番木瓜环斑病毒山东分离物的全基因组序列分析

Complete genomic sequence analysis of a Papaya ringspot virus isolate from Shandong province of China

番木瓜环斑病毒（Papayaringspotvirus，PRSV）属于马铃薯Y病毒科（Potyviridae）马铃薯Y病毒属（Potyvirus）。根据寄主范围可划分为P和W2个株系，其中P株系侵染番木瓜（CaricapapayaL．）和葫芦科（Cucurbitaceae）作物，而W株系只侵染葫芦科作物，两者血清学反应密切相关。PRSV可引起植株叶片褪绿、花叶、卷曲等症状，在果实表面形成环斑。

Papaya ringspot virus （PRSV） is a major limiting factor to cucurbit production worldwide. One zucchini sample showing symptoms of leaf mosaic and fruit ringspot was collected from Ji＇ nan city of Shan- dong province. Primary experiments showed that the sample was infected with PRSV, which was designated as PRSV-SD accordingly. The complete genomic fragment of PRSV-SD was obtained with RT-PCR. The results of sequencing showed that the full genomic sequence of PRSV-SD was 1 0337 nucleotides （nt） excluding the 3＇- terminal poly （A） tail. The 5＇- and 3＇-untranslated regions （UTR） were 90 and 206 nt, respectively. The putative polyprotein was 3 346 amino acids in length. Comparison of the PRSV-SD isolate with 18 other PRSV isolates revealed that they shared nucleotide identities of 82.1%-89.3% at the complete genomic levels and amino acid identities of 90.6%- 94.7% for the polyprotein. No recombination was detected throughout the genome of PRSV-SD. Phylogenetic analysis with complete genomic sequences indicated that the PRSV isolates were clustered into two major groups ： Asia and America and PRSV-SD was clustered to the Asia group. Selec- tion pressure analysis revealed that all of the 11 proteins of PRSV-SD were under negative selection, but posi- tive selection sites were detected in P1, P3, 6K1, NIa-pro and NIb. Our research results provide a theoretical foundation for the detection and prevention of PRSV.