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The endosperm structure of the wheat kernel determines its end-use quality. The known diversity in endosperm structure is related to the Pina- D1 and Pinb- D1 genes comprising the Ha locus on chromosome 5DS. We studied the effect of a gene introduced into bread wheat from the diploid relative, Aegilops speltoides, a putative donor of the B genome. Grain hardness and vitreousness were investigated in lines with homoeologous introgressions into chromosome 5A of spring wheat cultivar ‘Rodina’. One introgression changed the endosperm texture from hard to soft and had the same effect when transferred to other wheat genotypes. This indicated that its action was analogous to the dominant allele at the Ha locus. The temporary symbol Ha– Sp is given to the gene. Segregation for vitreousness in F offspring from monosomic hybrids was also investigated. Genetic variability for endosperm structure in wheat may be extended by manipulating both hardness and vitreousness. Wheat germplasm with introgressions from wild relatives can increase the genetic variability of milling characteristics. [ABSTRACT FROM AUTHOR]

Grain hardness plays an important role in determining both milling performance and quality of the end-use products produced from common or bread wheat. The objective of this study was to characterize allelic variations at the Pina and Pinb loci in Xinjiang wheat germplasm for further understanding the mechanisms involved in endosperm texture formation, and the status of grain texture in Chinese bread wheat. A total of 291 wheat cultivars, including 56 landraces, and 95 introduced and 140 locally improved cultivars, grown in Xinjiang, were used for SKCS measurement and molecular characterization. Among the harvested grain samples, 185 (63.6%), 40 (13.7%), and 66 (22.7%) were classified as hard, mixed and soft, respectively. Eight different genotypes for the Pina and Pinb loci were identified, including seven previously reported genotypes, viz., Pina-D1a/ Pinb-D1a, Pina-D1a/ Pinb-D1b, Pina-D1b/ Pinb-D1a, Pina-D1a/ Pinb-D1p, Pina-D1a/ Pinb-D1q, Pina-D1a/ Pinb-D1aa, Pina-D1a/ Pinb-D1ab, and a novel Pinb allele, Pinb-D1ac. This new allele, detected in Kashibaipi (local landrace) and Red Star (from Russia) has a double mutation at the 257th (G to A substitution) and 382nd (C to T substitution) nucleotide positions of the coding region. Pina-D1b, Pinb-D1b, and Pinb-D1p were the most common alleles in Xinjiang wheat germplasm, with frequencies of 14.3%, 38.1% and 28.6% in hard textured landraces, 25.5%, 56.9% and 11.8% in hard introduced cultivars, and 24.8%, 47.8% and 26.5% in hard locally improved cultivars, respectively. The restriction enzymes ApaI, SapI, BstXI and SfaNI were used to identify Pinb-D1ab or Pinb-D1ac, Pinb-D1b, Pinb-D1e and Pinb-Dg, respectively, by digesting PCR products of the Pinb gene. The unique grain hardness distribution in Xinjiang bread wheat, as well as the CAPs markers for identification of the Pinb alleles provided useful information for breeding wheat cultivars with optimum grain textures. [ABSTRACT FROM AUTHOR]

Puroindoline genes ( Pina and Pinb) form the molecular basis of wheat grain hardness or texture. Variations in either gene are reported to be associated with grain hardness in wheat. Here, a modified denaturing PAGE was used to detect Pina and Pinb allelic variations in 102 common wheat cultivars and other species related to wheat. Two variations of Pina ( Pina-D1b and Pina-D1p) and five variations of Pinb (null, Pinb-D1b, Pinb-D1u, Pinb-D1v and Pinb-D1w) were identified in common ( T. aestivum) and spelt wheats ( T. aestivum ssp. spelta). No allelic variation was found in Tibet semi-wild wheat ( T. aestivum ssp. tibetanum), club wheat ( T. compactum), or Aegilops tauschii. Puroindoline genes were absent in wild␣emmer ( T. turgidum var. dicoccoides). The sequencing results of the PCR fragments from Pina and Pinb (except for null type) indicated allelic variants carrying single base mutation, such as Pina-D1p, Pinb-D1u, Pinb-D1v and Pinb-D1w were novel types. Our results showed that the modified PAGE used in this study provided a satisfactory resolving power for identifying single nucleotide mutations; therefore, it is a practical and simple tool to study allelic variation of Pina and Pinb in wheat and related species. [ABSTRACT FROM AUTHOR]

Kernel texture is an important characteristic for both the milling and the end-use quality of wheat (Triticum aestivumL.). Gene sequence variation and mutations to the two puroindoline genes (PinaandPinb), located at theHalocus on chromosome 5DS, account for the majority of variation in wheat kernel texture. Other factors also influence kernel texture, including effects associated with different maternal parent backgrounds. To investigate the effect of two hard puroindoline alleles in different maternal backgrounds, a population of 228 recombinant inbred lines (RILs) derived from a reciprocal cross between two wheat cultivars ‘ID377s’ (Pina-D1b/Pinb-D1a) and ‘Klasic’ (Pina-D1a/Pinb-D1b) were examined in two succeeding generations (F7&F8). Kernel texture was determined using the Single Kernel Characterization System (SKCS) and the RIL puroindoline haplotype was identified by the sequence-specific PCR amplification of each gene. Analysis of variance identified a significant (P= 0.001) effect of the maternal parent and puroindoline mutation on kernel texture. RILs containing thePina-D1bmutation were significantly harder than lines containing thePinb-D1bmutation. RILs which had Klasic as the maternal parent were significantly harder than those which had ID377s as the maternal parent. When the maternal parent and puroindoline allele were analyzed in combination, RILs derived from Klasic as the maternal parent and thePina-D1ballele were significantly harder (P= 0.001) than those containing the same allele but ID377s as the maternal parent. The same occurred for RILs containing thePinb-D1ballele, lines with Klasic as the maternal parent were harder than lines with ID377s as the maternal parent. These results corroborate the harder phenotype of thePina-D1ballele and indicate a significant maternally-inherited contribution to kernel texture variation. [ABSTRACT FROM AUTHOR]

Twenty-two sorghum genotypes were evaluated for grain mould response, 13 morphological and biochemical traits thought to contribute to resistance, and 3 agronomic traits related to utilization. Measurements of grain mould (field grade score, threshed grade score, ergosterol content, and percentage germination) were strongly correlated with one another. Highly significant correlations between measures of grain mould and seed hardness, seed phenol content in acid methanol extract, and glume colour indicated that they strongly affected grain mould response. Harder grain, higher levels of seed phenols, and darker glumes contributed to grain mould resistance. Weaker and less consistent correlations between measures of grain mould and seed colour, seed flavan-4-ol content, glume phenol and flavan-4-ol contents, and glume cover indicated relatively less effect of these traits on grain mould response. Genotype means indicated that combinations of several traits are required to achieve resistance. Germplasm lines, including coloured-seeded lines IS 14375, IS 14387, IS 18144, and IS 18528, and white-seeded lines IS 21443, IS 24495 and IS 25017, showed greatest grain mould resistance. Improved lines generally had poorer grain mould resistance than these landraces. However, the best improved lines were comparable in resistance to white-seeded landraces. B58586, IS 14375 and IS 14387 are hard-seeded guinea sorghum lines that can be used as sources of grain mould resistance for West Africa. SP 33316, SP 33349 and GM 15018 are agronomically elite lines that can be used as sources of grain mould resistance for further improvement of white-seeded sorghum for South Asia and other regions. [ABSTRACT FROM AUTHOR]

Grain hardness (texture) in barley is a commercially important trait, associated with water-uptake during the steeping phase of malting, quantified by measuring endosperm hardness. Hordoindolines are seed proteins of barley, related to the wheat puroindoline proteins. The Hordoindoline genes Hina, Hinb-1 and Hinb-2 are orthologs of wheat Pin genes. The information on contributions of Hin genes to barley grain hardness is limited and somewhat ambiguous. Hence this study aimed to investigate the genetic diversity of Hin genes in 12 Australian barley cultivars and 14 landraces originating from geographic centers of diversity. The grain hardness was determined by the Single Kernel Characterisation System (SKCS) and ranged between 24.2–78.5 SKCS units for cultivars and 48.7–94.4 SKCS units for landraces. Hin gene amplifications and DNA sequencing indicated notable genetic diversity, with seven Hina, six Hinb-1 alleles and eight Hinb-2 alleles detected. Some of the SNPs led to substitutions at the potentially functionally important tryptophan rich domain and certain basic and hydrophobic residues in the putative proteins. A novel Hinb-1 allele with an insertion at nucleotide position 210, leading to a frame-shift mutation, was discovered in landrace L400211 from Ethiopia that had a high SKCS hardness value, indicating harder grain. The study suggests that Hin gene variations may contribute to barley grain hardness, and selection of certain alleles may be useful for breeding for varying barley grain textures. [ABSTRACT FROM AUTHOR]