Genetic Analysis And Mapping Of Early Leaf Senescence Mutant Zh75in Rice

Rice is an important food crop in China, and high yield has always been one of the important goalsof rice breeding. Presenility is a physiological phenomenon that reduced metabolic function of rice,especially in hybrid rice, which will influence the further increase of the yield in rice.Eearly senescence mutant zh75used in this study is from the Nipponbare by T-DNA insertionalmutagenesis, and genetic analysis showed that the gene is controlled by a single recessive gene,tentatively named zh75. An F2population was constructed from a cross of Indica rice variety Minghui63, and the linkage analysis between the F2mutation phenotype and T-DNA markers showed that themutant type was not caused by T-DNA. Thus, SSR molecular marker technology was used to carry outmap-based cloning of the mutant gene. The main results are as follows:1. The initial mapping of the senescence geneAccording to BERCA (Bulked-Extrems and Recessive-Class Approach), we constructed earlysenescence and non-premature individual DNA mixed pool, and used molecular markers that coveringrice genome which have polymorphism in two parents to screen the polymorphic markers in theabove-mentioned DNA mixed pool. We found that SSR molecular marker RM8236and RM5410on1stchromosome might have linkage with the target gene. Using94early senescence individual of F2, itwas further verified that the target gene was located between RM8236and RM5410spanning4.8cM.2. Fine mapping of the senescence geneTo fine-map zh75,24molecular marker were developed between RM8236and RM5410, and theearly senescence gene was located between the SSR markers RM165and RM1387spanning100.742Kbusing2936recessive mutant plant.3. The identification of candidate genesBy TIGR, NCBI and other rice database, the segment between RM165and RM1387was predictedto harbor a total of15genes, of which the acyl dehydrogenase gene (LOC_Os01g69080) havehigh-level links with the mutant phenotype according to the annotated function. LOC_Os01g69080wassequenced, and a mutation was found that the101stbase A transited to G in the3rdexon. Accordingly theencoding lysine was changed into glutamate. Therefore, LOC_Os01g69080can be a candidate gene ofzh75.