Abstract: Flowerdevelopment 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 Buxuenuo. Using scanning electron micrograph, we observed that the abaxial surface of the mutant Oslegrich 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)< χ²_0.05(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 a way for the OsLEG cloning and study on the molecular genetic mechanisms of the floral organ in monocot.

Key words: Rice(Qryza sativa L.), Floral organ, Long empty glumes mutant, Gene location