WRKY transcription factors play important roles in plants, including responses to stress; however, our understanding of the function of WRKY genes in plant responses to viral infection remains limited. In this study, we investigate the role of NbWRKY40 in Nicotiana benthamiana resistance to tomato mosaic virus (ToMV). NbWRKY40 is significantly downregulated by ToMV infection, and subcellular localization analysis indicates that NbWRKY40 is targeted to the nucleus. In addition, NbWRKY40 activates W-box-dependent transcription in plants and shows transcriptional activation in yeast cells. Overexpressing NbWRKY40 (OEWRKY40) inhibits ToMV infection, whereas NbWRKY40 silencing confers susceptibility. The level of salicylic acid (SA) is significantly higher in OEWRKY40 plants compared with that of wild-type plants. In addition, transcript levels of the SA-biosynthesis gene (ICS1) and SA-signaling genes (PR1b and PR2) are dramatically higher in OEWRKY40 plants than in the control but lower in NbWRKY40-silenced plants than in the control. Furthermore, electrophoretic mobility shift assays show that NbWRKY40 can bind the W-box element of ICS1. Callose staining reveals that the plasmodesmata is decreased in OEWRKY40 plants but increased in NbWRKY40-silenced plants. Exogenous application of SA also reduces viral accumulation in NbWRKY40-silenced plants infected with ToMV. RT-qPCR indicates that NbWRKY40 does not affect the replication of ToMV in protoplasts. Collectively, our findings suggest that NbWRKY40 likely regulates anti-ToMV resistance by regulating the expression of SA, resulting in the deposition of callose at the neck of plasmodesmata, which inhibits viral movement.

WRKY转录因子在植物中起重要作用，包括对胁迫的反应。但是，我们对以下功能的理解WRKY植物对病毒感染的反应中的基因仍然有限。在这项研究中，我们调查了NbWRKY40 在 烟草 对番茄花叶病毒（ToMV）具有抗性。 NbWRKY40ToMV感染可显着下调NbWRKY40，并且亚细胞定位分析表明NbWRKY40靶向细胞核。另外，NbWRKY40激活植物中W-box依赖性转录，并在酵母细胞中显示出转录激活。过度表达NbWRKY40 （OEWRKY40）抑制ToMV感染，而 NbWRKY40沉默赋予敏感性。与野生型植物相比，OEWRKY40植物中的水杨酸（SA）含量显着更高。此外，SA生物合成基因的转录水平（ICS1）和SA信号基因（PR1b 和 PR2）在OEWRKY40植物中比在对照中显着更高，但在 NbWRKY40-沉默的植物比对照。此外，电泳迁移率漂移分析表明NbWRKY40可以结合ICS1。愈伤组织染色表明，OEWRKY40植物的胞浆线虫减少，而OEWRKY40植物的胞浆线虫增加NbWRKY40沉默的植物。外源应用SA还可以减少病毒的积累NbWRKY40被ToMV感染的沉默植物。RT-qPCR表明NbWRKY40不影响ToMV在原生质体中的复制。总的来说，我们的发现表明NbWRKY40可能通过调节SA的表达来调节抗ToMV的抗性，导致of质在胞质瘤的颈部沉积，从而抑制了病毒的运动。