小麦抗叶锈病基因LrAlt的比较基因组学分析

Comparative genomics analysis of the wheat leaf rust resistance gene LrAlt

斯卑尔脱小麦材料Altgold含有小麦抗叶锈病基因LrAlt。该基因被定位于小麦2A染色体短臂末端。本研究基于小麦与短柄草和水稻基因组良好的共线性关系,对小麦抗叶锈病基因LrAlt进行比较基因组学分析,发现该基因所在基因组区域对应于短柄草第5染色体和水稻第4染色体的直系同源基因组区域,据此开发出与LrAlt连锁的EST-STS标记BE498683、BE471132.1、BG605273和CD454629,并构建了LrAlt的遗传连锁图谱,这4个EST-STS标记与Xbarc212共分离,位于LrAlt近着丝粒侧,距离LrAlt 1.9cM。同时,通过筛选Graingenes 2.0公布的位于LrAlt附近的SSR标记,发现Xbarc124、Xgwm614与LrAlt紧密连锁,均与Xbarc212共分离。本研究通过比较基因组学的策略和筛选Graingenes 2.0公布的SSR标记,共得到与LrAlt紧密连锁的9个新的分子标记,为构建LrAlt的高密度精细遗传连锁图谱、分子标记辅助选择和基因聚合奠定了基础。

Wheat leaf rust resistance gene LrAlt was identified in spelt wheat （Triticum spelta L.） accession Altgold and located on the distal part of the short arm of wheat chromosome 2A.Comparative genomics analysis showed that the genomic region containing LrAlt on 2AS was orthologous to Brachypodium （Brachypodium distachyon） chromosome 5 and rice （Oryza sativa L.） chromosome 4.Based on wheat-Brachypodium-rice genomic colinearity,EST-STS markers,BE498683,BE471132.1,BG605273,and CD454629 were linked to LrAlt.These four EST-STS markers cosegregating with Xbarc212 were proximal to LrAlt with a genetic distance of 1.9 cM.According to Graingenes 2.0,additional SSRs neighbouring the locus LrAlt were tested.Xbarc124 and Xgwm614 were confirmed to be linked to LrAlt,both of which were congregated with Xbarc212.By comparative genomics analysis and screening of SSRs,9 markers linked to LrAlt were established,which provide invaluable information for fine mapping,molecular assisted selection,and gene pyramiding of LrAlt.