摘要
烟草丛顶病主要由烟草丛顶病毒(Tobacco bushy top virus,TBTV)和烟草扭脉病毒(Tobacco vein distorting virus,TVDV)复合侵染引起。其中,TVDV的CP蛋白可分别包装TBTV和TVDV形成病毒粒子;但也存在TVDV单独侵染不携带TBTV的病样。本文利用RT-PCR对自然状态下携带TBTV的TVDV(采自云南弥渡)和不携带TBTV的TVDV(采自云南保山)的cp基因进行序列克隆,发现TVDV弥渡分离物的cp基因为618个核苷酸,而TVDV保山分离物的cp基因为621个核苷酸,二者的核苷酸序列一致性为90.02%,氨基酸序列一致性为89.81%;而长度相同的TVDV cp基因序列一致性为98.5%~100%。表明这2个cp基因属于2种不同类型。系统发育树分析也表明这2个cp基因属于进化距离较远的2个群。利用SWISS-MODEL进行同源建模,发现2种类型的TVDV CP蛋白的主要空间结构域基本一致,存在细小的结构域及结构域之间无规则卷曲角度的差异,整体空间结构没有发生明显改变。推断TVDV保山分离物CP蛋白中关键氨基酸的序列突变是导致CP无法包装TBTV,从而在病害传播过程中丢失TBTV的主要因素。
Typical tobacco bushy top disease was mainly caused by mixed infection of Tobacco bushy top virus( TBTV) and Tobacco vein distorting virus( TVDV). Coat protein( CP) encoded by TVDV could package the genome of TBTV and TVDV respectively,resulting in forming of virions and mediating the transmission by aphid. However,some disease samples in the field contain the TVDV in the absence of TBTV. In this study,cp genes of two types of TVDV( TVDV-MD isolate with the coexistence of TBTV and TVDV-BS isolate without the coexistence of TBTV),were cloned by RT-PCR and compared. The lengths of TVDV-MD and TVDV-BS cp genes are 618 nt and 621 nt,respectively. Moreover,nucleotide and amino acid identities of cp gene between TVDV-MD and TVDV-BS were 90. 02 % and 89. 81 %,suggesting that TVDV-MD and TVDV-BS CPs belong to different types. However,sequence identities of TVDV cp gene with the same length were 98. 5 %-100%.In addition,phylogenetic analysis also showed that these two types of cp gene respectively belong to two groupswith far distance. Although TVDV-MD CP and TVDV-BS CP have about 10% amino acid divergence,their structures predicted by SWISS-MODEL did not present remarkable difference with only slight alteration in minor elements and linker regions. Our results suggested that mutation on amino acid sequences rather than the change of structure of CP in TVDV-BS might cause the inability of packaging of TBTV and result in missing the TBTV during the transmission of tobacco bushy top disease.
出处
《植物病理学报》
CAS
CSCD
北大核心
2016年第2期241-246,共6页
Acta Phytopathologica Sinica
基金
国家自然科学基金资助项目(31370179)
山东省自然科学基金资助项目(ZR2013CM015)
关键词
烟草扭脉病毒
烟草丛顶病毒
外壳蛋白
同源建模
Tobacco vein distorting virus
Tobacco bushy top virus
coat protein
SWISS-MODEL