Identification Of Rice Leaf Senescence-Associated Genes

Rice is one of the most important food crops in the world and an excellent model for genomic research in cereals. Leaf senescence is the last stage of leaf development. It has important theoretical and practical significance to study the mechanism on rice leaf senescence and then find a way to purposefully control or delay leaf senescence. Although a large number of senescence-related mutants and senescence-associated genes have been identified, the regulatory mechanism of rice leaf senescence remains unclear. In this study, based on previous microarray data, our aims are isolation and functional characterization of the senescence-associated genes. Furthermore, these genes will provide important information to understanding the mechanism of leaf senescence, and may serve as useful tools in rice transgenic breeding.The main contents of this study are:relative expression levels of the candidate genes in flag leaves at different development stages, quantitative real-time analysis of the candidate-genes’ expression profile in various phytohormone treatments, plant expression vectors construction, Agrobacterium-mediated rice transformation, the related mutant phenotype investigation, and so on The main results in this study are as follows:1. Constructed11SAGs’(A1, A2, A3, A4, A6, A7, A1O, A12, A14, A15and A16) overexpression vector and3SAGs’(A2, A6and A11) dsRNA interference vector;2. Quantitative real-time PCR analyses of5SAGs’(A2, A4, A6, A12and A16) expression profile in flag leaves at7different development stages. The results indicated that A2, A4,A6and A12are leaf-senescence up regulated genes; the A16is a leaf-senescence down regulated gene;3. Quantitative real-time PCR analysis indicated that A2, A4, A6, A12and A16gene were significantly up-regulated or down-regulated by different phytohormone treatments;4.5over expression vectors (A20X, A40X, A60X, A140X and A160X) and2dsRNA interference vectors (RNAiA2and RNAiA6) were introduced into Zhonghuall by Agrobacterium-mediated transformaton All the TO transgenic plants were identified by PCR detection, Southern blotting analysis and the expression level detection;5. Research on the rice T-DNA insertion mutant of A12found that loss of function of this gene lead to premature senescence of flag leaf...