To understand the molecular mechanism of leaf morphogenesis in rice, ethylmethane sulfonate (EMS) treated Ilpoom mutant line with semi-narrow and adaxially rolled leaf phenotype was identified. The leaf rolling character is said to be more advantageous under high temperature and heat stress, and play as one of the defensive mechanisms. The F1 plants, generated from a cross of Ilpoom and mutant, showed normal phenotype. Genetic analysis of its F2 population suggested that the mutation was controlled by a single recessive gene with segregation ratio of 3:1. Using F2 mapping population derived from a cross of Ilpoom mutant and Milyang23, each chromosomes were screened with STS markers by the bulked segregant analysis (BSA) method. The candidate region was detected to a long arm of chromosome 1 near the centromeric region. Fine mapping of the locus is currently conducted. Moreover, other morphological characterizations of the mutant plants were identified. Cytological analysis of the leaf suggested that deformation of the bulliform cells led to the smaller size and less number of the bulliform cells, and caused leaf rolling trait.

Leaves are the organ for photosynthesis, respiration and transpiration, and have a major effect on crop yield. Therefore, leaf shape and structure are important agronomic traits in breeding for ideal type plant. We obtained a new abaxially rolled leaf mutant from Ilpum(Oryza sativa ssp. japonica) by the treatment of ethyl methane sulfonate(EMS). The abaxially rolled leaf mutant showed reduced plant height and panicle length, increased tiller number and panicle number than Ilpum. LRI(Leaf rolling index) analysis showed that the mutant have high value compared to the wild-type. In cross section analysis, the mutant was observed to have increased of bulliform cell number and size, and led to the outcurved leaf rolling. The phenotypes of the F1 plants derived from the cross between the mutant and Ilpum were normal. In F2 population, segregation ratio between the wild type and the mutant was 3:1. This genetic analysis indicated that leaf rolling is controlled by single recessive gene. Bulked segregant analysis(BSA) and genetic mapping were conducted using F2 population derived from the cross between mutant and Milyang23(Oryza sativa ssp. indica). According to the results, the gene was located on the long arm of chromosome2. Fine mapping is in progress.

Leaf structure is one of the important agronomic traits. A rolled leaf mutant was induced from an ethyl methane sulfonate (EMS)-treated japonica rice, 'Koshihikari'. The rolled leaf mutant showed phenotypes of reduced leaf width and leaf rolling. In addition, several abnormal morphological characteristics were observed, including dwarfism, defected panicle, delayed germination, and lower seed-setting. Microscopic analysis revealed that the number of small veins was decreased and the sizes of adaxial bulliform cells were reduced in the mutant leaves. The genetic study with two F2 populations from the crosses of the rolled leaf mutant with 'Koshihikari' and Milyang23 suggested that the mutant phenotype might be controlled by a single dominant gene.