Characterization and Fine Mapping of the ibf Mutant in Rice

The pigment is an important character in plant development. In the present study, we characterized and fine mapped one Inhibitor for brown furrows gene (ibf in rice (Oryza sativa L.). In the ibf mutant, brown pigments specifically accumulate in the furrows of hulls as seeds mature and reach a maximum level in dry seeds. Genetic analysis showed that the mutant phenotype is controlled by one recessive nuclear gene, which was finally mapped in a 90-kb region on the long arm of chromosome 9. Polymerase chain reaction and Southern blotting analysis revealed that there was a 26 kb deletion in the 90-kb region in the mutant. Since all the open reading frames outside the gap in the delimited region had no detectable difference in DNA sequence with the wild-type, we postulated that the ibf locus should be located in the gap. Through gene annotation and reverse transcription-polymerase chain reaction (RT-PCR) analysis, we selected OsKF1 encoding a kelch repeat-containing F-box family protein as the candidate gene of W.