Enhancing Resistance In Transgenic Tomato By RNAi Silencing Of Root-knot Nematode Parasitism Genes

Root-knot nematodes (RKN, Meloidogyne species) are the most economically important group of plant-parasitic nematodes worldwide, attacking nearly every food and fiber crop grown and cause major economic damage to agriculture production around the world which are responsible for the annual 125 billion dollars losses. (Chitwood,2003). Current control of root-knot nematodes is deficient. Chemical nematicides have traditionally been widely used in the field, but they have undesirable health and environment risks due to their toxicity and persistence. Potentially, the most cost-effective and sustainable method forreducing RKN damage to food and fiber crops is to develop resistant plants that suppress nematode development and reproduction.This research was to clone the fragments of root knot nematode parasitism genes, then RNAi expression vectors were construct. These vectors were transformed into the nematode susceptible tomato using Agrobacterium-mediated transformation and we obtained the tomato transgenic plants which confer resistance to the root knot nematodes. The main results were as follows:1. The fragments of nematode parasitism genes were cloned based on the published sequence Mi-crt (AF402771), Mi-vap (EF370396) and 16D10 (DQ087264). Then,RNAi expression vectors were constructed.2. The RNAi vectors were transferred into tomato using the Agrobacterium-mediated transformation. PCR results indicated that the foreign gene was integrated into the tomato genome.3. RT-PCR analysis indicated that the expression levels of the corresponding target genes of parasitic nematodes were lower in transgenic plants than that in the infect control.4. Nematode assays showed that some of the RNAi transgenic plants significantly improved their resistance to root knot nematodes.