Identification and gene mapping of a novel short root hair mutant in rice | 一个水稻短根毛突变体的鉴定和基因定位

Chinese. 目的鉴定和克隆水稻根毛突变体新基因，了解水稻根毛发育的分子遗传机理。方法通过T-DNA插入获得短根毛突变体。采用溶液培养、形态特征观察、杂交后代的表型分离统计及基于图位克隆技术的基因定位等方法，对突变体Ossrh1的表型、遗传和基因精细定位开展研究。结果突变体在苗期表现为根毛长度变短，只有野生型长度的36%左右，遗传分析表明该突变性状受1对隐性基因控制，利用Ossrh1和籼稻品种Kasalath杂交构建的F2群体对OsSRH1进行基因定位, 发现与第6染色体上的SSR（simple sequence repeat）标记RM3183和RM193连锁，OsSRH1距它们的遗传距离分别为0.9 cM和1.0 cM。通过在两标记间发展3个新的STS（sequence-tagged site）标记，将OsSRH1精细定位于标记T1757和T1768之间，物理距离约为115 kb。结论水稻短根毛突变体Ossrh1的性状由1对隐性核基因控制，该基因位于第6染色体的STS标记T1757和T1768之间115 kb范围内。

English. ObjectiveThe identification and cloning of novel root hair-related genes in rice would play an important role in understanding the molecular genetic mechanisms of root hair development.MethodA rice (Oryza sativa L.) mutant was isolated from a T-DNA insertion mutant library. Solution culture, phenotypic study, statistics analysis of segregation of different phenotypes as well as gene mapping by map-based cloning were used to study the phenotypic and genetic characteristics of the Ossrh1 mutant and map the OsSRH1 gene. Result The root hairs of young mutant seedlings were shorter and only 36% of the wild type. Genetic analysis indicated that the mutation was controlled by a single recessive nuclear gene. To map the OsSRH1 gene, an F2 population was generated by crossing the mutant Ossrh1 with wild type Kasalath. OsSRH1 was firstly mapped between the microsatellite markers RM3183 and RM193 on chromosome 6 with genetic distance of 0.9 cM and 1.0 cM, respectively. Three new polymorphic STS (sequence-tagged site) markers were developed in the region. OsSRH1 was finally mapped between markers T1757 and T1768 with a distance of 115 kb. Conclusion The Ossrh1 mutant is controlled by a recessive nuclear gene, which is located on chromosome 6, between T1757 and T1768 with a physical distance of 115 kb.