Abstract
Viruses hijack various organelles and machineries for their replication and movement. Ever more lines of evidence indicate that specific nuclear factors are involved in systemic trafficking of several viruses. However, how such factors regulate viral systemic movement remains unclear. Here, we identify a novel role for Nicotiana benthamiana high mobility group nucleoprotein (NbHMG1/2a) in virus movement. Although infection of N. benthamiana with Bamboo mosaic virus (BaMV) decreased NbHMG1/2a expression levels, nuclear-localized NbHMG1/2a protein was shuttled out of the nucleus into cytoplasm upon BaMV infection. NbHMG1/2a knockdown or even overexpression did not affect BaMV accumulation in inoculated leaves, but it did enhance systemic movement of the virus. Interestingly, the positive regulator Rap-GTPase activation protein 1 was highly upregulated upon infection with BaMV, whereas the negative regulator thioredoxin h protein was greatly reduced, no matter if NbHMG1a/2a was silenced or overexpressed. Our findings indicate that NbHMG1/2a may have a role in plant defense responses. Once its homeostasis is disrupted, expression of relevant host factors may be perturbed that, in turn, facilitates BaMV systemic movement.
Highlights
Viruses hijack various cellular machineries to utilize the molecules, subcellular structures, and trafficking systems required for their replication and movement (Huang et al, 2017a; Pitzalis and Heinlein, 2017)
Arabidopsis high mobility group (HMG) protein B3 is exported to the apoplast where it functions as a damageassociated molecular pattern (DAMP), recognizes avirulent factors of the nectrophic fungus Botrytis cinerea, and triggers defenses mediated by salicylic acid (SA) (Choi et al, 2016)
Expression of NbHMG1/2a was significantly decreased upon Bamboo mosaic virus (BaMV) infection in both inoculated and systemic leaves at 6 days post infection (Figure 1C), we did not detect any expression of NbHMG1/2b using different pairs of primers targeting the CDS and 3 untranslated region (UTR) under various conditions [healthy plants or plants infected with BaMV infectious clone pKBG or infiltrated with empty vector (EV) of the Tobacco rattle virus (TRV) (TRV-EV)]
Summary
Viruses hijack various cellular machineries to utilize the molecules, subcellular structures, and trafficking systems required for their replication and movement (Huang et al, 2017a; Pitzalis and Heinlein, 2017). Depending on the virus group, mobilized viral forms can be either viral nucleoprotein complexes or virions, with both forms usually being assisted by specific virus-encoded non-structural proteins (Hipper et al, 2013; Solovyev and Savenkov, 2014; Pitzalis and Heinlein, 2017). Ever more lines of evidence indicate that the translocation of viral MPs to nuclei, where they interact with specific nucleoproteins, is an essential step in promoting systemic viral infection (Lukhovitskaya et al, 2013; Solovyev and Savenkov, 2014; Lukhovitskaya et al, 2015). Arabidopsis high mobility group (HMG) protein B3 is exported to the apoplast where it functions as a damageassociated molecular pattern (DAMP), recognizes avirulent factors of the nectrophic fungus Botrytis cinerea, and triggers defenses mediated by salicylic acid (SA) (Choi et al, 2016)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
