Isolation And Characterization Of Bushy And Yellow Leaf Mutant(buy1) In Rice

Rice(Oryza Sativa)is not only a vital food crop for people to survive,but also the model for monocotyledonous plants study.As the major place for photosynthesis,leaf supply necessary carbonate to yield production,therefore,study on rice leaf color mutants is of great significance to practical production.To explore the molecular mechanism of leaf color and chloroplast development,we obtained a yellow-green leaf mutant named buy1,from an ethyl methanesulfonate(EMS)-mutagenized population.The phenotype is presented at the young seedling period.After the tillering period,this phenotype is weakened and the leaf turn to yellow.The chlorophyll contents of buy1 were significantly reduced at mature stage,whereas with a light decrease at young stage.We compared the ultrastructure of chloroplasts in the buy1 mutant and wild type at seedling stage using transmission electron microscopy,and found that chloroplast development was abnormal and photosynthetic capacity of the mutant were decreased.The adult buy1 mutant plants grown in the field had excessive tillers,smaller panicles,and fewer primary and secondary branches in panicles compared with wild type.The seed quality and plant height of the buy1 mutant were significantly lower than those of the wild type.BUY1 was mapped to chromosome 12 by map-based cloning approach,and sequencing analysis revealed that a single nucleotide mutation occurred in the intron-exon junction bases of BUY1 gene in the mutant,which caused the mis-cleavage of the mRNA to generate a new splicing recognition site.Blast analysis indicated that BUY1 encodes a carotenoid isomerase(CRTISO)domain protein and there are CRTISO members in rice genome.In order to study the function of BUY1 gene,we extracted RNA from different organs for tissue expression analysis and found that the highest expression of BUY1 gene is in leaf and leaf sheath.To further analysis whether the additional tillering phenotype of buy1 is correlated with hormones,we tested the expression of BUY1 under hormones treatment,we found that BUY1 is specifically induced by ABA,but not others hormones.