Variation in resistance level of potato genotypes and virulence level of potato cyst nematode populations

Abstract

In two experiments, using different testing methods, the number of newly formed cysts was determined on nine potato genotypes with resistance from various sources . Ten potato cyst nematode (PCN) populations were used in these experiments . Rank correlation between numbers of cysts over potato genotype-PCN population combinations for both experiments was high (r s = 0 .90) . Dendrograms for PCN populations and potato genotypes were constructed, based on a simultaneous hierarchical clustering procedure for potato genotype-PCN population interaction terms . Several virulence groups could be identified within Globodera rostochiensis as well as within G. pallida. Host genotypes, derived from the same sources of resistance, were clustered in different' resistance groups .

Investigation of resistance specificity amongst fifteen wild Solanum species to a range of Globodera pallida and G. rostochiensis populations

“…Significant effects for PCN population, potato genotype and the interaction between them was observed in all three experiments, confirming previous studies (Phillips & McNicol, 1986;Dellaert & Vinke, 1987;Arntzen & Bakker, 1988;Dellaert et al, 1988;Whitehead, 1991;Arntzen & Eeuwijk, 1992;Bendezu et al, 1998;Phillips & Trudgill, 1998). Analysis of covariance also indicated that although root growth explained some of the interaction effects, it did not greatly influence the significant interaction observed, discounting previous suggestions (Arntzen & Bakker, 1988).…”

“…Studies into the different responses of wild species, breeding lines and cultivars to a range of populations have demonstrated the interactions that can occur between potato genotypes and PCN populations (Phillips & McNicol, 1986;Dellaert & Vinke, 1987;Arntzen & Bakker, 1988;Dellaert et al, 1988;Whitehead, 1991;Arntzen & Eeuwijk, 1992;Bendezu et al, 1998;Phillips & Trudgill, * Corresponding author, e-mail: Mark.Phillips@scri.sari.ac.uk 1998). The interactions observed have been attributed to a range of factors including variation in root characteristics amongst genotypes (Arntzen & Bakker, 1988), the effect of minor genes (Arntzen & Bakker, 1988) and the source of resistance present in a genotype and the origin of the population (Phillips & Trudgill, 1998).…”

“…The initial identification of this intraspecific variation led to the classification of pathotypes of both species based on the multiplication rates of populations grown on a set of differential potato clones containing different sources of resistance (Canto-Saenz & de Scurrah, 1976Kort et al, 1977). However, such schemes have been heavily criticised due to a continuum of variation in virulence among populations, and at a European and Mediterranean Plant Protection Organization (EPPO) workshop in Münster in 1984 it was decided to replace the term 'pathotype' with 'virulence group' (Arntzen & Eeuwijk, 1992).…”

An Exact Test for Additivity in Two-Way Tables under Biadditive Modelling

“…1, and represents maize data (variety by year-location) from van Eeuwijk and Kroonenberg (1998). In the second data set, we have the number of newly formed cysts on 11 potato genotypes for five potato cyst nematode populations belonging to the species Globodera pallida (this data set is part of a larger table in Arntzen and van Eeuwijk, 1992). The numbers are means over five replicates.…”

“…On the other hand, Mandel's test cannot reject the null hypothesis of Downloaded by [The University of Manchester Library] at 11:19 22 December 2014 Table 3 Additivity test for r = 3, 2 = 5: comparison of our method (global test) and Mandel's test Figure 3. Biplot of potato cyst nematodes on potatoes data (Arntzen and van Eeuwijk, 1992). …”