Nicotiana benthamiana Methanol‐Inducible Gene (MIG) 21 Encodes a Nucleolus‐Localized Protein that Stimulates Viral Intercellular Transport and Downregulates Nuclear Import

Mechanical damage of plant tissues leads to the activation of methanol production and its release in the atmosphere. The gaseous methanol or vapors emitted by the damaged plant induce resistance in neighboring intact plants to bacterial pathogens but create favorable conditions for the viral infection spread. Among Nicotiana benthamiana methanol-inducible genes (MIGs) most are associated with plant defense and intercellular transport. Here we characterize NbMIG21 that encodes a 209-aa protein (NbMIG21p) which does not share any homology with annotated proteins. NbMIG21p was demonstrated to contain nucleolus localization signals (NoLS). Co-localization studies with fibrillarin and coilin, nucleolus and Cajal bodies marker proteins, revealed that NbMIG21p is distributed between these subnuclear structures. Our results show that recombinant NbMIG21 possess DNA-binding properties . Similar to gaseous methanol effect an increased NbMIG21 expression leads to the downregulation of the nuclear import of NLS-containing proteins as was demonstrated on the model GFP-NLS protein. Moreover, upregulated NbMIG21 facilitates tobacco mosaic virus (TMV) intercellular transport. We identified NbMIG21 promoter (PrMIG21) and showed that it is methanol-sensitive thus induction of NbMIG21 expression occurs at the level of transcription. Our findings suggest that methanol-activated NbMIG21 might participate in creating favorable conditions for the viral reproduction and spread.