水稻种子耐贮性QTLqSS-9的精细定位

[目的]在前期研究中,我们利用Koshihikari/Kasalath//Koshihikari衍生获得的回交重组自交系(backcross-inbred line,BIL)群体和染色体片段置换系(chromosome segment substitution line,CSSL)群体检测到1个控制种子耐贮性的QTL qSS-9.本研究在此基础上对qSS-9进一步进行定位分析.[方法]利用以‘Koshihikari’为背景、携带qSS-9的‘Kasalath’染色体片段置换系SL226,在多年环境下采用人工老化和自然老化两种处理方法,验证qSS-9的真实存在及稳定性;利用‘Koshihikari’×SL226构建的272个单株组成的F2分离群体对qSS-9进行遗传解析,同时,在F2分离群体中筛选出4个不同的交换单株,构建4个携带有不同长度‘Kasalath’片段的小片段置换系,对qSS-9进一步精细定位.[结果]含有qSS-9增效等位基因的置换系SL226在多年环境中老化处理后的种子发芽率均显著高于‘Koshihikari’;利用Windows QTL Cartographer 2.5软件在F2群体中检测到qSS-9,位于第9染色体标记RM7390与L9-13之间,LOD值为30.94,对表型变异的贡献率为44.02%;4个携带qSS-9的小片段置换系在人工老化处理后的种子发芽率均显著高于‘Koshihikari’.[结论]qSS-9定位在Indel标记Y7与Y13之间,该区间在‘Nipponbare’基因组上的物理距离约为478 kb.本研究为开展水稻耐贮性相关基因的克隆和耐贮性的遗传改良提供了理论基础.
[Objectives] qSS-9 controlling seed storability was identified using backcross-inbred lines(BILs)derived from the backcross Koshihikari(japonica)/Kasalath(indica)//Koshihikari and‘Kasalath’chromosome segment substitution lines(CSSLs)in a‘Koshihikari’genetic background in our previous study. Based on these results,qSS-9 was further fine-mapping in the present study. [Methods]Effect and stability of the‘Kasalath’allele of qSS-9 were validated using a chromosome segment substitution line,SL226,which harbored qSS-9 from‘Kasalath’in the genetic background of‘Koshihikari’under artificial aging or natural aging treatments in different environments. Subsequently,a secondary F2 population consisting of 272 individuals was derived from a cross between‘Koshihikari’and SL226 and was used for genetic dissection of qSS-9. Simultaneously,four sub-near isogenic lines(sub-NILs),which harbored different segment substitution from‘Kasalath’in the genetic background of‘Koshihikari’,were developed from four different recombinants which selected from the F2 population. These sub-NILs were used for fine-mapping of qSS-9. [Results]Germination rates of SL226 harbored the‘Kasalath’allele of qSS-9 were significantly higher than those of‘Koshihikari’after artificial aging or natural aging treatments in different years. The F2 population showed a continuous distribution in germination rates after artificial aging. QTL for seed storability was identified in the F2 population by Windows QTL Cartographer 2.5 software packages. A major QTL,qSS-9,was found and located between markers RM7390 and L9-13 on chromosome 9,with the LOD value of 30.94 and explained the phenotypic variation of 44.02%. Germination rates of the four sub-NILs were all significantly higher than that of‘Koshihikari’after artificial aging. [Conclusions]The qSS-9 locus was located between the Indel markers