Identification of a novel candidate gene for rolled leaf in rice

A semi-narrow and adaxially rolled leaf mutant, rl15(t), was induced from Korean japonica rice cultivar Ilpum by chemical mutagenesis using ethyl methanesulfonate. We characterized the mutant and identified the novel gene causing the mutant phenotype. Cytological analysis of mutant leaves indicated that the adaxial leaf-rolling phenotype is due to the reduced size and number of bulliform cells in the mutant. Genetic analysis showed that the rolled leaf trait is controlled by a single recessive gene, designated rl15(t). Using an F₂ mapping population generated from a cross between Milyang23 and the mutant, we mapped the candidate region to a 174 kb interval on the long arm of chromosome 1 near the centromeric region. Through whole genome sequencing in bulk and MutMap analysis, we identified the causal SNP within the candidate region. The results of RT-PCR analysis indicated that a splicing error occurred due to a base change from G to A at the beginning of the fifth intron of LOC_Os01g37837, which encodes a putative seryl-tRNA synthetase, resulting in the mutant phenotype. Further study of the rl15(t) gene will facilitate analysis of leaf architecture and morphogenesis in rice plants.