水稻剑叶光合性状的QTL分析

Quantitative Trait Loci for Photosynthetic Traits of Flag Leaf in Rice(Oryza sativa L.)

水稻剑叶全氮含量、净光合速率和蒸腾速率是影响生物产量的重要因子。利用[Nipponbare（粳稻）×Kasalath（籼稻）]×Nipponbare的回交重组自交系（Backcross recombinant inbred lines，BILs）群体在2005、2006连续两年对其剑叶抽穗后7d的全氮含量、净光合速率、蒸腾速率进行数量性状基因座（Quantity trait locus，QTL）定位。结果检测到5个控制全氮含量的QTLs（qTLN-1、qTLN-3a、qTLN-3b、qTLN-9和qTLN-12），分布在第1、第3、第9、第12这4条染色体上，其LOD值为2．67-19．07，贡献率为2．33％-18．70％，其中qTLN-3a、qTLN-9、qTLN-12是新检测到的位点。在第6染色体上检测到1个控制净光合速率的QTL，LOD值为3．06，贡献率为4．73％；控制蒸腾速率的1个QTL qTr-10，其LOD值为6．59，贡献率为7．45％。同时还发现控制单个性状的QTLs存在上位性互作，因而利用相应的以Nipponbare为背景的全基因组染色体片段置换系（Chromosome segment substitution lines，CSSLs）群体进一步剖析单个QTL效应，结果显示控制全氮含量的qTLN-3a、qTLN-9和控制净光合速率的qPn-6在不同环境下可以被重复检测到，且效应稳定。该结果将有利于光合功能基因的分子标记辅助（MAS）育种及其图位克隆。

Total leaf nitrogen （ TLN）, net photosynthetic rate （ Pn ） and transpiration rate （ Tr ） of flag leaves are important factors affecting biomass yield of rice （ Oryza sativa L. ）. A BILs （ backcross inbred lines） population derived from the cross of （Nipponbare × Kasalath）× Nipponbare was employed to detect quantitative trait loci （QTLs） underlying TLN, Pn and Tr, which were measured on the 7th day after heading in years 2005 and 2006. As a result, five QTLs （qTLN-1, qTLN-3a, qTLN-3b, qTLN-9 and qTLN-12） controlling TLN were detected on chromosomes 1,3, 9 and 12 with LOD scores ranging from 2. 67 to 19.07 and percentages of variance explained （PVE） from 2. 33% to 18. 70%, respectively.Among the QTLs reported in this paper, qTLN-3a, qTLN-9, qTLN-12 are newly detected. One QTL qPn-6 controlling P, was detected on chromosome 6, with LOD score of 3.06 and PVE of 4.73% and QTL for Tr, namely qTr-10, was detected with LOD 6. 59 and PVE of 7.45%. Meanwhile, complicated interactions among the QTLs were detected, thus a corresponding population of chromosome segment substitution lines （CSSLs） in Nipponbare genetic background was used in 2006 to further dissect the effect of single QTL. It was noteworthy that the QTLs controlling total nitrogen content namely qTLN-3a, qTLN-9 and QTL for net photosynthetic rate qPn-6 were detected repeatedly in different environments. These QTLs will be beneficial in marker-assisted breeding and map-based cloning for genes responsible for photosynthetic traits.