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Wheat (Triticum spp.) is crucial to food security. The source of a major proportion of humans’ total dietary carbohydrates and protein, it is among the world’s most widely grown crops and receives concomitantly large quantities of nitrogen (N) fertiliser. Wheat grain protein content (GPC; %) is a key to food quality, determining the baking quality of bread, the cooking quality of pasta, and the nutritional value of food products. For these reasons, wheat is classified and growers are typically paid predominantly on the basis of GPC, setting its farm income value. Global population growth encourages a justified focus on increasing yields. However, because grain proteins are diluted by carbohydrate (CHO) additions in the latter part of growing seasons, GPC is in an inverse relationship with yield: Improved yields are attended by the risk of reducing GPC. Moreover, GPC is influenced by interacting genetic and agronomic factors, soil properties and weather conditions that affect crops’ physiological status and stress levels and can therefore exhibit great spatial variability. Of the vast quantities of nitrogen (N) applied to wheat crops, a variable but substantial proportion is lost, inducing environmental damage and financial costs, which should be averted. Accurate GPC prediction could reduce N losses, assist in crop management decisions, and improve farm incomes. Nitrogen is central to proteins and can be strategically supplied to crops in order to achieve GPC benchmarks a precision agriculture (PA) approach. In such scenarios, estimates of GPC potential in advance of harvest could guide fertiliser dosing, improving fertiliser efficiency and potentially reducing costs. In contrast, where strategic fertiliser applications are not favoured, crop management could benefit from prior knowledge through strategic harvesting aimed at maximising payments per unit of grain at receival. However, GPC is a complex variable, influenced by multiple plant traits, themselves affected

Plants have evolved diverse mechanisms to cope with changes in their environment. Among the most important of these, the plant circadian clock adjusts physiology and development in response to daily and seasonal environmental rhythms. The cues perceived by plant circadian clocks are non-uniform across the biogeographical environment, and variation of circadian function is required between and within species. The overarching aim of this thesis was to identify how this functional clock variation arises in plants. Extant phenotypic variation in circadian rhythms across a naturally occurring species, Arabidopsis thaliana, and a cultivated species, bread wheat (Triticum aestivum), was quantified and compared. The respective contributions of this variation to local adaptation in Arabidopsis and agronomic traits in wheat were rigorously assessed. In Chapter 2, a transient luciferase imaging assay was used to measure circadian rhythms of 287 natural Arabidopsis accessions. Through genome-wide association mapping, three SNPs were identified in the evening-expressed clock gene EARLY FLOWERING 3 (ELF3) that were highly associated with variation in circadian period. Accessions harbouring these SNPs primarily occupy continental climates of Eastern Europe and Central Asia, and through physiological and population genetic analyses, evidence is provided that ELF3 has aided local adaptation to highly seasonal climates. The circadian rhythms of elite Australian wheat cultivars were measured using delayed leaf fluorescence in Chapter 3, and a large range in circadian period was detected. By leveraging existing and novel clock gene markers, specific combinations of clock gene alleles (chronotypes) were defined that are associated with circadian period. To test the importance of circadian rhythm variation to agricultural traits, the timing of leaf senescence and grain nutrition traits were measured across the same cultivars, and strong associations with circadian period were observed. A

Rising demands for protein worldwide are likely to drive increases in livestock production, as meat provides ∼40% of dietary protein. This will come at a significant environmental cost, and a shift toward plant-based protein sources would therefore provide major benefits. While legumes provide substantial amounts of plant-based protein, cereals are the major constituents of global foods, with wheat alone accounting for 15–20% of the required dietary protein intake. Improvement of protein content in wheat is limited by phenotyping challenges, lack of genetic potential of modern germplasms, negative yield trade-offs, and environmental costs of nitrogen fertilizers. Presenting wheat as a case study, we discuss how increasing protein content in cereals through a revised breeding strategy combined with robust phenotyping could ensure a sustainable protein supply while minimizing the environmental impact of nitrogen fertilizer., BN/Marie-Eve Aubin-Tam Lab

U ovom radu su ispitivane osobine kvaliteta zrna pet genotipova ozimog krupnika (Nirvana, KG-37-8/3, KG-54-7/3, KG-54-8/1 i KG-54- 2/3). Ogledi su izvedeni po principima organske proizvodnje tokom dve vegetacione sezone. Urađene su analize sadržaja proteina u zrnu i hektolitarska masa zrna. Sadržaj proteina, u proseku, se kretao u rasponu od 12,03% (KG-54-8/1) do 13,06% i 13,02% (KG-54-2/3 i KG-54-8/1). Vrednosti su bile statistički značajno veće (13,59%**) u prvoj nego u drugoj godini istraživanja (11,90%**). U ovim istraživanjima, u proseku za obe godine, najveću hektolitarsku masu imala je linija KG-37-8/3 (82,46 kg hl-1), koja je imala i najveću vrednost u celom ogledu (88,30 kg hl-1), a zatim linije KG-54-7/3 (79,16 kg hl-1) i KG-54-2/3 (78,80 kg hl-1). Analizom varijanse su ustanovljene statistički visoko značajne razlike između genotipova, godina i njihovih interakcija za obe ispitivane osobine kvaliteta zrna krupnika., In this work, the grain quality characteristics of five genotypes of winter wheat (Nirvana, KG37-8/3, KG-54-7/3, KG-54-8/1 and KG-54- 2/3) were examined. The experiments were carried out according to the principles of organic production during two growing seasons. Analyzes of grain protein content and hectoliter grain weight were performed. The protein content, on average, ranged from 12,03% (KG-54-8/1) to 13.06% and 13.02% (KG-54-2/3 and KG-54-8/1, respectively). The values were statistically significant higher (13.59%**) in the first than in the second year of the research (11.90%**). In these studies, on average for both years, line KG-37-8/3 (82.46 kg hl-1) had the highest hectoliter weight, which also had the highest value in the entire trial (88.30 kg hl-1 ), and then lines KG-54-7/3 (79.16 kg hl-1) and KG-54-2/3 (78.80 kg hl-1). Analysis of variance revealed statistically highly significant differences between genotypes, years and their interactions for both tested grain quality traits.

Wheat (Triticum spp.) is crucial to food security. Grain protein content (GPC) is key to its nutritional and economic value and is controlled by genetic and agronomic factors, soil properties and weather. GPC prediction from remote sensing could reduce nitrogen (N) losses, help management decisions, and improve profit. However, GPC prediction is complex because multiple plant traits influence GPC and their effects change through the growing season. Traits with known physiological links to GPC, which can be retrieved from imaging spectroscopy, include leaf area index (LAI), chlorophyll (Ca+b), and stress indicators. Further inspection of these and other traits retrieved from satellite data can advance research relevant to precision agriculture. Sentinel-2 (S2) timeseries (TS) were acquired for 6,355 ha of commercial dryland bread (T. aestivum) and durum (T. durum) wheat fields in south-east Australia through two consecutive years with dissimilar rainfall. Wheat growers provided ∼ 92,000 GPC data points from harvester-mounted protein monitors. For each, Ca+b, leaf dry matter, leaf water content (Cw) and LAI were retrieved from the S2 images by radiative transfer model inversion. A gradient boosted machine learning algorithm was applied to analyse these traits’ importance to GPC and to predict GPC in 30% of samples unseen by the algorithm in training. The strongest relationships between predicted and observed GPC (R2 = 0.86, RMSE = 0.56 %), in a model built from five S2 images across a season, were better than those from single-date hyperspectral (HS). In severe water stress, LAI was the main predictor of GPC early in the season, but this switched to Cw later. Trait importance was more evenly distributed in milder conditions. S2 TS had a clear accuracy advantage over single-date S2 and HS, especially in benign conditions, emphasising the potential of S2 TS for large-scale GPC monitoring.

Background: Barley has been bred for more than a century in the Nordic countries, with dramatic improvements of yield traits. In this study we investigate if this has come at the cost of lower grain protein and micronutrient (iron, zinc) content, by analysing 80 accessions representing four different improvement stages. We further re-sequenced the two grain protein content associated genes HvNAM-1 and HvNAM-2 in full and performed expression analyses of the same genes to search for genetic associations with nutrient content. Results: We found higher thousand grain weight in barley landraces and in accessions from the late improvement group compared to accessions from the mid of the twentieth century. Straw length was much reduced in late stage accessions. No significant temporal decrease in grain protein, iron or zinc content during twentieth century Nordic crop improvement could be detected. Out of the 80 accessions only two deviant HvNAM-1 sequences were found, represented by one accession each. These do not appear to be correlated to grain protein content. The sequence of HvNAM-2 was invariable in all accessions and no correlations between expression levels of HvNAM-1 and HvNAM-2 and with grain protein content was found. Conclusions: In contrast to studies in wheat, where a strong negative correlation between straw length and grain protein and micronutrient content has been found, we do not see this relationship in Nordic barley. The last 60 years of breeding has reduced straw length but, contrary to expectations, not protein and micronutrient content. Variation in grain protein and micronutrient content was found among the Nordic barley accessions, but it is not explained by variation of HvNAM genes. This means that HvNAM is an unexploited source of genetic variation for nutrient content in Nordic barley.

The objectives of this study were to identify genetic loci in the bread wheat genome that would influence yield stability and quality under water stress, and to identify accessions that can be recommended for cultivation in dry and hot regions. We performed a genome-wide association study (GWAS) using a panel of 232 wheat accessions spanning diverse ecogeographic regions. Plants were evaluated in the Israeli Northern Negev, under two environments: water-limited (D; 250 mm) and well-watered (W; 450 mm) conditions; they were genotyped with ~71,500 SNPs derived from exome capture sequencing. Of the 14 phenotypic traits evaluated, 12 had significantly lower values under D compared to W conditions, while the values for two traits were higher under D. High heritability (H2 = 0.5-0.9) was observed for grain yield, spike weight, number of grains per spike, peduncle length, and plant height. Days to heading and grain yield could be partitioned based on accession origins. GWAS identified 154 marker-trait associations (MTAs) for yield and quality-related traits, 82 under D and 72 under W, and identified potential candidate genes. We identified 24 accessions showing high and/or stable yields under D conditions that can be recommended for cultivation in regions under the threat of global climate change.

Wheat (Triticum spp.) is among the world's most widely grown crops and receives large quantities of nitrogen (N) fertiliser. Grain protein content (GPC) is influenced by genetic, agronomic and weather conditions affecting crops’ physiological status and stress levels; accurate GPC prediction has potential to reduce N losses and improve profit. Success in GPC estimation from remotely sensed plant traits has been limited. For progress to be made, it is necessary to robustly identify imaging spectroscopy-based physiological traits most closely associated with GPC in both experimental and commercial contexts. We present results from piloted hyperspectral flights and ground campaigns at two dryland field experiments with divergent water supply and wide-ranging N treatments, and from two years’ flights over 17 commercial fields planted to either bread (T. aestivum) or durum (T. durum) wheat, in the southern Australian wheat belt. Imagery was acquired with airborne hyperspectral and thermal sensors, with spatial resolutions of approx. 0.3 m and 0.5 m for experimental plots and 1 m/1.7 m in commercial fields. Leaf clip measurements, leaf and grain samples were collected and, in commercial fields, ∼40,000 records obtained from harvester-mounted protein monitors. Crop Water Stress Index (CWSI), solar-induced fluorescence (SIF), reflectance indices and PRO4SAIL radiative transfer model inverted parameters were retrieved for each plot and GPC record location. The photochemical reflectance index (PRI) related to xanthophyll pigments was consistently associated with GPC at both leaf and canopy scale in the plots and transect. In the commercial crops, a gradient boosted machine learning algorithm (GBM) ranked CWSI as the strongest indicator of GPC under severe water stress, while SIF, PRI and inverted biochemical constituents anthocyanins and carotenoids were consistently important under more benign conditions. Structural parameters inverted from the hyperspectral reflectance imag

Grain protein content (GPC) in wheat has been found to be regulated by the gene NAM-B1. Homologues to the NAM-B1 gene have been found in barley, HvNAM-1 and HvNAM-2. Previous studies have found that base mutations in the NAM-1 gene at base position 544 might have an impact on GPC. Previous studies also found that landrace of barley showed higher GPC than cultivated barley, indicating that plant improvement might have affected base mutations and therefore GPC. I wanted to study if there are any nutritional differences in Nordic barley and if those differences might correlate with haplotypes. Comparisons of barley varieties from four Nordic countries, and two varieties from the US used as low and high GPC controls, did not show any significant differences depending on their origin country and no differences regarding plant improvement status between the countries. When sequencing Nordic barley varieties, five haplotypes were found for the gene HvNAM-1, and two haplotypes for the gene HvNAM-2. A low polymorphism for both genes indicate a strong natural selection for the consensus haplotype which might be preferable for Nordic climate with a short growing season and cold temperatures. Even though it is not clear what is the cause of the low polymorphism in Nordic barley varieties, they showed a generally higher nutrient content than barley varieties of the high GPC and may be suitable for breeding for a yield with a high nutrient content.

Grain protein content (GPC) in wheat has been found to be regulated by the gene NAM-B1. Homologues to the NAM-B1 gene have been found in barley, HvNAM-1 and HvNAM-2. Previous studies have found that base mutations in the NAM-1 gene at base position 544 might have an impact on GPC. Previous studies also found that landrace of barley showed higher GPC than cultivated barley, indicating that plant improvement might have affected base mutations and therefore GPC. I wanted to study if there are any nutritional differences in Nordic barley and if those differences might correlate with haplotypes. Comparisons of barley varieties from four Nordic countries, and two varieties from the US used as low and high GPC controls, did not show any significant differences depending on their origin country and no differences regarding plant improvement status between the countries. When sequencing Nordic barley varieties, five haplotypes were found for the gene HvNAM-1, and two haplotypes for the gene HvNAM-2. A low polymorphism for both genes indicate a strong natural selection for the consensus haplotype which might be preferable for Nordic climate with a short growing season and cold temperatures. Even though it is not clear what is the cause of the low polymorphism in Nordic barley varieties, they showed a generally higher nutrient content than barley varieties of the high GPC and may be suitable for breeding for a yield with a high nutrient content.

Hunger is a problem faced by many people all over the world, and as the population grows, so does the need for food such as cereals. Because of this, the need for food with higher protein and nutrient content will be increasingly important. NAM-B1, a NAC-protein gene in wheat, has been shown to control the grain protein content and nutrient values, as well as senescence. In barley, two orthologous genes have been found, HvNAM1 and HvNAM2. This study focuses on Nordic barley accessions and how haplotypes of HvNAM1 and HvNAM2 correlate to the grain protein content (GPC) and nutrient content. No correlations between the different haplotypes of the HvNAM genes and the nutrient content and GPC were found. No differences in nutrient content and GPC were found in Nordic accessions originating from Sweden, Norway, Finland, or Denmark, nor were differences found for improvements status groups or for six-row barley and two-row barley. The Nordic accessions were shown to generally have high GPC when compared to control groups Karl and Lewis. However, even if the results of this study indicate that the HvNAM genes do not have major effects on the nutrient contents or GPC, Nordic barley might still be good material for plant improvement. Other factors such as other genes, environmental effects, and gene expression should therefore be investigated.

Hunger is a problem faced by many people all over the world, and as the population grows, so does the need for food such as cereals. Because of this, the need for food with higher protein and nutrient content will be increasingly important. NAM-B1, a NAC-protein gene in wheat, has been shown to control the grain protein content and nutrient values, as well as senescence. In barley, two orthologous genes have been found, HvNAM1 and HvNAM2. This study focuses on Nordic barley accessions and how haplotypes of HvNAM1 and HvNAM2 correlate to the grain protein content (GPC) and nutrient content. No correlations between the different haplotypes of the HvNAM genes and the nutrient content and GPC were found. No differences in nutrient content and GPC were found in Nordic accessions originating from Sweden, Norway, Finland, or Denmark, nor were differences found for improvements status groups or for six-row barley and two-row barley. The Nordic accessions were shown to generally have high GPC when compared to control groups Karl and Lewis. However, even if the results of this study indicate that the HvNAM genes do not have major effects on the nutrient contents or GPC, Nordic barley might still be good material for plant improvement. Other factors such as other genes, environmental effects, and gene expression should therefore be investigated.

In wheat, monocarpic senescence is a tightly regulated process during which nitrogen (N) and micronutrients stored pre-anthesis are remobilized from vegetative tissues to the developing grains. Recently, a close connection between senescence and remobilization was shown through the map-based cloning of the GPC (grain protein content) gene in wheat. GPC-B1 encodes a NAC transcription factor associated with earlier senescence and increased grain protein, iron and zinc content, and is deleted or non-functional in most commercial wheat varieties. In the current research, we identified 'loss of function' ethyl methanesulfonate mutants for the two GPC-B1 homoeologous genes; GPC-A1 and GPC-D1, in a hexaploid wheat mutant population. The single gpc-a1 and gpc-d1 mutants, the double gpc-1 mutant and control lines were grown under field conditions at four locations and were characterized for senescence, GPC, micronutrients and yield parameters. Our results show a significant delay in senescence in both the gpc-a1 and gpc-d1 single mutants and an even stronger effect in the gpc-1 double mutant in all the environments tested in this study. The accumulation of total N in the developing grains showed a similar increase in the control and gpc-1 plants until 25 days after anthesis (DAA) but at 41 and 60 DAA the control plants had higher grain N content than the gpc-1 mutants. At maturity, GPC in all mutants was significantly lower than in control plants while grain weight was unaffected. These results demonstrate that the GPC-A1 and GPC-D1 genes have a redundant function and play a major role in the regulation of monocarpic senescence and nutrient remobilization in wheat.

In wheat, monocarpic senescence is a tightly regulated process during which nitrogen (N) and micronutrients stored pre-anthesis are remobilized from vegetative tissues to the developing grains. Recently, a close connection between senescence and remobilization was shown through the map-based cloning of the GPC (grain protein content) gene in wheat. GPC-B1 encodes a NAC transcription factor associated with earlier senescence and increased grain protein, iron and zinc content, and is deleted or non-functional in most commercial wheat varieties. In the current research, we identified 'loss of function' ethyl methanesulfonate mutants for the two GPC-B1 homoeologous genes; GPC-A1 and GPC-D1, in a hexaploid wheat mutant population. The single gpc-a1 and gpc-d1 mutants, the double gpc-1 mutant and control lines were grown under field conditions at four locations and were characterized for senescence, GPC, micronutrients and yield parameters. Our results show a significant delay in senescence in both the gpc-a1 and gpc-d1 single mutants and an even stronger effect in the gpc-1 double mutant in all the environments tested in this study. The accumulation of total N in the developing grains showed a similar increase in the control and gpc-1 plants until 25 days after anthesis (DAA) but at 41 and 60 DAA the control plants had higher grain N content than the gpc-1 mutants. At maturity, GPC in all mutants was significantly lower than in control plants while grain weight was unaffected. These results demonstrate that the GPC-A1 and GPC-D1 genes have a redundant function and play a major role in the regulation of monocarpic senescence and nutrient remobilization in wheat.

Grain protein concentration (GPC) affects wheat nutritional value and several critical parameters for bread and pasta quality. A gene designated Gpc-B1, which is not functional in common and durum wheat cultivars, was recently identified in Triticum turgidum ssp. dicoccoides. The functional allele of Gpc-B1 improves nitrogen remobilization from the straw increasing GPC, but also shortens the grain filling period resulting in reduced grain weight in some genetic backgrounds. We developed isogenic lines for the Gpc-B1 introgression in six hexaploid and two tetraploid wheat genotypes to evaluate its effects on bread-making and pasta quality. In common wheat, the functional Gpc-B1 introgression was associated with significantly higher GPC, water absorption, mixing time and loaf volume, whereas in durum wheat, the introgression resulted in significant increases in GPC, wet gluten, mixing time, and spaghetti firmness, as well as a decrease in cooking loss. On the negative side, the functional Gpc-B1 introgression was associated in some varieties with a significant reduction in grain weight, test weight, and flour yield and significant increases in ash concentration. Significant gene × environment and gene × genotype interactions for most traits stress the need for evaluating the effect of this introgression in particular genotypes and environments.

Grain protein concentration (GPC) affects wheat nutritional value and several critical parameters for bread and pasta quality. A gene designated Gpc-B1, which is not functional in common and durum wheat cultivars, was recently identified in Triticum turgidum ssp. dicoccoides. The functional allele of Gpc-B1 improves nitrogen remobilization from the straw increasing GPC, but also shortens the grain filling period resulting in reduced grain weight in some genetic backgrounds. We developed isogenic lines for the Gpc-B1 introgression in six hexaploid and two tetraploid wheat genotypes to evaluate its effects on bread-making and pasta quality. In common wheat, the functional Gpc-B1 introgression was associated with significantly higher GPC, water absorption, mixing time and loaf volume, whereas in durum wheat, the introgression resulted in significant increases in GPC, wet gluten, mixing time, and spaghetti firmness, as well as a decrease in cooking loss. On the negative side, the functional Gpc-B1 introgression was associated in some varieties with a significant reduction in grain weight, test weight, and flour yield and significant increases in ash concentration. Significant gene × environment and gene × genotype interactions for most traits stress the need for evaluating the effect of this introgression in particular genotypes and environments.

The NAM-B1 gene is a NAC transcription factor that affects grain nutrient concentrations in wheat (Triticum aestivum). An RNAi line with reduced expression of NAM genes has lower grain protein, iron (Fe), and zinc (Zn) concentrations. To determine whether decreased remobilization, lower plant uptake, or decreased partitioning to grain are responsible for this phenotype, mineral dynamics were quantified in wheat tissues throughout grain development. Control and RNAi wheat were grown in potting mix and hydroponics. Mineral (Ca, Cu, Fe, K, Mg, Mn, P, S, and Zn) and nitrogen (N) contents of organs were determined at regular intervals to quantify the net remobilization from vegetative tissues and the accumulation of nutrients in grain. Total nutrient accumulation was similar between lines, but grain Fe, Zn, and N were at lower concentrations in the NAM knockdown line. In potting mix, net remobilization of N, Fe, and Zn from vegetative tissues was impaired in the RNAi line. In hydroponics with ample nutrients, net remobilization was not observed, but grain Fe and Zn contents and concentrations remained lower in the RNAi line. When Fe or Zn was withheld post-anthesis, both lines demonstrated remobilization. These results suggest that a major effect of the NAM genes is an increased efflux of nutrients from the vegetative tissues and a higher partitioning of nutrients to grain.

The NAM-B1 gene is a NAC transcription factor that affects grain nutrient concentrations in wheat (Triticum aestivum). An RNAi line with reduced expression of NAM genes has lower grain protein, iron (Fe), and zinc (Zn) concentrations. To determine whether decreased remobilization, lower plant uptake, or decreased partitioning to grain are responsible for this phenotype, mineral dynamics were quantified in wheat tissues throughout grain development. Control and RNAi wheat were grown in potting mix and hydroponics. Mineral (Ca, Cu, Fe, K, Mg, Mn, P, S, and Zn) and nitrogen (N) contents of organs were determined at regular intervals to quantify the net remobilization from vegetative tissues and the accumulation of nutrients in grain. Total nutrient accumulation was similar between lines, but grain Fe, Zn, and N were at lower concentrations in the NAM knockdown line. In potting mix, net remobilization of N, Fe, and Zn from vegetative tissues was impaired in the RNAi line. In hydroponics with ample nutrients, net remobilization was not observed, but grain Fe and Zn contents and concentrations remained lower in the RNAi line. When Fe or Zn was withheld post-anthesis, both lines demonstrated remobilization. These results suggest that a major effect of the NAM genes is an increased efflux of nutrients from the vegetative tissues and a higher partitioning of nutrients to grain.

Grain Protein Content (GPC) is an important determinant of grain quality in many crops, including barley and wheat. Recently, the map-based cloning of Gpc-B1, a wheat GPC quantitative trait locus (QTL), revealed a NAC transcription factor (TtNAM-B1) that was associated with increased grain protein, zinc, and iron content. In barley, a QTL for GPC was identified in a segregating population developed from a cross between 'Karl' (low GPC) and 'Lewis' (average GPC). This QTL was mapped near marker hvm74 on chromosome 6H and was suggested as a potential orthologue for Gpc-B1 on chromosome arm 6BS. In the current study, wheat genes that were previously mapped within a 0.8 cM segment spanning the TtNAM-B1 gene were converted into barley molecular markers. These new markers, together with the barley TtNAM-B1 orthologous gene (designated HvNAM-1 hereafter) were mapped on a 0.7 cM interval encompassing the peak of the barley QTL for GPC on chromosome arm 6HS. Sequence comparison of HvNAM-1 parental alleles showed two single nucleotide polymorphisms (SNPs) that result in two amino acid differences. Analysis of the allelic variation in a wild and cultivated barley collection revealed that the Karl haplotype was present only in nine out of 147 tested accessions. The colinearity between the wheat and barley GPC regions and the low frequency of the HvNAM-1 haplotype associated with low GPC suggest that the barley NAC transcription factor is responsible for the GPC QTL on barley chromosome 6H.

Grain Protein Content (GPC) is an important determinant of grain quality in many crops, including barley and wheat. Recently, the map-based cloning of Gpc-B1, a wheat GPC quantitative trait locus (QTL), revealed a NAC transcription factor (TtNAM-B1) that was associated with increased grain protein, zinc, and iron content. In barley, a QTL for GPC was identified in a segregating population developed from a cross between 'Karl' (low GPC) and 'Lewis' (average GPC). This QTL was mapped near marker hvm74 on chromosome 6H and was suggested as a potential orthologue for Gpc-B1 on chromosome arm 6BS. In the current study, wheat genes that were previously mapped within a 0.8 cM segment spanning the TtNAM-B1 gene were converted into barley molecular markers. These new markers, together with the barley TtNAM-B1 orthologous gene (designated HvNAM-1 hereafter) were mapped on a 0.7 cM interval encompassing the peak of the barley QTL for GPC on chromosome arm 6HS. Sequence comparison of HvNAM-1 parental alleles showed two single nucleotide polymorphisms (SNPs) that result in two amino acid differences. Analysis of the allelic variation in a wild and cultivated barley collection revealed that the Karl haplotype was present only in nine out of 147 tested accessions. The colinearity between the wheat and barley GPC regions and the low frequency of the HvNAM-1 haplotype associated with low GPC suggest that the barley NAC transcription factor is responsible for the GPC QTL on barley chromosome 6H.

Grain Protein Content (GPC) is an important determinant of grain quality in many crops, including barley and wheat. Recently, the map-based cloning of Gpc-B1, a wheat GPC quantitative trait locus (QTL), revealed a NAC transcription factor (TtNAM-B1) that was associated with increased grain protein, zinc, and iron content. In barley, a QTL for GPC was identified in a segregating population developed from a cross between 'Karl' (low GPC) and 'Lewis' (average GPC). This QTL was mapped near marker hvm74 on chromosome 6H and was suggested as a potential orthologue for Gpc-B1 on chromosome arm 6BS. In the current study, wheat genes that were previously mapped within a 0.8 cM segment spanning the TtNAM-B1 gene were converted into barley molecular markers. These new markers, together with the barley TtNAM-B1 orthologous gene (designated HvNAM-1 hereafter) were mapped on a 0.7 cM interval encompassing the peak of the barley QTL for GPC on chromosome arm 6HS. Sequence comparison of HvNAM-1 parental alleles showed two single nucleotide polymorphisms (SNPs) that result in two amino acid differences. Analysis of the allelic variation in a wild and cultivated barley collection revealed that the Karl haplotype was present only in nine out of 147 tested accessions. The colinearity between the wheat and barley GPC regions and the low frequency of the HvNAM-1 haplotype associated with low GPC suggest that the barley NAC transcription factor is responsible for the GPC QTL on barley chromosome 6H.

High grain protein content (GPC) is a frequent target of wheat breeding programmes because of its positive effect on bread and pasta quality. A wild wheat allele at the Gpc-B1 locus with a significant impact on this trait was identified previously. The precise mapping of several senescence-related traits in a set of tetraploid recombinant substitution lines (RSLs) segregating for Gpc-B1 is reported here. Flag leaf chlorophyll degradation, change in peduncle colour, and spike water content were completely linked to the Gpc-B1 locus and to the differences in GPC within a 0.3 cM interval corresponding to a physical distance of only 250 kb. The effect of Gpc-B1 was also examined in different environments and genetic backgrounds using a set of tetraploid and hexaploid pairs of isogenic lines. The results were consistent with those observed in the RSLs. The high GPC allele conferred a shorter duration of grain fill due to earlier flag leaf senescence and increased GPC in all four genetic backgrounds. The effect on grain size was more variable, depending on the genotype-environment combinations. These results are consistent with a model in which the wild-type allele of Gpc-B1 accelerates senescence in flag leaves producing pleiotropic effects on nitrogen remobilization, total GPC, and grain size.

Grain protein content (GPC) is important for human nutrition and has a strong influence on pasta and bread quality. A quantitative trait locus, derived from a Triticum turgidum ssp. dicoccoides accession (DIC), with an average increase in GPC of 14 g kg(-1) was mapped on chromosome 6BS. Using the wheat-rice colinearity, a high-density map of the wheat region was developed and the quantitative trait locus was mapped as a simple Mendelian locus designated Gpc-B1. A physical map of approx. 250 kb of the Gpc-B1 region was developed using a tetraploid wheat bacterial artificial chromosome library. The constructed physical map included the two Gpc-B1 flanking markers and one potential candidate gene from the colinear rice region completely linked to Gpc-B1. The relationship between physical and genetic distances and the feasibility of isolating genes by positional cloning in wheat are discussed. A high-throughput codominant marker, Xuhw89, was developed. A 4-bp deletion present in the DIC allele was absent in a collection of 117 cultivated tetraploid and hexaploid wheat germplasm, suggesting that this marker will be useful to incorporate the high GPC allele from the DIC accession studied here into commercial wheat varieties.

High grain protein content (GPC) is a frequent target of wheat breeding programmes because of its positive effect on bread and pasta quality. A wild wheat allele at the Gpc-B1 locus with a significant impact on this trait was identified previously. The precise mapping of several senescence-related traits in a set of tetraploid recombinant substitution lines (RSLs) segregating for Gpc-B1 is reported here. Flag leaf chlorophyll degradation, change in peduncle colour, and spike water content were completely linked to the Gpc-B1 locus and to the differences in GPC within a 0.3 cM interval corresponding to a physical distance of only 250 kb. The effect of Gpc-B1 was also examined in different environments and genetic backgrounds using a set of tetraploid and hexaploid pairs of isogenic lines. The results were consistent with those observed in the RSLs. The high GPC allele conferred a shorter duration of grain fill due to earlier flag leaf senescence and increased GPC in all four genetic backgrounds. The effect on grain size was more variable, depending on the genotype-environment combinations. These results are consistent with a model in which the wild-type allele of Gpc-B1 accelerates senescence in flag leaves producing pleiotropic effects on nitrogen remobilization, total GPC, and grain size.

High grain protein content (GPC) is a frequent target of wheat breeding programmes because of its positive effect on bread and pasta quality. A wild wheat allele at the Gpc-B1 locus with a significant impact on this trait was identified previously. The precise mapping of several senescence-related traits in a set of tetraploid recombinant substitution lines (RSLs) segregating for Gpc-B1 is reported here. Flag leaf chlorophyll degradation, change in peduncle colour, and spike water content were completely linked to the Gpc-B1 locus and to the differences in GPC within a 0.3 cM interval corresponding to a physical distance of only 250 kb. The effect of Gpc-B1 was also examined in different environments and genetic backgrounds using a set of tetraploid and hexaploid pairs of isogenic lines. The results were consistent with those observed in the RSLs. The high GPC allele conferred a shorter duration of grain fill due to earlier flag leaf senescence and increased GPC in all four genetic backgrounds. The effect on grain size was more variable, depending on the genotype-environment combinations. These results are consistent with a model in which the wild-type allele of Gpc-B1 accelerates senescence in flag leaves producing pleiotropic effects on nitrogen remobilization, total GPC, and grain size.

Grain protein content (GPC) is important for human nutrition and has a strong influence on pasta and bread quality. A quantitative trait locus, derived from a Triticum turgidum ssp. dicoccoides accession (DIC), with an average increase in GPC of 14 g kg(-1) was mapped on chromosome 6BS. Using the wheat-rice colinearity, a high-density map of the wheat region was developed and the quantitative trait locus was mapped as a simple Mendelian locus designated Gpc-B1. A physical map of approx. 250 kb of the Gpc-B1 region was developed using a tetraploid wheat bacterial artificial chromosome library. The constructed physical map included the two Gpc-B1 flanking markers and one potential candidate gene from the colinear rice region completely linked to Gpc-B1. The relationship between physical and genetic distances and the feasibility of isolating genes by positional cloning in wheat are discussed. A high-throughput codominant marker, Xuhw89, was developed. A 4-bp deletion present in the DIC allele was absent in a collection of 117 cultivated tetraploid and hexaploid wheat germplasm, suggesting that this marker will be useful to incorporate the high GPC allele from the DIC accession studied here into commercial wheat varieties.

Grain protein content (GPC) is an important factor in pasta and breadmaking quality, and in human nutrition. It is also an important trait for wheat growers because premium prices are frequently paid for wheat with high GPC. A promising source for alleles to increase GPC was detected on chromosome 6B of Triticum turgidum var. dicoccoides accession FA-15-3 (DIC). Two previous quantitative trait locus (QTL) studies found that the positive effect of DIC-6B was associated to a single locus located between the centromere and the Nor-B2 locus on the short arm of chromosome 6B. Microsatellite markers Xgwm508 and Xgwm193 flanking the QTL region were used in this study to develop 20 new homozygous recombinant substitution lines (RSLs) with crossovers between these markers. These 20 RSLs, plus nine RSLs developed in previous studies were characterized with four new RFLP markers located within this chromosome segment. Grain protein content was determined in three field experiments organized as randomized complete block designs with ten replications each. The QTL peaks for protein content were located in the central region of a 2.7-cM interval between RFLP markers Xcdo365 and Xucw67 in the three experiments. Statistical analyses showed that almost all lines could be classified unequivocally within low- and high- protein groups, facilitating the mapping of this trait as a single Mendelian locus designated Gpc-6B1. The Gpc-6B1 locus was mapped 1.5-cM proximal to Xcdo365 and 1.2-cM distal to Xucw67. These new markers can be used to reduce the size of the DIC chromosome segment selected in marker-assisted selection programs. Markers Nor-B2 and Xucw66 flanking the previous two markers can be used to select against the DIC segment and reduce the linkage drag during the transfer of Gpc-6B1 into commercial bread and pasta wheat varieties. The precise mapping of the high GPC gene, the high frequency of recombinants recovered in the targeted region, and the recent development of a tetrap

Grain protein content (GPC) is an important factor in pasta and breadmaking quality, and in human nutrition. It is also an important trait for wheat growers because premium prices are frequently paid for wheat with high GPC. A promising source for alleles to increase GPC was detected on chromosome 6B of Triticum turgidum var. dicoccoides accession FA-15-3 (DIC). Two previous quantitative trait locus (QTL) studies found that the positive effect of DIC-6B was associated to a single locus located between the centromere and the Nor-B2 locus on the short arm of chromosome 6B. Microsatellite markers Xgwm508 and Xgwm193 flanking the QTL region were used in this study to develop 20 new homozygous recombinant substitution lines (RSLs) with crossovers between these markers. These 20 RSLs, plus nine RSLs developed in previous studies were characterized with four new RFLP markers located within this chromosome segment. Grain protein content was determined in three field experiments organized as randomized complete block designs with ten replications each. The QTL peaks for protein content were located in the central region of a 2.7-cM interval between RFLP markers Xcdo365 and Xucw67 in the three experiments. Statistical analyses showed that almost all lines could be classified unequivocally within low- and high- protein groups, facilitating the mapping of this trait as a single Mendelian locus designated Gpc-6B1. The Gpc-6B1 locus was mapped 1.5-cM proximal to Xcdo365 and 1.2-cM distal to Xucw67. These new markers can be used to reduce the size of the DIC chromosome segment selected in marker-assisted selection programs. Markers Nor-B2 and Xucw66 flanking the previous two markers can be used to select against the DIC segment and reduce the linkage drag during the transfer of Gpc-6B1 into commercial bread and pasta wheat varieties. The precise mapping of the high GPC gene, the high frequency of recombinants recovered in the targeted region, and the recent development of a tetrap