侵染河南省番茄的番茄黄化曲叶病毒及伴随卫星DNA分子的基因组特征

从河南省长葛市的番茄病株上分离到4份病毒分离物HNCG1、HNCG2、HNCG3和HNCG4,为明确病原类型及其亲缘关系,首先采用检测双生病毒的简并引物进行检测,均能从样品中扩增出约500 bp的片段,4个序列同源性达99%。对HNCG4基因组DNA-A全序列测定表明,其全长为2 781 bp,与番茄黄化曲叶病毒(TYLCV)省内分离物(HNSQ1、HNNY1、HNLY1、HNQX)及其临近省份的河北分离物(TYLCV LF)、北京分离物(TYLCV BJ3)亲缘关系较近,序列同源性均达99%。进一步研究发现,HNCG1和HNCG4均伴随有1 347 bp的卫星DNAβ,而HNCG2和HNCG3中未检测到DNAβ。序列比对结果表明,HNCG1和HNCG4的DNAβ之间序列同源性为100%,与越南TYLCV分离物DX2的卫星DNAβ序列同源性最高,达88%。根据以上结果,引起河南省长葛市番茄黄化曲叶病的病毒为TYLCV,部分分离物伴随有卫星DNA分子。

Genomic Characterization of DNA-A and Associated Satellite DNA Molecule of Tomato Yellow Leaf Curl Virus Infecting Tomato in Henan

Four virus isolates including HNCG1,HNCG2,HNCG3 and HNCG4 were obtained from tomato plants showing leaf curl symptom in Changge city,Henan province. In order to clear the pathogens and find out the genetic relationship between each other,PCR was adopted firstly to detect the tomato samples using degenerate primers for geminiviruses. A 500 bp fragment was obtained from all the samples, and the nucleotide sequence identity between the four isolates reached 99%. The complete DNA-A sequence of HNCG4 was determined to be 2781 bp. Comparisons showed that the DNA-A of HNCG4 had the highest sequence identity(99%) with that of tomato yellow leaf curl virus(TYLCV) isolates HNSQ1,HNNY1, HNLY1,HNQX from Henan, and TYLCV LF, TYLCV BJ3 isolated from adjacent Hebei and Beijing, respectively. PCR analysis demonstrated that isolates HNCG1 and HNCG4 were associated with DNAβcomponent of 1347 bp, but isolates HNCG2 and HNCG3 were not. Sequence comparisons revealed that DNAβ of HNCG1 and HNCG4 was 100% similar to each other, and they shared the highest sequence identity(88%) with that of TYLCV Vietnam isolate DX2. In conclusion,leaf curl symptom of tomato in Changge city was caused by TYLCV,and partial isolates of the virus were associated with DNAβmolecule.