水稻灌浆期耐热害的数量性状基因位点分析

Mapping QTLs for Heat Tolerance During Grain Filling in Rice

利用由98个家系组成的Nipponbare/Kasalath//Nipponbare回交重组自交系群体及其分子连锁图谱,以粒重感热指数[(适温粒重-高温粒重)/适温粒重×100]为评价指标,采用混合线性模型的QTL定位方法,对水稻灌浆期耐热性的主效、上位性数量性状基因位点及其与环境的互作进行分析。共检测到3个灌浆期耐热性主效QTL,分别位于第1、4和7染色体上,LOD值为8.16、11.08和12.86,贡献率8.94%、17.25%和13.50%。其中位于第4染色体标记C1100-R1783之间的QTL,没有显著的上位性和环境互作效应,表明在不同环境和遗传背景中的表达较为稳定,在水稻耐热性育种中可能具有较大的利用价值,其耐热性等位基因来自亲本Kasalath,高温热害时可减少粒重损失3.31%。位于第1染色体标记R1613-C970之间的QTL和第7染色体标记C1226-R1440之间的QTL,耐热性等位基因来自亲本Nipponbare,分别可减少粒重损失2.38%和2.92%。这两个QTL均具有与环境的互作效应,其中第7染色体上的QTL还和其他基因位点有互作。检测到8对加性×加性上位性互作QTL,分布于第1、2、3、5、7、8、10和12染色体上。没有检测到上位性QTL与环境的互作效应。

A mapping population of 98 backcross inbred lines (BILs) derived from a backcross of Nipponbare/ Kasalath ∥Nipponbare, was treated with high and optimum temperature during grain filling, respectively. The grain weight heat sensitivity index \[GWHSI= (grain weight under optimum temperature-grain weight under high temperature)/grain weight under optimum temperature×100\] was used to evaluate the tolerance of rice to heat stress. A total of three QTLs conferring heat tolerance during grain filling were detected on chromosomes 1, 4 and 7, with LOD scores 8.16, 11.08 and 12.86, and explained 8.94%, 17.25% and 13.50% of the phenotypic variance, respectively. Of these, the QTL located in the C1100-R1783 region on chromosome 4 showed no QTL×environment interactions and epistatic effects, suggesting it could stably express in different environments and genetic background, and would be valuable in rice breeding for heat tolerance. The Kasalath allele of this QTL reduced 3.31% of the grain weight loss under heat stress. The other two QTLs, with additive effects 2.38% and 2.92%, were located in the regions of R1613-C970 on chromosome 1 and C1226-R1440 on chromosome 7, respectively. The tolerance alleles of both these QTLs were from Nipponbare. Both of these QTLs had significant environmental interactions, and the QTL on chromosome 7 was involved in epistatic interaction. Eight pairs of epistatic effect QTLs were detected on chromosomes 1, 2, 3, 5, 7, 8, 10 and 12, respectively.