大豆品种豫豆25抗疫霉根腐病基因的鉴定

Molecular Identification of Phytophthora Resistance Gene in Soybean Cultivar Yudou 25

大豆疫霉根腐病是大豆破坏性病害之一。防治该病的最有效方法是利用抗病品种。迄今,已在大豆基因组的9个座位鉴定了15个抗大豆疫霉根腐病基因,但是只有少数基因如Rps1c、Rps1k抗性在我国是有效的。因此,必需发掘新的抗疫霉根腐病基因,以满足抗病育种的需求。豫豆25具有对大豆疫霉菌的广谱抗性,是目前筛选出的最优异的抗源。以豫豆25为抗病亲本分别与豫豆21和早熟18杂交构建F2:3家系群体。两个群体的抗性遗传分析表明,豫豆25对疫霉根腐病的抗性由一个显性单基因控制,暂定名为RpsYD25。用SSR标记分析两个群体,RpsYD25均被定位于大豆分子遗传图谱N连锁群上。由于Rps1座位已作图在N连锁群,选择Rps1k基因中的一些SSR设计引物,检测RpsYD25与Rps1座位的遗传关系。结果表明,一个SSR标记Rps1k6与RpsYD25连锁,二者之间的遗传距离为19.4cM。因此,推测RpsYD25可能是Rps1座位的一个新等位基因,也可能是一个新的抗病基因。

Phytophthora root rot, caused by Phytophthora sojae, is a destructive disease on soybean. Use of resistant soybean cultivars is the most economical and effective method for controlling the disease. Up to now, nine loci for the resistance with 15 genes have been identified in soybean. However, only a few genes, such as Rps1c and Rps1k,were effectively resistant to populations of P. sojae in China, so mining new resistance genes is necessary greatly for the disease control. Soybean cv. Yudou 25 has broad spectrum resistance to P. sojae, and is an elite resistance source for Phytophthora root rot of soybean. To effectively utilize the cultivar in resistance breeding, in the present study, we identified and tagged the Phytophthora resistance gene in the cultivar by using SSR markers and bulked segregation analysis （BSA）. Two F2：3 populations were developed for resistance genetic analysis and resistance gene mapping. Using hypocotyls inoculation technique at the seedling stage in the glasshouse, the reaction to P. sojae isolate PSMC1 （virulence type 1b, 1d, 3a, 3b, 3c, 4, 5, 6, 7） in 82 and 98 F2：3 families derived from two crosses of Yudou 21×Yudou 25 and Zaoshu 18×Yudou 25, respectively, were identified. The segregation ratio in both populations fit into 1：2：1 for homozygous resistant, segregating and homozygous susceptible, showing that the cultivar resistance to Phytophthora root rot is controlled by a dominant single gene, with the temporary name of RpsYD25. On the basis of linkage analysis with SSR markers, RpsYD25 was located on soybean molecular linkage group （MLG） N in both populations. Five SSR markers were associated with RpsYD25 in an order of Sat_208-Satt530-RpsYD25-Sat_084-Satt125-Sat_236 in F2：3 population from the cross of Yudou 21×Yudou 25, RpsYD25 was flanked by Satt530 and Sat_084 with a distance of 6.3 and 7.7 cM, respectively. Five SSR markers were linked to RpsYD25 in an order of Satt125-RpsYD25-Sat_275-Sat_266-Satt660-GMABAB in F2：3 population from the cross of Zaoshu 18×Yudou 25, RpsYD25 was flanked by Satt125 and Sat_275 with a distance of 7.9 and 7.8 cM, respectively. Because RpsYD25 was mapped on MLG N near to Rps1 locus, the genetic relationship of RpsYD25 and Rps1 was detected by using the selected SSR markers contained in the Rps1k allele sequence. A SSR marker Rps1k6 in Rps1k allele was found to be linked to RpsYD25 with a genetic distance of 19.4 cM in F2：3 population from the crosses Yudou 21×Yudou 25. Therefore, the Phytophthora resistance gene RpsYD25 in cv. Yudou 25 might be a novel allele at Rps1 locus, or a novel gene.