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金山B-1是本室育成的一个优质水稻雄性不育保持系。为了改良金山B-1的稻瘟病抗性,我们以水稻品系75-1-127为供体,通过标记辅助连续回交将显性广谱抗稻瘟病基因Pi-9导入到金山B-1中。已知Pi-2与Pi-9等位或紧密连锁。根据前人报道的Pi-2的双侧标记和公共数据库提供的水稻基因组序列信息,我们开发了一个在金山B-1和75-1-127之间表现多态的SSR标记SRM22。该标记与Pi-9基因紧密连锁,估计与Pi-9的物理距离为309Kb,换算成遗传距离为0.73cM。在各世代皆利用SRM22对目标基因进行跟踪,并结合形态性状进行背景选择。在BC3F1代,将中选单株与不育系金山A-1进行杂交并检查其后代的育性,以测验这些单株的不育保持性。在BC3F2代,根据抗病标记、不育保持性(根据BC3F1推断)及形态性状,选得5个符合需要的单株,由此得到5个抗病性得到改良的金山B-1近等基因系(BC3F2:3)。抗病鉴定表明,所有育成株系的抗性水平皆显著高于金山B-1,说明抗病基因确实已经导入金山B-1,利用SRM22标记进行选择是可靠的。但值得注意的是,所有育成株系的抗性水平都略低于75-1-127,说明Pi-9的抗病能力会受到遗传背景的影响。
Jinshan B-1 is a high-quality male sterile CMS line bred in our lab. In order to improve the blast resistance of Jinshan B-1, we used the rice line 75-1-127 as a donor and introduced the dominant broad-spectrum blast resistance gene Pi-9 into Jinshan B-1 by marker-assisted continuous backcross . Pi-2 is known to be allelic or closely linked to Pi-9. Based on the previously reported double-sided markers of Pi-2 and rice genome sequence information provided by public databases, we developed an SSR marker SRM22 that displays polymorphism between Jinshan B-1 and 75-1-127. The marker is closely linked to the Pi-9 gene and is estimated to have a physical distance of 309 kb from that of Pi-9, converted to a genetic distance of 0.73 cM. SRM22 was used in all generations to track the target gene and to select the background combining morphological traits. In the BC3F1 generation, the selected plants were crossed with CMS-Jinshan A-1 and the fertility of their offspring was checked to test the infertility retention of these plants. In the BC3F2 generation, five plants were selected according to the disease resistance marker, sterility maintenance (based on BC3F1 deduction) and morphological traits, and five Jinshan B-1 near isogenic lines with improved disease resistance were obtained Department (BC3F2: 3). Resistance evaluation showed that the resistance level of all the breeding lines were significantly higher than Jinshan B-1, indicating that the resistance gene has indeed been introduced Jinshan B-1, SRM22 marker selection is reliable. However, it is noteworthy that the resistance level of all the bred lines was slightly below 75-1-127, indicating that the disease resistance of Pi-9 is affected by the genetic background.