| Carica papaya L. is one of the important fruits in the tropical and subtropical areas. It is famous for its delicious taste in the south. Papaya ringspot virus (PRSV) has become a serious papaya disease causing severe loss in agriculture and seed degeneration in the world. PRSV is one of potato virus Y (PVY) being one of the most important plant disease. RNA-mediated plant virus resistance is more effective and safer and is a powerful strategy in breeding virus-resistant plant including papaya. In this strategy coat protein gene of viruses were widely used. It is important to cultivate papaya plant with broad-spectrum-virus resistance in the base of studying the mechanisms of it in China. In this research, an anti-virus technique referring as genetic engineering strategy was used, then the genes of PRSV-CP from Hainan, Yunnan, Guangxi and Guangdong in different papaya production areas were cloned, and their sequences were compared. PRSV-CP genes'homologous segments was got by using RT-PCR technique, then differential primers used for cloning PRSV-CP 3 'end homologous DNA segments were designed, finally six kinds of RNA-mediated plant expression vectors are gained respectively: p2301CP+,p2301CP-,p2301CPU,p2301CPUL,pBCP+,pBCP-. Virus-resistant papaya plants transformed with PRVS Coat Protein (CP) gene, were produced by improved pollen-tube pathway mediated transformation system of papaya.In the experiment, It was discussed that several parameters including the length of papaya flower, different approaches to exogenous DNA being introduced into papaya. This might be a ideal condition as follows:①sunshine , the temperature might be 10℃-30℃;②the hermaphrodite flowers were 3.5 centimeters ;③the concentration of plasmid DNA was 11μg/μL,the female flower was about 2.0-4.0 centimeters;④the OD600 of Agrobacterium tumefaciens was 0.8-1.0 with Silwet L-77(0.5μL/mL),the female flower was about 3.0-4.5 centimeters.
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