The physiological function of the quantitative traits loci for the traits associated with the strong culm to develop the rice cultivars with high grain yield and biomass production.

抗倒伏是高产、高产水稻品种的重要农艺性状之一。为了定位控制水稻抗倒伏的染色体区域，我们利用一组回交自交系(BIL)和由Koshihikari与高抗倒伏品种杂交育成的染色体片段置换系(SLS)，利用QTL分析方法对控制茎秆机械强度的数量性状基因座(QTL)进行了估计和鉴定。确定了影响茎秆强度的有效数量性状基因座，命名为强CULM2(SCM2)和强CULM3(SCM3)。对该基因的定位克隆表明，SCM2基因与先前报道的控制穗部结构的基因APO1相同。一个携带SCM2的近等基因系由于该基因的多效性效应，表现出较强的茎秆强度和较多的小穗数量。虽然SCM2是APO1的功能增益突变体，但它没有APO1过表达突变体的负面效应，如穗数减少和小穗形态异常。利用QTL分析和定位克隆相结合的方法定位水稻抗倒伏基因，是提高水稻抗倒性和综合生产力的有效途径。

Lodging resistance is one of the most important agronomical traits for the rice cultivars with high grain yield and biomass production. To locate the chromosome regions controlling the lodging resistance in rice, we conducted to estimate and characterize the quantitative traits loci(QTLs) responsible for culm mechanical strength using QTL analyses, using a set of backcross inbred lines(BILs) and the chromosome segment substitution lines(SLs) developed from a cross between Koshihikari, and a high lodging resistant cultivars. We identified the effective quantitative trait loci(QTLs) for culm strength, which were designated STRONG CULM2(SCM2) and STRONG CULM3(SCM3). Positional cloning of the gene revealed that SCM2 was identical to APO1, a gene previously reported to control panicle structure. A near-isogenic line carrying SCM2 showed enhanced culm strength and increased spikelet number due to the pleiotropic effects of the gene. Although SCM2 is a gain-of-function mutant of APO1, it does not have the negative effects reported for APO1 over-expression mutants, such as decreased panicle number and abnormal spikelet morphology. The identification of lodging resistance genes by QTL analysis combined with positional cloning is a useful approach for improving lodging resistance and overall productivity in rice.