不同水分条件下水稻苗期根系性状的QTL分析

以超级杂交稻协优9308(协青早B/中恢9308)衍生的234个重组自交系(RIL)为材料,在正常水分和20%聚乙二醇(PEG-6000)模拟水分胁迫处理下对水稻苗期最长根长、总根长、根表面积、根体积、根平均直径、根尖数、根鲜重和根冠比进行QTL定位分析。采用复合区间作图法,共检测到影响8个根部性状的21个QTL,单个QTL可解释的表型变异介于4.80%～11.35%。其中,正常水分条件下检测到7个QTL,分布在第2、3、9、10、11染色体上;水分胁迫条件下检测到14个QTL,分布在第2、3、5、6、9染色体上。不同水分条件下检测到的QTL位点差异很大,表明不同水分条件下的遗传机制不同。在第3和第6染色体上各检测到1个根部性状的QTL簇,尤其在第3染色体RM6283-RM7370区间发现苗期根系性状与抗旱性及产量相关性状之间存在连锁关系,利用这些QTL紧密连锁的分子标记进行辅助选择,可望同时对多个相关性状进行遗传改良。

QTL MAPPING FOR ROOT TRAITS IN RICE SEEDLINGS UNDER DIFFERENT WATER SUPPLY CONDITIONS

A recombinant inbred line (RIL) population with 234 lines derived from a super hybrid rice Xieyou 9308 were treated with normal water condition and 20% polyethylene glycol (PEG-6000). Eight root traits including the maximum root length, total root length, root surface area, root volume, root average diameter, number of root tip, root fresh weight and root/shoot ratio were measured and further used for QTL analysis. A total of 21 QTLs were detected and each locus explained 4.80%~11.35% of phenotypic variance. 7 QTLs on chromosome 2, 3, 9, 10 and 11 under normal water condition and 14 QTLs on chromosome 2, 3, 5, 6, 9 under drought stress were detected, respectively. The QTLs detected under the two water supply conditions had significant differences, which indicated that there was different genetic mechanism controlling rice root traits at the two different water conditions. Two important QTL clusters on chromosome 3 and 6 for root traits were detected, especially the QTL for seedling root traits detected between RM6283 and RM7370 on chromosome 3 had linkage relation with the QTLs for drought resistance and yield related traits. It would be possible to improve multiple traits using DNA makers closely linked to these QTLs.