Exploiting natural variation in susceptibility of Arabidopsis thaliana to meloidogyne incognita to breed broad-spectrum resistance to root-knot nematodes M incognita

The root knot nematode Meloidogyne incognita is able to parasitize hundreds of plant species and is a major threat in nearly all vegetable-growing regions in the world. Current resistance is based on major dominant resistance (R) genes, which are frequently overcome by the occurrence of resistance-breaking races. Allelic variation in genetic loci associated with susceptibility to plant-parasitic nematodes within a single plant species has thus far not been used to breed durable broad-spectrum resistance in crops. Susceptibility investigation of 364 different ecotypes of A. thaliana to the root-knot nematode M. incognita was performed. A nine-fold difference in susceptibility to M. incognita was found between the most and the least susceptible ecotypes. This allelic variation can be caused by polymorphic transcript levels, and by allelic variation within transcripts of essential susceptibility genes. Genome wide association mapping was performed to determine loci that are contributing to the susceptibility factors in A. thaliana. Genes underlying these loci were investigated with T-DNA insertion mutation to confirm their contribution to the susceptibility of A. thaliana to M. incognita. Genes involved in endoreduplication, mitosis and protein degradation showed to be involved in the process of forming feeding cells by M. incognita in A. thaliana. These data indicate that allelic variation can be used to breed for broad-spectrum nematode resistance.