RNAi silencing of the Meloidogyne incognita Rpn7 gene reduces nematode parasitic success

RNA interference (RNAi) techniques provide a major breakthrough in functional analysis for plant parasitic nematodes (PPNs). It offers the possibility of identifying new essential targets and consequently developing new resistance transgenes. To validate the potential of Mi-Rpn7 as a target for controlling root knot nematode Meloidogyne incognita and to evaluate the feasibility of our modified platform for assessing silencing phenotypes, we knocked down the Rpn7 gene of M. incognita using RNAi in vitro and in vivo. After soaking with 408-bp Rpn7 dsRNA, pre-parasitic second-stage juvenile (J2) nematodes showed specific transcript knockdown, resulting in an interrupted locomotion in an attraction assay with Pluronic gel medium, and consequently in a reduction of nematode infection ranging from 55.2% to 66.5%. With in vivo expression of Rpn7 dsRNA in transformed composite plants, the amount of egg mass per gram root tissue was reduced by 34% (P < 0.05) and the number of eggs per gram root tissue was reduced by 50.8% (P < 0.05). Our results demonstrated that the silencing of the Rpn7 gene in M. incognita J2s significantly reduced motility and infectivity. Although it does not confer complete resistance, Mi-Rpn7 RNAi in hairy roots produced significant negative impacts on reproduction and motility of M. incognita. In addition, the presented modified procedure provides technique reference for PPN genes functional analysis or target screening.