广东番茄曲叶病毒G3分离物基因组DNA-A的分子特征

 从采集于广东花都的番茄曲叶病病株上分离到病毒分离物ToLCGDV-G3],序列分析结果表明,其DNA-A为单链环状,全长2744 nt,共有6个ORFs,其中病毒链上编码AV1(CP)、AV2,互补链上编码AC1、AC2、AC3和AC4。BLAST结果显示,与ToLCGDV-G3]基因组有同源关系的均属双生病毒科菜豆金色花叶病毒属。进一步比较结果表明,ToLCGDV-G3]与有同源性的菜豆金色花叶病毒属病毒的DNA-A全序列同源率最高为87.9%。其中IR的同源率为59.0%~85.3%,而AV1、AV2、AC1、AC2、AC3和AC4这6个ORFs同源率分别为73.6%~95.2%、64.0%~95.4%、71.7%~87.7%、69.6%~93.9%、67.7%~95.1%和64.1%~94.2%,它们各自编码的氨基酸序列同源率分别为76.3%~99.2%、52.6%~95.7%、69.7%~88.1%、51.9%~88.9%、63.4%~92.5%和33.0%~90.7%。系统进化关系分析结果显示,ToLCGDV-G3]与ToLCGDV-G2]亲缘关系最近,二者组成一个独立的分支,与其它40种菜豆金色花叶病毒属病毒的亲缘关系均较远。因此,ToLCGDV-G3]可能是一个先前未报道的双生病毒科菜豆金色花叶病毒属新种。

The molecular characteristics of DNA-A of tomato leaf curl Guangdong virus isolate G3

The ToLCGDV- was isolated from tomato plants showing leaf curl symptoms in Guangdong. The complete nucleotide sequence of ToLCGDV- DNA-A was determined. It contains 2744 nucleotides and encodes six potential ORFs, with two (AV1 and AV2) in virion-sense strand and four (AC1, AC2, AC3 and AC4) in complementary strands. BLAST results showed that all sequences homologous to ToLCGDV- DNA-A belonged to the genus Begomovirus of family Geminiviridae. Pairwise comparisons of ToLCGDV- DNA-A with those of other begomoviruses indicated that the overall identities were less than 88.0%. The identities of intergenic region (IR), AV1, AV2, AC1, AC2, AC3 and AC4 were 59.0%-85.3%, 73.6%-95.2%, 64.0%-95.4%, 71.7%-87.7%, 69.6%-93.9%, 67.7%- 95.1% and 64.1%-94.2% respectively, and that of their encoded amino acid sequences were 76.3%-99.2%, 52.6%-95.7%, 69.7%-88.1%, 51.9%-88.9%, 63.4%-92.5% and 33.0%-90.7% respectively. Phylogenetic analysis of DNA-A of ToLCGDV- and the selected begomoviruses showed that ToLCGDV- is most closely related to ToLCGDV-G2] than the other begomoviruses, and that the two viruses were clustered in a separate branch. These results suggest that ToLCGDV- should be a previously unreported begomovirus.