Genetic Analysis And Fine-Mapping Of PISTILLOID-STAMEN 1 (PS1) And PS2 Genes In Rice (Oryza Sativa L.ssp.indica)

Rice (Oryza sativa L. ssp. indica) is an important cereal crop and the model species of monocots. The molecular mechanism of floral organ development is a hotspot of plant development researches. In the recent years, knowledge of the molecular and genetic mechanisms that underlie floral induction, floral patterning, and floral organ identity has been exploded. Based on the elucidation of basic mechanisms primarily from work in 3 eudicot species, Antirrhinum majus, Arabidopsis thaliana and Petunia hybrida, an ABC model was proposed, which was revised as the ABCD model and the ABCE model later. Homeotic genes of A-, B- and C-classes encode MADS domain transcription factors, except for AP2 which encodes an AP2 domain protein. ABC-class MADS-box genes have been isolated from grass species, such as rice, maize, wheat and barley, by homology-based cloning. Rice A, B, C / D and E-class MADS-box genes belong to groups of genes known to be expressed preferentially in reproductive organs, thereby suggesting a major role in floral and seed development. These clues seem to suggest that the ABC model can clarify the mechanism of floral organ development both in eudicots and monocots. Studies using mutants for positional cloning of cereal MADS-box genes, however, have made above suggestion quite uncertain.