陕西省番茄黄化曲叶病毒基因间隔区缺失突变体的鉴定与不同分离物间群体进化研究

为明确番茄黄化曲叶病毒(tomato yellow leaf curl virus, TYLCV)基因组的变异情况, 分别从陕西省杨凌区?泾阳县?大荔县和阎良区采集了表现为番茄黄化曲叶病症状的抗病品种番茄样品20份以及感病品种番茄样品4份?经TYLCV特异性引物检测, 24个样品均为阳性?通过全长扩增测序获得了15个TYLCV分离物的基因组序列?序列分析显示, 其中7个分离物基因组大小为正常的2 781 bp, 而有8个TYLCV分离物基因组大小为2 768 bp?与正常基因组相比, 这8个分离物在基因间隔区(intergenic region, IR)的TATA-box与保守9核苷酸序列之间发生了13个核苷酸的缺失?对我国不同地区TYLCV分离物全基因组序列进行变异分析, 发现IR区域是发生核苷酸变异最大的区域?系统进化分析表明, 本研究分离到的15个TYLCV分离物均属于TYLCV-Israel进化分支下的中国亚群, 其中8个TYLCV IR缺失突变体与国内已报道的IR缺失突变体BJ04和BJ06亲缘关系较远, 而与本研究中分离得到的正常TYLCV分离物亲缘关系最近, 疑似为陕西地区出现的一类新TYLCV IR缺失突变体?本研究首次对我国不同地区多个TYLCV分离物出现IR区缺失现象进行了报道?

Identification of intergenic region deletion mutants of tomato yellow leaf curl virus and evolutionary analysis of different isolates in Shaanxi province

To determine the genome mutation of tomato yellow leaf curl virus (TYLCV), 20 TYLCV-resistant tomato samples and four TYLCV-susceptible tomato samples with symptoms of tomato yellow leaf curl disease were collected from Yangling, Jingyang, Dali and Yanliang in Shaanxi province. TYLCV was detected in all of the 24 tomato samples, and the complete genome sequences of 15 isolates were obtained. Sequence alignment analysis revealed that seven of these TYLCV isolates had a normal genome size of 2 781 bp, while eight TYLCV isolates had a genome size of 2 768 bp. Compared with the TYLCV isolates with normal genomes, the eight isolates with reduced genomes contained a 13-nt deletion in the intergenic region (IR) between the TATA-box and the nonanucleotide motif. Mutation analysis of the whole genome sequences of TYLCV isolates from different regions of China revealed the highest frequency of nucleotide mutation in the IR region. Phylogenetic analysis indicated that all of the 15 TYLCV isolates belonged to Chinese subgroup under the TYLCV-Israel evolutionary clade. Compared with the IR deletion mutants BJ04 and BJ06, the eight TYLCV IR deletion mutants were most closely related to the normal TYLCV isolates isolated in this study, which were suspected to be a new class of TYLCV IR deletion mutants occurred in Shaanxi province. To our knowledge, this is the first report of IR deletion in multiple TYLCV isolates from different regions in China.