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Chinese endemic wheat, comprising Tibetan semi-wild wheat (Triticum aestivum ssp. tibetanum), Yunnan hulled wheat (T. aestivum ssp. yunnanense), and Xinjiang rice wheat (T. petropavlovskyi), are genetically and morphologically unique. To examine the adult plant resistance to stripe rust among Chinese endemic wheat germplasms, a panel of 213 accessions was inoculated with mixed virulent races of wheat stripe rust (Puccinia striiformis f. sp. tritici) in four different field environments. Four traits associated with stripe rust resistance, infection type, final disease severity, disease index, and area under the disease progress curve, were used to evaluate the accessions. The phenotypic datasets were used for 55K single-nucleotide polymorphism (SNP) array-based genome-wide association studies to identify effective resistance loci. Eighty-nine accessions with stable resistance were identified in at least three of the four environments by phenotypic evaluation. Eleven markers located on chromosomes 1A, 2B, 5A, 5D, 7B, and 7D by the genome-wide association studies analysis showed significant associations with at least two resistance-associated traits in two of the environments. These loci, corresponding to seven genomic regions based on linkage disequilibrium decay distance, explained 9.3 to 26.0% of the total phenotypic variation. Five quantitative trait loci (QTLs) on chromosomes 1A, 2B, 7B, and 7D overlapped or were in close proximity to previously reported QTLs based on the consensus and physical maps using the reference sequence of bread wheat (IWGSC RefSeq v1.0). The other two QTLs were potential novel QTLs given their physical positions. Haplotype variants of QTL QYr.sicau-2BS showed subspecies-specific inheritance of the stripe rust resistance locus. Resistant loci among Chinese endemic wheat germplasms could be introduced into common wheat cultivars, and the high-confidence SNP markers will aid in marker-assisted selection in breeding for stripe rust disease resistance.

Chinese endemic wheat, comprising Tibetan semi-wild wheat (Triticum aestivum ssp. tibetanum), Yunnan hulled wheat (T. aestivum ssp. yunnanense), and Xinjiang rice wheat (T. petropavlovskyi), are genetically and morphologically unique. To examine the adult plant resistance to stripe rust among Chinese endemic wheat germplasms, a panel of 213 accessions was inoculated with mixed virulent races of wheat stripe rust (Puccinia striiformis f. sp. tritici) in four different field environments. Four traits associated with stripe rust resistance, infection type, final disease severity, disease index, and area under the disease progress curve, were used to evaluate the accessions. The phenotypic datasets were used for 55K single-nucleotide polymorphism (SNP) array-based genome-wide association studies to identify effective resistance loci. Eighty-nine accessions with stable resistance were identified in at least three of the four environments by phenotypic evaluation. Eleven markers located on chromosomes 1A, 2B, 5A, 5D, 7B, and 7D by the genome-wide association studies analysis showed significant associations with at least two resistance-associated traits in two of the environments. These loci, corresponding to seven genomic regions based on linkage disequilibrium decay distance, explained 9.3 to 26.0% of the total phenotypic variation. Five quantitative trait loci (QTLs) on chromosomes 1A, 2B, 7B, and 7D overlapped or were in close proximity to previously reported QTLs based on the consensus and physical maps using the reference sequence of bread wheat (IWGSC RefSeq v1.0). The other two QTLs were potential novel QTLs given their physical positions. Haplotype variants of QTL QYr.sicau-2BS showed subspecies-specific inheritance of the stripe rust resistance locus. Resistant loci among Chinese endemic wheat germplasms could be introduced into common wheat cultivars, and the high-confidence SNP markers will aid in marker-assisted selection in breeding for stripe rust disease resistance. [ABSTRACT FROM AUTHOR]

As a primitive hexaploid wheat resource distributed only in Tibet, Tibetan semi-wild wheat ( Triticum aestivum subsp. tibetanum Shao) possesses unique characteristics that could be exploited in wheat breeding programs. Its good root system could offer a stable platform for above-ground components. To detect possible excellent locus for root traits from Tibetan semi-wild wheat, we identified QTLs for root traits using a recombinant inbred line population derived from a cross between Tibetan semi-wild wheat Q1028 and Zhengmai 9023. A total of 15 QTLs on eight chromosomes were detected, including four major QTLs, QMrl.sau-7B, QTrl.sau-4B, QAd.sau-7A, and QSa.sau-4B. The phenotypic variation explained by each of these QTLs ranges from 5.67% to 16.68%. Positive alleles of six QTLs were derived from Q1028. Several novel QTLs for root traits were identified. In addition, significant correlations were detected amongst root traits and agronomic traits. Taken together, these results suggest that Tibetan semi-wild wheat and the newly identified novel QTLs could be useful in future breeding programs. [ABSTRACT FROM AUTHOR]

Hairiness is a common character in planta. Glume hairiness (Hg) is present in the full spectrum of bread wheat and its close relatives and was mainly studied in phenotypic diversity, species evolution, and mapping as a morphological marker. Previous studies indicated that Hg was controlled by a single dominant gene Hg on the short arm of chromosome 1A. However, to date, systematic and comprehensive study of Hg is not available; and markers flanking Hg were rather limited as well, hindering the fine mapping and even cloning of this gene. In the study reported here, aiming at genetically analyze Hg gene systematically, a linkage map of a recombinant inbred line (RIL) generated from the cross between the Tibetan semi-wild wheat ( Triticum aestivum subsp. tibetanum Shao) Q1028 and a cultivated wheat Zhengmai 9023 (ZM9023) was constructed using diversity array technology (DArT) and reported simple sequence repeat (SSR) markers. Five SSR markers (saufc2, saufc9, saufc17, saufc25, saufc90) were further developed to accurately locate Hg in this study. Of these five SSR markers all linked to Hg, saufc2 was genetically most closed to Hg with a distance of 1.6 cM. The effectiveness of the five newly developed SSR markers were validated in another RIL derived from Q1028 and a cultivated line 99E18. To our knowledge, this is the first report on fine mapping of Hg in bread wheat. The accurate localization of the Hg and the development of the markers flanked it should facilitate the cloning of this gene and further the study of its possible physiological function in bread wheat. [ABSTRACT FROM AUTHOR]

Tibetan semi-wild wheat ( Triticum aestivum ssp. tibetanum Shao) is a hexaploid wheat resource distributed only in Tibet that has an interesting type of seed dormancy in addition to hulled glumes and brittle spikelets. A whole-genome linkage map of T. aestivum ssp. tibetanum was constructed for a population of 186 recombinant inbred lines using 645 diversity array technology (DArT) markers, 127 simple sequence repeat markers and three R- 1 genotyping markers. Seed dormancy was evaluated at five post-ripening stages from 2010 to 2013. Comprehensive quantitative trait locus (QTL) mapping by inclusive composite interval mapping analysis identified seven QTLs for seed dormancy, designated as Qsd.sau- 1B, Qsd.sau- 3A, Qsd.sau- 3B, Qsd.sau- 3D, Qsd.sau- 4A1, Qsd.sau- 4A2, and Qsd.sau- 7A, on chromosomes 1BL, 3AL, 3BL, 3DL, 4AS, 4AL, and 7AL, which explained 8.9, 7.2, 10.8, 7.0, 11.4, 9.4, and 12.7 % of phenotypic variation, respectively. Qsd.sau- 4A1 and Qsd.sau- 7A have only rarely been reported in domesticated common wheat but were prominent in T. aestivum ssp. tibetanum accession Q1028. Qsd.sau- 4A1 was associated with intense, short-duration dormancy and was recognized as an ideal QTL for wheat breeding. [ABSTRACT FROM AUTHOR]