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Cell-to-cell movement is an important step for initiation and spreading of virus infection in plants. This process occurs through the intercellular connections, termed plasmodesmata (PD), and is usually mediated by one or more virus-encoded movement proteins (MP) which interact with multiple cellular factors, among them protein kinases that usually have negative effects on MP function and virus movement. In this study, we report physical and functional interaction between MP of Tobacco mosaic virus (TMV), the paradigm of PD-moving proteins, and a receptor-like kinase BAM1 from Arabidopsis and its homolog from Nicotiana benthamiana. The interacting proteins accumulated in the PD regions, colocalizing with a PD marker. Reversed genetics experiments, using BAM1 gain-of-function and loss-of-function plants, indicated that BAM1 is required for efficient spread and accumulation the virus during initial stages of infection of both plant species by TMV. Furthermore, BAM1 was also required for the efficient cell-to-cell movement of TMV MP, suggesting that BAM1 interacts with TMV MP to support early movement of the virus. Interestingly, this role of BAM1 in viral movement did not require its protein kinase activity. Thus, we propose that association of BAM1 with TMV MP at PD facilitates the MP transport through PD, which, in turn, enhances the spread of the viral infection.

Tobacco mosaic virus (TMV) is one of the most economically damaging plant viruses because of its wide host range and transmission mode. TMV manipulates the plant to produce viral proteins, instead of resistant ones. However, microbes with pathogenic defenses have been beneficial against the biotic stress caused by TMV. Through DNA metabarcoding, the microbe communities between parts of the phyllosphere and rhizosphere infected by TMV were compared over a two-week period. Overall, there was a variation of microbial presence and higher species richness in the mock-inoculated than viral inoculated plants. After one week, the mock inoculated plant organs had higher species richness than viral inoculated plant organs due to the presence of viral threat. After two weeks, the viral inoculated soil had the second highest species richness due to the soil being colonized and the presence of defense mechanisms. In addition, there was a wide range of taxa present such as Proteobacteria, Bacteroidetes, Acidobacteria, and Cyanobacteria. [ABSTRACT FROM AUTHOR]