Abstract: It's important to study the mechanisms of the rice floral development,because the rice floral organs provides the basis of the rice grain formation.We found a rice floral organ mutant from tissue culture mutation generations,called function of reproductive organ(fro1(t)).The floret shape of fro1(t) mutant is similar to that of tiny green capsicum with a couple of distorted lemma and palea,but the spekelets cannot bloom even though after heading;the glumes almost degenerated and lodicules are homeotically transformed into leaf-like organ;stamen had a distorted and enlarged filament,and the anter also showed a distorted surface yet without any pollen;the number of stamen is 2-6,and noticely some of that are homeotically transformed into pistil-like organ with stigmas-like structure on the top;the ovary showed a nomal development,but most of styles cause a fusion with 3-4 stigmas.By SEM we found that the gene regulates the determination of the floral meristem and specification of floral organ identity.We carried out fine mapping of the gene responsible for the mutated trait.The result showed that the mutated trait was located on the long arm of rice chromosome 8 between the marker InDel0802 and RM23432,with genetic distance of 0.58 cM and 1.3 cM respectively.All the above suggests that the FRO1(t) gene may be a novel gene which regulates all whorls of floral organs in rice.Study of FRO1(t) will support a key evidence to uncover the molecular mechanisms of the rice floral development.

Key words: Rice, floral development, mutant fro1(t), gene-mapping