水稻向地性突变体的鉴定与遗传和定位分析

从水稻籼稻品种E优428的诱变M1代群体中获得向地性突变体la(t),该突变体在苗期倒伏生长,成熟期呈匍匐型生长,其它性状未发现异常。初步的生理研究表明该突变体不受外源激素(2,4-D,赤酶素)和光照的影响,并失去了感受重力的能力。遗传分析表明,该突变属单基因隐性突变,将该基因暂定名为la(t)。利用该突变体与籼稻品种D62B杂交,构建了F2代分离群体,用微卫星标记分析,将该基因定位于水稻第11染色体上的微卫星标记Lu2和Lu18之间,与目的基因分别相距1.0和1.7cM。通过电子杂交的方法将该基因所在区域的遗传图谱整合到国际水稻基因组计划的水稻第11染色体物理图谱中,其la(t)基因两端毗连的Lu2和Lu18SSR标记之间的物理距离约为140～200kb。为用图位克隆法分离此目的基因和研究水稻向地性生长的分子机理奠定基础。

Identification and Gene Mapping of a Gravitropism Mutant in Rice

A gravitropism mutant la(t) was isolated from M2 of indica type rice (Oryza sativa L.) E-you 428 treated with ethyl methanesulfonate (EMS). This mutant grew lodgingly at the young seedling stage, and the new tillers including main stem showed lazy growth habit as being older and new tillers being formed. This mutation has no obvious relation to added plant hormones Indole-3-carboxylic acid (IAA), zeatin(ZT), Gibberellic acid(GA3)and light. The results of genetic analysis suggested that this mutation was recessive and controlled by one nuclear gene, named as la(t) temporarily. The F2 population derived from la(t) D62B was the mapping population, and the related gene was mapped between two SSR markers LU2 and LU18 on 11th chromosome based on PCR, with distances 1.0 and 1.7cM, respectively. These results will help us for further study on cloning the gravitropic gene.