Characterization and Molecular Mapping of Rolled Leaf Mutant and Elongated Uppermost Internode Mutant in Rice

Abstract

To understand the various plant architecture and morphogenesis in rice (Oryza sativa L.), ethyl methanesulfonate treated Ilpum mutant with narrow and rolled leaf phenotype and Koshihikari mutant with elongated uppermost internode trait were identified. The leaf rolling trait is said to be more advantageous under high temperature and heat stress. Cytological analysis of the leaf suggested that smaller size and less number of the bulliform cells caused leaf rolling. Ilpum/rl crossed F1 plants 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 M23/rl F2 mapping population, each chromosome was screened with STS markers by the BSA method. The candidate region was detected to a long arm of chromosome 1, near the centromeric region. Through whole genome sequencing and its MutMap analysis, the causal SNP within the candidate region was identified. The result of RT PCR suggested that splicing error was occurred due to a base change from G to A at the beginning of 5th intron of Loc_Os01g37837, a gene which encode putative seryl-tRNA synthetase, and various forms of transcripts were presented. A novel gene that cause change of leaf morphology into narrow and rolled leaf was newly discovered. Eui mutant showed significantly increased first three internodes. The phenotype of F2 progenies of Koshihikari/eui was determined by measuring the length of first and second internodes. The distribution of each measurement implied that the mutant phenotype was controlled by a single recessive gene. BSA result showed that the flanking region was set to a long arm of chromosome 5. Further narrow down was conducted into 984kb of the markers S0595e and S05101c, including EUI1. However, sequencing result suggested that the eui didnt have mutation correspond to EUI1. Another gene than EUI1 is thought to be related with internode elongation trait in chromosome 5.