| Abstract Detail
Plant Protection Young, Gillian K [1], Cooke, Louise R [2], Kirk, William W [1], Tumbalam, Pavani [1]. The effect of field resistance, aggressiveness and inoculum concentration on competitive selection of Phytophthora infestans in Northern Ireland. IN recent years distinct clonal lineages composed of ‘new’ genotypes of Phytophthora infestans have emerged on a global scale. It has been suggested that increased aggressiveness provided a competitive advantage which led to the rapid increase and subsequent selection of these genotypes. The current investigation has used multiple cultivars and genotypes to study the isolate x cultivar interaction, and thus investigate the potential influence of cultivar, aggressiveness and field resistance on selection of the surrounding late blight population. Multiple isolates of representative genotypes were chosen from the local population of P. infestans in Northern Ireland. Detached leaflets of four potato cultivars with differing levels of field resistance to foliar late blight were inoculated with a mixed sporangia/zoospore suspension composed of standardized inoculum from each genotype. Two concentrations of inoculum were used in the study. The ability of each genotype to infect was subsequently determined through the characterization of single-spored isolates from each lesion. Additionally each genotype was tested individually for aggressiveness on detached leaflets of all four cultivars at both inoculum concentrations. Parameters were % infection, latent period and lesion expansion rate at day five and day seven after inoculation. Extreme differences were observed in the ability of the different genotypes to infect different cultivars. The effect of inoculum concentration was also significant. Trends from aggressiveness testing of single genotypes did not explain the extreme selection which occurred under competitive conditions. These results demonstrate that competition between genotypes can be important within populations of P. infestans. Factors other than aggressiveness of individual isolates may be involved and require further investigation.
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1 - Michigan State University, Plant Pathology, 35 Plant Biology Building, Wilson Road, East Lansing, MI, 48824, United States
2 - Department of Agriculture and Rural Development, Applied Plant Science Division, Newforge Lane, Belfast, BT9 5PX, UK
Keywords:
P. infestans
competition
aggressiveness
selection.
Session: Poster-8
Location: Ballroom CD/Monona Terrace
Date: Tuesday, July 25th, 2006
Time: 8:00 AM
Abstract ID:279 |
