芜菁花叶病毒山东分离物外壳蛋白基因的克隆及序列分析

 从山东省3地市感病的白菜和萝卜上分离到芜菁花叶病毒6个分离物，将其分别命名为TuMV-SD1、TuMV-SD2、TuMV-SD3 、TuMV-SD4、 TuMV-SD5和TuMV-SD6。利用RT-PCR克隆了这6个分离物的外壳蛋白基因，测定了它们的核苷酸序列，并进行了序列分析。结果表明，6个分离物的CP基因均为867个碱基，核苷酸序列同源性较高, 达97.0%～99.4%；它们与World-B组分离物的同源性最高，达91.8%～100%；与Brassica- Raphanus (BR) 致病型分离物的同源性次之，在89.1%～91.0%之间；与basal-B组分离物的同源性最低，仅86.0%～90.3%。基于TuMV的CP基因核苷酸序列的分子进化树显示，TuMV分离物可分为4组，本研究所分离到的6个TuMV山东分离物属于第四组，即world-B组。用分离到的6个TuMV分离物对已获得的转TuMV CP基因的抗病毒大白菜进行攻毒试验。结果表明，尽管作为转基因的CP基因与这6个分离物的CP基因只有88.2%～88.9%的同源性，但转基因大白菜对这6个分离物均具有明显抗性。

Cloning and Sequence Analysis of Coat Protein Genes of Turnip Mosaic Virus Isolates Obtained from Shandong

Six isolates of turnip mosaic virus named TuMV-SD1, TuMV-SD2, TuMV-SD3, TuMV-SD4, TuMV-SD5, and TuMV-SD6 were isolated from infected Chinese cabbages and radishes in three different regions (Taian, Yantai, and Zaozhuang) in Shandong province. A pair of primers was designed and synthesized based on the nucleotide sequences of coat protein (CP) genes of TuMV reported. The CP genes of the six TuMV isolates were cloned by RT-PCR method. The sequences of all the CP genes from the six isolates were sequenced and compared with the CP gene sequences of TuMV reported in GenBank. The results showed that the sequences of the six CP genes were all 867 nucleotides in length, and the isolates shared high sequence homology from 97.0% to 99.4% among them. They also shared high homologies of 91.8% to 100% with the sequences of world-B group isolates, of 89.1% to 91.0% with the sequences of Brassica-Raphanus (BR) pathotype isolates, and of 86.0% to 90.3% with the sequences of basal-B group isolates. TuMV isolates reported so far were devided into four groups based on phylogenetic analysis of the CP gene sequences. All the six isolates analysized in this study belonged to the fourth group, i.e. world-B group. Resistance assay revealed that the transgenic Chinese cabbage containing a CP gene of TuMV was resistant to infections of all the six isolates, although the CP transgene only shared a homology of less than 90%with the CP genes of the six TuMV isolates.