Nicotiana benthamiana phosphatidylinositol 4-kinase type II regulates chilli leaf curl virus pathogenesis

Geminiviruses are single-stranded DNA viruses that can cause significant losses in economically important crops. In recent years, the role of different kinases in geminivirus pathogenesis has been emphasized. Although geminiviruses use several host kinases, the role of phosphatidylinositol 4-kinase (PI4K) remains obscure. We isolated and characterized phosphatidylinositol 4-kinase type II from Nicotiana benthamiana (NbPI4KII) which interacts with the replication initiator protein (Rep) of a geminivirus, chilli leaf curl virus (ChiLCV). NbPI4KII-mGFP was localized into cytoplasm, nucleus or both. NbPI4KII-mGFP was also found to be associated with the cytoplasmic endomembrane systems in the presence of ChiLCV. Furthermore, we demonstrated that Rep protein directly interacts with NbPI4KII protein and influenced nuclear occurrence of NbPI4KII. The results obtained in the present study revealed that NbPI4KII is a functional protein kinase lacking lipid kinase activity. Downregulation of NbPI4KII expression negatively affects ChiLCV pathogenesis in N. benthamiana. In summary, NbPI4KII is a susceptible factor, which is required by ChiLCV for pathogenesis.