Effect of the nud gene on grain yield in barley

Naked barleys are less yielding than the hulled ones while the reason for this difference has not beendefinitely clarified. To investigate the effect of the nud gene on yield, a barley doubled haploid (DH, Proctor 7Nudinka) population was initially tested in three environments and a QTL study was run on the entire populationas well as on two nud/NUD DH subpopulations. Among the agronomic traits studied, a QTL effect was found atnud locus on chromosome 7H only for yield and thousand grain weight (TGW), while a second QTL was found on6H, although contributed by the naked parent. Other QTLs for TGW were identified on 2H, 3H and 5H. Most QTLsfound in the entire population were confirmed by the study on the two groups. No interaction was observed betweenQTLs. To provide a more accurate evaluation of the effects of the nud gene upon grain yield, its components andother agronomic traits, sixteen naked advanced backcross (AB) BC5F2 lines in the hulled background of cultivarArda were prepared and evaluated in a replicated yield trial for two years. The only differences found betweenAB lines and Arda in grain yield and TGW were due to hull weight (11.97% of kernel weight). No differences wereobserved in other traits such as grains/m2, grains per spike, plant height, heading date and mildew resistance. Inconclusion, we think to have clarified that the effect of the nud gene on yield is due to hulls, and we did not findany pleiotropic effect of nud on other traits. This suggests, together with the finding of a QTL contributed by thenaked parent, that there is a great potential to improve naked barley up to the yield levels of hulled barley

Determinants of barley grain yield in drought-prone Mediterranean environments

The determinants of barley grain yield in drought-prone Mediterranean environments have been studied in the Nure x Tremois (NT) population. A large set of yield and other morpho-physiological data were recorded in 118 doubled haploid (DH) lines of the population, in multi-environment field trials (18 site-year combination). Agrometeorological variables have been recorded and calculated at each site too. Four main periods of barley development were considered, vegetative, reproductive early and late grain filling phases, to dissect the effect on yield traits of the growth phases. Relationships between agrometeorological variables, grain yield (GY) and its main components (GN and GW) were also investigated by correlation. Results firstly gave a clear indication of the involvement of water consumption in determining GY and GW (r2=0.616, P=0.007 and r2=0.703, P=0.005, respectively) calculated from sowing to the early grain filling period, while GN showed its highest correlation with the total photothermal quotient (PQ) calculated for the same period (r2=0.646, P=0.013). With the only exception of total PQ calculated during the vegetative period, all significant correlations with GY were associated to water-dependent agrometeorological parameters. As a second result, the NT segregating population allowed us to weight the amount of interaction due to genotypes over environments or to environments in relation to genotypes by a GGE analysis; 47.67% of G+GE sum of squares was explained by the first two principal components. Then, the introduction of genomic information at major barley genes regulating the length of growth cycle allowed us to explain patterns of adaptation of different groups of NT lines according to the variants (alleles) harbored at venalization (Vrn-H1) in combination with earliness (Eam6) genes. The superiority of the lines carrying the Nure allele at Eam6 was confirmed by factorial ANOVA testing the four possible haplotypes obtained combining alternative alleles at Eam6 and Vrn-H1. Maximum yield potential and differentials among the NT genotypes was finally explored through Finlay-Wilkinson model to interpret grain yield of NT genotypes together with yield adaptability (Ya), as the regression coefficient bi; Ya ranged from 0.71 for NT77 to 1.20 for NT19. Lines simply harboring the Nure variants at the two genes behaved as highest yielding (3.04 t ha-1), and showed the highest yield adaptability (bi=1.05). The present study constitutes a starting point towards the introduction of genomic variables in agronomic models for barley grain yield in Mediterranean environments

Epigenetic chromatin modifiers in barley: IV. The study of barley Polycomb group (PcG) genes during seed development and in response to external ABA

<p>Abstract</p> <p>Background</p> <p>Epigenetic phenomena have been associated with the regulation of active and silent chromatin states achieved by modifications of chromatin structure through DNA methylation, and histone post-translational modifications. The latter is accomplished, in part, through the action of PcG (Polycomb group) protein complexes which methylate nucleosomal histone tails at specific sites, ultimately leading to chromatin compaction and gene silencing. Different PcG complex variants operating during different developmental stages have been described in plants. In particular, the so-called FIE/MEA/FIS2 complex governs the expression of genes important in embryo and endosperm development in <it>Arabidopsis</it>. In our effort to understand the epigenetic mechanisms regulating seed development in barley (<it>Hordeum vulgare</it>), an agronomically important monocot plant cultivated for its endosperm, we set out to characterize the genes encoding barley PcG proteins.</p> <p>Results</p> <p>Four barley <it>PcG </it>gene homologues, named <it>HvFIE</it>, <it>HvE(Z), HvSu(z)12a</it>, and <it>HvSu(z)12b </it>were identified and structurally and phylogenetically characterized. The corresponding genes <it>HvFIE</it>, <it>HvE(Z), HvSu(z)12a</it>, and <it>HvSu(z)12b </it>were mapped onto barley chromosomes 7H, 4H, 2H and 5H, respectively. Expression analysis of the <it>PcG </it>genes revealed significant differences in gene expression among tissues and seed developmental stages and between barley cultivars with varying seed size. Furthermore, <it>HvFIE </it>and <it>HvE(Z) </it>gene expression was responsive to the abiotic stress-related hormone abscisic acid (ABA) known to be involved in seed maturation, dormancy and germination.</p> <p>Conclusion</p> <p>This study reports the first characterization of the <it>PcG </it>homologues, <it>HvFIE, HvE(Z)</it>, <it>HvSu(z)12a </it>and <it>HvSu(z)12b </it>in barley. All genes co-localized with known chromosomal regions responsible for malting quality related traits, suggesting that they might be used for developing molecular markers to be applied in marker assisted selection. The <it>PcG </it>differential expression pattern in different tissues and seed developmental stages as well as in two barley cultivars with different seed size is suggestive of a role for these genes in barley seed development. <it>HvFIE </it>and <it>HvE(Z) </it>were also found to be induced by the plant hormone ABA implying an association with ABA-mediated processes during seed development, germination and stress response.</p

Determinants of barley grain yield in drought-prone Mediterranean environments

The determinants of barley grain yield in drought-prone Mediterranean environments have been studied in the Nure x Tremois (NT) population. A large set of yield and other morpho-physiological data were recorded in 118 doubled haploid (DH) lines of the population, in multi-environment field trials (18 site-year combination). Agrometeorological variables have been recorded and calculated at each site too. Four main periods of barley development were considered, vegetative, reproductive early and late grain filling phases, to dissect the effect on yield traits of the growth phases. Relationships between agrometeorological variables, grain yield (GY) and its main components (GN and GW) were also investigated by correlation. Results firstly gave a clear indication of the involvement of water consumption in determining GY and GW (r2=0.616, P=0.007 and r2=0.703, P=0.005, respectively) calculated from sowing to the early grain filling period, while GN showed its highest correlation with the total photothermal quotient (PQ) calculated for the same period (r2=0.646, P=0.013). With the only exception of total PQ calculated during the vegetative period, all significant correlations with GY were associated to water-dependent agrometeorological parameters. As a second result, the NT segregating population allowed us to weight the amount of interaction due to genotypes over environments or to environments in relation to genotypes by a GGE analysis; 47.67% of G+GE sum of squares was explained by the first two principal components. Then, the introduction of genomic information at major barley genes regulating the length of growth cycle allowed us to explain patterns of adaptation of different groups of NT lines according to the variants (alleles) harbored at venalization (Vrn-H1) in combination with earliness (Eam6) genes. The superiority of the lines carrying the Nure allele at Eam6 was confirmed by factorial ANOVA testing the four possible haplotypes obtained combining alternative alleles at Eam6 and Vrn-H1. Maximum yield potential and differentials among the NT genotypes was finally explored through Finlay-Wilkinson model to interpret grain yield of NT genotypes together with yield adaptability (Ya), as the regression coefficient bi; Ya ranged from 0.71 for NT77 to 1.20 for NT19. Lines simply harboring the Nure variants at the two genes behaved as highest yielding (3.04 t ha\u20131), and showed the highest yield adaptability (bi=1.05). The present study constitutes a starting point towards the introduction of genomic variables in agronomic models for barley grain yield in Mediterranean environments

Physical Mapping of Bread Wheat Chromosome 5A: An Integrated Approach

The huge size, redundancy, and highly repetitive nature of the bread wheat [Triticum aestivum (L.)] genome, makes it among the most difficult species to be sequenced. To overcome these limitations, a strategy based on the separation of individual chromosomes or chromosome arms and the subsequent production of physical maps was established within the frame of the International Wheat Genome Sequence Consortium (IWGSC). A total of 95,812 bacterial artificial chromosome (BAC) clones of short-arm chromosome 5A (5AS) and long-arm chromosome 5A (5AL) arm-specific BAC libraries were fingerprinted and assembled into contigs by complementary analytical approaches based on the FingerPrinted Contig (FPC) and Linear Topological Contig (LTC) tools. Combined anchoring approaches based on polymerase chain reaction (PCR) marker screening, microarray, and sequence homology searches applied to several genomic tools (i. e., genetic maps, deletion bin map, neighbor maps, BAC end sequences (BESs), genome zipper, and chromosome survey sequences) allowed the development of a high-quality physical map with an anchored physical coverage of 75% for 5AS and 53% for 5AL with high portions (64 and 48%, respectively) of contigs ordered along the chromosome. In the genome of grasses, Brachypodium [Brachypodium distachyon (L.) Beauv.], rice (Oryza sativa L.), and sorghum [Sorghum bicolor (L.) Moench] homologs of genes on wheat chromosome 5A were separated into syntenic blocks on different chromosomes as a result of translocations and inversions during evolution. The physical map presented represents an essential resource for fine genetic mapping and map-based cloning of agronomically relevant traits and a reference for the 5A sequencing projects

Quality and sustainability of farm, food and forest productions

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Marker-assisted characterization of frost tolerance in barley (Hordeum vulgare L.)

Five molecular markers associated to two frost tolerance QTLs (Fr-H1 and Fr-H2) were tested both on nine Turkish accessions, classified by breeders as highly frosttolerant, and on a previously described sample of 26 barleys, winter, facultative and spring. Accessions were characterized in terms of frost tolerance under both field conditions and artificial freezing test at -12\ub0C. The Turkish lines resulted to be equal or superior to the most tolerant European genotypes tested, showing that they can be used to improve the frost tolerance of the EU barley germplasm. The marker HvBM5A (Vrn-H1 and Fr-H1) resulted to be the best predictor for assisted selection within this germplasm, because of its high correlation between allelic variation and phenotypic traits. Only HvCBF4 of the 3 HvCBF markers tested at Fr-H2 was associated to the trait, but at lower significance than HvBM5A. The PCR-based molecular marker of Vrn-H1 can thus be used in barley breeding not only for selection of facultative and winter types, but also for fast routine selection of frost tolerant genotype

Molecular Characterization Of The Barley Fr-H2 QT Locus

Frost resistance-H2 is major quantitative trait locus that, in combination with VRN-H1/Fr-H1, affects freezing tolerance of barley. Mapping coincident with Fr-H2 are QTLs regulating COR proteins accumulation and a cluster of more than 14 genes encoding CBF transcription factors – at present the best candidates to explain the effects given by the locus. Expression analyses, conducted on a ‘Nure’ x ‘Tremois’ barley mapping population segregating for VRN-H1/Fr-H1 and Fr-H2, revealed that transcript levels of all cold-induced CBF genes at Fr-H2 were significantly higher in recombinants harboring the vrn-H1 winter allele than in recombinants harboring the Vrn-H1 spring allele. Also, steady-state HvCBF2 and HvCBF4 levels were significantly higher in recombinants harboring the Nure allele at Fr-H2. In a positional cloning effort, a large mapping population consisting of more than 3,698 meiotic events was used to fine map Fr-H2. Recombinants between 12 CBF genes under Fr-H2 have been identified in a total genetic distance of 0.81 cM. The few recombinants between the different HvCBF sub-clusters were chosen and taken to homozygosity in order to separate the effects of the single HvCBF genes. At the same time, a PCR-based screening strategy of the genomic BAC library of cv ‘Morex’ was undertaken, and selected clones assembled into contigs through high information content fingerprinting (HICF). BAC-end sequencing is being used to close remaining gaps and to create anchor points between the genetic and physical maps of the region. Alignment of the genetically colinear region of ‘Nure’ against ‘Tremois’, alongside ‘Dicktoo’ and ‘Morex’, revealed several key molecular differences that we hypothesize accounts for the nature of Fr-H2. The likely scenario is that both a ‘structural’ and a ‘regulatory’ component act together to enhance the tolerance. The first component could be likely due to either allelic or number variation of HvCBF genes at Fr-H2 where “more” CBFs could be better, while the second one would be due to the winter allele of VRN-H1/Fr-H1