Abstract
The flo2 mutant shows decreased expression of many genes involved in starch synthesis and storage proteins, suggesting that the Flo2 gene may encode a multi-functional regulatory factor for biosynthesis of storage substances in rice grains. Fine mapping determined the responsible gene for flo2 locating at 110 cM of chromosome 4 and following DNA sequencing including other 7 flo2 alleles revealed point mutations in this region causing stop codon or splicing error. The corresponding genomic fragment from the wild-type plant recovered the flo2 phenotype in a flo2 mutant. RBE1 and RA16 expressions were also recovered, which greatly decreased in flo2 mutant. Taken together, this gene was identified to be the origin of flo2 mutation and termed OsCEO1 (Conductor of Endosperm Organogenesis 1). OsCEO1 expressed higher in leaves and immature seeds. Yeast 2-hybrid analysis detected 14 candidates that may have direct interaction with OsCEO1.
