Classical and molecular approaches for managing nematodes affecting potato

Abstract

Potato cyst (Globodera spp.), root-knot (Meloidogyne spp.), and root lesion (Pratylenchus spp.) nematodes are the most economically important nematodes of potatoes in temperate climates. Potato cyst nematodes occur worldwide and include two species, Globodera pallida (the white cyst nematode) and Globodera rostochiensis (the golden nematode), each composed of several pathotypes. The gene H1 which confers a high level of resistance to the golden nematode pathotype Rol, has been bred into several potato cultivars that are grown worldwide. Mapping of the H) gene has led to the development of a molecular marker to screen segregating populations for resistance to the golden nematode and to monitor the use of resistant cultivars in statutory control programs. Pathotype Ro2 of the golden nematode that overcomes H1-mediated resistance was recently discovered in New York State in the United States, and a high level of resistance to this pathotype has been identified. Several sources of resistance to G. pallida are known and have been used in traditional potato breeding programs to develop cultivars resistant to this species. Molecular markers that are closely linked to genes for resistance to two G. pallida pathotypes have been identified in different regions of the potato genome. Although resistance to root-knot and root lesion nematodes has been identified, limited success has been realized in the use of this resistance either through classical or molecular techniques to manage these nematodes on potatoes. Engineered resistance genes are currently being developed that may prove effective against both species of potato cyst nematodes as well as other nematode parasites of potato.