[Genetic analysis and identification of candidate genes for a narrow leaf mutant (zy17) in rice]

Control of organ size by cell proliferation and cell expansion is a fundamental process in plant development, but little is known about the genetic and molecular mechanisms that determine organ size in plants. To understand the genetic and molecular mechanisms of organ growth control, we isolate a set of mutants with altered leaf size and identify the narrow leaf mutant, zhaiye 17 (zy17) (zhaiye means narrow leaf in Chinese). zy17 exhibits narrow leaves, slightly short plants, small panicles, reduced panicle branches and decreased grain numbers per panicle compared with the wild type. Our cytological analyses show that the narrow leaf phenotype of zy17 is caused by the reduced number of cells, indicating that ZY17 regulates cell proliferation. Genetic analyses show that the zy17 mutant phenotypes are controlled by a single gene. Using the whole genome resequencing approach and linkage analysis, we identify Os02g22390, Os02g28280 and Os02g29530 as candidate genes. Os02g22390 encodes a retrotransposon protein with the mutation occurring in the intronic region; Os02g28280 encodes a protein with unknown function with a base substitution resulting in non-synonymous mutation; Os02g29530 encodes a protein containing the PFAM domain related to glycosyltransferase, with a 2 bp deletion mutation causing a premature termination. Further studies on these three candidate genes will be helpful for understanding the molecular mechanism of organ size control in rice.