Genetic Analysis And Mapping Of Lipase Gene For Durable Storage Rice

Being the first enzyme during the lipid hydrolysis and oxidation, lipase was one of the main factor leading to rice aging during rice storage.The low activity of lipase in rice embryos would help alleviate seeds aging and improve the storage stability of rice breed. Based on two parents PT₄₆ which belonging to high lipase activity and WP₂₀ which belonging to low lipase activity,and their F₂ population, this research was carried out by the accurate and genetic analysis of lipase activity.Moreover, the gene for control activity of lipase was mapped with SSR markers. Finally, the significance of rice storability was appraised during artificially accelerating aging experiments.The results were as follows:1. Accurate mensuration and genetic analysis of lipase activity of rice embryos Embryos lipase activity of two parents and their F₂ population was measured with fatty acidcolorimetry method. Based on data of their lipase activity and x² test, the distribution of F₂ genotypes was 1:2: 1 according to Mendelian rules, demonstrated that the activity of lipase was controlled by a single gene and trait of low lipase activity was a recessive trait.2. Mapping of gene for low lipase activity in rice embryosWith F₂ population between PT₄₆ and WP₂₀, the gene of low lipase activity was mapped in the 3rd chromosome of rice by bulk-segregation analysis. Furthermore, the distance was 14.8 cM,4.0cM with marker RM7,RM232, respectively. Therefore, this gene was temporarily designated as lla (low lipase activity) .3. Correlation analysis between lipase activity in embryos and durable storage characteristics of seedsStorability of two parents and their F₂ population were appraised with their grermination rate and aging index by artificially accelerating aging experiments.Correlation analysis was conducted combining aging index and data of their lipase activity. The results showed that seed germination rate of high lipase activity materials was not only decreased rapidly with increasing of aging time,but also their aging index was improved quickly.But the aging index of low lipase activity materials was changed slowly, namely,the low lipase activity materials had better durable storage characteristics. After 10 and 20 days for artificially accelerating aging,the correlation coefficient were r=0.6165** and r=0.4703** between the lipase activity and aging index, respectively.The results demonstrated that stable positive correlation was between aging index and the lipase.