestivum L. / Kathrin Bürling. Landwirtschaftliche Fakultät". Bonn : Universitäts- und Landesbibliothek Bonn, 2011. http://d-nb.info/1016599897/34.

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44

Mateo, Alfonso. "Roles of LESIONS SIMULATING DISEASE1 and Salicylic Acid in Acclimation of Plants to Environmental Cues : Redox Homeostasis and physiological processes underlying plants responses to biotic and abiotic challenges". Doctoral thesis, Stockholm University, Department of Botany, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-698.

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In the natural environment plants are confronted to a multitude of biotic and abiotic stress factors that must be perceived, transduced, integrated and signaled in order to achieve a successful acclimation that will secure survival and reproduction. Plants have to deal with excess excitation energy (EEE) when the amount of absorbed light energy is exceeding that needed for photosynthetic CO2 assimilation. EEE results in ROS formation and can be enhanced in low light intensities by changes in other environmental factors.

The lesions simulating disease resistance (lsd1) mutant of Arabidopsis spontaneously initiates spreading lesions paralleled by ROS production in long day photoperiod and after application of salicylic acid (SA) and SA-analogues that trigger systemic acquired resistance (SAR). Moreover, the mutant fails to limit the boundaries of hypersensitive cell death (HR) after avirulent pathogen infection giving rise to the runaway cell death (rcd) phenotype. This ROS-dependent phenotype pointed towards a putative involvement of the ROS produced during photosynthesis in the initiation and spreading of the lesions.

We report here that the rcd has a ROS-concentration dependent phenotype and that the light-triggered rcd is depending on the redox-state of the PQ pool in the chloroplast. Moreover, the lower stomatal conductance and catalase activity in the mutant suggested LSD1 was required for optimal gas exchange and ROS scavenging during EEE. Through this regulation, LSD1 can influence the effectiveness of photorespiration in dissipating EEE. Moreover, low and high SA levels are strictly correlated to lower and higher foliar H2O2 content, respectively. This implies an essential role of SA in regulating the redox homeostasis of the cell and suggests that SA could trigger rcd in lsd1 by inducing H2O2 production.

LSD1 has been postulated to be a negative regulator of cell death acting as a ROS rheostat. Above a certain threshold, the pro-death pathway would operate leading to PCD. Our data suggest that LSD1 may be subjected to a turnover, enhanced in an oxidizing milieu and slowed down in a reducing environment that could reflect this ROS rheostat property. Finally, the two protein disulphide isomerase boxes (CGHC) present in the protein and the down regulation of the NADPH thioredoxin reductase (NTR) in the mutant connect the rcd to a putative impairment in the reduction of the cytosolic thioredoxin system. We propose that LSD1 suppresses the cell death processes through its control of the oxidation-reduction state of the TRX pool. An integrated model considers the role of LSD1 in both light acclimatory processes and in restricting pathogen-induced cell death.

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45

Hettenhausen, Christian [Verfasser], Ian T. [Akademischer Betreuer] Baldwin, Ralf [Akademischer Betreuer] Oelmüller e Tina [Akademischer Betreuer] Romeis. "Mitogen-activated protein kinase 4 (MPK4) functions in development and resistance to biotic and abiotic stresses in Nicotiana attenuata / Christian Hettenhausen. Gutachter: Ian T. Baldwin ; Ralf Oelmüller ; Tina Romeis". Jena : Thüringer Universitäts- und Landesbibliothek Jena, 2012. http://d-nb.info/1021921246/34.

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46

Adam, Muhammed Saleem. "A knowledgebase of stress reponsive gene regulatory elements in arabidopsis Thaliana". Thesis, University of the Western Cape, 2011. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_9599_1362393100.

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Stress responsive genes play a key role in shaping the manner in which plants process and respond to environmental stress. Their gene products are linked to DNA transcription and its consequent translation into a response product. However, whilst these genes play a significant role in manufacturing responses to stressful stimuli, transcription factors coordinate access to these genes, specifically by accessing a gene&rsquo
s promoter region which houses transcription factor binding sites. Here transcriptional elements play a key role in mediating responses to environmental stress where each transcription factor binding site may constitute a potential response to a stress signal. Arabidopsis thaliana, a model organism, can be used to identify the mechanism of how transcription factors shape a plant&rsquo
s survival in a stressful environment. Whilst there are numerous plant stress research groups, globally there is a shortage of publicly available stress responsive gene databases. In addition a number of previous databases such as the Generation Challenge Programme&rsquo
s comparative plant stressresponsive gene catalogue, Stresslink and DRASTIC have become defunct whilst others have stagnated. There is currently a single Arabidopsis thaliana stress response database called STIFDB which was launched in 2008 and only covers abiotic stresses as handled by major abiotic stress responsive transcription factor families. Its data was sourced from microarray expression databases, contains numerous omissions as well as numerous erroneous entries and has not been updated since its inception.The Dragon Arabidopsis Stress Transcription Factor database (DASTF) was developed in response to the current lack of stress response gene resources. A total of 2333 entries were downloaded from SWISSPROT, manually curated and imported into DASTF. The entries represent 424 transcription factor families. Each entry has a corresponding SWISSPROT, ENTREZ GENBANK and TAIR accession number. The 5&rsquo
untranslated regions (UTR) of 417 families were scanned against TRANSFAC&rsquo
s binding site catalogue to identify binding sites. The relational database consists of two tables, namely a transcription factor table and a transcription factor family table called DASTF_TF and TF_Family respectively. Using a two-tier client-server architecture, a webserver was built with PHP, APACHE and MYSQL and the data was loaded into these tables with a PYTHON script. The DASTF database contains 60 entries which correspond to biotic stress and 167 correspond to abiotic stress while 2106 respond to biotic and/or abiotic stress. Users can search the database using text, family, chromosome and stress type search options. Online tools have been integrated into the DASTF
database, such as HMMER, CLUSTALW, BLAST and HYDROCALCULATOR. User&rsquo
s can upload sequences to identify which transcription factor family their sequences belong to by using HMMER. The website can be accessed at http://apps.sanbi.ac.za/dastf/ and two updates per year are envisaged.

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47

Kancharla, Jahnavi Reddy. "Generation of Transgenic Medicago Sativa Overexpressing "Osmotin-Chitinase" Gene Chimera". TopSCHOLAR®, 2011. http://digitalcommons.wku.edu/theses/246.

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Medicago is widely used as a forage crop. It is often susceptible to various pathogenic infections and exhibits low growth in drought and extreme climatic conditions. In the current study, a strategy was developed for over-expressing an “Osmotin-Chitinase” gene chimera in transgenic Medicago that could potentially confer resistance to different biotic and abiotic stresses. Seed germination of several cultivars of Medicago (M. sativa ssp. sativa, M. sativa ssp. falcata, M. sativa ssp. caerulea, M. truncatula, and M. Rugosa) was tested to determine the cultivars with good germination rates. Among these, M. sativa ssp. sativa showed an average of 80% germination over a period of one week and was subsequently selected for regeneration and transformation experiments. Different explants (cotyledons, hypocotyls, petioles) were tested for regeneration. Among these, hypocotyl explants showed highest (46.17 %) percent regeneration. Escherichia coli harboring Osmotin-Chitinase (OSM-CHI) gene chimera cloned into binary vector pBTEX with nptII as a selection marker was mobilized in Agrobacterium tumefaciens strain EHA105 which was employed in the transformation of hypocotyl explants of Medicago. Transformed calli were grown on callus inducing medium containing kanamycin for screening. Further screening of the positive transgenics was performed using PCR. Southern hybridization was carried out for further confirmation of successful transformation. Transformed shoots will be grown on the root inducing medium for developing into plantlets which would then be transferred to the green house and later tested for their degree of resistance to various biotic and abiotic stresses.

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48

Berenguer, Helder Duarte Paixão. "Eucalyptus predisposition to Neofusicoccum kwambonambiense under water stress". Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/22330.

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Mestrado em Biologia Molecular e Celular
In Portugal, Eucalyptus, particularly Eucalyptus globulus, occupies more than 800 000 ha and, due to being a major source of biomass for fiberboard, industrial charcoal, fuel wood and paper pulp, has become a key genus, with a considerable economic importance. However, E. globulus productivity faces new pressures, with climate change-driven drought as one of the most hostile ones. Drought can lead to growth impairment and yield reduction: directly; or indirectly, through the increase of plant susceptibility to pathogens by a predisposition mechanism. Neofusicoccum kwambonambiense is an endophytic opportunist phytopathogen known to severely affect E. globulus, whose incidence has already been reported in Portugal. Taking all in consideration, it is of major importance to assess the predisposition effect that drought may have on the N. kwambonambiense - E. globulus interaction. For such purpose, four treatment groups were established: E. globulus were firstly subjected to a 66-days acclimation period in which plants were periodically watered (80% of field capacity). After that, two groups were exposed to a progressive water supply restriction. The other two remained well-watered. Once water-stressed plants achieved 18% of field capacity (23 days), a well-watered and a water-stress group were inoculated with N. kwambonambiense. All treatments were kept in these conditions throughout a 65 days’ period, at which moment a set of morphological, physiological and biochemical parameters was obtained. Well-watered plants, despite being infected with N. kwambonambiense, presented an overall photosynthetic increase, which enabled plant defense through the production of sugars, proline and salicylic acid. Oxidative damages (partially observed through malondialdehyde content), were avoided in part due to proline and soluble sugars. Water stress lead to a direct growth impairment confirmed through an indole-acetic-acid content decrease. A water-potential reduction occurred, which, together with abscisic acid, lead to stomatal closure and overall photosynthetic efficiency decline. Oxidative damages weren’t properly managed and further affected E. globulus. Furthermore, N. kwambonambiense was found to promote a jasmonic acid content increase, typical of necrotrophic pathogens, which may suggest a lifestyle change from hemibiotrophic to necrotrophic as plant cells progressively degenerate. Ultimately, water-stressed E. globulus presented larger external lesion extensions and steam cankers and a superior internal fungi progression. Our results conclusively demonstrate that water stress created a better substrate for fungi development and decreased the plant’s ability to respond. Such resulted in higher susceptibility and disease severity confirming predisposition.
Em Portugal, o eucalipto, particularmente o Eucalyptus globulus, ocupa mais de 800 000 ha. Devido a ser uma importante fonte de biomassa para painéis de fibras, carvão industrial, lenha e pasta de papel, tornou-se um género chave de considerável importância económica. Contudo, a produtividade de E. globulus tem encontrado novas pressões, sendo a seca resultante das alterações climáticas, uma das mais hostis. A seca pode levar a uma diminuição do crescimento e produtividade: diretamente; ou indiretamente através do aumento da suscetibilidade a agentes patogénicos através da predisposição. O fungo ascomiceto Neofusicoccum kwambonambiense é um agente fitopatogénico endofítico oportunista que se sabe afetar severamente E. globulus, e cuja presença já fora confirmada em Portugal. Tomando tal em consideração, torna-se importante avaliar o efeito de predisposição que a seca poderá ter na interação N. kwambonambiense - E. globulus. Para tal foram criados quatro grupos de tratamento: E. globulus foram primeiramente sujeitos a um período de aclimatização de 66 dias no qual foram periodicamente irrigados (80% de capacidade de campo). Seguidamente, dois grupos foram sujeitos a uma diminuição progressiva da irrigação. Os outros dois grupos permaneceram bem regados. Uma vez que os tratamentos stressados atingiram 18% de capacidade de campo (23 dias), um grupo bem regado e um grupo stressado foram inoculados com N. kwambonambiense. Todas os tratamentos foram mantidos nestas condições durante um período de 66 dias, findo o qual foi obtido um conjunto de parâmetros morfológicos, fisiológicos e bioquímicos. As plantas bem regadas, apesar de terem sido inoculadas com N. kwambonambiense apresentaram um aumento dos parâmetros fotossintéticos o que terá permitido a defesa da planta através de uma produção amplificada de açúcares, prolina e ácido salicílico. Danos oxidativos (parcialmente observados através do conteúdo em malondialdeído) foram evitados, em parte, devido à ação da prolina e açúcares solúveis. O stress hídrico levou a uma diminuição do crescimento confirmado pela redução do conteúdo em ácido-indole-acético. Ocorreu uma diminuição do potencial hídrico, a qual, em conjunto com o aumento do ácido abscísico, levou ao fecho dos estomas e diminuição da fotossíntese. Os danos oxidativos não foram controlados, afetando o estado do E. globulus. Ademais, o N. kwambonambiense provocou um aumento do conteúdo em ácido jasmónico, típico de agentes patogénicos necrotróficos, o que poderá sugerir que o fungo passou de um estilo de vida hemibiotrófico para necrotrófico, à medida que as células degeneravam. Os E. globulus stressados apresentavam maiores lesões externas e cancros, conjuntamente com uma maior progressão interna do fungo. Os nossos resultados comprovam que a seca criou um melhor substrato para o desenvolvimento do fungo e diminuiu a capacidade de resposta da planta. Tal resultou num aumento da suscetibilidade e severidade da doença confirmando a predisposição.

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49

De, Bont Linda. "Importance de l'homéostasie du NAD dans la productivité et la résistance aux stress chez Arabidospis thaliana". Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112283.

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Le développement et le fonctionnement harmonieux des plantes dépendentde cofacteurscomme le nicotinamide adénine dinucléotide (NAD). Outre ses rôles dansle recyclage rédox,le NAD est aussi impliqué dans des processus de signalisationcellulaire, particulièrementsollicités en situation de stress. Cela fait du NAD l’un desdéterminants majeurs del’homéostasie énergétique des plantes et donc des rendements descultures. Par uneapproche de génétique inverse ciblant la L-aspartate oxydase (AO),première enzyme de lavoie de biosynthèse du NAD, nous avons obtenu des plantes aux teneursconstitutivementaugmentées et diminuées en nucléotides à pyridine. L’étude de cesplantes a permisd’établir que (1) le NAD stimule la croissance, le développement et laproductivité desplantes, (2) coordonne les métabolismes photosynthétique, respiratoireet azoté, et (3)intervient dans les mécanismes de résistance aux stress biotiques etabiotiques. Les travauxcités ci-dessus font l’objet d’une valorisation industrielle
The harmonious development and functioning of plants depend on severalcofactors such asnicotinamide adenine dinucleotide. Besides its roles in redox recycling,the NAD is alsoinvolved in cellular signalling processes, which are central actors instress situations. TheNAD is thus one of the main determinants of plant energy homeostasis,and therefore of cropyield. Through a reverse genetics approach targeting the L-aspartateoxidase (AO) – the firstcommitted enzyme of NAD biosynthesis – plants with constitutive eitherincreased ordecreased levels of pyridine nucleotides have been obtained. A furtherstudy of these plantsenabled to show that the NAD (1) can improve the growth, development andproductivity ofplants, (2) coordinates photosynthetic, respiratory and nitrogenmetabolisms, and (3) actsupon biotic and abiotic stress resistance mechanisms. This research isbeing valuedindustrially

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Felicio, Mariane Silva. "Estudo de associação genômica ampla aplicada ao conteúdo de macronutrientes em grãos de Coffea arabica L". Botucatu, 2020. http://hdl.handle.net/11449/192701.

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Abstract (sommario):

Orientador: Douglas Silva Domingues
Resumo: O café é uma das commodities agrícolas tropicais mais comercializadas no mundo. Coffea arabica é a principal espécie utilizada para a produção comercial de café. A espécie é originária da Etiópia. Ela é única espécie alotetraploide do gênero (2n = 4x = 44) e se reproduz predominantemente por autofecundação. As cultivares comerciais de C. arabica possuem baixa diversidade genética, o que indica a necessidade de introgressão de alelos de germoplasma para o melhoramento dessas cultivares. Acessos do centro de origem da espécie possuem maior diversidade que as cultivares comerciais e podem ser utilizados para a identificação de novos alelos. O conteúdo de macronutrientes em grãos do cafeeiro tem impacto direto na qualidade do produto. No entanto, a base molecular da composição mineral de grãos de cafeeiro ainda é pouco conhecida. Com isso, o objetivo desse trabalho foi identificar marcadores SNP possivelmente associados com a composição de macronutrientes em grãos de C. arabica. Para alcance deste objetivo, foram comparados três métodos de imputação de genótipos, bem como foi realizado o mapeamento associativo em estudo de associação genômica ampla (GWAS). Foi utilizado um painel de 110 genótipos de C. arabica, composto por genótipos elite do programa de melhoramento do Instituto Agronômico do Paraná (3), cultivares comerciais (11) e acessos selvagens (96). Foram realizadas análises da composição de cinco macronutrientes (N, P, K, Ca e Mg) em grãos de cafeeiro coletados de 70 e 1... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Coffee is one of the most traded tropical commodities in the world. Coffea arabica is the main species used for commercial production. The species is originally from Ethiopia. In the Coffea genus, C. arabica is the only allotetraploid species (2n = 4x = 44) and it reproduces predominantly by self-fertilization. The commercial cultivars of C. arabica have a narrow genetic base that indicates the need for the introgression of new alleles from germplasm into coffee breeding programs. Wild accessions of C. arabica, from Ethiopia, have higher genetic diversity and can be used to identify new alleles. The macronutrient composition of the coffee grains has a direct impact on grain quality. However, the molecular basis for the mineral composition in coffee grains still poorly understood. Thus, the aim of this work was to perform mapping association analyses using the genome-wide association study (GWAS) technique to identify single nucleotide polymorphisms (SNPs) associated with macronutrient content in coffee grains from C. arabica. We also tested three imputation methods (haplotype missing allele imputation - Beagle, K-nearest neighbors, and Random Forest) in the genotypic data, and mapped it to two C. arabica reference genomes from the cultivar Caturra red and the spontaneous dihaploid Et39. We used a panel of 110 C. arabica genotypes, including elite landraces from the IAPAR coffee breeding program (3), commercial cultivars (11) and wild accessions (96). Analysis of the compositi... (Complete abstract click electronic access below)
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