Silencing of Putative Plasmodesmata-Associated Genes PDLP and SRC2 Reveals Their Differential Involvement during...

Plant viruses utilize a subset of host plasmodesmata-associated proteins to establish infection in plants. In the present study, we aimed to understand the role of two plant genes, one encoding a putative plasmodesma located protein (PDLP) and a homolog of soybean gene regulated by cold 2 protein (SRC2) during Cucumber mosaic virus (CMV) infection. Virus-induced gene silencing (VIGS) was used to silence PDLP and SRC2 genes in Nicotiana benthamiana and in two related solanaceous plants, N. tabacum and Capsicum chinense Jacq. (Bhut Jolokia). Up to 50% downregulation in the expression of the PDLP gene using the TRV2-PDLP VIGS construct was observed in N. benthamiana and N. tabacum while, using the same gene construct, 30% downregulation of the target mRNA was observed in C. chinense. Similarly, using the TRV2-SRC2 VIGS construct, a 60% downregulation of the SRC2 mRNA was observed in N. benthamiana, N. tabacum, and a 40% downregulation in C. chinense as confirmed by qRT-PCR analysis. Downregulation of the PDLP gene in N. benthamiana resulted in delayed symptom appearance up to 7-12 days post inoculation with reduced CMV accumulation compared to the control plants expressing TRV2-eGFP. In contrast, SRC2-silenced plants showed enhanced susceptibility to CMV infection compared to the control plants. Our data suggest that the PDLP gene might facilitate infection of CMV, thus being a susceptibility factor, while the SRC2 gene could play a role in resistance to CMV infection in N. benthamiana.