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Articoli di riviste sul tema "Synthetic auxins"
1
Moncada, Alessandra, Filippo Vetrano, Alessandro Esposito, and Alessandro Miceli. "Effects of NAA and Ecklonia maxima Extracts on Lettuce and Tomato Transplant Production." Agronomy 12, no. 2 (2022): 329. http://dx.doi.org/10.3390/agronomy12020329.
Testo completoAbstract (sommario):
Ecklonia maxima and the commercial biostimulants produced from it contain various plant growth regulators that are responsible for the growth stimulation recorded in many crops. Auxins are one of the major plant growth regulators contained in E. maxima extracts. The aim of this research was to evaluate the growth-promoting effect of a seaweed extract from E. maxima on lettuce and tomato transplant production under nursery conditions, and to compare the effect of this extract with an equal concentration of synthetic auxin. Two doses of natural or synthetic exogenous auxins (50 or 100 μg L−1) were supplied to the substrate through the irrigation water with an ebb and flow system, 4, 11, and 18 days after sowing. A commercial biostimulant based on E. maxima extract was used as a source of natural auxin, while 1-naphthaleneacetic acid (NAA) was used as a synthetic auxin. Seedlings supplied only with water were used as a control. Tomato seedlings treated with 100 μg L−1 of natural auxins from E. maxima extract produced the tallest plants (+22%), with a higher leaf number (+12%), a wider leaf area (+44%), and a stronger stem (+12%), whereas lettuce seedling growth was promoted by all the treatments, but with a greater effect with increasing auxin supplementation and when using E. maxima extract, compared to NAA. The results showed that the supplementation of exogenous synthetic auxin (NAA), or an E. maxima extract containing natural auxins, can have a growth-promoting effect on lettuce and tomato seedlings. This effect was more evident on lettuce than tomato. The biostimulant produced from E. maxima extracts improved seedling quality and promoted shoot and root growth more than the NAA used as a synthetic source of auxins.
2
Prieto-Martínez, Fernando D., Jennifer Mendoza-Cañas, and Karina Martínez-Mayorga. "To Bind or Not to Bind? A Comprehensive Characterization of TIR1 and Auxins Using Consensus In Silico Approaches." Computation 12, no. 5 (2024): 94. http://dx.doi.org/10.3390/computation12050094.
Testo completoAbstract (sommario):
Auxins are chemical compounds of wide interest, mostly due to their role in plant metabolism and development. Synthetic auxins have been used as herbicides for more than 75 years and low toxicity in humans is one of their most advantageous features. Extensive studies of natural and synthetic auxins have been made in an effort to understand their role in plant growth. However, molecular details of the binding and recognition process are still an open question. Herein, we present a comprehensive in silico pipeline for the assessment of TIR1 ligands using several structure-based methods. Our results suggest that subtle dynamics within the binding pocket arise from water–ligand interactions. We also show that this trait distinguishes effective binders. Finally, we construct a database of putative ligands and decoy compounds, which can aid further studies focusing on synthetic auxin design. To the best of our knowledge, this study is the first of its kind focusing on TIR1.
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Yue, Wang, Sun Fulai, Gao Qingrong, Zhang Yanxia, Wang Nan, and Zhang Weidong. "Auxins Regulations of Branched Spike Development and Expression of TFL, a LEAFY-Like Gene in Branched Spike Wheat (Triticum aestivum)." Journal of Agricultural Science 9, no. 2 (2017): 27. http://dx.doi.org/10.5539/jas.v9n2p27.
Testo completoAbstract (sommario):
Branched spike wheat is a hexaploid germplasm with branched rachis on its main rachises, and the crucial period for branched rachises occurrence and development is just after the two ridges stage of shoot apex. Natural [indole-3-acetic acid (IAA), indole-3butyric acid (IBA)] and synthetic [(1-naphthaleneacetic acid (NAA), 2,4-Dichlorophenoxyacetic acid (2,4-D)] auxins were applied at this period to investigate the spike traits, seedling growth and photosynthesis related characters and expression of a putative homologue of the LEAFY in branched spike wheat. The four types of experienced auxins induced similar effects on these foresaid characters, although the impact extents were different among the auxins treatments. More branched rachis, spikelets, fertile florets and longer branched rachis were obtained in plants with IAA and IBA at 0.1 mM or NAA and 2,4-D at 1.0mM than those plants with no auxin treated. Auxin treatments also increased fresh and dry mass, photosynthetic pigment and parameters. TFL, a LEAFY-like gene was cloned in branched spike wheat and TFL mRNA expression was quantified using real-time reverse transcriptase-PCR. Application of the auxins accelerated the rise in TFL expression during the periods of branched rachises occurrence and extension. The data supports the hypothesis that auxins play a central role in the regulation branched spike development and TFL might correlate with the development of branched rachises in branched spike wheat.
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Kudirka, Dalia T., and Blanche B. Brightwell. "The indirect effect of exogenous auxin on initiation of cell divisions in wheat root expiants (Triticum aestivum) during callus induction." Canadian Journal of Botany 67, no. 7 (1989): 1979–84. http://dx.doi.org/10.1139/b89-251.
Testo completoAbstract (sommario):
Mitotic activity (indices) was measured in apical and nonapical regions of primary root explants excised from 2-day-old germinating seedlings of wheat (Triticum aestivum Thell em L.) and cultured in the presence of the synthetic auxins 3,6-dichloro-O-anisic acid (dicamba) and 2,4-dichlorophenoxyacetic acid (2,4-D). Mitotic activity in the root apical meristem decreased with increasing concentration of auxin in the culture media. Correlated with the decrease of mitotic activity in the root apical meristem was an increase of mitotic activity in nonapical regions of the root. The degree of cell division activity initiated in nonapical regions of the root was (i) inversely proportional to the degree of inhibition of cell divisions in the root apex, but (ii) independent of the concentration of auxin in the culture medium. These data suggest that the primary effect of these synthetic auxins on mitotic activity in wheat root explants is to suppress cell divisions in the primary root apex and not to stimulate cell divisions in the nonapical regions of the root. Cell cycle control in nonapical regions of the root appears to be a function of factor(s) emanating from mitotically active cells of the primary apical meristem.
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СHETVERIKOV, Sergey, Arina FEOKTISTOVA, Maxim TIMERGALIN, et al. "Mitigation of the negative effect of auxinic herbicide by bacterial suspension of Pseudomonas protegens DA1.2 in wheat plants under drought conditions." Acta agriculturae Slovenica 119, no. 1 (2023): 1. http://dx.doi.org/10.14720/aas.2023.119.1.2764.
Testo completoAbstract (sommario):
<p class="042abstractstekst"><span lang="EN-US">Effect of auxin-producing bacterial strain (<em>Pseudomonas protegens</em> DA1.2) was investigated under conditions of drought and herbicide treatment in wheat plants. Positive effect of the bacterial suspension on wheat plants treated with auxinic herbicide under drought conditions was manifested in reducing the content of malondialdehyde and proline, preventing inhibition of plant growth and normalizing chlorophyll content. Under combined stress, changes in concentrations and redistribution of phytohormones in plants were detected. An imbalance in auxin distribution between shoots and roots could be the reason for the decrease in plant resistance to drought in combination with the herbicide. Treatment of plants with the bacterial suspension restored normal shoot-to-root ratio of auxins in plants. Thus, this bacterial strain showed the properties of synthetic auxin antidotes and can be recommended for optimizing the technology of herbicide application under drought conditions.</span></p>
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Tsygankova, VA, V. Andrusevich Ya, NM Vasylenko, SG Pilyo, SV Klyuchko, and VS Brovarets. "Screening of Auxin-like Substances among Synthetic Compounds, Derivatives of Pyridine and Pyrimidine." Journal of Plant Science and Phytopathology 7, no. 3 (2023): 151–56. http://dx.doi.org/10.29328/journal.jpsp.1001121.
Testo completoAbstract (sommario):
The effect of known synthetic compounds Ivin (N-oxide-2,6-dimethylpyridine), Methyur (sodium salt of 6-methyl-2-mercapto-4-hydroxypyrimidine), Kamethur (potassium salt of 6-methyl-2-mercapto-4-hydroxypyrimidine) and new synthetic compounds, derivatives of pyrimidine (No. 1 - 7) on the rooting of isolated stem cuttings of haricot bean (Phaseolus vulgaris L.) variety Bilozernaya was studied. The growth regulatory activity of synthetic compounds Ivin, Methyur, Kamethur, and synthetic compounds, derivatives of pyrimidine (No. 1 - 7) was compared with the activity of auxins IAA (1H-indol-3-yl)acetic acid) and NAA (1-naphthylacetic acid). The conducted studies showed that the regulatory effect of synthetic compounds Ivin, Methyur, Kamethur, and synthetic compounds, derivatives of pyridine (No. 1 - 7) on the rooting of isolated stem cuttings of haricot bean was similar to the auxins IAA and NAA. The synthetic compounds Ivin, Methyur, and Kamethur, and synthetic compounds, derivatives of pyrimidine (No. 1, 4, 5, and 7) showed the highest auxin-like activity. The indicators of the total number of roots (pcs) and total length of roots (cm) obtained on isolated stem cuttings of haricot bean immersed in a water solution of synthetic compounds Ivin, Methyur, Kamethur and synthetic compounds, derivatives of pyridine (No. 1, 4, 5 and 7), used at a concentration of 10-7 M, statistically significantly exceeded similar indicators obtained on control isolated stem cuttings of haricot bean immersed in distilled water. The practical use of synthetic compounds Ivin, Methyur, Kamethur, and synthetic compounds, derivatives of pyrimidine (No. 1, 4, 5 and 7) is proposed to improve the vegetative propagation of haricot bean plants (Phaseolus vulgaris L.) and other plant species of the family Fabaceae by stem cuttings.
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Mihaljević, S., and B. Salopek-Sondi. " Alanine conjugate of indole-3-butyric acid improves rooting of highbush blueberries." Plant, Soil and Environment 58, No. 5 (2012): 236–41. http://dx.doi.org/10.17221/34/2012-pse.
Testo completoAbstract (sommario):
Auxins and their synthetic analogues are commonly used for rooting of cuttings, but their efficiency depends on experimental set-up and, even more importantly, on species or cultivar, and type of explants investigated. In attempt to improve rooting procedure for highbush blueberries (Vaccinium corymbosum L.), we investigated alanine conjugate of indole-3-butyric acid (IBA-Ala) as potential root-promoting compound and compared with commonly used auxins indole-3-butyric acid (IBA) and indole-3-acetic acid (IAA). The effect of different concentrations of auxins on the rooting of highbush blueberry stem cuttings (var. Bluecrop, Bluetta, Burlington and Jersey) and in vitro-derived microcuttings (var. Jersey) was investigated. Auxin treatments significantly promoted rooting of all four varieties in comparison to control. The most efficient rooting promoter in all varieties appeared IBA-Ala (provided up to 83%, and 93% of the rooted cuttings and microcuttings, respectively). Furthermore, IBA-Ala caused a vigorous, well-branched root system that resulted in better acclimatization and survival of plants. Results suggest the application of IBA-Ala may be beneficial for rooting of difficult-to-root varieties of blueberry and related species and their practical application in the nursery industry. &nbsp;
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Pacholczak, Andrzej, Karolina Nowakowska, Natalia Mika, and Monika Borkowska. "The effect of the biostimulator Goteo on the rooting of ninebark stem cuttings." Folia Horticulturae 28, no. 2 (2016): 109–16. http://dx.doi.org/10.1515/fhort-2016-0013.
Testo completoAbstract (sommario):
Abstract As a consequence of restrictions on the use of preparations containing synthetic auxins in nursery production, there is a necessity to replace them with more environmentally friendly biopreparations efficiently stimulating plant growth. The aim of the presented experiment was to compare the effects of the synthetic auxin indole-3-butyric acid (IBA) and the biostimulator Goteo on the rooting of ninebark stem cuttings (Physocarpus opulifolius ‘Dart’s Gold’ and ‘Red Baron’) and to get some insight into the latter’s mechanisms of action in plants. Applications of the biostimulator Goteo produced comparable or slightly weaker effects compared to the treatments with IBA. Goteo stimulated elongation in new growth of cuttings when applied in watering or two-fold spraying methods. Application of the biostimulator resulted in increased levels of chlorophyll, soluble sugars and indole derivatives, while the contents of free amino acids and polyphenolic acids decreased. The above results indicate that, if necessary, Goteo may replace the synthetic auxin IBA in the propagation of ninebark in the future.
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Gho, Yun-Shil, Min-Yeong Song, Do-Young Bae, Heebak Choi, and Ki-Hong Jung. "Rice PIN Auxin Efflux Carriers Modulate the Nitrogen Response in a Changing Nitrogen Growth Environment." International Journal of Molecular Sciences 22, no. 6 (2021): 3243. http://dx.doi.org/10.3390/ijms22063243.
Testo completoAbstract (sommario):
Auxins play an essential role in regulating plant growth and adaptation to abiotic stresses, such as nutrient stress. Our current understanding of auxins is based almost entirely on the results of research on the eudicot Arabidopsis thaliana, however, the role of the rice PIN-FORMED (PIN) auxin efflux carriers in the regulation of the ammonium-dependent response remains elusive. Here, we analyzed the expression patterns in various organs/tissues and the ammonium-dependent response of rice PIN-family genes (OsPIN genes) via qRT–PCR, and attempted to elucidate the relationship between nitrogen (N) utilization and auxin transporters. To investigate auxin distribution under ammonium-dependent response after N deficiency in rice roots, we used DR5::VENUS reporter lines that retained a highly active synthetic auxin response. Subsequently, we confirmed that ammonium supplementation reduced the DR5::VENUS signal compared with that observed in the N-deficient condition. These results are consistent with the decreased expression patterns of almost all OsPIN genes in the presence of the ammonium-dependent response to N deficiency. Furthermore, the ospin1b mutant showed an insensitive phenotype in the ammonium-dependent response to N deficiency and disturbances in the regulation of several N-assimilation genes. These molecular and physiological findings suggest that auxin is involved in the ammonium assimilation process of rice, which is a model crop plant.
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Holik, Ladislav, Jiří Volánek, and Valerie Vranová. "Effect of Plant Growth Regulators on Protease Activity in Forest Floor of Norway Spruce Stand." Forests 12, no. 6 (2021): 665. http://dx.doi.org/10.3390/f12060665.
Testo completoAbstract (sommario):
Soil proteases are involved in organic matter transformation processes and, thus, influence ecosystem nutrient turnovers. Phytohormones, similarly to proteases, are synthesized and secreted into soil by fungi and microorganisms, and regulate plant rhizosphere activity. The aim of this study was to determine the effect of auxins, cytokinins, ethephon, and chlorocholine chloride on spruce forest floor protease activity. It was concluded that the presence of auxins stimulated native proteolytic activity, specifically synthetic auxin 2-naphthoxyacetic acid (16% increase at added quantity of 5 μg) and naturally occurring indole-3-acetic acid (18%, 5 μg). On the contrary, cytokinins, ethephon and chlorocholine chloride inhibited native soil protease activity, where ethephon (36% decrease at 50 μg) and chlorocholine chloride (34%, 100 μg) showed the highest inhibitory effects. It was concluded that negative phytohormonal effects on native proteolytic activity may slow down organic matter decomposition rates and hence complicate plant nutrition. The study enhances the understanding of rhizosphere exudate effects on soil microbial activity and soil nitrogen cycle.
Tesi sul tema "Synthetic auxins"
1
Koreki, Axelle. "Recherche de déterminants génétiques de la résistance aux herbicides auxiniques chez le Coquelicot (Papaver rhoeas L.) dans un but de diagnostic." Electronic Thesis or Diss., Bourgogne Franche-Comté, 2024. http://www.theses.fr/2024UBFCK005.
Testo completoAbstract (sommario):
Le coquelicot (Papaver rhoeas) est une adventice cosmopolite très répandue dans les cultures de céréales d’hiver en Europe qui présente un haut potentiel d’invasion et de propagation dans les cultures. Il est principalement contrôlé par les herbicides inhibiteurs de l’ALS et les herbicides auxiniques. L’utilisation intensive de ces deux modes d’action à conduit à l’évolution de la résistance dans de nombreuses populations de coquelicot à travers l’Europe. La résistance aux herbicides implique deux catégories de mécanismes : la résistance liée à la cible (RLC) et la résistance non liée à la cible (RNLC). Chez le coquelicot, seuls des mécanismes de RNLC ont été identifiés, mais les gènes spécifiques restent inconnus. Ce travail de thèse a donc plusieurs objectifs : (i) identifier et potentiellement valider les déterminants génétiques de la résistance aux herbicides auxiniques chez le coquelicot et (ii) évaluer la présence de résistance aux herbicides auxiniques dans des populations françaises de Coquelicot. Dans une première partie, nous avons caractérisé phénotypiquement le matériel végétal disponible via des tests biologiques de sensibilités aux herbicides (Chapitre 1) pour évaluer la situation de la résistance des coquelicots aux herbicides auxiniques en France. Nous avons montré que la résistance au 2,4-D en France était répandue, voire très bien installée dans certaines zones. Nous avons également identifié deux parcelles en Italie et en Grèce où des plantes résistantes à l’halauxifène-méthyl ont été détecté, suggérant un début d’évolution de la résistance à ce nouvel herbicide de synthèse. Les populations avec un ratio équilibré d’individus résistants et sensibles ont été utilisées pour la production de matériel végétal pour les approches de biologie moléculaire de la deuxième partie.Dans une deuxième partie, nous avons étudié la résistance constitutive au 2,4-D et à l’halauxifène-méthyl parmi 14 populations via le séquençage de l’ARN (RNAseq) (Chapitre 2). Nous avons montré que les profils d’expression des plantes sensibles et résistantes étaient propres à chaque population. Parmi les gènes différentiellement exprimés chez les plantes résistantes, certaines familles de gènes potentiellement impliqués dans la métabolisation des herbicides (CYP450, GST, transporteurs ABCs etc.) ou des cascades de régulation (facteurs de transcription, protéines kinases) ont été identifiées. Sur la base de ces résultats, le niveau d’expression de ces gènes à été validé via une approche de RT-qPCR à partir d’un échantillon plus large de plantes. L’ensemble des résultats indiquent qu’il existe potentiellement une grande variété de mécanismes de résistance inter- et intra-population. Le deuxième RNAseq (Chapitre 3) visait à étudier la réponse transcriptomique des plantes résistantes et sensibles entre 4h et 48h après l’application du 2,4-D dans deux populations. Nous avons identifié une grande diversité de gènes et de familles de gènes spécifiquement induits chez les plantes résistantes des deux populations, mais leur rôle dans la résistance n’a pas pu être vérifié. Comme dans la résistance constitutive, il peut potentiellement s’agir d’enzymes de détoxication, de transporteurs, voire de potentiels gènes cibles de l’auxine ou de gènes associés à la réponse générale au stress. De plus, le 2,4-D induit une réponse rapide qui est détectable dans les 4h suivant le traitement quels que soient le phénotype et la population. Enfin, la comparaison des gènes différentiellement exprimés de façon constitutive entre les deux approches de RNAseq démontre que l’absence de gènes communs est potentiellement due à une diversité élevée de mécanismes de résistance intra- et -inter populations, ou au fait que les mécanismes qui contribuent le plus à la résistance sont dû à des mutations de structure<br>Corn poppy (Papaver rhoeas) is a very widespread cosmopolitan weed in winter crops cereal in Europe which has a high potential for invasion and spread in crops. It is mainly controlled by ALS inhibitor herbicides and auxin herbicides. The intensive use of these two modes of action has led to the evolution of resistance in many poppy populations across Europe. Herbicide resistance involves two categories of mechanisms: target-site-based resistance (TSR) and non-target-site-based resistance (NTSR). In poppy, only NTSR mechanisms have been identified, but the specific genes remain unknown. This work therefore has several goals: (i) identify and potentially validate the genetic determinants of resistance to auxin herbicides in corn poppy and (ii) evaluate resistance status to auxin herbicides in French poppy populations.In a first part, we phenotypically characterized the plant material available using herbicides sensitivity bioassays (Chapter 1) to assess the resistance status of poppies to auxin herbicides in France. We have shown that resistance to 2,4-D in France was widespread, even very well established in certain areas. We also identified two areas in Italy and Greece where resistant plants to halauxifen-methyl were detected, suggesting the beginning of the evolution of resistance to this new synthetic herbicide. Populations with a balanced ratio of resistant and sensitive individuals were used for plant material production for the molecular biology approaches of the second part.In a second part, we studied constitutive resistance to 2,4-D and halauxifen-methyl among 14 populations via RNA sequencing (RNAseq) (Chapter 2). We showed that the expression profiles of sensitive and resistant plants were specific to each population. Among the genes differentially expressed in resistant plants, some gene families potentially involved in the metabolism of herbicides (CYP450, GST, ABC transporters, etc.) or regulatory cascades (transcription factors, protein kinases) have been identified. Based on these results, the expression level of these genes was validated via an RT-qPCR approach using a larger sample of plants. All the results indicate that there is potentially a wide variety of inter- and intra-population resistance mechanisms.The second RNAseq (Chapter 3) aimed to study the transcriptomic response of resistant and sensitive plants between 4h and 48h after the application of 2,4-D in two populations. We identified a large diversity of genes and gene families specifically induced in resistant plants from both populations, but their role in resistance could not be verified. As in constitutive resistance, these can potentially be detoxification enzymes, transporters, or even potential auxin target genes or genes associated with the general stress response. In addition, 2,4-D induces a rapid response which is detectable within 4 hours following treatment regardless of the phenotype and population.Finally, the comparison of constitutively differentially expressed genes between the two RNAseq approaches demonstrates that the absence of common genes is potentially due to a high diversity of intra- and -inter population resistance mechanisms, or to the fact that the mechanisms that contribute the most to resistance are due to structural mutations
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Leung, Ching-man, and 梁靜雯. "Characterization of two auxin-induced ACC synthase genes in tomatoes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B36748845.
Testo completo
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Yamada, Masashi. "The role of the Transport Inhibitor Response2 (TIR2) gene in auxin synthesis in Arabidopsis." [Bloomington, Ind.] : Indiana University, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337252.
Testo completoAbstract (sommario):
Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2008.<br>Title from PDF t.p. (viewed on Feb. 17, 2010). Source: Dissertation Abstracts International, Volume: 69-12, Section: B, page: 7343. Adviser: Mark Estelle.
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Ellison, P. A., A. M. Jedele, T. E. Barnhart, R. J. Nickles, D. Murali, and O. T. DeJesus. "Production of [11C]cyanide for the synthesis of indole-3-[1-11C]acetic acid and PET imaging of auxin transport in living plants." Helmholtz-Zentrum Dresden - Rossendorf, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-166188.
Testo completoAbstract (sommario):
Introduction
Since its development by Al Wolf and colleagues in the 1970s1, [11C]cyanide has been a useful synthon for a wide variety of reactions, most notably those producing [1-11C]-labeled amino acids2. However, despite its position as rote gas-phase product, the catalytic synthesis is difficult to optimize and often only perfunctorily dis-cussed in the radiochemical literature. Recently, [11C]CN– has been used in the synthesis of indole-3-[1-11C]acetic acid ([11C]IAA), the principal phytohormone responsible for a wide variety of growth and development functions in plants3. The University of Wisconsin has expertise in cyclotron production and radiochemistry of 11C and previous experience in the PET imaging of plants4,5. In this abstract, we present work on optimizing [11C]CN– production for the synthesis of [11C]IAA and the PET imaging of auxin transport in living plants.
Material and Methods
[11C]CH4 was produced by irradiating 270 psi of 90% N2, 10% H2 with 30 µA of 16.1 MeV protons from a GE PETtrace cyclotron. After irradiation, the [11C]CH4 was converted to [11C]CN– by passing through a quartz tube containing 3.0 g of Pt wire and powder between quartz wool frits inside a 800–1000 ˚C Carbolite tube furnace. The constituents and flow rate of the [11C]CH4 carrier gas were varied in an effort to optimize the oven\'s catalytic production of [11C]CN– from CH4 and NH3. The following conditions were investigated:
i. Directly flowing irradiated target gas versus trapping, purging and releasing [11C]CH4 from a −178 ˚C HayeSep D column in He through the Pt furnace.
ii. Varying the amount of anhydrous NH3 (99.995%) mixed with the [11C]CH4 carrier gas prior to the Pt furnace. Amounts varied from zero to 35 % of gas flow.
iii. Varying the purity of the added NH3 gas with the addition of a hydride gas purifier (Entegris model 35KF), reducing O2 and H2O impurities to < 12 ppb.
iv. Varying the flow rate of He gas carrying trapped, purged and released [11C]CH4.
After flowing through the Pt furnace, the gas stream was bubbled through 300 µL of DMSO containing IAA precursor gramine (1 mg), then passed through a 60×5 cm column containing ascarite to absorb [11C]CO2, followed by a −178˚C Porapak Q column to trap [11C]CH4 and [11C]CO.
After bubbling, the DMSO/gramine vial was heated to 140 ˚C to react the gramine with [11C]CN–, forming the intermediate indole-3-[1-11C]acetonitrile ([11C]IAN), which was subsequently purified by solid phase extraction (SPE). The reaction mixture was diluted into 20 mL water and loaded onto a Waters Sep-Pak light C18 cartridge, followed by rinsing with 5 mL of 0.1% HCl : acetonitrile (99 : 1) and 10 mL of the same mixture in ratio 95 : 5, and finally eluted with 0.5 mL of diethyl ether. The ether was subsequently evaporated under argon flow, followed by the hydrolysis of [11C]IAN to [11C]IAA with the addition of 300 µL 1 M NaOH and heating to 140 ˚C for 5 minutes. After hydrolysis, the solution was neutralized with 300 µL 1 M HCl and purified using preparative high-performance liquid chromatography (HPLC) using a Phenomenex Luna C18 (10μ, 250×10mm) column with a mobile phase acetonitrile : 0.1% formic acid in H2O (35 : 65) at flow rate of 3 mL/min. The [11C]IAA peak, eluting at 12 minutes, was collected and rotary evaporated to dryness, then again after the addition of 5 mL acetonitrile, followed by its reconstitution in 50 µL of water. Analytical HPLC was performed on the [11C]IAA before and after this evaporation procedure using a Phenomenex Kinetex C18 (2.6μ, 75× 4.6 mm) column with a linear gradient elution over 20 minutes of 10 : 90–30 : 70 (acetonitrile : 0.1% formic acid) at a 1 mL/min flow rate, eluting at 7.6 minutes.
The transport of [11C]IAA was monitored following administration through the severed petiole of rapid cycling Brassica oleracea (rcBo) using a Siemens microPET P4 scanner. Transport was compared following administration to the first true leaf versus the final fully formed leaf in plants with and without exposure to the polar auxin transport inhibitor naphthylphthalamic acid (NPA).
Results and Conclusion
Optimization of the [11C]CN– gas phase chemistry was performed using two key metrics for measuring conversion yield. First is the fraction of total produced radioactivity that trapped in the DMSO/gramine solution (denoted %DMSO), and second, the fraction of DMSO/gramine-trapped activity that was able to react with gramine to form [11C]IAN (denoted %CN–). Under certain conditions, the former of these metrics experienced significant losses due to unconverted [11C]CH4 or through combustion, forming [11C]CO2 or [11C]CO. The latter metric experienced losses due to production of incomplete oxidation products of the CH4-NH3 reaction, such as methylamine. Total [11C]CH4 to [11C]CN– con-version yields is reported by the product of the two metrics. It was initially hypothesized that the irradiation of a 90% N2, 10% H2 target gas would produce sufficient in-target-hot-atom-produced NH3 to convert [11C]CH4 to [11C]CN– in the Pt furnace. However, conversion yields were found to be low and highly variable, with 13 ± 8 % trapping in DMSO/gramine, 9 ± 9 % of which reacted as CN– (n = 15). While in disagreement with previous reports1, this is likely as a result the batch irradiation conditions resulting ammonia losses in the target chamber and along the tubing walls. Yields and reproducibility were improved when combining the target gas with a stream of anhydrous NH3 gas flow with conversion yields reported in TABLE 1. However, these yields remained undesirably low, potentially as a result of the 10% H2 carrier gas having an adverse effect on the oxidative conversion of [11C]CH4 to [11C]CN–. To remedy this, the irradiated target gas was trapped, purged, released in He and combined with NH3 gas before flowing through the Pt furnace. Initial experiments using 99.995% anhydrous NH3 gas resulted in very poor (< 0.1%) [11C]CN– yields as a result of nearly quantitative combustion forming [11C]CO2. Installation of a hydride gas purifier to reduce O2 and H2O impurities in NH3 improved yields for CH4 in He, but did not significantly affect those from [11C]CH4 in N2/H2 target gas. In disagreement with previous reports2, conversion yields were found to be highly sensitive to overall carrier gas flow rate, with lower flow rates giving the best yields, as shown in TABLE 1. Optimization experiments are continuing.
The total decay-corrected yield for the 1 hour synthesis of [11C]IAA in 50 µL of water is 2.3 ± 0.7 %, based on the total produced [11C]CH4 with a specific activity ranging from 1–100 GBq/µmol. The principal radiochemical impurity was determined to be indole-3-carboxylic acid. The SPE procedure isolating the [11C]IAN intermediate product was optimized to minimize this impurity in the final sample.
After a rapid distribution of the administered [11C]IAA through the cut petiole and throughout the rcBO plant, upward vascular transport of auxin and downward polar auxin transport was visualized through time-activity curves (TACs) of regions of interest along the shoot. Comparison of these TACS with and without exposure to NPA yields insight into the fundamental physiological process of polar auxin transport in plants.
In conclusion, the Pt-catalyzed oxidative conversion of [11C]CH4 and NH3 to [11C]CN– is a challenging process to optimize and highly sensitive to carrier gas composition and flow rate. Optimization for our experimental conditions yielded several results which disagreed with previous reports. [11C]IAA produced using [11C]CN– is well suited for PET imaging of polar auxin transport in living plants.
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(8932271), Connor L. Hodgskiss. "WEED CONTROL SYSTEMS IN SYNTHETIC AUXIN-RESISTANT SOYBEANS." Thesis, 2020.
Cerca il testo completoAbstract (sommario):
<p>Herbicide-resistant weed populations have become problematic throughout the Eastern Corn Belt, with 18 unique herbicide-resistant weed biotypes confirmed in Indiana alone. In response to these resistant populations, the agricultural chemical industry has responded by developing glyphosate-resistant crops paired with resistance to synthetic auxin herbicides such as dicamba and 2,4-D.</p><p>This research evaluates weed population shifts in cropping systems using row crops that are resistant to synthetic auxin herbicides. Identifying weed population shifts will allow future research to be targeted to weed species that would become more prevalent in cropping systems using synthetic auxin-resistant crops. The use of multiple sites of action will be needed in order to prevent weed shifts in both conventional and no-till corn-soybean production systems. Weed densities and species richness were reduced within field evaluations when six or more herbicide sites of action were implemented with residual herbicides in both corn and soybean years over a seven-year period. Additionally, soil seedbank weed densities and species richness were reduced within 2,4-D-resistant soybean production systems. Additional strategies other than the application of herbicides may be needed to manage weed populations in the future due to the high levels of herbicide-resistant weed populations in the Midwest.</p><p>Off-target movement of these synthetic auxin herbicides, has been a concern, and label-mandated buffer areas are required near sensitive areas. Investigation of whether cover crops can be an effective tactic in managing weeds in these label-mandated buffer areas was conducted. Cover crop utilization in buffer areas has not been investigated in Indiana. Additionally, termination timing is becoming more prominent as farm operators are increasingly terminating cover crops after planting. Our results demonstrate that using cover crops that utilize cereal rye and that are terminated at, or after the time of soybean planting will be beneficial in suppressing waterhemp, grasses, and sometimes horseweed within label-mandated buffer areas, but not for suppression of giant ragweed. However, delaying termination of cover crops can result in soybean yield reductions and caution should be used. Terminating cover crops with glyphosate and auxin and a residual herbicide was more effective than glyphosate alone, but would not be permitted within label-mandated buffer areas.L</p>
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"The role of the TRANSPORT INHIBITOR RESPONSE2 (TIR2) gene in auxin synthesis in Arabidopsis." INDIANA UNIVERSITY, 2009. http://pqdtopen.proquest.com/#viewpdf?dispub=3337252.
Testo completoLibri sul tema "Synthetic auxins"
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Estelle, Mark. Auxin signaling: From synthesis to systems biology : a subject collection from Cold Spring Harbor Perspectives in Biology. Cold Spring Harbor Laboratory Press, 2011.
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Leyser, Ottoline, Dolf Weijers, and Karin Ljung. Auxin Signaling: From Synthesis to Systems Biology, Second Edition. Cold Spring Harbor Laboratory Press, 2021.
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Gleń-Karolczyk, Katarzyna. Zabiegi ochronne kształtujące plonowanie zdrowotność oraz różnorodność mikroorganizmów związanych z czernieniem pierścieniowym korzeni chrzanu (Atmoracia rusticana Gaertn.). Publishing House of the University of Agriculture in Krakow, 2019. http://dx.doi.org/10.15576/978-83-66602-39-7.
Testo completoAbstract (sommario):
Horseradish roots, due to the content of many valuable nutrients and substances with healing and pro-health properties, are used more and more in medicine, food industry and cosmetics. In Poland, the cultivation of horseradish is considered minor crops. In addition, its limited size causes horseradish producers to encounter a number of unresolved agrotechnical problems. Infectious diseases developing on the leaves and roots during the long growing season reduce the size and quality of root crops. The small range of protection products intended for use in the cultivation of horseradish generates further serious environmental problems (immunization of pathogens, low effectiveness, deterioration of the quality of raw materials intended for industry, destruction of beneficial organisms and biodiversity). In order to meet the problems encountered by horseradish producers and taking into account the lack of data on: yielding, occurrence of infectious diseases and the possibility of combating them with methods alternative to chemical ones in the years 2012–2015, rigorous experiments have been carried out. The paper compares the impact of chemical protection and its reduced variants with biological protection on: total yield of horseradish roots and its structure. The intensification of infectious diseases on horseradish leaves and roots was analyzed extensively. Correlations were examined between individual disease entities and total yield and separated root fractions. A very important and innovative part of the work was to learn about the microbial communities involved in the epidemiology of Verticillium wilt of horseradish roots. The effect was examined of treatment of horseradish cuttings with a biological preparation (Pythium oligandrum), a chemical preparation (thiophanate-methyl), and the Kelpak SL biostimulator (auxins and cytokinins from the Ecklonia maxima algae) on the quantitative and qualitative changes occurring in the communities of these microorganisms. The affiliation of species to groups of frequencies was arranged hierarchically, and the biodiversity of these communities was expressed by the following indicators: Simpson index, Shannon–Wiener index, Shannon evenness index and species richness index. Correlations were assessed between the number of communities, indicators of their biodiversity and intensification of Verticillium wilt of horseradish roots. It was shown that the total yield of horseradish roots was on average 126 dt · ha–1. Within its structure, the main root was 56%, whereas the fraction of lateral roots (cuttings) with a length of more than 20 cm accounted for 26%, and those shorter than 20 cm for 12%, with unprofitable yield (waste) of 6%. In the years with higher humidity, the total root yield was higher than in the dry seasons by around 51 dt · ha–1 on average. On the other hand, the applied protection treatments significantly increased the total yield of horseradish roots from 4,6 to 45,3 dt · ha–1 and the share of fractions of more than 30 cm therein. Higher yielding effects were obtained in variants with a reduced amount of foliar application of fungicides at the expense of introducing biopreparations and biostimulators (R1, R2, R3) and in chemical protection (Ch) than in biological protection (B1, B2) and with the limitation of treatments only to the treatment of cuttings. The largest increments can be expected after treating the seedlings with Topsin M 500 SC and spraying the leaves: 1 × Amistar Opti 480 SC, 1 × Polyversum WP, 1 × Timorex Gold 24 EC and three times with biostimulators (2 × Kelpak SL + 1 × Tytanit). In the perspective of the increasing water deficit, among the biological protection methods, the (B2) variant with the treatment of seedlings with auxins and cytokinins contained in the E. maxima algae extract is more recommended than (B1) involving the use of P. oligandrum spores. White rust was the biggest threat on horseradish plantations, whereas the following occurred to a lesser extent: Phoma leaf spot, Cylindrosporium disease, Alternaria black spot and Verticillium wilt. In turn, on the surface of the roots it was dry root rot and inside – Verticillium wilt of horseradish roots. The best health of the leaves and roots was ensured by full chemical protection (cuttings treatment + 6 foliar applications). A similar effect of protection against Albugo candida and Pyrenopeziza brassicae was achieved in the case of reduced chemical protection to one foliar treatment with synthetic fungicide, two treatments with biological preparations (Polyversum WP and Timorex Gold 24 EC) and three treatments with biostimulators (2 × Kelpak SL, 1 × Tytanit). On the other hand, the level of limitation of root diseases comparable with chemical protection was ensured by its reduced variants R3 and R2, and in the case of dry root rot, also both variants of biological protection. In the dry years, over 60% of the roots showed symptoms of Verticillium wilt, and its main culprits are Verticillium dahliae (37.4%), Globisporangium irregulare (7.2%), Ilyonectria destructans (7.0%), Fusarium acuminatum (6.7%), Rhizoctonia solani (6.0%), Epicoccum nigrum (5.4%), Alternaria brassicae (5.17%). The Kelpak SL biostimulator and the Polyversum WP biological preparation contributed to the increased biodiversity of microbial communities associated with Verticillium wilt of horseradish roots. In turn, along with its increase, the intensification of the disease symptoms decreased. There was a significant correlation between the richness of species in the communities of microbial isolates and the intensification of Verticillium wilt of horseradish roots. Each additional species of microorganism contributed to the reduction of disease intensification by 1,19%.
Capitoli di libri sul tema "Synthetic auxins"
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Schmitzer, Paul, Jeffrey Epp, Roger Gast, William Lo, and Jeff Nelson. "Herbicidal Carboxylic Acids as Synthetic Auxins." In Bioactive Carboxylic Compound Classes: Pharmaceuticals and Agrochemicals. Wiley-VCH Verlag GmbH & Co. KGaA, 2016. http://dx.doi.org/10.1002/9783527693931.ch20.
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Tsygankova, V. A., Ya V. Andrusevich, O. I. Shtompel, et al. "New Auxin and Cytokinin Related Compounds Based on Synthetic Low Molecular Weight Heterocycles." In Auxins, Cytokinins and Gibberellins Signaling in Plants. Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-05427-3_16.
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Andres, Jennifer, and Matias D. Zurbriggen. "Genetically Encoded Biosensors for the Quantitative Analysis of Auxin Dynamics in Plant Cells." In Plant Synthetic Biology. Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-1791-5_11.
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Ismagul, Ainur, Gulnur Iskakova, John C. Harris, and Serik Eliby. "Biolistic Transformation of Wheat with Centrophenoxine as a Synthetic Auxin." In Methods in Molecular Biology. Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4939-0446-4_15.
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Nagata, Toshiyuki, and Yohsuke Takahashi. "Auxin-mediated activation of DNA synthesis via par genes in tobacco mesophyll protoplasts." In Molecular and Cell Biology of the Plant Cell Cycle. Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1789-0_10.
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Arroo, R. R. J., H. Meijers, A. Develi, A. F. Croes, and G. J. Wullems. "Effect of auxin on thiophene synthesis and root morphology in Tagetes patula hairy root cultures." In Progress in Plant Growth Regulation. Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2458-4_91.
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Boivin, P., S. Kohl, P. Label, and P. Doumas. "Profil hormonal de l’orge et qualité brassicole." In European Brewery Convention. Oxford University PressOxford, 1993. http://dx.doi.org/10.1093/oso/9780199634668.003.0015.
Testo completoAbstract (sommario):
Abstract Endogenous plant cereals, including synthesis. These An HPLC separation different groups growth substances mediate physiological processes in seed dormancy, germination and hydrolytic enzyme processes are central to the production of good malt. and an enzyme linked immunosorbent assay (ELISA) with of polyclonal antibodies have been used for the determination of barley endogenous hormones: gibberellins, abscisic acid, auxin and cytokinins. Differences in main endogenous plant growth substances have been detected in barley varieties having different malting qualities.
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Dalton, David R. "Roots, Shoots, Leaves, and Grapes." In The Chemistry of Wine. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190687199.003.0015.
Testo completoAbstract (sommario):
As noted earlier and as anticipated by Charles and Francis Darwin it has been argued that plants sense the direction of gravity (gravitropism) by movement of starch granules found in cells called statocytes that contain compartments (organelles) called statoliths. The synthesis of statoliths appears to occur in the plastid (plant organelle) compartments called amyloplasts (Figure 7.1, 1). It has been suggested that this gravitropic signal then leads to movement of plant hormones such as indole-3-acetic acid (auxin) (Figure 7.2), through the phloem opposite to the pull of gravity to promote stem growth. Chloroplasts (Figure 7.1, 2) are cell compartments (plastids or organelles) in which photosynthesis is carried out. The process of photosynthesis, discussed more fully later, is accompanied by the production of adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and inorganic phosphate (Pi) (Figure 7.3). ATP is consumed and converted to ADP and Pi in living systems. The cycle of production and consumption allows ATP to serve as an “energy currency” to pay for the reactions in living systems. Beyond this generally recognized critical function of chloroplasts, it has recently been pointed out that light/ dark conditions affect alternative splicing of genes which may be necessary for proper plant responses to varying light conditions. The organelles or plastids which contain the pigments for photosynthesis and the amyloplasts that store starch are only two of many kinds of plastids. Other plastids, leucoplasts for example, hold the enzymes for the synthesis of terpenes, and elaioplasts store fatty acids. Apparently, all plastids are derived from proplastids which are present in the pluripotent apical and root meristem cells. The cell wall (Figure 7.1, 3) is the tough, rigid layer that surrounds cells. It is located on the outside of the flexible cell membrane, thus adding fixed structure. A representation of a portion of the cell wall (as made up of cellulose and peptide cross-linking) is shown below in Figure 7.7. The cells will have different sizes as a function of where they are found (e.g., leaf, stalk, root), but in every case, the cell wall limits the size of the membrane that lies within.
Atti di convegni sul tema "Synthetic auxins"
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Mizin, Danila V., Stepan V. Vorobyev, and Vladimir N. Koshelev. "Promising synthetic auxins from alkylphenols: a DFT study." In Third International Scientific and Practical Symposium on Materials Science and Technology (MST-III 2023), edited by Ramazon Abdullozoda and Shahriyor Sadullozoda. SPIE, 2024. http://dx.doi.org/10.1117/12.3016533.
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Lutfullin, M. T., D. S. Pudova, O. E. Moiseeva, D. L. Zaripova, and A. M. Mardanova. "Genetic determinants responsible for growth-promoting properties of the rhizospheric bacterium Brevibacterium sp. MG-1." In 2nd International Scientific Conference "Plants and Microbes: the Future of Biotechnology". PLAMIC2020 Organizing committee, 2020. http://dx.doi.org/10.28983/plamic2020.156.
Testo completoAbstract (sommario):
The paper presents data on sequencing and genome annotations of the Brevibacterium sp. MG-1, capable of synthesizing IAA and siderophores. The genes responsible for the synthesis of ACC deaminase, auxins and hydroxamate type siderophores were identified.
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Abdurashytov, S. F., T. N. Melnichuk, E. R. Chirak, A. Y. Egovtseva, E. R. Abdurashytova, and E. E. Andronov. "Associative growth-stimulating strains of bacteria and their whole genome sequencing." In 2nd International Scientific Conference "Plants and Microbes: the Future of Biotechnology". PLAMIC2020 Organizing committee, 2020. http://dx.doi.org/10.28983/plamic2020.005.
Testo completoAbstract (sommario):
Strains Paenarthrobacter nitroguajacolicus L1, P. nitroguajacolicus M3, Bacillus sp. B5 and Agrobacterium tumefaciens R1 are growth-promoting agents for winter wheat. The effectiveness of their interaction with plants is probably provided by 4-9 groups of genes responsible for the synthesis of auxins, according to the recognized RAST subsystems.
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Tsygankova, V., I. Voloshchuk, Ya Andrusevich, S. Pilyo, and V. Brovarets. "Study of the growth-stimulating properties of pyrimidine derivatives on sugar sorghum (Sorghum saccharatum L.) variety Zubr." In international scientific-practical conference. MYKOLAYIV NATIONAL AGRARIAN UNIVERSITY, 2024. http://dx.doi.org/10.31521/978-617-7149-78-0-47.
Testo completoAbstract (sommario):
The growth-stimulating properties of synthetic pyrimidine derivatives on sugar sorghum (Sorghum saccharatum L.) variety Zubr grown for 2 weeks in laboratory conditions were studied. The morphometric indicators of sorghum plants treated with an aqueous 10-6 M solution of pyrimidine derivatives were compared with the indicators of sorghum plants treated with an aqueous 10-6 M solution of synthetic plant growth regulators Ivin, Methyur, Kamethur and phytohormone auxin IAA. Control sorghum plants were treated with distilled water. Conducted studies have shown that synthetic pyrimidine derivatives exhibit stimulating properties on the growth and development of shoots and roots of sorghum plants similar to auxin IAA, or Ivin, Methyur and Kamethur. Under the influence of synthetic pyrimidine derivatives, the morphometric indicators of sorghum plants increased significantly: the average length of shoots (mm), the average length of roots (mm), the average biomass (g) of 10 plants, compared to similar indicators of control sorghum plants. The relationship between the chemical structure and growth-stimulating properties of synthetic pyrimidine derivatives was analyzed. The use of the most biologically active synthetic compounds to stimulate the growth of sugar sorghum (Sorghum saccharatum L.) variety Zubr during the growing season is proposed
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Seldimirova, O. A., G. R. Kudoyarova, I. R. Galin, D. S. Veselov, and N. N. Kruglova. "Morphogenesis in vitro and peroxidase activity in barley cv. Steptoe and its ABA-deficient mutant AZ34: effects of inhibitors of ABA synthesis and auxin transport." In 2nd International Scientific Conference "Plants and Microbes: the Future of Biotechnology". PLAMIC2020 Organizing committee, 2020. http://dx.doi.org/10.28983/plamic2020.217.
Testo completoAbstract (sommario):
The relationship between the effect of ABA on morphogenesis in vitro and auxin transport, as well as the role of peroxidases in the action of ABA on morphogenesis in vitro in the ABA-deficient barley mutant AZ34 and its parent form cv. Steptoe was studied.
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Koseoglou, Eleni. "Inactivation of tomato WAT1 leads to reduced susceptibility to Clavibacter michiganensis through downregulation of bacterial virulence factor." In IS-MPMI Congress. IS-MPMI, 2023. http://dx.doi.org/10.1094/ismpmi-2023-9.
Testo completoAbstract (sommario):
Tomato bacterial canker caused by Clavibacter michiganensis (Cm) is considered to be one of the most destructive bacterial diseases of tomato. To date, no resistance to the pathogen has been identified. While several molecular studies have identified (Cm) bacterial factors involved in disease development, the plant genes and mechanisms associated with susceptibility of tomato to the bacterium remain largely unknown. Here, we show for the first time that tomato gene SlWAT1 is a susceptibility gene to Cm. We inactivated the gene SlWAT1 through RNAi and CRISPR/Cas9 to study changes in tomato susceptibility to Cm. Furtermore, we analysed the role of the gene in the molecular interaction with the pathogen. Our findings demonstrate that SlWAT1 functions as an S gene to genetically diverse Cm strains. Inactivation of SlWAT1 reduced free auxin contents and ethylene synthesis in tomato stems and suppressed the expression of specific bacterial virulence factors. However, CRISPR/Cas9 slwat1 mutants exhibited severe growth defects. The observed reduced susceptibility is possibly a result of downregulation of bacterial virulence factors and reduced auxin contents in transgenic plants. This is the first time it has been shown that an S gene can regulate the expression of virulence factors.
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Muslihatin, Wirdhatul, Nurul Jadid, Ika D. Puspitasari, and Chusnul E. Safitri. "Growth of vegetative explant Moringa oleifera on different composition of auxin and cytokinin and its synthetic seed germination." In PROCEEDING OF INTERNATIONAL BIOLOGY CONFERENCE 2016: Biodiversity and Biotechnology for Human Welfare. Author(s), 2017. http://dx.doi.org/10.1063/1.4985415.
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"Dual RNA sequencing revealed a novel function of the key nitrogen fixation activator NifA in beta rhizobia: repression of bacterial auxin synthesis during symbiosis." In IS-MPMI Congress. IS-MPMI, 2023. http://dx.doi.org/10.1094/ismpmi-2023-36.
Testo completoRapporti di organizzazioni sul tema "Synthetic auxins"
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O'Neill, Sharman, Abraham Halevy, and Amihud Borochov. Molecular Genetic Analysis of Pollination-Induced Senescence in Phalaenopsis Orchids. United States Department of Agriculture, 1991. http://dx.doi.org/10.32747/1991.7612837.bard.
Testo completoAbstract (sommario):
The project investigated the molecular genetic and biochemical basis of pollination-induced senescence of Phalaenopsis flowers. This experimental system offered unique advantages in that senescence is strictly regulated by pollination, providing the basis to experimentally initiate and synchronize senescence in populations of flowers. The postpollination syndrome in the Phalaenopsis orchid system was dissected by investigating the temporal and spatial regulation of ACC synthase gene expression. In the stigma, pollen-borne auxin induces the expression of the auxin-regulated ACC synthase (PS-ACS2) gene, resulting in ACC synthesis within 1 h following pollination. Newly formed ACC is oxidized by basal constitutive ACC oxidase to ethylene, which then induces the expression of the ethylene-regulated ACC synthase(PS-ACS1) and oxidase (ACO1) genes for further autocatalytic production of ethylene. It is speculated that during the 6-h period following pollination, emasculation leads to the production or release of a sensitivity factor that sensitizes the cells of the stigma to ethylene. ACC and ethylene molecules are translocated from the stigma to the labellum and perianth where ethylene induces the expression of PS-ACS1 and ACO1 resulting in an increased production of ACC and ethylene. Organ-localized ethylene is responsible for inrolling and senescence of the labellum and perianth. The regulation of ethylene sensitivity and signal transduction events in pollinated flowers was also investigated. The increase in ethylene sensitivity appeared in both the flower column and the perianth, and was detected as early as 4 h after pollination. The increase in ethylene sensitivity following pollination was not dependent on endogenous ethylene production. Application of linoleic and linoleic acids to Phalaenopsis and Dendrobium flowers enhanced their senescence and promoted ethylene production. Several major lipoxygenase pathway products including JA-ME, traumatic acid, trans-2-hexenal and cis-3-hexenol, also enhanced flower senescence. However, lipoxygenase appears to not be directly involved in the endogenous regulation of pollination-induced Phalaenopsis and Dendrobium flower senescence. The data suggest that short-chain saturated fatty acids may be the ethylene "sensitivity factors" produced following pollination, and that their mode of action involves a decrease in the order of specific regions i the membrane lipid bilayer, consequently altering ethylene action. Examination of potential signal transduction intermediates indicate a direct involvement of GTP-binding proteins, calcium ions and protein phosphorylation in the cellular signal transduction response to ethylene following pollination. Modulations of cytosolic calcium levels allowed us to modify the flowers responsiveness to ethylene.
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Granot, David, and Noel Michelle Holbrook. Role of Fructokinases in the Development and Function of the Vascular System. United States Department of Agriculture, 2011. http://dx.doi.org/10.32747/2011.7592125.bard.
Testo completoAbstract (sommario):
Plant vascular tissues are superhighways whose development and function have profound implications for productivity, yield and stress response. Preliminary studies by the PI indicated that sugar metabolism mediated by fructokinases (FRKs) has a pronounced effect on the transport properties of the xylem. The goal of this research was to determine how the main fructokinase gene, FRK2, and the only plastidic fructokinase, FRK3, influence vascular development and physiology, emphasizing processes that occur at both the cellular and organismic level. We found that both genes are expressed in vascular tissues, but FRK3 is expressed primarily in vascular tissues of mature petioles. Vascular anatomy of plants with antisense suppression of FRK2 uncovered that FRK2 is necessary for xylem and phloem development, most likely due to its role in vascular cell-wall synthesis, and affects vascular development all over the plant. As a result, suppression of FRK2 reduced hydraulic conductivity of roots, stem and leaves and restricted sugar phloem transport. Vascular anatomy of plants with RNAi suppression of FRK3 uncovered that FRK3 is required for vascular development in mature petiole but its role is partially complemented by FRK2. Suppression of FRK3 combined with partial suppression of FRK2 had effects completely different from that of FRK2 suppression, resulting in wilting of mature leaves rather than young leaves of FRK2 suppressed plants, and decreased export of photoassimilates. This primary effect of FRK2 suppression on mature petioles had a secondary effect, reducing the hydraulic conductivity in roots and stem. The very fact that a plastidic fructokinase plays a role in vascular development is quite surprising and we are still seeking to uncover its metabolic mode-of-action. Yet, it is clear that these two fructokinases have different roles in the coordination between photosynthetic capacity and vascular development. We have started analyzing the role of the last third FRK, FRK1, and discovered that it is also expressed exclusively in vascular tissues. It appears therefore, that all FRKs studied here are involved in vascular development. An interesting unexpected outcome of this study was the connection of FRK2 with hormonal regulation of vascular development, most likely auxin. This observation together with the yet to be solved questions on the exact roles of FRK3 are the subjects of our current efforts.
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Friedman, Haya, Julia Vrebalov, and James Giovannoni. Elucidating the ripening signaling pathway in banana for improved fruit quality, shelf-life and food security. United States Department of Agriculture, 2014. http://dx.doi.org/10.32747/2014.7594401.bard.
Testo completoAbstract (sommario):
Background : Banana being a monocot and having distinct peel and pulp tissues is unique among the fleshy fruits and hence can provide a more comprehensive understanding of fruit ripening. Our previous research which translated ripening discoveries from tomato, led to the identification of six banana fruit-associated MADS-box genes, and we confirmed the positive role of MaMADS1/2 in banana ripening. The overall goal was to further elucidate the banana ripening signaling pathway as mediated by MADS-boxtranscriptional regulators. Specific objectives were: 1) characterize transcriptional profiles and quality of MaMADS1/2 repressed fruit; 2) reveal the role of additional MaMADSgenes in ripening; 3) develop a model of fruit MaMADS-box mode of action; and 4) isolate new components of the banana ripening signaling pathway. Major conclusion: The functions of the banana MaMADS1-5 have been examined by complimenting the rinor the TAGL1-suppressed lines of tomato. Only MaMADS5 exhibited partial complementation of TAGL1-suppressed and rinlines, suggesting that while similar genes play corresponding roles in ripening, evolutionary divergence makes heterologous complementation studies challenging. Nevertheless, the partial complementation of tomato TAGL1-surpessed and rinlines with MaMADS5 suggests this gene is likely an important ripening regulator in banana, worthy of further study. RNA-seqtranscriptome analysis during ripening was performed on WT and MaMADS2-suppressed lines revealing additional candidate genes contributing to ripening control mechanisms. In summary, we discovered 39 MaMADS-box genes in addition to homologues of CNR, NOR and HB-1 expressed in banana fruits, and which were shown in tomato to play necessary roles in ripening. For most of these genes the expression in peel and pulp was similar. However, a number of key genes were differentially expressed between these tissues indicating that the regulatory components which are active in peel and pulp include both common and tissue-specific regulatory systems, a distinction as compared to the more uniform tomato fruit pericarp. Because plant hormones are well documented to affect fruit ripening, the expressions of genes within the auxin, gibberellin, abscisic acid, jasmonic acid, salicylic and ethylene signal transduction and synthesis pathways were targeted in our transcriptome analysis. Genes’ expression associated with these pathways generally declined during normal ripening in both peel and pulp, excluding cytokinin and ethylene, and this decline was delayed in MaMADS2-suppressed banana lines. Hence, we suggest that normal MaMADS2 activity promotes the observed downward expression within these non-ethylene pathways (especially in the pulp), thus enabling ripening progression. In contrast, the expressions of ACSand ACOof the ethylene biosynthesis pathway increase in peel and pulp during ripening and are delayed/inhibited in the transgenic bananas, explaining the reduced ethylene production of MaMADS2-suppressed lines. Inferred by the different genes’ expression in peel and pulp of the gibberellins, salicylic acid and cytokinins pathways, it is suggested that hormonal regulation in these tissues is diverse. These results provide important insights into possible avenues of ripening control in the diverse fruit tissues of banana which was not previously revealed in other ripening systems. As such, our transcriptome analysis of WT and ripening delayed banana mutants provides a starting point for further characterization of ripening. In this study we also developed novel evidence that the cytoskeleton may have a positive role in ripening as components of this pathway were down-regulated by MaMADS2 suppression. The mode of cytoskeleton involvement in fruit ripening remains unclear but presents a novel new frontier in ripening investigations. In summary, this project yielded functional understanding of the role and mode of action of MaMADS2 during ripening, pointing to both induction of ethylene and suppression of non-ethylene hormonal singling pathways. Furthermore, our data suggest important roles for cytoskeleton components and MaMADS5 in the overall banana ripening control network. Implications: The project revealed new molecular components/genes involved in banana ripening and refines our understanding of ripening responses in the peel and pulp tissues of this important species. This information is novel as compared to that derived from the more uniform carpel tissues of other highly studied ripening systems including tomato and grape. The work provides specific target genes for potential modification through genetic engineering or for exploration of useful genetic diversity in traditional breeding. The results from the project might point toward improved methods or new treatments to improve banana fruit storage and quality.