Comparative Analysis On Gene Expression Of OsCPK9 And PR In Different Rice Cultivars Induced By Methyl Jasmonate And Salicylic Acid

Rice is a staple food for nearly one-half of the world's population. Rice blast caused by Magnaporthe grisea is one of the most devastating diseases in rice in most rice growing countries or areas,which is the most serious constraint to world food security. Rice self-defense resistance is the most promising method of blast disease control. But the rice responses to rice blast fungus are an extremely complex physiological and pathological process, involving a large array of genes and signaling componets. OsCPK9, a calcium depedent protein kinase, has been found to be induced by Magnaporthe grisea specifically in rice, suggesting that OsCPK9 should be related to the rice resistance reaction in response to blast fungus infection. In this study, methyl jasmonate and salicylic acid were used to induce the system acquired resistance to Magnaporthe grisea in rice seedlings, and semi-quantitative PT-PCR was applied to analyze the gene expression changes of OsCPK9 and four pathogen related protein genes OsPR1a,OsPR1b,OsPR2 and OsPR10 in seedling of different resistant rice cultivars, with the aim to clarify the position of OsCPK9 in the signaling pathway in response to Magnaporthe grisea infection.The main results are as follows:1) Constitutive gene expression of OsCPK9 was related to the resistance of rice cultivars. Expression change of OsCPK9 gene after phytohormone treatments was not obvious.2). OsPR1b and OsPR10 gene could respond to the methyl jasmonate and salicylic acid signaling; There was significant differences of induced expression for these two genes in rice cultivars with different resistance.3) OsPR1a could only respond to methyl jasmonate inducer, while OsPR2 could only respond to salicylic acid inducer.The results show that OsCPK9 probably participates in resistance to rice blast pathogen cultivars with different resistance, and is not located in the same signaling pathway with the four pathogen related protein genes mentioned. The upstream signaling is different even for the four pathogen related protein genes. The results thus obtained not only are helpful for reveling the comlex physiological and pathological process of rice resitance to blast pathogen infection, but also laid the foundation for further research on function of OsCPK9 gene and its role in defense mechanisms of blast pathogen infection in rice.