Genetic Analysis And Identification Of Candidate Genes For A Narrow Leaf Mutant(zy17)in Rice

Leaf is the important component part of rice plant type as well as the most important organ of photosynthesis. Control of leaf width is basic process of plant developmental biology; it is affected by cell division and cell extension. However, the mechanism of the control of leaf width is still not clear. To understand the molecular mechanism of leaf width control, based on the background of KYJ (KuanYeJing), we isolated a set of mutants with altered leaf size induced by ethylmethanesulfonate (EMS) mutagenesis. Compared with the wild type, the narrow leaf mutant zhaiye17(zyl7) showed more narrow leaves, slightly shorter plants, smaller panicles, reduced panicle branches and decreased grain number per panicle. A set of phenotype observation, genetic analysis and cytological analysis were applied to the mutant in this study. By constructing F2generation combined with whole genome resequencing approach and linkage analysis, the candidate genes of ZY17mutant were identified and relevant plasmids were constructed as well. This study laid theoretical foundation to better understand molecular mechanism of rice leaf shape development. The major research results were summarized as follows:1. It can be found in electron microscope scanning analysis that the cell size of lower epidermis cell surface of mutant zy17did not have significant difference compared with wile type KYJ, but the cell number and vascular bundle number decreased dramatically. This result suggested that cell division was affected and the leaf cell number was reduced in ZY17.2. The genetic analysis of zyl7showed that zyl7mutant was recessive mutation, and was controlled by a pair of single gene, namely single gene recessive mutation.3. Based on MutMap technology, the target genes were selected by resequencing method. By analyzing the resequencing data, two candidate genes were screened, i.e. LOC_Os02g28280and LOC_Os02g29530. dCAPS verification indicated the mutation in two candidate genes of mutant zy17. The mutation of two candidate genes were co-segregated with the mutant phenotype in F2population, it can be further proved that LOC_Os02g28280and LOC_Os02g29530were the candidate genes of narrow leaf mutant.4. Protein analysis of candidate genes demonstrated that LOC_Os02g28280encoded a protein with258amino acid residues which was function unknown. The point mutation of the candidate gene leaded to protein translation error, the42nd AA altered from Asp to Asn. LOC_Os02g29530encoded a protein containing PFAM structural domain related to glycosyl transferase. After the gene mutation, protein translation was terminated early.5. To further determine which one is the mutation gene of ZY17, the genome complementary plasmids and over-expression plasmids were constructed, and rice genetic transformation was applied.