Gene Mapping Of Rice Mutants Yll(t) And Espl-2Induced By Radiation

We obtained a yellow leaf and lethal mutant yll (t) and an enclosed sheathedpanicle1-2mutant esp1-2from japonica cultivar Nipponbare induced by radiation. Inthis study, we analyzed the phenotypic characteristics and genetic regulation of thesetwo mutants, and mapped the genes. The main results are as follows:1. Genetic analysis and gene mapping of mutant yll (t)The yellow leaf and lethal mutant yll (t) showed yellow color at seedling stage,and died after three-leaf stage. The content of chlorophyll a, chlorophyll b andcarotenoid of yll (t) were greatly reduced, and they were only2.5%,2.7%and12.8%of wild type's respectively. Genetic analysis showed that yll (t) was controlled by arecessive gene. Using a F2gene mapping population, we fine mapped the YLL (t) geneinto a1000kb physical distance between molecular markers IDY41and IDY19onchromosome8, and the genetic distance was0.12cM. Further analysis showed thatthere was a171kb-deletion region between IDY33and IDY35, and31genes werepredicted in the deletion region according to rice genome annotation database. A genenamed LOC_Os08g15500encodes an expressed protein, and it is homologous toPGR7(proton gradient regulation7) and GluTRBP (Glutamyl-tRNA reductasebinding protein). So LOC_Os08g15500was chosen as the candidate gene.2. Genetic analysis and gene mapping of mutant esp1-2The phenotypes of enclosed sheathed panicle1-2mutant esp1-2were similar toesp1-1. Compared with wild type, esp1-2showed different characteristics: reducedplant height, shortened uppermost internode, shorter and smaller panicle with partialenclosed in flag leaf sheaths, reduced number of primary branches, secondarybranches and the grains, and increased number of degeneration of spikelets. Geneticanalysis showed that esp1-2was contrllled by a recessive gene, which was allelic withesp1-1. Based on the gene mapping result of esp1-1, using a F2population, the geneESP1was mapped into a256kb physical distance between the markers Indel19and Indel14on chromosome11, and the genetic distance was0.3cM. There was a140kb-deletion between GRM88and Indel21, and the region was included in the deletionregion of esp1-1. There were15genes in the140kb-deletion region according to therice genome annotation database, of which4genes encode a putative receptor proteinkinase CLAVATA1precursor, a putative PHD-finger domain containing protein, aputative peptide transporter PTR2and a putative O-methyltransferase, respectively.So these4genes were chosen as the candidate genes.