Identification And Analysis Of The Complete Sequence Of The Virus Isolates Infecting Watermelon In Shanxi Province

Watermelon is a flowering dicotyledonous plant, which is not only a good fruit to share in summer hot days, but also has important medicinal value, which is why it’s called natural baihutang, a traditional medicine for fever. In recent years, with the rapid increasing of Watermelon planting, virus infection problems in Watermelon have become increasingly serious. It is so essential to find out the virus causing the losses of Watermelon planting.In order to identify the viral pathogens that induced the disease of Watermelon from Shanxi Province, biological inoculation, extraction of double-stranded RNA (dsRNA), sequence-independent amplification (SIA) and RT-PCR method were used.(1) Identification the pathogens that induced their disease by biological inoculation, the disease was likely to be caused by viruses.(2) dsRNAs were extracted from the infected Watermelon samples, and got the pure dsRNA by the way of Plant virus dsRNA extraction method.(3) dsRNAs were extracted to be used as temples in SIA, analysing the obtained viral sequences by NCBI. Based on the results of analysis, we initially identified that the viral pathogen infected Shanxi Province Watermelon was Cucumber green mottle mosaic virus(CGMMV).The viruse on Watermelon was named as CGMMV-SX.(4)To further characterize the CGMMV-SX, the complete sequence of CGMMV-SX is cloned and determined. The results shows that CGMMV-SX comprise6412nucleotides and has a typical Tobamovirus genome organization with4open reading frames, respectively, Coding129/186kDa,29kDa and17.3kDa protein. Nucleotide sequence similarity searches show that the homology of CGMMV-SX and isolates from Asian countries such as China, Korea and Japan are higher than the homology of the isolates from European countries. Especially with the homology of Jiangsu isolate JSHZ12(GenBank No.KC852073.1) and Henan Zhengzhou isolate hn (GenBank No. KC851866.1) are as high as99.6%and99.4%. With the homology of the European isolates are lower, for example the homology of Russia and Spain isolates are89.9%and89.8%respectively. Phylogenetic comparisons based on amino acid sequences of CGMMV-SX and other reported isolates showe that CGMMV-SX formed an independent branch with Jiangsu isolate JSHZ12and Henan Zhengzhou isolate hn. Therefore, CGMMV-SX is most closely related to JSHZ12and hn. The relationship of CGMMV-SX is as father as the isolates with Russia and Spain, belong to two different branches. CGMMV-SX and other Tobamovirus isolates, such as YM (GenBank GenBank No. AB162006.1) and ZGMMV (GenBank No.AJ295949.1) related farthest.