| Sorghum(Sorghum bicolor) is one of the five major crops in the world only after rice(Oryza sativa), maize(Zea mays), wheat(Triticum aestivum) and barley(Hordeum vulgare L.). It has been widely used as food, feed, fiber and fuel. Normally, sorghum is grown in arid and semi-arid areas, with high drought tolerance. Sorghum has a relatively small genome and is highly homologous with other C4 plants, hence being used as a model plant for C4 crops.Stay-green trait in the plant means the delayed initiation of leaf senescence delay or reduced progression of the senescence process, resulting in the characteristic maintaining of functional high leaf green areas. Leaf senescence or the stay-green is inf luenced by many endogenous and exogenous factors. Typically, plants with stay-green characters have better drought resistance and can achieve high biomass and yield potentials. Sorghum is a crop with good stay-green trait. This study aims to analyze the variation of the stay-green traits and to identify relevant quantitative trait loci and/or genes in sorghum,.The main results are as follows:1. Intensive investigation of the stay-green phenotypes in inbred lines Ji-2731 and E-tian showed that the two inbred line differed largely in the onset and progression of leaf senescence, resulting in contrast stay-green phenotypes.2. A group of F5/6 RILs from crossing Ji-2731×E-tian was used to identify genetic loci controlling stay-green in sorghum. Combining the results of a genetic linkage map consisting of 355 SSR and Indels maskers and the stay-green phenotyping of individual RILs, I identif ied two genetic loci for stay-green on chromosomes 1 and 4, respectively. Additional genetic loci associated with other agronomic traits such as plant growth rate and growth period were also found.3. By exploring the senescence transcriptome data of sorghum, a total of 222 transcription factors associated with stay-green trait were found. Among them, five genes showed significantly differential expression in dark- induced leaf senescence, while the var iation of the genomic sequences of two tanscriptional factors was associated with the senescence phenotype in a diversity panel of sorghum.To sum up, this study investigated and studied the manifestation of stay-green trait of sorghum. Quantitative trait locus of green traits of sorghum was preliminarily located,and digged out the genes associated with stay-green and senescence of sorghum. |
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