Arabidopsis thaliana mutants with an altered susceptibility to the root-knot nematode Meloidogyne incognita.

Sedentary endoparasitic nematodes of plants are obligate parasites of roots in which they complete their sophisticated life cycle. To study the plant/root-knot nematode interaction, a screening was performed for mutants of Arabidopsis thaliana that were less susceptible to nematode infection. Ethyl methanesulfonate-mutagenized A. thaliana M2 seeds (13,000) were germinated and the seedlings were screened in vitro for nematode susceptibility. Another 5,000 plants were screened in a sand mixture under glasshouse conditions. Ten mutants that were at least a 2-fold less susceptible than the wild-type were retained and analyzed in more detail in vitro as well as in the greenhouse. All mutants with a fairly normal morphology had only a slightly, but reproducibly, decreased susceptibility to nematodes. One mutant (AMi 2) with a 17-fold lower susceptibility to nematode infection and an aberrant phenotype could be rescued by tryptophan.