Marchant Wendy G, Gautam Saurabh, Dutta Bhabesh, Srinivasan Rajagopalbabu
Department of Entomology, University of Georgia, Griffin, GA 30223.
Department of Plant Pathology, University of Georgia, Tifton, GA 31793.
Phytopathology. 2022 Mar;112(3):720-728. doi: 10.1094/PHYTO-06-21-0248-R. Epub 2022 Mar 3.
Begomoviruses are whitefly-transmitted viruses that infect many agricultural crops. Numerous reports exist on individual host plants harboring two or more begomoviruses. Mixed infection allows recombination events to occur among begomoviruses. However, very few studies have examined mixed infection of different isolates/variants/strains of a species in hosts. In this study, the frequency of mixed infection of tomato yellow leaf curl virus (TYLCV) variants in field-grown tomato was evaluated. At least 60% of symptomatic field samples were infected with more than one TYLCV variant. These variants differed by a few nucleotides and amino acids, resembling a quasispecies. Subsequently, in the greenhouse, single and mixed infection of two TYLCV variants (variant #2 and variant #4) that shared 99.5% nucleotide identity and differed by a few amino acids was examined. Plant-virus variant-whitefly interactions including transmission of one and/or two variants, variants' concentrations, competition between variants in inoculated tomato plants, and whitefly acquisition of one and/or two variants were assessed. Whiteflies transmitted both variants to tomato plants at similar frequencies; however, the accumulation of variant #4 was greater than that of variant #2 in tomato plants. Despite differences in variants' accumulation in inoculated tomato plants, whiteflies acquired variant #2 and variant #4 at similar frequencies. Also, whiteflies acquired greater amounts of TYLCV from singly infected plants than from mixed-infected plants. These results demonstrated that even highly similar TYLCV variants could differentially influence component (whitefly-variant-plant) interactions.
双生病毒是由粉虱传播的病毒，可感染多种农作物。关于单个寄主植物携带两种或更多种双生病毒的报道众多。混合感染会使双生病毒之间发生重组事件。然而，很少有研究考察同一物种的不同分离株/变体/株系在寄主中的混合感染情况。在本研究中，对田间种植的番茄中番茄黄化曲叶病毒（TYLCV）变体的混合感染频率进行了评估。至少60%有症状的田间样本感染了不止一种TYLCV变体。这些变体在几个核苷酸和氨基酸上存在差异，类似于准种。随后，在温室中，对两种核苷酸同一性为99.5%、氨基酸存在少许差异的TYLCV变体（变体#2和变体#4）进行了单感染和混合感染研究。评估了植物-病毒变体-粉虱之间的相互作用，包括一种和/或两种变体的传播、变体的浓度、接种番茄植株中变体之间的竞争以及粉虱对一种和/或两种变体的获取。粉虱以相似的频率将两种变体传播到番茄植株上；然而，在番茄植株中，变体#4的积累量大于变体#2。尽管接种的番茄植株中变体的积累存在差异，但粉虱获取变体#2和变体#4的频率相似。此外，粉虱从单感染植株中获取的TYLCV量比从混合感染植株中获取的更多。这些结果表明，即使是高度相似的TYLCV变体也可能对组成部分（粉虱-变体-植物）之间的相互作用产生不同影响。
