| Sweet potato are important food, feed, industrial materials and new energy crops in our country.But sweet potato is easy infected by various viruses which can lower the production and quality.Recent years,there are already30viruses reported and at least8viruses are found in China as follows:Sweet potato feathery mottle virus(SPFMV),Sweet potato virus G(SPVG),Sweet potato latent virus (SPLV),Sweet potato leaf curl virus (SPLCV),Sweet potato chlorotic stunt virus(SPCSV),Cucumber mosaic virus(CMV),Sweet potato vein mosaic virus(SPVMV) and Sweet potato chlorotic fleck virus(SPCFV). Geminiviruses is an important ssDNA virus which can damage various crops seriously and lower the production dramaticlly.At present,reasearch on the distribution and molecule variations about geminiviruses of sweet potato in our country is not clear. Our rearch make preliminary identification for the geminiviruses of sweet potato which is collected from some major production area in our country.We detect30samples of sweet potato collected from different areas by PCR with the universal primer BM-M/BN-C and get results that7samples contain geminivirus.es DNA-A genome of the7isolates is cloned and sequenced. The results of sequencing showed that the similarity aomong the7nucleotide sequences Of DNA-A is between78.1%-99.6%.The lowest similarity is78.1%contrasted by SU-10-19and G-JIN-11-2and the highest similarity is99.6%contrasted by SU-10-3-2and SU-10-19.Analyse suggest that nucleotide similarity is lower between viruses from different areas but higher between viruses from same area. According to the species division standard of Begomovirus,we draw a conclusion that G-YU-11-20and G-YU-11-26belong to a same species as well as SU-10-3-2and SU-10-19and three another isolates are different species.Contrast between7sequences and other geminiviruses result that G-JI-11-2and G-GUI-11-5are new species which the similarity with other geminiviruses is under89%; G-JI-11-3is a strain of sweet potato leaf curl Georgia virus SPLCGV and G-YU-11-20, G-YU-11-26, SU-10-3-2, SU-10-19are all the srains of Sweet potato leaf curl virus (SPLCV). The coat protein gene of one isolate SPLCV-SU[3-2] from Jiangsu has been cloned and expressed.Sequencing suggest that CP gene was consisted of765nts and encoded254amino acid residues. The CP gene is cloned into expression vector pGEX-4T-3for over-expression in prokaryotic cells BL21. The SDS-PAGE showed that about54.25kDa specific fusion protein was produced after induction by IPTG. It’s the first time to complete the prokaryotic expression of SPLCV CP gene in our country and lay the foundation for the special antibodies preparation and serologic testing system for SPLCV establishing. |
