Significant effects of RNAi silencing of the venom allergen-like protein (Mhi-vap-1) of the root-knot nematode Meloidogyne hispanica in the early events of infection

Gene silencing using RNAi is a powerful tool for functional analysis of nematode genes and can provide a new strategy for the management of root-knot nematodes. The transcript of the venom allergen-like protein gene (Mhi-vap-1) of Meloidogyne hispanica is localized in the subventral oesophageal gland cells of second-stage juveniles (J2) and the gene is highly transcribed in this developmental nematode stage. The purpose of this study was to assess whether the silencing of the Mhi-vap-1 gene could affect nematode attraction to roots, penetration, development and reproduction in tomato plants. The optimum soaking time to generate silencing of this gene was determined by quantitative RT-PCR analysis of the relative expression of the Mhi-vap-1 gene in the J2 incubated with the soaking solution for 24, 32 and 48h. At 48h, the relative expression of Mhi-vap-1 decreased, which indicates that this period of time is optimum to silence this nematode gene using the RNAi method. Silencing of the Mhi-vap-1 gene interfered with the completion of the nematode life cycle and caused a reduction in nematode attraction to roots, penetration and infection of plants. A small difference in the number of females and galls formed was also observed, which caused a small decrease in the nematode reproduction factor. The use of RNAi silencing of the Meloidogyne effector gene Mhi-vap-1 showed that this gene is important for the plant-nematode interaction during the early events of infection and could be a target gene for anti-nematode strategies.