Chilli veinal mottle virus HCPro interacts with catalase to facilitate virus infection in Nicotiana tabacum

Plant symptoms are derived from specific interactions between virus and host components. However, little is known about viral or host factors that participate in the establishment of systemic necrosis. Here, we showed that helper component proteinase (HCPro) encoded by Chilli veinal mottle virus (ChiVMV), could directly interact with catalase 1 (CAT1) and catalase 3 (CAT3) of Nicotiana tabacum (N. tabacum) in cytoplasm to facilitate viral infection. In vitro, the activities of CAT1 and CAT3 were inhibited by the interaction between HCPro and CATs. The C terminus of HCPro was essential for their interaction and also required for the decrease of enzyme activities. Interestingly, the mRNA and protein level of catalases were up regulated in N. tabacum plants in response to ChiVMV infection. N. tabacum plants with HCPro overexpression or CAT1 knockout were more susceptible to ChiVMV infection, which was similar to that in H2O2 pretreated plants, and the overexpression of CAT1 inhibited ChiVMV accumulation. Besides, neither CAT1 nor CAT3 could affect the RNA silencing suppression (RSS) activity of HCPro. Our results confirmed that the interaction between HCPro and catalase promoted the development of plant systemic necrosis. This work demonstrated a novel role of HCPro in virus infection and pathogenicity.

Keywords: Chilli veinal mottle virus; Nicotiana tabacum; HCPro; catalase; suppressor of RNA silencing; systemic necrosis.