大豆对大豆花叶病毒株系SC6和SC17抗病基因的精细定位

针对我国北方和长江流域大豆产区广泛分布的SMV株系SC6和SC17，利用2个抗病大豆品种Q0926和中豆35分别与感病品种南农1138-2和南农菜豆5号配制2个抗感杂交组合Q0926×南农1138-2和中豆35×南农菜豆5号以及一个抗抗组合Q0926×中豆35，研究3个组合的F₁、F₂、F_2:3抗性遗传规律,探讨Q0926对SC6和中豆35对SC17及2个抗病品种对同一SMV株系抗性基因的等位关系，并对大豆对2个株系的抗病基因进行了标记定位。结果显示，Q0926×南农1138-2和中豆35×南农菜豆5号2个抗感杂交组合在分别接种SC6和SC17后，F₁表现抗病，F₂呈3抗∶1感分离比例，F_2:3家系呈1抗∶2分离∶1感病的分离比率，表明Q0926对SC6和中豆35对SC17的抗病性分别由1对显性基因控制；抗抗组合Q0926×中豆35的F₁和F₂在接种2个株系后均未发现感病单株，表明Q0926与中豆35对SC6和SC17株系的抗病基因分别是等位或紧密连锁的。分别利用2个抗感组合的F₂和F_2:3群体对2个抗病基因的定位结果显示，第2染色体上的25个SSR标记与抗SC6的基因R_SC6连锁，最近的2个标记与抗性基因R_SC6的排列次序和遗传距离为BARCSOYSSR_02_0617(0.775 cM)-R_SC6-BARCSOYSSR_02_0621(0.519 cM)；第2染色体上的38个SSR标记与抗SC17的基因R_SC17连锁。最近的2个标记与抗性基因R_SC17的排列次序和遗传距离为BARCSOYSSR_02_0622(0.264 cM)-R_SC17-BARCSOYSSR_02_0627(0.262 cM)，其对应的物理区间分别为52 kb和60 kb。抗性遗传研究为抗大豆花叶病毒育种的亲本选配、后代选择提供了理论指导，抗性基因的标记定位研究为抗性基因的分子标记辅助选择和抗病基因的图位克隆奠定了基础。

Fine Mapping of Resistance Genes to SMV Strains SC6 and SC17 in Soybean

SMV strains SC6 and SC17 were prevalen in the North China and the Huang-Huai and Yangtze Valleys soybean production regions. Two soybean cultivars Q0926 and Zhongdou 35, which were resistant to SC6 and SC17, were respectively crossed with Nannong 1138-2 and Nannongcaidou 5, which were susceptible to SC6 and SC17, to determine inheritance of resistance to SC6 or SC17. Q0926 was also crossed with Zhongdou 35 to study allelic relationships of the resistance genes from the two soybean cultivars. On the basis of the results, the resistance genes to SC6 and SC17 were fine mapped. The results showed that the F₁ plants presented complete resistance, F₂ population were segregated with a ratio of 3R:1S, F_2:3 population were segregated with a ratio of 1R:2Seg:1S in resistant (R)×susceptible (S) crosses. These results indicated that the resistances of Q0926 and Zhongdou 35 to SC6 and SC17 were controlled by a single dominant gene respectively. The F₁ plants displayed complete resistance, and F₂ populations of the crosses Q0926×Zhongdou 35 were not segregated, indicating that the resistance genes to SC6 and SC17 were alleles or very closely linked. Genetic maps showed that 25 SSR markers were linked to theresistance gene to SC6 (designated R_SC6) and the genetic distance and order of the two closest SSR markers to R_SC6 were BARCSOYSSR_02_0622 (0.264 cM)-R_SC17- BARCSOYSSR_02_0627 (0.262 cM). The 38 SSR markers were linked tothe resistance gene to SC17 (designated R_SC17) and the genetic distance and order of the two closest SSR markers to R_SC6 were BARCSOYSSR_02_0622 (0.264 cM)-R_SC17 -BARCSOYSSR_02_0627 (0.262 cM),their corresponding physical intervals were 52 kb and 60 kb. The studies on inheritance of resistance to SMV provide a theoretical guidance to programs of resistance breeding to SMV. Fine map of resistance genes laid the foundation for molecular marker-assisted selection and map-based cloning of resistance genes.