Sukumaran Sivakumar, Reynolds Matthew P, Sansaloni Carolina
Global Wheat Program, International Maize and Wheat Improvement Center (CIMMYT), Texcoco, Mexico.
Genetic Resources Program, International Maize and Wheat Improvement Center (CIMMYT), Texcoco, Mexico.
Front Plant Sci. 2018 Feb 6;9:81. doi: 10.3389/fpls.2018.00081. eCollection 2018.
Understanding the genetic bases of economically important traits is fundamentally important in enhancing genetic gains in durum wheat. In this study, a durum panel of 208 lines (comprised of elite materials and exotics from the International Maize and Wheat Improvement Center gene bank) were subjected to genome wide association study (GWAS) using 6,211 DArTseq single nucleotide polymorphisms (SNPs). The panel was phenotyped under yield potential (YP), drought stress (DT), and heat stress (HT) conditions for 2 years. Mean yield of the panel was reduced by 72% (to 1.64 t/ha) under HT and by 60% (to 2.33 t/ha) under DT, compared to YP (5.79 t/ha). Whereas, the mean yield of the panel under HT was 30% less than under DT. GWAS identified the largest number of significant marker-trait associations on chromosomes 2A and 2B with -values 10 to 10 and the markers from the whole study explained 7-25% variation in the traits. Common markers were identified for stress tolerance indices: stress susceptibility index, stress tolerance, and stress tolerance index estimated for the traits under DT (82 cM on 2B) and HT (68 and 83 cM on 3B; 25 cM on 7A). GWAS of irrigated (YP and HT combined), stressed (DT and HT combined), combined analysis of three environments (YP + DT + HT), and its comparison with trait and stress indices identified QTL hotspots on chromosomes 2A (54-70 cM) and 2B (75-82 cM). This study enhances our knowledge about the molecular markers associated with grain yield and its components under different stress conditions. It identifies several marker-trait associations for further exploration and validation for marker-assisted breeding.
了解重要经济性状的遗传基础对于提高硬粒小麦的遗传增益至关重要。在本研究中，对一个由208个品系组成的硬粒小麦群体（包括来自国际玉米和小麦改良中心基因库的优良材料和外来品种），使用6211个DArTseq单核苷酸多态性（SNP）进行全基因组关联研究（GWAS）。该群体在产量潜力（YP）、干旱胁迫（DT）和热胁迫（HT）条件下进行了两年的表型分析。与YP（5.79吨/公顷）相比，该群体在HT条件下的平均产量降低了72%（至1.64吨/公顷），在DT条件下降低了60%（至2.33吨/公顷）。然而，该群体在HT条件下的平均产量比DT条件下低30%。GWAS在2A和2B染色体上鉴定出数量最多的显著标记-性状关联，其P值为10至10，整个研究中的标记解释了性状7-25%的变异。确定了胁迫耐受性指数的共同标记：胁迫敏感指数、胁迫耐受性以及针对DT（2B上82 cM）和HT（3B上68和83 cM；7A上25 cM）条件下性状估计的胁迫耐受性指数。对灌溉（YP和HT组合）、胁迫（DT和HT组合）、三种环境的联合分析（YP + DT + HT）及其与性状和胁迫指数的比较，在2A染色体（54-70 cM）和2B染色体（75-82 cM）上鉴定出QTL热点。本研究增进了我们对不同胁迫条件下与籽粒产量及其构成因素相关分子标记的了解。它鉴定出了几个标记-性状关联，以供进一步探索和验证用于标记辅助育种。
