Suppression of Phytophthora capsici using double-stranded RNAs targeting NLP effector genes in Nicotiana benthamiana

Abstract

RNA interference (RNAi) is a gene regulatory mechanism that involves the interaction of small interfering RNAs (siRNAs) and RNA-induced silencing complex (RISC). Dicer cleaves exogenous double-stranded RNA (dsRNA) into siRNAs, which get incorporated into RISC and bind to complementary sequences on the target mRNA to induce its degradation. In this study, we adopted RNAi technology using dsRNAs to suppress Phytophthora capsici, which causes diseases in solanaceous crops, including pepper. We designed and synthesized dsRNAs targeting the P. capsici effector genes PcNLP2 and PcNLP6, respectively. These genes encode necrosis and ethylene-inducing peptide 1-like proteins in P. capsici, which are known to promote oomycete infection. Nicotiana benthamiana leaves were first infiltrated with dsRNAs and inoculated with P. capsici 2 days later. We confirmed significant suppression of P. capsici and PcNLP2, PcNLP6 expression in dsRNA-treated leaves. In addition, we found that downregulation of PcNLP2 and PcNLP6 distinctly affected the expression of some defense-related genes. These results suggest that dsRNA mediated RNAi technology can be used to suppress various pathogens, and may contribute toward crop protection.