一个水稻长护颖突变体的遗传分析和基因定位

Genetic Analysis and Gene Mapping of a Long Empty Glumes Mutant in Rice (Oryza sativa L.)

花器官发育异常突变体是研究植物花发育分子机理的重要材料。本研究在特种栽培稻品种"鸭血糯"中发现一个长护颖自然突变体,命名为Osleg(Oryza sativa long empty glumes)。组织细胞学分析表明,该突变体护颖的远轴表皮细胞凸凹不平,毛状体较多,许多瘤状体轴向平行排列,与外稃表皮细胞结构相似。遗传分析结果表明,该突变性状受一对隐性基因控制。将Osleg纯合体与籼稻品种9311杂交构建F2定位群体,利用已公布的水稻SSR标记和自行设计的STS标记对突变位点进行基因定位,最终将OsLEG定位在水稻7号染色体短臂上的LC15和LC25标记之间,物理距离约207kb,为进一步克隆OsLEG基因和研究禾本科植物花器官的分子调控机理提供了重要科学依据。

Flower development plays an important role in the life cycle of plant. However, the molecular mechanism of floral organ development has not been clear in rice （Oryza sativa L.）. The mutants with abnormal flower organ were important materials for researching the flower development. In this study, a spontaneous mutant named Osleg, with two long empty glumes, was discovered from special rice cultivar Yaxuenuo. Using scanning electron micrograph, we observed that the abaxial surface of the mutant Osleg rich in trichomes was rough and some tubercles were arranged in parallel, which has the similar structure to the epidermic cells of the lemma. The results suggested that the mutant traits could be evolved from the two lemmas during the evolution of Oryza. To mapping the gene OsLEG, we used mutant Osleg and 9311 as parents to structure F2 population. On the basis of the field observation, the ratio of normal empty glumes to long empty glumes was 4302：1485, fitting the 3：1 ratio [χ2（0.246） χ20.05（3.84）]. Genetic analysis showed that the mutant character was controlled by a single recessive gene. Ultimately using the published SSR markers and designed some STS makers, the OsLEG was mapped to a 207-kb region between the STS markers LC15 and LC25 on the short arm of chromosome 7 across two BAC clones. With in this region, there were forty-six predicted genes in the rice database [TIGR release 5（RAP2 build 4.0）]. None of them was related directly to glumes in rice. But, one encoded F-box protein had connection with floral development and could be related to the OsLEG to a certain extent. Those studies will pave the way for the OsLEG cloning and study on the molecular genetic mechanisms of the floral organ in monocot.