Tomato cultivars containing the Tm-2² resistance gene have been widely known to resist tobacco mosaic virus (TMV) and tomato mosaic virus. Tomato brown rugose fruit virus (ToBRFV), a new emerging tobamovirus, can infect tomato plants carrying the Tm-2² gene. However, the virulence determinant of ToBRFV that overcomes the resistance conferred by the Tm-2² gene remains unclear. In this study, we substituted the movement protein (MP) encoding sequences between ToBRFV and TMV infectious clones and conducted infectivity assays. The results showed that MP was the virulence determinant for ToBRFV to infect Tm-2² transgenic Nicotiana benthamiana plants and Tm-2²-carrying tomato plants. A TMV MP chimera with amino acid residues 60–186 of ToBRFV MP failed to induce hypersensitive cell death in the leaves of Tm-2² transgenic N. benthamiana plants. Chimeric TMV containing residues 60–186 of ToBRFV MP could, but chimeric ToBRFV containing 61–187 residues of TMV MP failed to infect Tm-2² transgenic N. benthamiana plants, indicating that 60–186 residues of MP were important for ToBRFV to overcome Tm-2² gene-mediated resistance. Further analysis showed that six amino acid residues, H⁶⁷, N¹²⁵, K¹²⁹, A¹³⁴, I¹⁴⁷, and I¹⁶⁸ of ToBRFV MP, were critical in overcoming Tm-2²-mediated resistance in transgenic N. benthamiana plants and tomato plants. These results increase our understanding of the mechanism by which ToBRFV overcomes Tm-2²-mediated resistance.

中文翻译：

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鉴定能够感染具有 Tm-22 抗性基因的植物的番茄棕色皱纹果实病毒的遗传决定因素

众所周知，含有Tm-2 ²抗性基因的番茄品种能够抵抗烟草花叶病毒(TMV) 和番茄花叶病毒。番茄褐皱果病毒（ToBRFV）是一种新出现的烟草病毒，可以感染携带Tm-2 ²基因的番茄植株。然而，克服Tm-2 ²基因赋予的抗性的ToBRFV 毒力决定因素仍不清楚。在这项研究中，我们替换了 ToBRFV 和 TMV 感染性克隆之间的运动蛋白 (MP) 编码序列，并进行了感染性测定。结果表明，MP是ToBRFV侵染Tm-2 ²转基因本氏烟草植物的毒力决定因素。携带Tm-2 ²的番茄植物。具有 ToBRFV MP 氨基酸残基 60-186 的 TMV MP 嵌合体未能在Tm-2 ²转基因本氏烟草植物的叶子中诱导过敏性细胞死亡。含有 ToBRFV MP 残基 60-186 的嵌合 TMV 可以，但含有 61-187 个 TMV MP 残基的嵌合 ToBRFV 未能感染Tm-2 ²转基因本氏烟草植物，表明 60-186 个 MP 残基对于 ToBRFV 克服很重要Tm-2 ²基因介导的抗性。进一步分析表明，六个氨基酸残基，H ⁶⁷，N ¹²⁵，K ¹²⁹，A ¹³⁴ToBRFV MP 的I ¹⁴⁷和 I ¹⁶⁸对克服转基因本氏烟草植物和番茄植物中的Tm-2 ²介导的抗性至关重要。这些结果增加了我们对 ToBRFV 克服Tm-2 ²介导的抗性的机制的理解。