Intra- and interspecific variation of root-knot nematodes, Meloidogyne spp., with regard to resistance from wild tuber bearing Solanum species

Genotypes of wild Solanum species were tested to determine the level of resistance to root-knot nematodes and to detect the presence of virulent populations within Meloidogyne chitwoodi, M. fallax and M. hapla. High resistance to all tested populations of M. chitwoodi and M. fallax was observed in genotypes of Solanum bulbocastanum, S. hougasii, S. cardiophyllum and S. fendleri. Some genotypes of S. chacoense and S. stoloniferum showed moderate resistance to M. fallax, but no or lesser resistance to M. chitwoodi. There was little variation in virulence in populations of M. chitwoodi and M. fallax found on resistant plants. In contrast, large differences in virulence toward resistant genotypes of S. bulbocastanum, S. hougasii, S. chacoense, S. gourlayi, S. sparsipilum and S. spegazzinii were observed between four populations of M. hapla. It was found that resistance to M. chitwoodi, M. fallax and/or M. hapla is not linked to resistance to the nematode species adapted to high temperature, i.e., M. incognita, M. arenaria and M. javanica.