Cloning And Characterization Of Pathogenicity-Related Genes And Functional Analysis Of Chorismate Mutase Gene In Meloidogyne Arenaria

Root-knot nematodes (Meloidogyne spp.) are economically important pests for agricultural crops worldwide. These root endoparasites are widely distributed from the tropical south to the temperate north in China, infecting many crops species and causing crop losses up to 70%. Due to the current restriction in the use of chemical nematicides, host resistance is being considered as the most efficient method to control root-knot nematodes. Resistance genes against root-knot nematodes have been characterized in many plant species. In particular, the tomato Mi gene, which confers effective resistance to the three major root-knot nematode species M. arenaria, M. incognita and M. javanica, is, so far, one of the best-identified resistance genes. Resistance is mediated by a hypersensitive response (HR) consisting of a local necrosis of root cells around the invading nematode. Mi resistance was identified in the wild tomato species Lycopersicon peruvianum. Up to now, all the available tomato cultivars with resistance to Meloidogyne spp. included the Mi gene. However, use of this resistance could be hampered by the occurrence of resistance-breaking virulent populations of root-knot nematodes. In fact, natural Meloidogyne biotypes virulent against the tomato Mi gene have been described from a number of recent reports. So far, the molecular mechanisms involved in virulence or avirulence to plant resistance genes are largely unknown in nematodes.In plants and microorganisms, chorismate mutase catalyses the conversion of chorismate to prephenate, providing the precursors for the biosynthesis of phenylalanine and tyrosine at the final step of the shikimate pathway, which is a primary metabolic route found in plants and microbes. Moreover, chorismate (or prephenate) is a precursor for a range of compounds including plant defense-related salicylic acid, aromatic amino acids, the phytohormone, indole-3-acetic acid, and a great number of other secondary metabolites. Therefore these chorismate-derived compounds (CDCs) play crucial roles in plant growth, development, defence and interactions with other organisms. Interference in these plant pathways by a nematode chorismate mutase could potentially disrupt general plant defenses,...