侵染广东黄秋葵的木尔坦棉花曲叶病毒及伴随卫星DNA的分子特征

从广东省表现黄脉曲叶的黄秋葵病株上分离到病毒分离物Okra06,PCR检测结果显示,该病毒属双生病毒科Geminiviridae菜豆金色花叶病毒属Begomovirus.基因克隆及序列分析结果表明,其基因组仅含A组分(DNA-A),全长为2 737 nt,推导编码6个开放阅读框(Open reading frame,ORF).该组分与木尔坦棉花曲叶病毒(Cotton leafcurl Multan virus,CLCuMV)分离物G6的核苷酸序列相似性最高,为99.7%;二者编码的6个ORF相似性分别为100%、100%、99.6%、99.8%、100%和99.7%.该病毒还伴随有卫星分子β(DNAβ),全长为1 346 nt,推导其互补链上编码1个ORF(C1).该分子与伴随CLCuMV分离物G6 DNAβ的核苷酸序列相似性也最高(99.5%).DNAβ系统进化分析显示,Okra06 DNAβ与CLCuMV-[G6]DNAβ、CLCuMV-[Gx08]DNAβ亲缘关系最近,三者形成一个独立分支;进一步与其他CLCuMV DNAβ和CLCuV DNAβ聚类在一起.这些结果证明,侵染广东黄秋葵的病毒分离物Okra06属于CLCuMV,且该分离物与引起广东朱槿曲叶病的CLCuMV-G6应同属木尔坦棉花曲叶病毒朱槿株系.

Molecular Characterization of Cotton leaf curl Multan virus and the Associated Satellite DNA Infecting Okra in Guangdong

The virus isolate Okra06 was obtained from the diseased okra plants exhibiting yellow vein and leaf curl symptoms in Guangzhou,Guangdong Province.The results of PCR detection indicated that the virus belonged to the genus Begomovirus of the family Geminiviridae.The genome of the virus was cloned and sequenced.The results showed that it had only A component(DNA-A).The complete nucleotide sequence of DNA-A was determined to be 2 737 nucleotides,encoding six potential ORFs.The comparison showed that Okra06 DNA-A had the highest nucleotide sequence identity(99.7%) with CLCuMV-.Six ORFs shared 100%,100%,99.6%,99.8%,100% and 99.7% nucleotide sequence identities with CLCuMV – ,respectively.The Okra06 was also associated with satellite DNA β molecular.The full-length sequence of DNA β was determined to be 1 346 nucleotides,encoding one potential ORF(C1).The comparison further showed that Okra06 DNA β had the highest nucleotide sequence identity(99.5%)with G6 DNA β.Phylogenetic analysis revealed that DNA β of isolate Okra06,G6 and Gx08 were more closely related than the other begomoviruses associated with DNA β,and were clustered in a separate branch and further clustered with other isolates of CLCuMV DNA β or CLCuV DNA β.Those results revealed that the virus isolate Okra06 infecting okra plants in Guangdong belonged to the species CLCuMV,and it should be the Hibiscus strain.