水稻超短根突变体ssr1的遗传分析和基因定位

Genetic Analysis and Gene Mapping of a Super Short Root Mutant ssr1 in Rice (Oryza sativa L.)

该研究从甲基磺酸乙酯(EMS)诱变的籼稻‘Kasalath’突变体库中筛选到1个根系超短的突变体,命名为ssr1(super short root 1),8d苗龄突变体的主根和不定根长度分别只有野生型的8.89%和2.29%,其不定根发生正常,但侧根的发生和伸长都受到严重抑制,且根毛也非常短。此外,ssr1植株整体矮小,株高不到野生型的一半。遗传分析结果表明,该突变性状由1对隐性核基因控制。利用图位克隆技术将SSR1基因定位在第9染色体的STS(sequence tagged site)分子标记9g7047K和9g7290K之间,物理距离约为243kb,在定位区间共发现39个预测基因,经分析其中没有已克隆的根系发育基因。对SSR1的定位为进一步克隆该基因和阐明水稻根构型的分子机理奠定了基础。

In this study, a mutant with super short primary and adventitious roots, less lateral roots and short root hairs was isolated from an EMS （ethyl methane sulfonate）-generated rice mutant library in the Kasalath background,designated as ssrl （super short root 1）. At the 8 d old stage,the length of primary and adventitious roots of ssrl was only 8.89% and 2.29% of the wild type （WT） ,respectively. The initia- tion of adventitious roots of ssrl was similar as WT, while the initiation and elongation of lateral roots were severely impaired and root hairs were also much shorter than that of WT. Moreover, ssrl showed dwarf phenotype with plant height less than half of WT. Genetic analysis indicated that the mutant phenotype was controlled by a single recessive nuclear gene. Map-based cloning analysis located SSR1 to a 243 kb region between STS（sequence tagged site）markers 9g7047K and 9g7290K on chromosome 9. The region contains 39 putative genes with none reported to be related to root development of rice. This result will be helpful for the cloning of SSR1 and further characterization of molecular genetic mechanisms underlying root architecture in rice.