Selection of genetic lines of Globodera pallida with different levels of virulence to resistant potato genotypes

Abstract

Potato cyst nematodes (PCN), Globodera pallida and G. rostochiensis, are major pests of the potato crop. Knowledge of species and virulence groups present in field populations is important in the control of these nematodes by means of resistant cultivars. The choice of appropriate potato genotypes to classify the degree of virulence of PCN populations would be made easier if nematode populations with known levels of virulence could be selected. The main goal of the present work was to select and characterize lines of G. pallida, using controlled matings. Lines were selected from three populations of G. pallida by making controlled crosses between individuals raised on two partially resistant potato genotypes (cv. Vantage and clone 12380) and the susceptible cv. Désirée. From a total of 531 controlled matings, about 40% fertilized females were obtained. The variation in virulence present in 24 of these lines and two parent G. pallida populations was evaluated by measuring their multiplication rates on several host differential genotypes. Reproduction rates were different in terms of both the numbers of eggs and the numbers of cysts produced. It was possible to select a range of “populations” (i.e. lines) with different virulence levels.