Department of Plant Breeding and Genetics, 240 Emerson Hall, Cornell University, Ithaca, NY 14853, USA.
Theor Appl Genet. 2011 Dec;123(8):1257-68. doi: 10.1007/s00122-011-1664-y. Epub 2011 Aug 3.
The recent emergence of wheat stem rust Ug99 and evolution of new races within the lineage threatens global wheat production because they overcome widely deployed stem rust resistance (Sr) genes that had been effective for many years. To identify loci conferring adult plant resistance to races of Ug99 in wheat, we employed an association mapping approach for 276 current spring wheat breeding lines from the International Maize and Wheat Improvement Center (CIMMYT). Breeding lines were genotyped with Diversity Array Technology (DArT) and microsatellite markers. Phenotypic data was collected on these lines for stem rust race Ug99 resistance at the adult plant stage in the stem rust resistance screening nursery in Njoro, Kenya in seasons 2008, 2009 and 2010. Fifteen marker loci were found to be significantly associated with stem rust resistance. Several markers appeared to be linked to known Sr genes, while other significant markers were located in chromosome regions where no Sr genes have been previously reported. Most of these new loci colocalized with QTLs identified recently in different biparental populations. Using the same data and Q + K covariate matrices, we investigated the interactions among marker loci using linear regression models to calculate P values for pairwise marker interactions. Resistance marker loci including the Sr2 locus on 3BS and the wPt1859 locus on 7DL had significant interaction effects with other loci in the same chromosome arm and with markers on chromosome 6B. Other resistance marker loci had significant pairwise interactions with markers on different chromosomes. Based on these results, we propose that a complex network of gene-gene interactions is, in part, responsible for resistance to Ug99. Further investigation may provide insight for understanding mechanisms that contribute to this resistance gene network.
最近出现的小麦秆锈菌 Ug99 和该谱系内新菌株的进化威胁着全球小麦生产，因为它们克服了已广泛部署多年的有效茎锈病抗性（Sr）基因。为了鉴定赋予小麦对 Ug99 菌株成株期抗性的基因座，我们采用关联作图方法对来自国际玉米和小麦改良中心（CIMMYT）的 276 个当前春小麦品系进行了分析。利用多样性数组技术（DArT）和微卫星标记对这些系进行了基因型分析。在 2008、2009 和 2010 年肯尼亚 Njoro 的茎锈病抗性筛选苗圃中，对这些系进行了 Ug99 抗茎锈病的成株期表型数据收集。发现 15 个标记与茎锈病抗性显著相关。一些标记似乎与已知的 Sr 基因相关，而其他显著标记位于先前未报道 Sr 基因的染色体区域。这些新基因座中的大多数与最近在不同双亲和群体中鉴定的 QTL 共定位。使用相同的数据和 Q + K 协变量矩阵，我们利用线性回归模型研究了标记之间的相互作用，以计算成对标记相互作用的 P 值。包括 3BS 上的 Sr2 基因座和 7DL 上的 wPt1859 基因座在内的抗性标记基因座与同一染色体臂上的其他基因座和 6B 染色体上的标记有显著的互作效应。其他抗性标记基因座与不同染色体上的标记有显著的成对相互作用。基于这些结果，我们提出基因-基因相互作用的复杂网络部分解释了对 Ug99 的抗性。进一步的研究可能为理解有助于该抗性基因网络的机制提供启示。
