Resistance of Potato Tubers to a Highly Aggressive Isolate of Phytophthora infestans in Relation to Tuber Age

Abstract

The goal of these studies was to evaluate the influence of tuber age on the expression of resistance to Phytophthora infestans in five selected potato genotypes (three cultivars and two clones) varying in tuber resistance and maturity type, and also to select the best time for testing potato tubers for resistance to blight. Resistance was evaluated by inoculating whole tubers at 13 different times as they progressively aged during growth and storage. Tuber age was expressed as weeks after planting. Tubers were rated from week 13 (late July) until week 43 (late February) for tubers planted on 27-28 April, over three consecutive seasons (2001)(2002)(2003). Analysis of variance performed on tuber resistance data showed significant effects of genotype, year and tuber age. Significant contributions of genotype × year, genotype × tuber age, year × tuber age and year × genotype × tuber age interactions were also detected. A slight increase in tuber resistance with tuber age was observed for cvs Bzura, Sokół and Irga, while the opposite trend was observed for the clones 97-A-63 and DG 92-227. Changes in tuber resistance with age of tested genotypes were not related to their maturity type. The period of most stable expression of tuber resistance was observed when tubers were tested between the 16th and 28th week after planting.

Laboratory Assessment of Potato Resistance to Phytophthora Infestans

“…The whole tuber test is based on the method described by Bjor (1987). The previous data indicate that the tuber slice and whole tuber tests should be performed between the 16 th and 28 th week after planting the tuber because the resistance is the most stable at this time and the tubers are already mature but not too old for testing (Lebecka et al, 2006). Regardless of the test type it is recommended to use susceptible and resistant standard cultivars, for example a set proposed by the EUCABLIGHT (www.euroblight.net).…”

R2-like Gene Contributes to Resistance to Phytophthora infestans in Polish Potato Cultivar Bzura

“…The presence of demissum-derived R genes in Bzura is also expected (Dorrance and Inglis 1997;Lebecka et al 2006;Świeżyński et al 1991). So far, only the presence of the R1 gene in Bzura was confirmed (Gebhardt et al 2004).…”