Xyloglucan Endotransglycosylase/Hydrolase Downregulation Increases Nicotiana benthamiana Tolerance to Tobacco Mosaic Virus Infection.

The biological functions of the multiple members of the xyloglucan endotransglycosylase/hydrolase (XTH) protein family are rather diverse: XTHs are cell wall remodeling enzymes that participate in plant growth and development, are involved in responses to various environmental stresses and interactions with pathogenic and symbiotic microorganisms. However, XTHs' role upon viral infection remains poorly understood. Here we identified and characterized Nicotiana benthamiana XTH (NbXTH) which is involved in responses to viral infection. We demonstrated that NbXTH is a positive regulator of intercellular transport. NbXTH suppression leads to the inhibition of tobacco mosaic virus (TMV) local spread, resulting in the increased tolerance of N. benthamiana plants to TMV. Therefore, NbXTH could be regarded as a susceptibility factor.