Using an interspecific near-isogenic line derived from Oryza sativa ssp.indica (Shuhui 527)×O .rufipogon Griff.(Yuanjiang common wild rice Hehuatang 3)as materials,a QTL for heat tolerance at the heading stage in the heat-tolerant near-isogenic rice line YJ10-03-01 was analyzed.A total of 360 simple sequence repeat(SSR)markers evenly distributed across 12 chromosomes were used to detect polymorphisms between YJ10-03-01 and indica restorer Shuhui 527, and nine were polymorphic.Single marker analysis revealed that markers on chromosome 5 were associated with heat tolerance at the heading stage using seed setting percentage as index for heat tolerance.By interval mapping using F2 population(1 ,027 plants)from YJ10-03-01 ×Shuhui 527,a QTL for heat tolerance was detected on the short arm of chromosome 5 .The QTL explained 8.6% and 1 9.4% of phenotypic variances in the F2 and F3 generations under heat stress (artificial climate chamber),respectively.Recombinant plants were screened for two flanking markers,RM7320 and RM7444,in F3 generation,and substitution mapping suggested that the QTL was located in an interval of about 304.2 kb between markers RM5 92 and RM1 7921 ,we designated the QTL as qHTH5 (quantitative trait locus for heat tolerance at the heading stage on chromosome 5).%对元江普通野生稻(Oryza rufipogon Griff．)(简称元江普野)荷花塘3号为供体、籼稻(O ．sativa ssp．indica )恢复系蜀恢527为轮回亲本构建的种间近等基因系群体进行数量性状位点(QTL)分析,在近等基因导入系 YJ10-03-01中鉴定了一个抽穗扬花期耐热 QTL.利用均匀分布在水稻12条染色体上的360个 SSR 标记检测近等基因系 YJ10-03-01和籼稻恢复系蜀恢527,共获得9个多态性标记.单标记分析表明第5染色体短臂上的多态性标记与抽穗扬花期耐热性极显著相关.进一步在人工气候室模拟高温条件下处理 YJ10-03-01与蜀恢527杂交得到 F2分离群体(1027个单株)并进行 SSR 标记分析,以水稻结实率为耐热指标,利用复合区间作图方法在第5染色体短臂上检测到一个抽穗扬花期耐热性 QTL,暂命名为qHTH5.该 QTL 在 F2及 F3世代分别解释8．6％和19．4％的表型变异.在 F3世 代,继续利用目标区间标记 RM7320和RM7444之间的 SSR 标记鉴定纯合重组体,利用置换作图法将 QTL 定位在约304．2 kb 之内(RM592－RM17921).
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