香蕉束顶病毒海口分离物基因组的克隆及序列分析

Cloning and sequencing of genome of banana bunchy top virus Haikou isolate

以海口香蕉束顶病株的幼嫩假茎和叶片总DNA为模板,通过反向PCR法克隆了香蕉束顶病毒(Banana bunchy top virus,BBTV)海口分离物(命名为BBTV-HaiKou)的6个DNA组分的全长序列。结果表明,DNA1～6序列全长分别为1106、1040、1058、1040、1013和1082nt。各组分非编码区各包含一个茎环共同区和一个主要共同区,同源性分别为91.55%和88.45%。各组分编码区均编码一个开放可读框(ORF),其中DNA1 ORF内部还有一个小的ORF。序列分析表明,BBTV-HaiKou分离物与其它分离物间的DNA1最为保守,DNA2变异最大。DNA1组分核苷酸序列与亚洲组、南太平洋组各分离物及ABTV(Abacá bunchy top virus)分离物同源性分别为93.1%～99.1%,89.6%～90.7%和76.2%～77.4%,相应的编码蛋白氨基酸序列同源性在BBTV和ABTV中分别为93.4%～100%和85.7%。根据Karan等的分类方法,确定BBTV-HaiKou分离物属于亚洲组成员。

The genome of the isolate of Banana bunchy top virus （BBTV） from Haikou was cloned and sequenced by the polymerase chain reaction （PCR） with total DNA from banana pseudostem and leaf showing typical BBTV symptom as template. The isolate originated from banana （Musa sp.） was designated BBTV-Haikou. The sequence analysis indicated that six full-length segments were 1 106, 1 040, 1 058, 1 040, 1 013 and 1 082 nt, respectively. All the segments contained an intergenic region and an open reading frame （ORF） except the segment 1, which had a small ORF in the main ORF. In the intergenic region（IR）, there were a stem-loop common region （CR-SL） and a major common region （CR-M）, which shared 91.55% and 88.45% identity, respectively. Comparison of the viral sequence from different country showed that DNA1 sequence was more conservative than other components, but DNA2 sequence mutation rate was higher than others, sharing homologies of 93.08% and 75.67%, respectively. Nucleotide sequence analysis between DNA1 of the isolate and that of the Asian group, Pacific group of BBTV and the two isolates of ABTV（Abacá bunchy top virus）showed that DNA1 of BBTV-Haikou shared 93.1%-99.1%, 89.6%-90.7% and 76.2%-77.4% nucleotide sequence identity, also 93.4%~100% and 85.7% deduced amino acids identity in BBTV and ABTV, respectively. According to the Karan′s method of classification, the BBTV-Haikou isolate was belonged to the Asian group.