一株突破va基因型烟草抗性的PVY病毒分离物的鉴定

Identification of a PVY virus isolate breaking down va-genotype tobacco resistance

【背景和目的】近来,能突破va基因型抗性的马铃薯Y病毒(Potato virus Y,PVY)毒株在烟草上不断出现。2016年,我们分离到一株抗性突破的毒株PVY-CJ,本文对该病毒分离物进行了验证和鉴定。【方法】采用病毒重新接种、多重RT-PCR、RT-PCR分段扩增病毒全长基因组、PVY病毒分子进化分析及病毒蛋白VPg蛋白序列比对等方法对PVY-CJ毒株进行了验证和鉴定。【结果】三种重新接种了PVY-CJ的va基因型烟草品种均发病。多重RT-PCR结果将PVY-CJ鉴定为PVYNTN株系。序列分析表明,PVY-CJ全长基因组包含一个全长9180 nt的开放读框,其编码一个3060 AA的多聚蛋白。分子进化分析进一步验证了其归类于PVYNTN株系。相比其他PVYNTN株系毒株,PVY-CJ的VPg蛋白105位氨基酸出现了一个由赖氨酸到谷氨酸的替换,而这一氨基酸替换导致了其对va基因来源抗性的突破。【结论】我们首次报道并鉴定了国内一株能突破va基因型烟草抗性的PVY毒株—PVY-CJ。这为进一步研制PVY抗病烟草品种提供了材料。

[Background]Recently,the Potato virus Y(PVY)strains breaking down the resistance of va-genotype tobacco varieties have emerged on cultivated tobacco constantly.In 2016,we isolated a va-resistance breaking-down PVY strain,which was named as PVYCJ.This isolate was verified and identified in this study.[Methods]Re-inoculation on the va-genotype tobacco varieties,multiple RTPCR,segmented amplification of the whole PVY genome by RT-PCR,molecular phylogenetic analysis and the sequence alignment of VPg protein of PVY strains were adopted to confirm and identify PVY-CJ strain.[Results]Test data showed:1)All the 3 va-genotype tobacco varieties showed symptoms of infection when they were inoculated with PVY-CJ inoculum;2)PVY-CJ was classified as PVYNTN strain according to the result of multiple RT-PCR;3)Sequence analysis showed that the whole genome of PVY-CJ contained an open reading frame of 9180 nt encoding a polyprotein of 3060 amino acids;4)the result of molecular phylogenetic analysis further classified PVY-CJ as PVYNTN strain;5)Compared with other PVYNTN strains,a substitution of lysine to glutamic acid happened at 105 amino acid of VPg protein of PVY-CJ,which led to a breaking down of va-geno source resistance.[Conclusion]We reported and identified a PVY strain which could break down the resistance of va-genotype tobacco varieties in the mainland of China for the first time.This study provides material for breeding new PVY-resistant tobacco varieties.