粳稻品种吉粳809的稻瘟病抗性基因分析

摘要

稻瘟病是水稻生产中危害最为严重的病害之一,种植抗病品种是抵御稻瘟病危害的有效措施。本研究利用吉粳809的2个亲本材料吉粳88与93072配制的回交分离群体进行稻瘟病人工接种,采用抗、感极端分池法定位双亲的稻瘟病抗性基因,结合基因型分析,推断吉粳809的抗性基因组成。结果表明,回交群体对强致病菌GD9-1表现为4个主效抗病基因Pi-2(t)、Pi-7-1(t)、Pi-7-2(t)和Pi-11(t)分离,对弱致病菌GD19-1表现单个主效抗病基因Pi-2(t)分离,其中 Pi-2(t)基因同时抗2个菌株。除 Pi-2(t)位点抗性等位基因来自吉粳88,其余3个位点的抗性等位基因均来自93072。比较基因组研究表明, Pi-2(t)可能与Pi-b等位, Pi-11(t)可能与Pi-47(t)或Pik等位,而Pi-7-1(t)和Pi-7-2(t)是2个新的抗性位点,分别与RM21260和RM8037连锁,遗传距离为0.11 cM和6.97 cM。利用与上述4个抗病位点紧密连锁的SSR标记和来自3000份水稻种质资源重测序开发的56K芯片鉴定抗性位点吉粳809与双亲基因型的异同,推断吉粳809抗性基因组成,发现吉粳809携带轮回亲本吉粳88的Pi-2(t)和来自供体亲本93072的Pi-11(t)2个基因,合理地解释了吉粳809抗性明显好于吉粳88的原因。对如何通过不同主效抗性基因聚合特别是充分利用原来抗病品种中“丧失”抗性残效基因来改良品种的稻瘟病抗性进行了讨论。%Blast is one of the most hazardous diseases in rice production. Planting resistance variety is an effective solution to control the disease. In this study, a backcross population derived from two parents, Jijing 88 and 93072, was selected to identify blast resistance genes using bulked extremes and recessive class under artificial inoculation and further to deduce the composition of resistance genes in Jijing 809 developed from Jijing 88 and 93072. Four major resistance genes, i.e.,Pi-2(t), Pi-7-1(t), Pi-7-2(t), andPi-11(t), were responsible for segregation of resistance to the strong virulent strain GD9-1, and only one resistance genePi-2(t) for segregation of resistance to the weak virulent strain GD19-1. Among them,Pi-2(t) was effective to both strains. The favorable alleles at all loci were from 93072 except for the allele atPi-2(t) from Jijing 88. According to genomic comparison,Pi-2(t) was deduced to be allelic toPi-b, andPi-11(t) toPi-47(t) orPik; whereasPi-7-1(t)andPi-7-2(t) were two novel resistance genes, which were linkages to SSR markers with RM21260 (0.11 cM) and RM8037 (6.97 cM). Genotypes on the four above-referenced loci were compared between Jijing 809 and its parents by using closely linked SSR markers and a set of 56k gene chip developed from re-sequenced data of 3000 accessions of rice germplasm. The results indicated that the resistance genes inJijing 809,Pi-2(t) andPi-11(t), were inherited from the recurrent parent Jijing 88 and the donor parent 93072, respectively, which reasonably ex-plained the higher blast resistance in Jijing 809 than in Jijing 88. Finally, we discussed how to pyramid different known major resistant genes, especially to make full use of the ‘defeated’ resistance gene in the original resistant variety to improve blast resis-tance in rice.