番木瓜环斑病毒海南分离株全基因组序列分析

番木瓜环斑病毒(Papaya ringspot virus,PRSV)是马铃薯Y病毒属(genus Potyvirus)的成员之一.病毒粒体呈线状,长700～900nm,直径为12.5nm.为单分体正链RNA病毒,由多种蚜虫以非持久方式传播.依寄主范围可划分为P型和W型两种.其中P型株系(PRSV-P)是制约生产的重要病原,除了给番木瓜生产带来严重危害,也会危害葫芦科作物.W型株系(PRSV-W)是危害葫芦科作物的主要病原,虽然和PRSV-P型株系血清学反应密切相关,但不侵染番木瓜.

Sequence Analysis of the Complete Genome of Papaya Ringspot Virus Hainan Isolate

Total RNA was extracted from infected papaya(Carica papaya L.) leaves in Hainan Province, and the full-length sequences of papaya ringspot virus were amplified by RT-PCR and RACE, and its complete genomic sequence was assembled,named Hainan-P isolate.The RNA genome sequence of Hainan-P isolate was 10323 nucleotides (nts)in length,excluding the 3'-terminal poly(A) tail. And it was composed of a single open reading frame encoding a polyprotein of 3343 amino acids. The result of homology analysis with twelve GenBank PRSV isolates showed that the polyprotein identity of Hainan-P ranged from 89.8% to 93.2%, that was higher than the complete nt homology of 82.3% to 89.1%. The P1 amino acid was the least conserved( sharing homology only between 65.4% and 80.1%), whereas HC-Pro,CI and CP were the most conserved. Phylogenetic tree were constructed by the Neighbor-joining method in MEGA 3.1, which showed that PRSV isolates were obviously relevant to geographical origin,and it was impossible to delineate host-specific (P type and W type)evolution.