Genetic analysis and gene mapping of bgl, a gene controlling grain length and quality in rice

Abstract

Grain size is one of the important agronomic traits that determine rice yield. Map-based cloning of rice grain size-related genes impacts the genetic regulation mechanism of rice yield formation. Here we identified bgl mutant in rice which exhibits increase in grain length and panicle length with the decrease in number of grains per panicle and no observable difference in grain thickness and number of tillers as compared to the wild type (WT). Scanning electron microscopy observation of bgl mutant spikelets hull indicates an upsurge in number of external epidermal cells in a longitudinal way than the WT. Hence, it is likely that the long-grain phenotype was due to increased cell number longitudinally. Starch granule in both bgl and WT were large, sporadically polyhedral and densely packed, indicating no differences, signifying that both bgl mutant and WT have less chalkiness content. Genetic analysis showed that the bgl mutant was controlled by a recessive single gene, and was finely located on chromosome 3 through map-based cloning, within a physical distance of 40kb. Sequencing analysis revealed A to T substitution in the seventeen exons of LOC_Os03g44500 resulted in an amino acid change from Tryptophan (Try) to Phenylalanine (Phe). Taken together bgl mutant has a pleiotropic effect on grain yield and grain quality.