Functional Analysis Of OsRBCS And OsUBC2, Two Rice Genes Related To Denfensing For Sheath Blight

Sheath blight,caused by Rhizoctonia solani is an important disease of rice around the world.Currently,there are not good resistant resourses to be used in rice breeding programs.So,the disease has caused huge loss of rice production in some areas.In our previous work,52 differential expressed cDNAs from rice induced by sheat blight infection were identified through suppression subtractive hybridization.Among them, 16 clones had identity of genes with known annotated functions,including 10 defense response genes.One of the differential clone 4B11 may contain the fragment of gene encoding ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit protein in rice.Another clone 8A1 may contain the fragment of gene enconding Ubiquitin-conjugating enzyme E2 in rice.They were designated as OsRBCS and OsUBC2,respectively.To understand the function of these two genes in rice disease resistance,two over expression vectors pub-osrbcs and pub-osubc2 were constructed, and pub-osrbcs was transferred to rice and the transgenic plants were obtained.To further understand the function of OsRBCS in disease resistance response,the resistance of transgenic plants was evaluated.The transgenic plants were inoculated with the fungal pathogen R.solani CL-1 and MH-2,which were isolated and purified from the breeding field of Changle and Minhou in Fuzhou.The result showed the transgenic rice plants increased resistance to R.solani infection.Therefore,it confirmed that OsRBCS gene involved in rice defense response to sheath blight.To study the function of OsUBC2 gene,the over expression vector pub-OsUBC2 was transferred to rice variety MINGHUI 86 through Agrobacterium tumefaciens.For the first transferring.we obtained 12 transgenic rice plants,The staining showed that the GUS gene expressed in all parts of transgenic plants.The plasmid pTCK303 was as the back bone for constructing RNAi vectors.The RNAi fragment from gene OsUBC2 named OsUBC2i.Then two-step cloning method was used for RNAi vector construction and at last formed an inverted repeat separated by the rice intron.