[Phylogenetic and Bioinformatics Analysis of Replicase Gene Sequence of Cucumber Green Mottle Mosaic Virus]

The replicase genes of five isolates of Cucumber green mottle mosaic virus from Jiangsu, Zhejiang, Hunan and Beijing were amplificated, sequenced and analyzed. The similarities of nucleotide acid sequences indicated that 129 kD and 57 kD replicase genes of CGMMV-No. 1, CGMMV-No. 2, CGMMV-No. 3, CGMMV-No. 4 and CGMMV-No. 5 were 99.64% and 99.74%, respectively. The similarities of 129 kD and 57 kD replicase genes of CGMMV-No. 1, CGMMV-No. 3 and CGMMV-No. 4 were 99.95% and 99.94%, while they were lower between CGMMV-No. 2 and the rest of four reference sequences, just from 99.16% to 99.27% and from 99.04% to 99.18%. All reference sequences could be divided into six groups in neighbor-joining (NJ) phylogenetic trees based on the replicase gene sequences of 129 kD, 57 kD protein respectively. CGMMV-No. 1, CGMMV-No. 3 and CGMMV-No. 4 were clustered together with Shandong isolate (Accession No. KJ754195) in two NJ trees; CGMMV-No. 5 was clustered together with Liaoning isolate (Accession No. EF611826) in two NJ trees; CGMMV-No. 2 was clustered together with Korea watermelon isolate (Accession No. AF417242) in phylogenetic tree of 129 kD replicase gene of CGMMV; Interestingly, CGMMV-No. 2 was classified as a independent group in phylogenetic tree of 57 kD replicase gene of CGMMV. There were no significant hydrophobic and highly coiled coil regions on 129 kD and 57 kD proteins of tested CGMMV isolates. Except 129 kD protein of CGMMV-No. 4, the rest were unstable protein. The number of transmembrane helical segments (TMHs) of 129 kD protein of CGMMV-No. 1, CGMMV-No. 2, CGMMV-No. 3 and CGMMV-No. 5 were 6, 6, 2 and 4, respectively, which were 13, 13 and 5 on the 57 kD protein of CGMMV-No. 2, CGMMV-No. 4 and CGMMV-No. 5. The glycosylation site of 129 kD protein of tested CGMMV isolates were 2, 4, 4, 4 and 4, and that of 57 kD protein were 2, 5, 2, 5 and 2. There were difference between the disorders, globulins, phosphorylation sites and B cell antigen epitopes of 129 kD and 57 kD proteins of tested CGMMV isolates. The current results that there was no significant difference between the replicase gene sequences, it was stable and conservative for intra-species and clearly difference for inter-species. CGMMV-No. 1, CGMMV-No. 3, CGMMV-No. 4 and CGMMV-No. 5 had. a close genetic relationship with Shandong and Liangning isolates (Accession No. KJ754195 and EF611826), they are potentially originate from the same source. CGMMV-No. 2 was closer with Korea isolate. High sequence similarity of tested samples were gathered for a class in phylogenetic tree. It didn't show regularity of the bioinformatics analysis results of 129 kD and 57 kD proteins of tested CGMMV isolates. There was no corresponding relationship among the molecular phylogeny and the bioinformatics analysis of the tested CGMMV isolates.