VIEW ARTICLE

Genetics

Stable Virulence Against the Tomato Resistance Mi Gene in the Parthenogenetic Root-Knot Nematode Meloidogyne incognita. Philippe Castagnone -Sereno, INRA Laboratoire de Biologie des Invertébrés, 123 bd Francis Meilland, BP 2078, 06606 Antibes Cédex, France; Michel Bongiovanni, and Antoine Dalmasso. INRA Laboratoire de Biologie des Invertébrés, 123 bd Francis Meilland, BP 2078, 06606 Antibes Cédex, France. Phytopathology 83:803-805. Accepted for publication 18 April 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/Phyto-83-803.

Natural and laboratory-selected Meloidogyne incognita lineages virulent against the Mi resistance gene of tomato were propagated over 18 successive generations on a resistant and on a susceptible tomato cultivar. After every three generations, their behavior on Mi-resistant tomatoes was assessed using miniaturized culture and inoculation conditions in order to determine whether the nematode was able to revert back to an avirulent phenotype in the absence of the selection pressure. Virulence appeared to be a stable character in M. incognita. Even if slight differences in the evolution of nematode reproduction were observed between the wild and selected virulent populations over successive generations, none of the populations lost the ability to overcome the Mi resistance gene.