利用回交和MAS技术改良优质两系不育系金山s-2的稻瘟病抗性

 以水稻品系5173为抗性供体亲本，通过连续回交和MAS技术将稻瘟病抗性基因Pi-2导入优质低温敏核不育系金山s-2的遗传背景中。在各世代皆利用与Pi-2紧密连锁的SSR标记SRM24对目标基因进行“前景选择”，并结合形态性状进行“背景选择”，直至BC₃F ₂, 获得抗病标记纯合且其它性状与金山s-2非常相似的植株9株。在BC₃F ₁，对中选的4个单株利用SRAP标记进行遗传背景分析表明，它们与受体亲本金山s-2具较高的遗传相似系数；对选育出的株系的温敏不育性特性观察表明，获得的4个近等基因系，它们保持了亲本育性稳定、临界温度低和可繁性好的特性；对BC₃F 1∶2株系抗病鉴定结果表明，通过标记选出的单株均表现抗病，说明利用SRM24对Pi-2基因进行选择是可靠的，能够满足需要。因此，在BC₃F ₁决选出4个单株可望替代不抗病的金山s-2直接应用于生产。

Improving the Resistance of Jinshan S-2 to Rice Blast through Marker-Assisted Backcross Breeding

In this study, blast resistant gene Pi-2 was introduced into rice sterile line Jinshan s-2, via successive backcrosses using line 5173 as the donor. The marker SRM24 was employed to trace the target gene in every generation until BC₃F ₂. Nine desirable plants were selected in BC₃F₂ according to their blast resistance markers and other morphological traits. The 4 selected lines were analyzed in BC₃F1 by sequence related amplified polymorphism (SRAP) markers for comparing genetic background with recurrent parent, Jinshan s-2. The result showed they appeared high similarity with recurrent parent. And they maintained also male sterility of the acceptor. It was found that the isogenic lines had resistance of rice blast by artificial inoculation in BC3F1∶2, suggesting that the resistant gene had been really introduced into Jinshan s-2 and so using SRM24 for the selection was reliable. Therefore, near isogenic lines of Jinshan s-2 with improved blast resistance were acquired