Dissertations / Theses on the topic 'Hordeum'

The fungal pathogen Puccinia hordei Otth. is the causal agent of the leaf rust disease on barley. It is an economically important disease worldwide. The pathogen occurs in all barley growing regions of Australia. The present study assessed a diverse African barley germplasm for resistance to this disease in the seedling (10 pathotypes) and adult (one pathotype) growth stages which resulted in identification of new sources of high and moderate adult plant resistance (APR) different from the known APR genes Rph20 and Rph23. In addition, known seedling resistance genes were also postulated. The African barley collection was also assessed for seedling resistance to three pathotypes of the stem rust pathogen P. graminis tritici (Pgt). New seedling resistance for Pgt that lacked the molecular markers for the known Pgt resistant genes Rpg1 and Rpg5 were identified in 18 accessions. Genetic and molecular characterisation was conducted in new APR to P. hordei identified in six barley lines, four from Africa and two from Uruguay. Using the Diversity Array Technology (DArT) molecular markers a monogenic resistance locus identified in a line was mapped on chromosome 6H based on selective genotyping. Using DArT molecular markers, the first designated seedling leaf rust resistance gene Rph1 was mapped at 8.85 – 10.48 cM interval on the short arm of chromosome 2H using two mapping populations. Genetic, cytogenetic and molecular characterisation was carried out on two barley lines displayed resistance to the wheat yellow rust pathogen P. striiformis tritici (Pgt) and the barley grass yellow rust (BGYR) pathogen P. striiformis pseudo-hordei revealed that each line carried two and three effective genes against Pst and BGYR, respectively, with two common genes effective against both pathogens in each genotype. A locus conferring hypersensitive resistance to BGYR was mapped between 11.76 and 18.57 cM in chromosome 1H.

Wild Hordeum species, from the four genome groups of X, H, I and Y, were assessed for physiological traits associated with tolerance to salinity and waterlogging. When grown in saline conditions, a number of wild Hordeum species had exceptional ‘exclusion’ of Na+ and Cl- from the young leaves, and also maintained tissue K+ concentrations, compared with Hordum vulgare ssp. vulgare (cv. ‘Golf’). For example, at 150 mol m-3 NaCl, the K+:Na+ in youngest, fully expanded leaf blades of wild Hordeum species averaged 5.2, compared with 0.8 in H. vulgare. H. marinum was more salt tolerant than H. vulgare, with a relative growth rate 30% higher than H. vulgare at 150 mol m-3 NaCl. At 300 mol m-3 NaCl, glycinebetaine plus proline contributed to 15% of πsap in expanding leaf blades of H. marinum, compared with 8% in H. vulgare. When grown in stagnant conditions, 16 accessions (approximately half of those evaluated) formed a barrier to radial O2 loss (ROL) in basal zones of adventitious roots. In the Triticeae, this trait had previously only been described in one species, H. marinum. The barrier to ROL occurred only in accessions from wetland or intermediate habitats, and was also related to genome type, being present in accessions with the X or the H genome (Hordeum vulgare has the I genome). In stagnant conditions, aerenchyma formed was, on average; 22% in accessions with the X genome; 19% in those with the H genome; and 15 and 16% in those with the I or the Y genomes, respectively. The combination of a barrier to ROL and aerenchyma enhances longitudinal O2 movement in adventitious roots, permitting roots to penetrate deeper into anaerobic substrates. In H. marinum, induction of the barrier to ROL was associated with a 97% reduction in apparent O2 diffusivity across the external layers of the basal zones of roots, compared with near the root tip. The barrier results from physical resistance to radial O2 movement, although when roots were cooled to suppress respiration some additional leakage of O2 was detected, indicating respiration also contributes to the low rates of ROL from the basal regions of roots. Low radial O2 permeability in the roots of stagnantly-treated H. marinum was associated with secondary thickening, putatively lignin or suberin deposits, in the hypodermis. These changes in root structure, however, did not influence root hydraulic conductivity, assessed for individual adventitious roots and whole root systems. Thus, diversity amongst Hordeum species in expression of traits for tolerance to waterlogging (an inducible barrier to ROL and aerenchyma) and salinity (Na+ and Cl- ‘exclusion’) were documented in this study. Traits for root aeration did not compromise the capacity of roots to take up water, presumably being of importance for growth in soils with fluctuating water levels (i.e. wet/dry cycles). The high degree of salinity tolerance in several Hordeum species, and especially in H. marinum, is consistent with field observations that these species occur in salt affected areas

Leaf rust caused by Puccinia hordei is one of the most common and widely distributed rust diseases of barley. Deploying genetic resistance is considered as the most effective and environmentally friendly approach to control this disease. Among 27 designated loci conferring resistance to P. hordei, three genes, namely Rph1, Rph15, and Rph22, have been previously isolated. In this study, the Rph3 gene was isolated using the positional cloning approach. A high-resolution map of the gene constructed using 10,411 F2 plants from six segregating populations delimited the Rph3 locus between two markers covering an interval of 0.024 cM. The physical map revealed that these two closest markers delimited a region of 8.5kb bp in Rph3-carrying cultivars such as cv. Barke and 98kb bp in cultivars lacking Rph3 such as cv. Morex. Two putative genes were determined within the 8.5kb region using FGENESH. The candidate gene for Rph3 was validated by mutational analysis, where four independent point mutations confirmed that ORF2 is Rph3. The resistance gene Rph3 encodes a protein of unknown function that does not belong to any known plant disease resistance protein family. The amino acid sequence showed no sequence homology to any domains/motifs of known function. Predictions using various tools revealed five to seven transmembrane helices in the structure of RPH3. Gene expression was locally induced at the infection site by pathotypes avirulent for Rph3. The current results suggest that the Rph3 gene acts like an executor gene that is regulated by transcriptional activator-like (TAL) effectors. A second study determined that resistance to P. hordei pathotype 5477 P- in the barley line 67:ZBS15 was conferred by two genes interacting in a complementary manner. One of these two genes is Rph3 and the other one was supposed to be Rph5 or an allele of Rph5 or an independent locus in the same genomic region as that of Rph5.

Barley leaf rust, caused by Puccinia hordei (Ph), is a major disease of barley crops worldwide. In Australia, for more than two decades now, barley leaf rust has appeared as a significant national limitation to the production of high quality barley, as a consequence of ongoing emphasis on barley production in disease prone high rainfall areas, and boosted reliance on barleys with high malt quality, some of which lack effective resistance. Understanding the economic advantage of genetic resistance over fungicides, breeders have attempted to utilize single gene resistance to leaf rust, but poor durability of such resistance with the development of new rust pathogen variants has rendered many important Australian barley varieties susceptible. The poor durability of these genes in Australia is believed to be at least in part due to sexual recombination by the pathogen on the alternate host Ornithogalum umbellatum in South Australia, resulting in high pathotypic and genetic diversity. Although it is known that alternate host species O. umbellatum contributes to the epidemiology of Ph in various regions, few studies have investigated its role in generating genetic variability and new pathotypes. The present studies identified four pathotypes from 25 single pustule isolates of Ph established from aecial infections from O. umbellatum collected from South Australia in 2001. Given that only 11 pathotypes of this pathogen were identified from 88 samples collected in the pathogenicity survey for 2001- 2002 from all of Australia, the recovery of four pathotypes from only 25 isolates from aecia from a single plant of O. umbellatum indicated that the alternate host had enabled the generation of significant pathogenic variability. Based on variability as determined by nine polymorphic SSR markers, six SSR genotypes were identified. While three of these comprised single isolates only, the remaining three included isolates of different pathotypes. The results clearly indicate that O. umbellatum is a source of both pathogenic and genetic variability in P. hordei in South Australia. Studies were conducted to discover and characterise new sources of resistance to Ph for germplasm enhancement and resistance diversification. A set of Canadian breeding lines/cultivars were screened in the greenhouse with an array of pathotypes at the seedling iv growth stage, in field at adult plant growth stages, and with molecular markers linked to known genes conferring Adult Plant Resistance (APR) to leaf rust. The results showed that a vast majority of lines (67%) carried the seedling resistance gene Rph3. Remaining lines resistant to at least one of the pathotypes either carried Rph4 (4%), Rph2+Rph12 (4%) or uncharacterised genes (8%). All lines were susceptible at the seedling stage with the predominant pathotype 5457P+, permitting a critical appraisal of the presence of APR to leaf rust in field tests with this pathotype. These studies identified APR to Ph in 10 of 24 (42%) lines tested, a result that was considered as being promising. The molecular marker analysis indicated that the APR in 12 of these lines is likely distinct from known APR genes Rph20 and Rph23, and hence novel. This is a significant finding in an attempt to identify potentially new sources of APR to leaf rust. Genetic studies were undertaken to characterise and map a new and unique resistance gene (RphFT) in the Chinese barley variety Fong Tien. RphFT was mapped to chromosome 5HL at a genetic position of 142.1 cM using DArT-seq markers. The gene was also confirmed to be present in Australian cultivars Yagan and Lockyer based on allelic tests. It is recommended that the RphFT locus be catalogued as Rph25 in accordance with the rules and numbering system of barley gene nomenclature. Overall, the present studies made a significant contribution in identifying new sources of APR, postulation and confirmation of several known existing seedling and APR genes, and in providing an increased understanding of the role played by the alternate host O. umbellatum in creating genetic variability in P. hordei.

Hordeum bulbosum L. (bulbous barley grass) is an important genetic resource for barley (Hordeum vulgare L.) improvement. As the sole member of the secondary genepool of Hordeum; H. bulbosum represents a relatively untouched source of genetic diversity which can provide novel allelic variation for traits critical to the future of barley breeding. In order to access this resource efficiently, a complete set of molecular marker resources is necessary to assist the introgression of chromatin from H. bulbosum into a barley genetic background. For breeders to access traits from H. bulbosum for barley improvement, recombinant lines need to be developed to transfer regions of the H. bulbosum genome into a barley background for trait identification and for incorporation into elite barley breeding programs. The chromosomal location of H. bulbosum introgressions in thirty eight unique recombinant lines was performed using RFLP analysis using mostly distal probes from barley genetic linkage maps However, this analysis was labour intensive, restrictive and prone to inconsistencies due to low intensity signals and complex banding in H. bulbosum. Due to the low level of interspecific recombination detected between the two species, a retrotransposon-like marker, pSc119.1, was developed which could be used to quickly screen progeny from an interspecific cross to determine which lines possessed introgressions of chromatin from H. bulbosum. After initial screening, putative recombinants were further characterised using co-dominant single locus PCR markers from throughout the genome. A focus was made on using the EST resources of barley and wheat, combined with the rice genome to create intron-spanning markers. Subsequent allele-sequencing revealed high frequencies of species-diagnostic single nucleotide polymorphisms (SNPs) in the intron regions of these markers, coupled with relatively low frequencies of species-diagnostic SNPs in the flanking exon regions. Overall, interspecific SNP frequencies were not significantly higher in intron-spanning markers than those consisting of exon-only sequence. However, species-diagnostic indels were more frequently discovered within intron sequence providing additional polymorphism. Recombinant lines with phenotypes that differed from the barley parent allowed those traits to be assigned to particular chromosomal regions. These characterised recombinant lines will provide a resource for barley breeders to identify novel traits for barley improvement and allow identification of new alleles in different chromosomal locations for current traits, allowing greater flexibility for cultivar construction. A targeted backcross population of the recombinant line 38P18/8/1/10 (possessing leaf rust resistance derived from H. bulbosum) was created. The introgressed region was saturated for PCR markers using a variety of marker types and techniques (AFLP, cDNA-AFLP). Two lines were subsequently identified with introgressions of reduced size relative to the parental recombinant line, both of which have retained the leaf rust resistance trait. The leaf rust resistance was finally linked to two co-dominant EST-based markers located on chromosome 2HL by using these two lines and the direct screening of progeny from interspecific hybrids possessing introgression junctions in the region of interest. In general, recombinant material between barley and H. bulbosum suffers from certation effects which cause distorted segregation that favours heterozygous and homozygous barley genotypes. Two unique lines have been identified during this research that possess gametocidal-type loci that result in the absolute retention of H. bulbosum chromatin with the termination of gametes lacking the introgression (barley genotype only).

Afin d'améliorer nos pratiques agricoles dans le contexte d'une agriculture durable, plusieurs agents de lutte biologique (ALB) ont été développés, testés et sont maintenant utilisés dans le monde pour combattre les pertes de rendements causées par les maladies. Blumeria graminis f. sp. hordei ( Bgh) est l'agent pathogène responsable du blanc de l'orge et peut réduire les rendements de cette culture jusqu'à 40%. Un champignon épiphyte, Pseudozyma flocculosa, a été découvert et identifié en 1987 en association étroite avec le blanc du trèfle. Les chercheurs ont alors remarqué que ce champignon exhibait une forte activité antagoniste contre le blanc en détruisant les structures de l'agent pathogène. Suite à d'autres travaux, il est apparu que ce comportement antagoniste était dirigé contre tous les membres des Erysiphales et semblait lié à la synthèse d'un glycolipide antifongique soit la flocculosine. Toutefois, on n'est toujours pas parvenus à associer l'efficacité de l'ALB avec la production de ce glycolipide. Ces observations suggèrent que d'autres facteurs seraient impliqués lorsque les deux protagonistes, l'ALB et le blanc, sont en contact. L'objectif principal de ce projet était donc de chercher d'autres mécanismes moléculaires pouvant expliquer l'interaction P. flocculosa-blanc et orge, en faisant une analyse transcriptomique complète des trois protagonistes en même temps. L'interaction tripartite a été échantillonnée à différents temps suivant l'inoculation de P. flocculosa sur des feuilles d'orge présentant déjà une intensité de blanc d'environ 50%. Les échantillons de feuilles prélevés ont ensuite été utilisés pour l'extraction de l'ARN qui ont été ensuite transformés en ADNc pour la préparation des librairies. Cinq répliquats ont été effectués pour chaque temps et le tout a été séquencé à l'aide de séquençage par synthèse Illumina HiSeq. Les séquences obtenues (reads) ont ensuite été analysées à l'aide du logiciel CLC Genomics Workbench. Brièvement, les séquences obtenues ont été cartographiées sur les trois génomes de référence. Suite à la cartographie, les analyses d'expression ont été conduites et les gènes exprimés de façon différentielle ont été recherchés. Cette étape a été conduite en portant une attention particulière aux gènes codant pour un groupe de protéines appelées CSEP pour “candidate secreted effector proteins” qui seraient possiblement impliquées dans l'interaction tripartite. Parmi les protéines exprimées de façon différentielle en présence du blanc ou en absence de ce dernier, nous avons pu constater que certaines CSEP étaient fortement exprimées en présence du blanc. Ces résultats sont prometteurs et nous offrent une piste certaine pour l'élucidation des mécanismes impliqués dans cette interaction tripartite.

Four experiments were conducted with the objectives of (i) comparing the suitability of various H. bulbosum clones for haploid production, (ii) determining the parental effects of H. bulbosum and barley genotypes on percentage of pollinated florets yielding caryopses with rescuable embryos and on embryo viability, (iii) comparing different stages for embryo culture and caryopsis culture, and (iv) attempting to produce barley haploids directly from cultured immature caryopses. The results demonstrated: that reproductive characteristics of H. bulbosum clones varied with environmental conditions; that the hybrid H. bulbosum clones MBC-3 and MBC-4 were superior to their parents Cb2920 and Cb2929 as pollen donors; that both parental genotypes and date of harvesting after pollination had large effects on percentage of pollinated florets yielding caryopses with rescuable embryos and on embryo viability; that haploid plantlets can be generated from haploid caryopsis culture without embryo rescue, but only at a low frequency and with a slow rate of germination.

Žinoma, kad pastovi nehistoninių polipetidų frakcija yra išgryninama kartu su eukariotine DNR ir sudaro labai tvirtus (galbūt kovalentinius) kompleksus tarp branduolio baltymų ir DNR. Nustatyta, kad Erlicho ascito tvirtuose DNR-baltymų kompleksuose yra baltymas C1D, baltymai, pasižymintys fosfataziniu ir kinaziniu aktyvumais, kai kurie proteazių slopikliai ir kiti, dar neištirti baltymai. Nepaisant intensyvių tyrinėjimų, eukariotinių ląstelių tvirti DNR-baltymų kompleksai vis dar lieka menkai aprašyti ir yra objektas tolimesniems tyrimams. Augalų TBP-DNR kompleksai kol kas buvo tyrinėti labai mažai. Šiame darbe charakterizuojami miežių Hordeum vulgare tvirti DNR-baltymų kompleksai. Mes tyrėme TBP-DNR kompleksus iš miežių skirtingų ūglių organų ir skirtingų vystymosi stadijų ląstelių: lapų, šaknų, koleoptilės. Norint ištirti tokių nukleoproteidų funkcijas, svarbu charakterizuoti individualius komplekso komponentus: polipeptidus ir DNR. Taigi, išskyrėme tvirtai su DNR sąveikaujančius baltymus iš miežių skirtingos diferenciacijos bei skirtingo amžiaus ląstelių: pirminių lapelių, šaknų, koleoptilės ir juos charakterizavome. Taip pat išskyrėme ir charakterizavome DNR fragmentus iš miežių pirminių lapelių bei vandeninės brandos ir pieninės brandos grūdų TBP-DNR kompleksų. Parodėme, kad miežių TBP baltymai yra 15-160 kDa, dauguma baltymų yra rūgštiniai. Kai kurie iš miežių TBP baltymų (10, 25, 38, 40 ir 55 kDa) pasižymi fosfataziniu, galbūt, Ser/Thr aktyvumu. Nustatėme, kad tam... [toliau žr. visą tekstą]<br>Despite a great deal of research, the functional significance of tightly bound DNA-protein complexes is not yet clear, therefore these complexes are perfect object for pioneering research. Very little is known about plant TBP-DNA complexes. In this work we investigated barley TBP-DNA complexes from different organs (first leaves, roots and coleoptiles) at different developmental stages. We characterized individual components of tightly bound DNA-proteins complexes: polypeptides (TBP) and DNA. We isolated and characterized TBP proteins from barley first leaves, roots and coleoptiles of different age and differentiation stage. Also we isolated and characterized the DNA fragments from barley first leaves and water ripe and milky ripe grain TBP-DNA complexes. We demonstrated that in different developmental stages of coleoptiles, first leaves and roots TBP-DNA complexes were identified as a group of 15-160 kDa proteins, most of TBPs are acidic. Some of barley TBPs (10, 25, 38, 40 and 55 kDa) exhibit phosphatase, maybe Ser/Thr activity. We have identified also that some of TBPs tyrosines were phosphorylated, this modification depends on organ and developmental stage. Identified barley TBPs were involved in fundamental genetic processes, as well as in chromatin rearrangement and regulation processes. Nuclear matrix proteins, enzymes, transcription factors, serpins, immunophilins, and transposon polypeptides were identified among TBPs. We demonstrated that expression of TBPs depends... [to full text]

L'androgénèse est une technique permettant de produire des lignées haploi͏̈des doublées à partir de microspores initialement destinées à produire des grains de pollen. Chez l'orge (Hordeum vulgare L. ), cette technique induit la régénération de plantules albinos en proportion importante constituant un frein à son exploitation industrielle. Notre étude à reposé sur un double objectif fondamental et appliqué, visant 1/ à comprendre les mécanismes gouvvernant la formation de plantules albinos en s'intéressant principalement à la structure des plastes et 2/ à optimiser le pourcentage de plantules androgénétiques chlorophyliennes chez le cv. D'hiver modèle Igri et chez 5 cvs. De printemps. Ce travail est basé sur la comparaison du déroulement de l'androgénèse entre le cultivar d'hiver Igri régénérant principalement des plantules chlorophyliennes et le cultivar de printemps Cork ne donnant que des plantules albinos. Au stade de prélèvement des anthères 15,3±2,7% des plastes des microspores du cv. D'hiver Igri contiennet encore de l'ADN contre 1,7±0,47% pour le cv. De printemps Cork. Après la phase de prétraitement et durant la phase d'induction, cette différence se retrouve au plan structural. Les plastes des embryons du cv. Igri suivent une voie de différenciation en chloroplastes alors que ceux du cv. Cork accumulent simplement de l'amidon en grande quantité, des plastoglobules et des corps prolamellaires. Le cv. Igri fournit une majorité de plantules (108,7 plantules régénérées pour 100 anthères répondantes) avec un G/A égal à 9,4. Le cv. Cork fournit le même nombre de plantules androgénétiques qui sont albinos à 99,7%. Il ressort de cette étude que le programme plastidial des microspores des 2 cvs. Est différent dès le stade de prélèvement des anthères. La phase de prétraitement réoriente bien le programme nucléaire des 2 cvs. Vers un programme sporophytique. Par contre, seul le génome plastidial des cvs. De printemps ne semble pas, dans nos conditions de culture, pouvoir se réorienter vers un programme chlorophylien. Le prétraitement est plus important que la phase d'induction quant à la production de plantules chlorophyliennes. Un prétraitement au mannitol (3,2%) à 4°C durant 3 jours (au lieu d'un prétraitement parle froid à 4°C durant 28 jours. )

The pattern of production, development and survival of component tillers of spring barley (Hordeum distichum) cv. Triumph was investigated. Tiller appearance followed a well-defined pattern, with the emergence of the main shoot followed by that of primary tillers and by higher order tillers. The earliest emerged tillers survived the longest and contributed the largest percentage to grain yield; many of the higher order tillers died prematurely with those surviving contributing little to the grain yield of the whole plant. Tiller death and suppression of tiller production were coincident with the reproductive phase of main shoot development; some late tillering after anthesis was observed. The nutritional and hormonal control of tillering was investigated by applying a range of nutrient and plant growth regulator treatments. Pre-tillering applications of the growth retardant, Terpal, rapidly diminished the growth of the main shoot stem, leaves and roots whilst displaying a promotory effect on tillering. Terpal increased the production and early outgrowth of higher order tillers enabling a greater proportion of these to survive and produce ears; this did not result in any overall increase in yield as mean ear size was reduced. Another growth retardant, Cerone, and the auxin-antagonist, TIBA, similarly promoted tillering. The control of apical dominance systems in uniculm and tillering varieties of barley and wheat were compared. Tiller buds were revealed in the leaf axils of young uniculm plants and in barley it was impossible to initiate their outgrowth whereas several treatments, notably Terpal, Cerone and TIBA promoted tiller production in the uniculm wheat plants. These results are discussed with respect to competition for assimilates/nutrients and the roles of endogenous ethylene, auxin, gibberellins and cytokinins. The possibility of using growth regulators to modify tillering on a commercial scale is discussed and the prospect of seed treatment as a useful method of growth regulator application is also considered.

La dormance primaire des grains d’orge correspond à une inaptitude à germer à l’obscurité à des températures supérieures à 10-15°C et la lumière bleue renforce cette dormance. L’incubation des grains dans des conditions ne permettant pas leur germination (30°C, hypoxie, lumière bleue) induit une perte de l’aptitude à germer après leur transfert à 10 ou 15°C, à l’obscurité et dans l’air. Ce phénomène qui correspond à une induction de dormance secondaire, est observé après 3 jours à 30°C ou à 15°C en hypoxie (5% O2) et après une exposition des grains à 10°C en présence de lumière bleue d’au moins 5 jours. A 30°C, elle nécessite une teneur en eau supérieure à 0. 50 g H2O g-1 MS et est associée à de fortes teneurs en ABA de l’embryon après le transfert à 15°C, alors que la teneur en ABA est peu affectée par l’hypoxie. La lumière bleue entraîne une forte augmentation de la teneur en ABA des embryons et de leur sensibilité à l’ABA et à l’hypoxie. Le rôle d’HvNCED1 (synthèse de l’ABA) semble prépondérant pour l’induction à 30°C alors que celui d’HvNCED2 est plus important en hypoxie, et l’expression des 2 gènes est fortement induite par la lumière bleue. Dans tous les cas, l’induction de la dormance secondaire est associée à une réduction de la signalisation des GA due à une augmentation de l’expression de gènes impliqués dans leur catabolisme et une inhibition de ceux impliqués dans leur synthèse, HvGA2ox3 et HvGA3ox2 jouant un rôle prépondérant. Nos résultats montrent clairement l’implication de la balance ABA/GA et que le profil d’expression des gènes impliqués dans celle-ci dépend des facteurs environnementaux induisant la dormance secondaire<br>Primary dormancy of barley seeds corresponds to an inability to germinate at temperatures higher than 10-15°C, which is reinforced in presence of blue light. Incubation of grains in unfavourable conditions (30°C, hypoxia, blue light) results in a loss of subsequent germination ability at 10 or 15°C, in darkness and in air. This phenomenon considered as an induction of secondary dormancy, is observed after incubation of the grains for 3 days at 30° C or at 15°C in hypoxia (5% O2), or for at least 5 days at 10°C in the presence of blue light. At 30°C, it requires an embryo water content higher than 0. 50 g H2O g-1 DM, and is associated with an increase in embryo ABA content after transfer at 15°C, while ABA content in slightly changed by hypoxia. Blue light results in a strong increase in embryo ABA content and in embryo sensitivity to ABA and hypoxia. The role of HvNCED1 (ABA synthesis) seems dominant in the induction at 30°C, while HvNCED2 seems more important in the induction by hypoxia, and the expression of both genes is strongly induced by blue light. In all cases, the induction of secondary dormancy is associated with a reduction of GA signalling due to increased expression of genes involved in GA catabolism and inhibition of those involved in their synthesis, but HvGA2ox3 and HvGA3ox2 appear to play a leading role. Our results clearly show the involvement of the ABA/GA balance, and that the expression pattern of genes involved in ABA/GA metabolism depends on the environmental factors that induce secondary dormancy

Bibliography: leaves 229-250. The aims of the study were to develop a reliable method for screening for Zn efficiency as an alternative to the current field-based methods, and to determine the extent of genotypic variation in tolerance to Zn deficiency in barley.

Kompleksinis sunkiųjų metalų poveikis vasariniams miežiams (Hordeum vulgare L., veislė ‘Aura DS’). Tyrimo objektas vasariniai miežiai (Hordeum vulgare L., veislė ‘Aura DS’). Tyrimams šie augalai buvo pasirinkti dėl jų gero daigumo ir greito augimo. Tiriamojo darbo tikslas, yra įvertinti sunkiųjų metalų (Cd, Cu Ni, Zn, Pb ir Cr) kompleksinį poveikį vasarinių miežių augimui ir nustatyti sąveikos tarp jų tipą. Tiriamas darbas buvo atliekamas dviem etapais. Pirmiausia tiriamas diferencijuotas (pavienis) Cd, Cu Ni, Zn, Pb ir Cr poveikis vasariniams miežiams (nustatytos EC50 koncentracijos pagal sausos biomasės sumažėjimą lyginant su kontrole intervale nuo 40 iki 60 % : Cd-10,4; Cu-2,6; Ni-10,84; Zn-160; Pb-66,9 ir Cr-14,51 µM). Koncentracijos kompleksiniams tyrimams pasirinktos atskirai įvertinus diferencijuotą poveikį vasarinių miežių sausai biomasei. Kompleksinis tyrimas atliktas tik su dvigubomis (Cd, Cu Ni, Zn, Pb ir Cr) metalų sąveikomis. Kompleksinio tyrimo tirpalus sudarė du atskiri metalai, kurių koncentracijos buvo perpus mažesnės EC50 reikšmėms. Lyginant tarpusavyje EC50 (vieno metalo) ir 0,5xEC50 (dviejų komplekse esančių metalų) poveikių rezultatus, nustatyti galimi sąveikos tarp metalų tipai: antagonizmas, sinergizmas ir suminė sąveika. Sunkiųjų metalų koncentracijos buvo parenkamos juos dedant į mitybinį tirpalą, t.y. kontrolė ir atitinkamas kiekis metalo druskų. Kontrolę sudarė: 0,4 mM CaCl2, 0,65 mM KNO3, 0,25 mM MgCl2•6H2O, 0,01 mM (NH4)2SO4, 0,04 mM NH4NO3... [toliau žr. visą tekstą]<br>Integrated heavy metals impact on spring barley (Hordeum vulgare L.). The object of the research is summer barely (Hordeum vulgare L., breed “Aura DS”). These plants were chosen for the research for their good germination rate and quick growing. The aim of the research work is to evaluate the complex effect of heavy metals (Cd, Cu, Ni, Zn, Pb and Cr) on the growth of summer barely and to determine the type of the interaction between these metals. The research work was done in two stages. At first, the differentiated (discrete) effect of Cd, Cu, Ni, Zn, Pb and Cr on growth of summer barley was investigated (EC50 concentrations were assessed depending on the reduction of dry biomass compared with control in the interval of 40 – 60%: Cd-10,4; Cu-2,6; Ni-10,84; Zn-160; Pb-66,9 and Cr-14,51 µM). Concentrations for complex research of heavy metals were chosen after differentiated effect of these metals on the dry biomass of summer barley was evaluated separately. Complex research was made only with dual interactions of these (Cd, Cu, Ni, Zn, Pb and Cr) metals. The solutions for complex research were made of two separate metals, and the concentrations of these metals were a half EC50 values. The types of possible interactions between these heavy metals were determined when the results of EC50 (one metal) and 0,5xEC50 (two metals in complex) effects were compared: antagonism, synergy and total interaction. Selected concentrations of heavy metals were put in the nutritional solution... [to full text]

This study was designed to explore correlations between flower and seed characters and the relationship of flower and seed characters to yield. Thirty six lines selected from Composite Cross XXXII material were planted in a randomized block design with four replications. At anthesis, spikes from each plot were collected and fixed in 70% alcohol. At the same time, an equivalent spike was tagged to be harvested at maturity. Measurements of flower characters were made on the preserved spikes and seed. Length, width and weight were obtained on the mature spikes. Flower volume was calculated by multiplying the area of lemma and palea by flower thickness. Correlations indicated that selection for flower characters at anthesis would be an effective selection technique for seed characters.

Barley (Hordeum vulgare) ranks in fourth place among cultivated cereals for worldwide production and is a recognized model organism for genetic and genomic studies in the Triticeae tribe, which includes wheats (Triticum species) and rye (Secale cereale). Root and shoot architecture traits are key factors in plant performance, competition with weeds, adaptation and stress responses thus having an important impact on yield and yield stability. Breeders have proposed hypothetical optimal morphological parameters to improve production in relation to different environmental conditions. Leaf size and orientation are determinants of canopy transpiration and radiation interception e.g. in dry and sunny Mediterranean environments reduced size and erect orientation of the leaves can reduce water loss by transpiration and allow deeper light penetration into the canopy. Tillering influences crop performance, biomass and grain production, e.g. a reduction in tillering compensated by an increase dimension and number of kernels per spike could be a strategy of adaptation to dry climates. A reduction in plant height and an augment in stem thickness is connected to lodging resistance. Root system extension is connected to the ability of the plant to reach water. The objectives of this project were to dissect genetic variability for shoot and root morphological traits in barley, identifying genomic regions and characterizing genes controlling these traits, and exploring how different traits influence each other. To this end, two approaches were undertaken depending on the trait(s) under study: • the first exploited natural variation in a panel of modern and old European barley cultivars to carry out association mapping of flowering date, stem diameter, spike fertility, leaf dimension, plant height, tillering and root extension (Chapters 2 and 3); • the second was to characterize the ontogenetic basis of increased tillering using as a case study the many-noded dwarf6.6 (mnd6.6) high tillering barley mutant (Chapter 4). In the first approach, we focused on winter barley because of its agronomic interest in the Mediterranean area, where genetic improvement of drought tolerance is particularly important. We analyzed a panel of 142 European winter barley cultivars (67 two-rowed and 75 six-rowed) with a view to conduct a genome wide association scan (GWAS) for shoot and root architecture traits in two separate sets of experiments. To this end, genotyping data for 4,083 SNPs were available from previous projects of which 2,521 mapped on the POPSEQ barley reference map. PCoA results indicated the existence of two major sub-populations in our germplasm panel, corresponding to two-rowed and six-rowed barley cultivars. In order to study shoot developmental traits (Chapter 2) the panel was phenotyped during the growing season 2012-2013 in a field trial at Fiorenzuola d’Arda, Piacenza, Italy. The experimental scheme consisted in 3 replicates (each being a plot of 24 well spaced plants) in randomized blocks. For selected traits data were integrated and analyzed together with those coming from a parallel field trial that was carried out at the University of Shiraz, Iran (data courtesy of Dr. Elahe Tavakol). Flowering date (FD) and leaf width (LW) were measured in both Italy and Iran, leaf length (LL) was measured only in Iran, plant height (PH), spike length (SL), number of fertile rachis node per spike (NFRN) tillering (T) and (SD) were measured only in Italy. Best Linear Unbiased Estimators (BLUEs) of FD, LW were calculated as the phenotypic values estimated for each genotype in a mixed linear model, where genotypes were set as fixed factor and location, location-genotype interaction and replicates as random factors. For BLUEs calculation of all other traits only replicates were used as random factors. BLUEs were subjected to GWAS analyses, using a mixed linear model (MLM) correcting for population structure with a Q matrix (PCA first three coordinate) and for individuals co-ancestry using a K matrix (a pair-wise matrix defining the degree of genetic covariance among individuals). Significance of marker-trait associations was evaluated based on false discovery rate (FDR)-adjusted p-values (threshold value for significant association was set at 0.05). All traits except tillering exhibited good heritability. Few QTLs were detected in GWAS (five for FD, two for LW, three for LL, one for PH, two for SL, two for NFRN, one for tillering, no one for SM). Flowering date exhibited significant correlation with leaf dimension and spike length and six markers designed on Photoperiod-H1 (Ppd-H1) gene (the major determinant for photoperiod response in barley) were the most significantly associated to FD, LW, LL and SL. In particular the recessive ppd- H1 allele causing reduced photoperiod sensitivity, delayed flowering date and increased leaf dimension and spike length compared to the Ppd-H1 allele. Three markers diagnostic for the HvCEN gene (which regulates flowering date independently from photoperiod) were significantly associated to FD and SL. These results suggested that genes for flowering date could have pleiotropic effects on other morphological traits that may mask other genetic effects. For this reason we tested a novel approach repeating GWAS for LW, LL and SL using flowering date as a cofactor (fixed effect) in further analyses. For SL and LW no new significant associations were found with this method, while new significant associations were uncovered for LL, including two markers on chromosome 5H mapped in a region where narrow leaf dwarf 1a (nld-1a) mutant had previously been previously mapped. Tillering and NFRN were only associated to markers diagnostic INTERMEDIUM-C (INT-C), one of the two main genes controlling row type: in our panel two-rowed genotypes had a significantly higher number of tillers and NFRN compared to six- rowed varieties, confirming the known pleiotropic effects of row-type genes on tillering and NFRN and the balancing of patterns of development by breeding practice for the particular row-type. Based on these results, we run GWAS for NFRN and tillering using row-type as covariate. With this model, we found six markers associated with NFRN on chromosome 5H, in the region hosting HvCO12, HvCO13, HvCO15, XvCCA-1, HvLHY, genes involved in control of flowering date. These same markers, were associated to the duration of the phase between awn primordia formation and tipping (awn arising from flag leaf) in a recently published GWAS study. Together, results from Chapter 2 provide the first evidence of the involvement of the Ppd-H1 gene in control of leaf size and spike length. Thus few QTLs were detected that explain the phenotypic variation for our morphological traits, with some major genes having strong pleiotropic effects that mask minor genetic effects. The use of traits that appear to influence others measures as covariates in GWAS models seems to be a promising approach, although the statistical power of this strategy is still to be evaluated. Germplasm collections with uniform growth habit and row-type are an attractive alternative to prevent confounding effects and allow additional loci to be detected. In Chapter 3, we explored natural genetic variation in root extension using the same winter barley panel as Chapter 2 in growth chamber experiments. In order to evaluate root growth we built 50 cm deep cylindrical pots (called rhizotrons) and used digital scans of the root system to measure total root extension with the winRHIZO software. Based on a series of preliminary tests, we used siliceous sand supplemented with controlled release fertilizer to analyze 4th leaf stage plants from 31 genotypes (9 plants per genotype). Root extension per se exhibited 75% heritability, while normalizing root extension on shoot dry weight resulted in low variability (22%) likely due to low heritability of shoot dry weight in our system. These results support the validity of our protocol for evaluation of genetic variation in root extension in barley and other cereals and indicate significant variation exists in our germplasm panel. Thus, the already collected material will be analysed to phenotype the entire panel. In the future, more variability may be uncovered by exploring wild barleys (Hordeum vulgare spp. spontaneum) or landraces. Tillering is a plastic trait affected by the complex interplay of genetic and hormonal factors with environmental conditions such as plant density/light quality and nutrient availability, which likely complicated genetic dissection of this trait in our field experiment on the winter barley panel (Chapter 2). To circumvent the limited power of the GWAS approach for this trait and understand more about the mechanisms subtending tiller formation, we decided to use the mnd6.6 mutant as a case study to investigate the ontogenetic basis of high tillering in barley and its relation to leaf development. Mutant and wild-type plants were grown in growth in a controlled chamber under long day conditions, and dissected weekly from the emergence to anthesis, registering the development of axillary buds, leaves and tillers together with internode elongation, in relation to shoot apical meristem (SAM) stage. Results show that the mutant is not altered in timing of apical meristem development and differentiation to spike, but has a shorter phyllochron that leads to an increment in the number of leaves per vegetative axis. This in turn results in a higher number of axillary buds and a higher number of tillers. The HvMND6 gene was recently identified and our results are consistent with the activity of the previously characterized rice homologue PLASTOCHRON1, indicating an evolutionarily conserved link between plastochron/phyllochron duration and tillering. Concluding, while significant genetic variation was identified for various traits within the gene pool of our winter barley collection, variability of morphological traits as leaf dimension was subordinated to the length of vegetative period. Indeed, flowering date is one of the major factors on which breeding practice has worked to adapt barley to different environments. Beyond modern European varieties, barley breeding for new ideotypes should explore wider genetic resources as Hordeum spp. spontaneum or landraces. In any case, the existence of correlations between different phenotypes calls for careful evaluation of sources of traits to avoid undesired effects on other traits, e.g. due to the relation between tillering and phyllochrone, breeding for early plant vigour through shortening phyllochron, may have pleiotropic effects and result in increased tillering whose benefits would have to be evaluated.

Endo-β-mannanase is an endohydrolase enzyme responsible for the breakdown of mannan-containing polysaccharides common in the cell walls of many plants. The action of endo-β-mannanase in barley, its optimum temperature and pH for action, temporal and spatial localization, activity in the presence of hormones and sugars and its effect on the seed's mechanical strength were assayed. The development of a spectrophotometric assay for endo-β-mannanase detection was also trialed. The optimum temperature and pH for these experiments were found to be 37℃ and pH 7. Using these parameters, the endo-β-mannanase enzyme was found to be initially localized in the seed coat and moved through to the endosperm over time. The detected level of enzyme activity increased in the presence of gibberellic acid and glucose, or decreased when abscisic acid was added. Similar results were seen when the embryo was removed and the endosperm and seed coat were incubated in hormone- and sugar-containing media. The presence of exogenous endo-β-mannanase did not affect the mechanical strength of the seed but there was a strong correlation between increasing endo-β-mannanase activity and decreasing mechanical strength over time. The spectrophotometric assay for quantifying endo-β-mannanase in extracts showed promise but did not reach fruition due to unexplained sources of variation. The localization and regulation of endo-β-mannanase in barley were similar to those seen in other plants, such as tomato, lettuce and coffee. These findings have biotechnological applications within the brewery industry. By increasing the mobilization of reserves such as mannan, it is thought that the seedling can utilize this secondary carbohydrate source instead of, or at least supplementing, glucose which was mobilized from starch. This will theoretically reduce the starch and glucose lost during the malting period leaving a higher sugar content free for fermentation.

Drought is a major threat to world agriculture. In order to identify proteins associated with plant drought tolerance, barley varieties bred in the UK (Golden Promise) and Iraq (Basrah) were compared. The variety Basrah showed physiological adaptations to drought when compared to Golden Promise, for example relative water content after one week of drought was much higher for Basrah than for Golden Promise in the leaves as well as the roots. Also the water loss rate was significantly different between the two varieties, with the Basrah variety loosing water at about half the rate of Golden Promise. DIGE analyses were carried out on proteins from roots and leaves under control and drought conditions. 24 leaf and 45 root proteins were identified by MALDI-TOF MS spectrometry. The relative expression patterns of the identified proteins fell into a number of distinct classes. The variety Basrah is characterised by constitutive expression or higher drought-induced expression levels of proteins regulating ROS production and protein folding. Photosynthetic enzymes, by contrast, were downregulated in Basrah. Enzyme assays showed a good correlation between DIGE-derived protein abundance estimates and enzyme activity in extracts. Overall this study shows that the enhanced drought tolerance of variety Basrah is driven by an enhanced regulation of ROS under drought. A number of transcription factors with enhanced expression in Basrah under drought conditions were also identified; it is hypothesised that these may contribute to the drought tolerant phenotype and thus make interesting targets for barley breeding experiments.

L'embryogenèse pollinique est une technique d'amélioration des espèces qui permet d'obtenir des plantes haploïdes doublées. Les microspores initialement programmées pour former des grains de pollen sont réorientées afin de produire des plantes haploïdes. Cette technique voit son utilisation réduite chez les céréales à cause de la régénération de plantes albinos. Nous avons cherché à optimiser le protocole afin d'améliorer les rendements en plantules chlorophylliennes chez des cultivars récalcitrants et à identifier les mécanismes moléculaires impliqués dans la réorientation de la microspore en nous focalisant sur les défenses. Notre travail a porté sur la culture d'anthères chez l'orge (Hordeum vulgare L. ). Afin d'améliorer le protocole, nous avons utilisé le cv. D'hiver Igri régénérant majoritairement des plantules chlorophylliennes et cinq cvs. De printemps produisant exclusivement des plantules albinos. L'apport de sulfate de cuivre dans les milieux de prétraitement et de culture a permis d'augmenter le nombre d'anthères formant des embryons, le nombre de plantules régénérées et le pourcentage de plantules chlorophylliennes régénérées chez l'ensemble des cvs. Testés. L'étude de la saison à laquelle les plantes mères sont cultivées a fait apparaitre que les rendements de la culture d'anthères étaient meilleurs pendant les mois les plus longs de l'année. Nous avons également constaté que les résultats obtenus dépendent de la position de l'épi sur le plateau de tallage. Enfin le suivi de la production d'O2- et le suivi d'expression de différents gènes de réponse aux stress nous a permis de mettre en évidence l'activation des défenses dans l'anthère au cours du prétraitement<br>The production of doubled haploid through pollen embryogenesis represents a modern tool for the improvement of cultivated species enabling plant breeders to produce homozygous lines in a few months. Pollen embryogenesis consists in the regeneration of haploid plantlets from microspores, which are initially destined to develop into pollen grains. This technique allows to decrease the time and the cost of classical selection, and to study the mechanisms involved in the embryo formation. Albinism restrains the use of pollen embryogenesis in cereals. This study is based on applied and fundamental aspects in order to 1- optimize the anther culture protocol and to improve green plantlet regeneration in recalcitrant cvs. And 2- identify molecular mechanisms involved in the switch of microspore, especially defenses. In order to optimize the protocole of anther culture in barley (Hordeum vulgare L. ) we used the winter cv. Igri which regenerates chlorophyllous plantlets at 90%, and 5 spring cvs. Giving rise mostly to albino plantlets. The copper sulphate addition in media improved the anthers response, the quantity of regenerated plantlets and the percentage of regenerated chlorophyllous plantlets, with all tested cvs. Spring and summer are the best seasons for pollen embryogenesis in cvs used. Finally, we noticed that results also depended on spike position on the tillering plate. Our results indicate that the pretreatment induces defence mechanisms in anthers, as revealed by an oxidative burst and expression gene induction. Copper sulphate addition in the media induced more progressive and less important induction of gene expression

Changes in chlorophyll content, carotenoid content and composition, abscisic acid and phaseic acid levels, hydrolytic enzyme activity and polypeptide pattern were monitored during senescence of the primary attached leaves of Hordeum vulgare L. cv. Dyan. Senescence occurred due to the normal course of leaf development or was induced by incubation of leaves in darkness. Loss of chlorophyll and total leaf protein was retarded in light whereas it continued rapidly in leaves from dark-incubated seedlings. Chlorophyll alb ratio increased with the progression of senescence, suggesting that chlorophyll b was referentially degraded during this process. Loss of total protein coincided with enhanced activity of acid and neutral proteases. In contrast, loss of chlorophyll was not accompanied by an increase in· peroxidase activity, suggesting that this enzyme was not responsible for initiating chlorophyll breakdown. Carotenoid and abscisic acid levels were monitored in the same tissue extracts. The results obtained show that the increase in endogenous levels of abscisic acid, induced by senescence, correlated with enhanced epoxidation of the xanthophyll cycle, ie., increased conversion of zeaxanthin to antheraxanthin and all-trans-violaxanthin. In addition, an increase in abscisic acid levels occurred concomitant with a decrease in all-trans-violaxanthin and 9'-cis-neoxanthin, suggesting an apparent 1:1 relationship on a molar basis. It is therefore proposed that enhanced abscisic acid production, due to foliar senescence, arises from fluctuations in carotenoid turnover. Polypeptide patterns in isolated chloroplasts, purified thylakoid and stromal fractions were very similar for leaves incubated in either light or darkness. A decrease in intensity of bands was observed in isolated chloroplasts and stromal fractions. Intensity of bands in thylakoids remained unchanged with the progression of senescence. Protein standards of peroxidase and lipoxygenase co-migrated with proteins of the isolated chloroplast. Although tentative, some proteins of the chloroplast may be representative of precursors of hydrolytic enzymes which are known to increase during senescence.

Made available in DSpace on 2016-12-08T16:44:42Z (GMT). No. of bitstreams: 1 PGPV11MA101.pdf: 1302742 bytes, checksum: b7efc06d336ca4a49c0225d1d0b03cfb (MD5) Previous issue date: 2011-02-08<br>The objectives of the work were: a) to obtain the damage function equations for multiple pathosystem to calculate the EDT to time fungicides application; b) to quantify the control and damage of the yield components, and c) To relate the brown spot incidence and severity in different growth stages. The experiments were carry out at the NBN Seeds Company during the 2009 and 2010 crop seasons, located in Muitos Capões county, Rio Grande do Sul state, Brazil and in the Agro science Center at Santa Catarina State University only in 2010. The cultivar BRS Cauê was used as susceptible cultivar to brown spot and powdery mildew. The experiments design was in randomized block with four replications. The nine treatments consisting of different rates (half and recommended rates) and fungicide applications number (one, two, three and four) of mixture strobilurin and triazole fungicides, generating the disease gradients intensity. The total area of 5.0 x 2.5 m was the experimental unit in both experiments. The fungicide applications and incidence and severity assessment were done at EC 22, EC 31, EC 39, EC 45 and EC 56 plant development stages. Plants from central rows of each plot were manually harvested and grain yield (GY), one-thousand grain weight (TGW) and granulometry (G) were evaluated. In the first chapter, the damage function equations between disease intensity and GY for each plant development stages, obtained by regression analysis, in both 2009-10 crop growing seasons were significant and negative indicative that increasing disease severity lead into decreasing grain yield. The damage coefficients of these equations can be used to calculate the economic damage threshold. In the second chapter, the values of disease intensity were used to calculate the area under disease progress curve (AUDPC). The GY, TGW, G and AUDPC values were tested using the mean comparison between treatments and the percentage of damage and disease control were determinated. The largest 2009 crop damage was 45.87%, 15.47% and 25.84% for GY, G and TGW, respectively. The ultimate control was 68.11% when considered the severity and four foliar applications, independent of the used dose. In 2010, the greatest damage were 31.16%, 14.02% and 10.76% in Muitos Capões and 39.44%, 23.59% and 45.88%, in Lages, for GY, 10 TGW and G, respectively. The highest percentage of control, based on the leaf severity were 71.63% and 73.96% for Muitos Capões and Lages, respectively. The greater control, independent of used dose were obtained with three and four applications in Muitos Capões and four applications in Lages. In the third chapter, brown spot incidence and severity data were subjected to regression analysis and correlation and the obtained values were significant and positive. The brown spot and powdery mildew diseases incidence and severity recommended by the Technique Indication of crop (TIC) to initiate fungicide applications is 20% and 5% respectively. The severity average values for initiating chemical control are 0.77% and 0.34% respectively for 2009 and 2010 crop seasons when the incidence diseases were substituted in the equations. These values are lower than TIC recommended values<br>Os objetivos do trabalho foram: a) obter equações de função de dano para patossistema múltiplo para calcular o LDE servindo como critério indicador de aplicação de fungicidas; b) quantificar controle e dano nos componentes de rendimento; e c) relacionar incidência e severidade foliar da mancha marrom em diferentes estádios fenológicos. Os experimentos foram conduzidos nas safras agrícolas 2009 e 2010 na NBN Sementes no município de Muitos Capões, RS; e, na safra de 2010 no Centro de Ciências Agroveterinárias no município de Lages, SC. Em todos os experimentos foi utilizada a cultivar BRS Cauê suscetível à mancha marrom e oídio. O delineamento foi blocos casualisados, com quatro repetições e nove tratamentos constituídos de diferentes doses (meia dose e dose indicada) e número (uma, duas, três e quatro) de aplicações de fungicidas triazóis e estrobilurinas para gerar os gradientes de intensidade das doenças. A área de cada unidade experimental correspondeu a 5,0 x 2,5 m. As aplicações e as avaliações da incidência e severidade foliar ocorreram nos estádios de crescimento (EC) EC 22, EC 31, EC 39, EC 45 e EC 56. A colheita foi manual cortando as plantas das linhas centrais de cada parcela. Foram avaliados rendimento de grãos (RG), massa de mil grãos (MMG) e granulometria (G). No primeiro capítulo, as equações de função de dano entre intensidade de doença e RG para cada EC, obtidas por análise de regressão, em ambas as safras agrícolas, foram significativas e negativas, ou seja, à medida que aumentou a intensidade de doença, diminuiu o RG. Os coeficientes de dano obtidos podem ser utilizados no cálculo do limiar de dano econômico. No segundo capítulo, os valores de intensidade das doenças foram usados para o cálculo da área abaixo da curva de progresso da doença (AACPD). Os valores de RG, MMG, G e AACPD foram submetidos ao teste de comparação de médias. Foram determinados o percentual de dano e de controle das doenças. Na safra 2009, os maiores danos foram 45,87%, 15,47% e 25,84% para RG, MMG e G, respectivamente. O controle máximo foi 68,11% considerando a severidade foliar e quatro aplicações, independente da dose usada. Em 2010, os maiores danos foram 31,16%, 14,02% e 10,76% em Muitos Capões e 39,44%, 23,59% e 8 45,88% em Lages, respectivamente para R, MMG e G. Com base na severidade obteve-se controle de 71,63% e 73,96% em Muitos Capões e Lages, respectivamente. Em Muitos Capões três e quatro aplicações e em Lages quatro aplicações, independente da dose, apresentaram maior percentual de controle. No terceiro capítulo, os dados de incidência e severidade foliar de mancha marrom foram submetidos à análise de regressão e correlação. As equações obtidas foram significativas e positivas. A incidência e a severidade foliar recomendado pela Indicação Técnica da cultura (ITC) para iniciar as aplicações de fungicidas é de 20% e 5%, respectivamente. Substituindo esse valor de incidência nas equações obtidas têm-se valores médios de severidade para iniciar o controle químico de 0,77% e 0,34% respectivamente para 2009 e 2010, inferior ao recomendado pela ITC

Genetic studies were carried out to determine the inheritance of unknown seedling resistance (USR) to leaf rust (caused by Puccinia hordei Otth.) in the barley cultivar Ricardo. In the greenhouse Ricardo/Gus F3 (187 lines) and BC1F2 (130 lines) populations based studies using an array of P. hordei pathotypes (pts), revealed that the USR in Ricardo was conferred by a single dominant gene, which was tentatively named RphRic. Bulk segregant analysis (BSA) of the F3 population using a multiplex-ready PCR technique mapped RphRic on chromosome 4H flanked by markers GBM1220 and GBM1003 at distances of 17.4 cM and 20.4 cM, respectively. Being the first gene for leaf rust resistance mapped on chromosome 4H, RphRic was catalogued as Rph21. Phenotyping of Ricardo/Peruvian (Rph2) F3 populations and genotyping of both parents using the Rph2-linked marker ITS1 confirmed the presence of Rph2 in Ricardo. The Ricardo/Gus F3 and BC1F2 populations segregated for the presence of an additional gene when tested under field conditions using the same pathotype (pt), 5457P+ (used in greenhouse). This uncharacterised adult plant resistance (APR) against P. hordei, found in Ricardo, appeared to be distinct from Rph20 when genotyped using a closely linked marker bPb-0837. Responses of 113 advanced breeding lines and cultivars of barley (Hordeum vulgare L. subsp. vulgare), along with the susceptible control genotype Gus, were assessed against P. hordei pts in the greenhouse at seedling and field at adult plant growth stages. The tests revealed the presence of APR in 68 lines, USR in 23 lines and the seedling resistance gene Rph3 in three lines. Marker bPb-0837 was present in 35 of the 68 lines carrying APR, which suggested that these 35 lines carry APR gene Rph20. The remaining 33 lines, which lacked the Rph20 linked marker, likely carry new sources of APR. Pedigree analysis of the 68 lines found to carry APR revealed that 32 were related to cultivar (cv.) Gull and to H. laevigatum, two were related to cv. Bavaria and one related to cvv. Manchuria and Taganrog. Ancestral pedigree analysis also revealed the common presence of cv. Diamant (X-ray mutant) in the parentage of lines likely carrying Rph20. The remaining 19 lines lacked detectable seedling resistance and were susceptible in the field at adult plant growth stages. Four international barley nurseries comprising 820 lines with 579 unique pedigrees were sourced from the International Centre for Agricultural Research in the Dry Areas (ICARDA) and analysed for resistance against isolates of P. hordei, P. graminis f. sp. tritici (Pgt) and barley grass stripe rust (BGYR). Overall analyses of the responses of 783 lines (excluding 37 missing lines) to P. hordei showed that 728 (93%) carried the major seedling resistance gene Rph3, five (0.65%) carried USR, six (0.75%) carried uncharacterised APR and 44 (5.6%) lines were susceptible at all growth stages. Of the six lines identified with uncharacterised APR, three likely carried Rph20 based on the presence of the Rph20-linked marker bPb-0837. Based on tests with several control genotypes, marker bPb-0837 was found to be more reliable than Ebmag0833 in detecting the presence of Rph20. All lines were resistant to Pgt pt 98-1,2,3,5,6 when tested as seedlings in the greenhouse. Out of the 783 lines tested, 164 produced immune responses, 284 produced resistant (1= to 3) responses and 335 produced mesothetic (X type) responses against pt 98-1,2,3,5,6. All but two 783 lines were highly resistant to BGYR in greenhouse tests, showing immune responses. The usefulness of 148 simple sequence repeats (SSRs) in revealing variability among Australian isolates of P. hordei were assessed. The markers comprised 71 developed for Pgt, 40 developed for P. triticina (Pt) and 37 developed for P. coronata f. sp. avenae (Pca). SSRs were tested across 22 pts of P. hordei from Australasia including one isolate of each of the control pathogens [Pt, Pgt, P. striformis f. sp. tritici (Pst), BGYR and P. graminis f. sp. avenae (Pga)]. Genotyping of P. hordei was also conducted with the PCR-fingerprinting primers M13 and (GACA)4. The SSRs developed from Pgt and Pt showed 100% cross amplification in P. hordei, while only nine Pca SSRs showed amplification in P. hordei. Of the 148 markers tested, only two Pgt SSRs (F4-15 and F7-22) were polymorphic. Both PCR-fingerprinting primers revealed polymorphisms among the isolates, with (GACA)4 generating the most informative fragments. Both SSRs and PCR fingerprinting markers out grouped the control pathogens Pt, Pgt, Pst, BGYR and Pga from the P. hordei pts. Polymorphic information content (PIC) values of SSR markers F4-15 and F7-22 were calculated as 0.50 and 0.55 respectively. Molecular analyses revealed evidence of clonal lineages among the P. hordei pts, supporting the hypothesis that some of the pts arose from mutational changes in the virulence of a founder pt. Sexual recombination within P. hordei in Australia on the alternate host Ornithogalum umbellatum may have resulted in some new pts with different virulence against Rph genes. This is the first study of Australasian pts of P. hordei using PCR-fingerprinting technique and SSR genotyping.

A l’ordi, la llum i la temperatura controlen la floració a través de la interacció entre els gens de vernalització i fotoperíode. Es coneix menys sobre l’efecte d’altres atributs, com la qualitat de llum. L’objectiu principal d’aquesta tesi és profunditzar en el control genètic del temps de floració a l’ordi, centrant-se en la temperatura, el fotoperíode i la qualitat espectral, afectarà la fenologia i els gens que controlen. Aquest treball es revela la regulació dels principals gèneres de floració sota condicions no inductives, ha presentat nous candidats de la ruta de floració i ha aprofundit en la resposta als canvis de longitud del dia i de qualitat de llum. Les diferències genotípiques trobades i els mecanismes genètics proposats en aquest treball poden ser útils per al disseny d’idiotips d’ordi millor adaptats per a futures condicions climàtiques.<br>En cebada, la luz y la temperatura controlan la floración a través de la interacción entre los genes de vernalización y fotoperíodo. Se conoce menos sobre el efecto de otros atributos, como la calidad de luz. El objetivo principal de esta tesis es profundizar en el control genético del tiempo de floración en cebada, centrándonos en cómo la temperatura, el fotoperíodo y la calidad espectral, afectan la fenología y los genes que la controlan. En este trabajo se ha revelado la regulación de los principales genes de floración bajo condiciones no-inductivas, se han propuesto nuevos candidatos de la ruta de floración y se ha profundizado en la respuesta a los cambios de longitud de día y de calidad de luz. Las diferencias genotípicas encontradas y los mecanismos genéticos propuestos en este trabajo pueden ser herramientas útiles para el diseño de ideotipos de cebada mejor adaptados para futuras condiciones climáticas.<br>In barley, temperature and light cues control flowering through the interaction between vernalization and photoperiod genes. Less is known about the effect of other attributes, as light quality. The main objective of this thesis is to increase our knowledge on the genetic control of flowering time in barley, focusing on how temperature, photoperiod and spectral quality, affect to phenology and the flowering time genes. In this work, the regulation of the main flowering genes under non-inductive conditions was revealed, new candidates for the flowering pathway were proposed, and the response to changes in day length and light quality has been deepened. The genotypic differences found and the genetic mechanisms proposed in this work can be useful tools for the design of barley ideotypes better adapted for future climatic conditions.

Bibliography: leaves 183-211. This study evaluates the backcross breeding method for the introgression in barley of agronomically important traits into a malting quality background using molecular markers.

Despite a great deal of research, the functional significance of tightly bound DNA-protein complexes is not yet clear, therefore these complexes are perfect object for pioneering research. Very little is known about plant TBP-DNA complexes. In this work we investigated barley TBP-DNA complexes from different organs (first leaves, roots and coleoptiles) at different developmental stages. We characterized individual components of tightly bound DNA-proteins complexes: polypeptides (TBP) and DNA. We isolated and characterized TBP proteins from barley first leaves, roots and coleoptiles of different age and differentiation stage. Also we isolated and characterized the DNA fragments from barley first leaves and water ripe and milky ripe grain TBP-DNA complexes. We demonstrated that in different developmental stages of coleoptiles, first leaves and roots TBP-DNA complexes were identified as a group of 15-160 kDa proteins, most of TBPs are acidic. Some of barley TBPs (10, 25, 38, 40 and 55 kDa) exhibit phosphatase, maybe Ser/Thr activity. We have identified also that some of TBPs tyrosines were phosphorylated, this modification depends on organ and developmental stage. Identified barley TBPs were involved in fundamental genetic processes, as well as in chromatin rearrangement and regulation processes. Nuclear matrix proteins, enzymes, transcription factors, serpins, immunophilins, and transposon polypeptides were identified among TBPs. We demonstrated that expression of TBPs depends... [to full text]<br>Žinoma, kad pastovi nehistoninių polipetidų frakcija yra išgryninama kartu su eukariotine DNR ir sudaro labai tvirtus (galbūt kovalentinius) kompleksus tarp branduolio baltymų ir DNR. Nustatyta, kad Erlicho ascito tvirtuose DNR-baltymų kompleksuose yra baltymas C1D, baltymai, pasižymintys fosfataziniu ir kinaziniu aktyvumais, kai kurie proteazių slopikliai ir kiti, dar neištirti baltymai. Nepaisant intensyvių tyrinėjimų, eukariotinių ląstelių tvirti DNR-baltymų kompleksai vis dar lieka menkai aprašyti ir yra objektas tolimesniems tyrimams. Augalų TBP-DNR kompleksai kol kas buvo tyrinėti labai mažai. Šiame darbe charakterizuojami miežių Hordeum vulgare tvirti DNR-baltymų kompleksai. Mes tyrėme TBP-DNR kompleksus iš miežių skirtingų ūglių organų ir skirtingų vystymosi stadijų ląstelių: lapų, šaknų, koleoptilės. Norint ištirti tokių nukleoproteidų funkcijas, svarbu charakterizuoti individualius komplekso komponentus: polipeptidus ir DNR. Taigi, išskyrėme tvirtai su DNR sąveikaujančius baltymus iš miežių skirtingos diferenciacijos bei skirtingo amžiaus ląstelių: pirminių lapelių, šaknų, koleoptilės ir juos charakterizavome. Taip pat išskyrėme ir charakterizavome DNR fragmentus iš miežių pirminių lapelių bei vandeninės brandos ir pieninės brandos grūdų TBP-DNR kompleksų. Parodėme, kad miežių TBP baltymai yra 15-160 kDa, dauguma baltymų yra rūgštiniai. Kai kurie iš miežių TBP baltymų (10, 25, 38, 40 ir 55 kDa) pasižymi fosfataziniu, galbūt, Ser/Thr aktyvumu. Nustatėme, kad tam... [toliau žr. visą tekstą]

ABSTRACT The original objective of this work was to compare the cellular processes in salt tolerant and salt sensitive plants cells to gain insight into the mechanisms that confer halotolerance. Halotolerant and salt sensitive cell lines were derived from the model glycophyte Arabidopsis thaliana; in addition cell suspension cultures from the dicot halophytes Beta vulgaris and Atriplex halimus were also generated. Unfortunately, severe disruptions were encountered following a serious fire; persistent power failures, and failures of new equipment hampered progress with this work. For this reason, only comparisons between the Arabidopsis cell lines were completed. The halotolerant (HHS) cell lines survival strategy is to prevent Na accumulation when grown in < 100 mM NaCl. Wild type (WT) cells grow faster than HHS cells in the absence of NaCl, but rapidly take up Na in 50 mM NaCl where their growth is severely affected, and fail to grow completely above 100 mM NaCl. No evidence was found to suggest this growth impairment arose from osmotic stress or nutrient ion deficiencies. Protein profiling of HHS cells identified a number of proteins whose abundance is regulated by salt stress. These included proteins involved in ion transport, central metabolism, and general stress responses. The implications of these findings are discussed. In a separate project, a whole plant approach was taken to establish the physiological mechanisms that account for the reported difference in halotolerance between two commercially grown barley lines originating from China. Measurements on growth and development, plant water status, tissue ion profiling, photosynthesis rates, and transpiration rates suggested the tolerant line (Zhou 1) enters the reproductive phase of its life cycle approximately one week earlier than the sensitive line (Zhou 85), and this critical period allows floral development resulting in improved yields. This early ii flowering is not associated with the well characterized PpD-H1 locus controlling early flowering in cereals. The main conclusion from this study is that for glycophytes that do not complete a full life cycle above 100 mM NaCl (which includes all of the world’s major crops), it is the ionic component of salinity stress that impairs growth and yield. Further research on salinity stress in crops should focus on understanding the processes that control ionic balance rather than osmoregulation.

O Brasil é um importante importador de cevada sendo este cereal um dos mais sensíveis ao alumínio tóxico (Al3+) dentre as gramíneas. O Al3+ inibe o crescimento radicular levando à redução na absorção de água e nutrientes. O gene HvAACT1 codifica um transportador de citrato responsável pela tolerância em cevada. Existe pouca informação sobre a diversidade genética de cevada brasileira e sobre sua variabilidade quanto a tolerância ao Al3+. Assim, os objetivos deste trabalho foram caracterizar a variabilidade genotípica e fenotípica da tolerância ao Al3+ em genótipos de cevada cultivada e silvestre, analisar a região transcrita do gene HvAACT1 e a diversidade genética de cevada brasileira. Em hidroponia foram fenotipados 65 genótipos (59 de cevada cultivada e seis de silvestre). Com base nestes dados, 22 genótipos foram selecionados para fenotipagem de curta duração em solo. Os genótipos cultivados no Brasil, Antarctica 01 e MN 6021, foram utilizados como controles de tolerância e sensibilidade, respectivamente. Tolerância superior a Antarctica 01 foi encontrada em seis genótipos, e apenas um foi inferior a MN 6021. O genótipo Golden Promise, reconhecido como sensível, foi classificado como tolerante em hidroponia e intermediário em solo. Dentre os genótipos avaliados em solo, Dayton e Murasakimochi superaram Antarctica 01, e a linhagem transgênica L5 apresentou o melhor desempenho. Foi observada correlação de 52% entre as avaliações de hidroponia e solo. O sequenciamento do gene HvAACT1 nos genótipos Antarctica-01 e FM404, tolerantes, e MN 6021 e Paraí-I, sensíveis, revelou alta similaridade da região transcrita. O marcador 21-indel não apresentou associação com a tolerância em hidroponia, entretanto, em solo houve associação. Uma inserção de 1 kb no promotor de HvAACT1, associada à tolerância, foi observada apenas nos genótipos Dayton e Murasakimochi, que foram mais tolerantes que Antarctica-01 em solo e hidroponia. A tolerância ao Al3+ nos genótipos brasileiros não está associada a nenhum dos marcadores analisados. Em relação à variabilidade genética, o conteúdo de informação polimórfica dos materiais brasileiros foi menor uando comparados aos materiais estrangeiros e aos genótipos silvestres. Em geral, a menor diversidade dos materiais brasileiros pode ser explicada pelo uso de ancestrais comuns. O cromossomo 4H, onde reside o gene HvAACT1, apresentou o menor polimorfismo juntamente com o cromossomo 6. A incorporação do alelo contendo a inserção de 1 kb no promotor do gene HvAACT1, bem como a utilização da linhagem transgênica L5, podem ser alternativas para melhorar o desempenho de cevada brasileira em solo ácido. Os programas de melhoramento de cevada no Brasil devem considerar o uso de materiais mais diversos no sentido de aumentar a tolerância de cevada e, eventualmente, rendimento.<br>Brazil is an important barley importer being that cereal one of the most sensitives to toxic aluminium (Al3+) among grasses. The Al3+ inhibits root growth, which can lead to reduced uptake of water and nutrients. The HvAACT1 gene encodes a citrate transporter responsible for Al3+ tolerance in barley. There is little information about the genetic diversity in Brazilian barley and about its variability regarding Al3+ tolerance. In this context, the objectives of this study were to characterize the Al3+ tolerance and the genetic variability of cultivated and wild genotypes from the Embrapa Wheat barley core collection, to analyze the transcribed region of the HvAACT1 gene and genetic diversity in Brasilian barley. Phenotyping was performed in hydroponics for 65 genotypes (59 cultivated and six wild genotypes). Based on the hydroponics data, 22 genotypes were selected for short-term soil experiment. The genotypes grown in Brazil, Antarctica 01 and MN 6021, were used as tolerant and sensitive controls, respectively. Tolerance higher than Antarctica 01 was found in six genotypes and only one showed higher sensitivity than MN 6021. The genotype Golden Promise, worldwide recognized as sensitive, was classified as tolerant in hydroponics and intermediate in soil. In soil, Dayton and Murasakimochi surpassed Antarctica 01, and the transgenic line, L5, presented the best performance. A 52% correlation was obtained between the hydroponics and soil data. The structural region of the HvAACT1 gene was highly similar between the genotypes Antarctica 01 and FM404, tolerant, and MN 6021 e Paraí-I, sensitive. The 21-indel marker could not be associated with tolerance based on the hydroponics data, however, in soil, a correlation was detected. The 1 kb insertion in the HvAACT1 promoter region, which is associated with tolerance, was identified only in Dayton and Murasakimochi, which performed better than Antarctica01 in soil and hydroponics. The variability in Al3+ tolerance among Brazilian genotypes is not associated with the analyzed markers. About the genetic variability, the polymorphic information content among Brazilian genotypes was lower in comparison to the foreign and wild accessions. In general, the lower diversity in Brazilian barley can be explained by the use of common ancestors. Chromosome 4, where the HvAACT1 gene is located, presented the lowest polymorphism together with chromosome 6. The incorporation of the allele containing the 1 kb insertion in the HvAACT1 promoter region as well as the utilization of the transgenic line L5 could be alternatives to improve the performance of Brazilian barley in acidic soil. The barley breeding programs in Brazil should consider the use of more diverse materials in order to increase the barley tolerance to stresses and, eventually yield.

Thesis (Ph.D.) - University of Glasgow, 2007.<br>Ph.D. thesis submitted to the Division of Biochemistry and Molecular Biology, Biomedical and Life Sciences (IBLS), University of Glasgow, 2007. Includes bibliographical references. Print version also available.