title: Impact of disease on diversity and productivity of plant populations.
abstract: Experiments were conducted on the role of intra- and inter-genotypic competition in ecological processes operating at the population scale in diseased plant populations.Combinations ofArabidopsis thalianagenotypes showing variation for phenotypic traits relating to competitive ability and pathogen compatibility were infected with the oomyceteHyaloperonospora arabidopsidisandTurnip yellows virusin separate experiments. Plant fitness and competitive ability were estimated from phenotypic measurements.Pathogen-induced reduction in competitive ability for susceptible genotypes increased the competitive ability of resistant genotypes, resulting in maintenance of yield via competitive release. The two diseases had different effects on competitive interactions between plants. In experiments involving the oomycete, the highest yields were produced by mixtures of two weakly competing genotypes.TheArabidopsismodel system has elucidated the ecological processes by which compensatory competitive interactions can increase the buffering capacity of plant populations under pathogen attack. Highly competitive genotypes may not maximize the productivity of the population as a whole, as they may over-yield at the expense of less competitive, more productive genotypes. The specific outcomes of competitive interactions cannot be generalized because they depend on the disease and the host genotypes.
authors.affiliation: Crop Genetics Department John Innes Centre Norwich Research Park Norwich NR4 7UH UK; School of Biological Sciences University of East Anglia Norwich NR4 7TJ UK; Present address: Department of Crop Science, TEAGASC Crops Environment and Land Use Programme, Oak Park Carlow Ireland.
authors.forename: Henry E
authors.initials: HE
authors.lastname: Creissen
authors.affiliation: School of Biological Sciences University of East Anglia Norwich NR4 7TJ UK; Department of Bioscience Aarhus University 8000 Aarhus C Denmark.
authors.forename: Tove H
authors.initials: TH
authors.lastname: Jorgensen
authors.affiliation: Crop Genetics Department John Innes Centre Norwich Research Park Norwich NR4 7UH UK.
authors.forename: James K M
authors.initials: JK
authors.lastname: Brown
keywords: Arabidopsis thaliana; Hyaloperonospora arabidopsidis; Turnip yellows virus; compensatory interactions; genotype mixtures; overyielding; plant disease; yield stability