Final Report Summary - SARA (Natural sources of aphid resistance in Arabidopsis)
To date, little is known about the molecular mechanisms of plant defencee against aphids. Few genetic loci that contribute to resistance against aphids have been identified and even fewer genes have been cloned to date. In general, resistance to insects can be considered a quantitative trait where several or many genes contribute to the phenotype. Typically, such traits vary genetically within species, and in suitable plant models this variation can be used to identify the genetic loci causing resistance. The aim of this project was to exploit natural genetic variation in Arabidopsis thaliana to determine the genetic basis of resistance against the green peach aphid Myzus persicae.
Aphid proliferation screens were conducted on 19 different Arabidopsis accessions. These tests revealed statistically significant differences in plant resistance against the green peach aphid. Based on these results, a mapping population was chosen to identify quantitative trait loci (QTL) for resistance against Myzus. The parental lines for this mapping population were selected such that they maximized the difference between aphid susceptibility and resistance, but had similar germination and growth rates to reduce undesired variation caused by different developmental states.
The mapping population consisted of 127 recombinant inbred lines and, again, lines displayed statistically significant differences in resistance against Myzus. However, no QTL of medium or large effect could be detected, suggesting that the genetic architecture of aphid resistance is of highly quantitative nature, with many genes each contributing only a very small effect to the phenotype. While this genetic architecture is highly interesting from an evolutionary point of view, it is disappointing from an agricultural perspective, because (at least in the utilized mapping population) no major resistance genes are present that could be exploited for marker-assisted selection or by other means in breeding programmes of crucifer crops to improve resistance against Myzus persicae in a sustainable manner.
Aphid proliferation screens were conducted on 19 different Arabidopsis accessions. These tests revealed statistically significant differences in plant resistance against the green peach aphid. Based on these results, a mapping population was chosen to identify quantitative trait loci (QTL) for resistance against Myzus. The parental lines for this mapping population were selected such that they maximized the difference between aphid susceptibility and resistance, but had similar germination and growth rates to reduce undesired variation caused by different developmental states.
The mapping population consisted of 127 recombinant inbred lines and, again, lines displayed statistically significant differences in resistance against Myzus. However, no QTL of medium or large effect could be detected, suggesting that the genetic architecture of aphid resistance is of highly quantitative nature, with many genes each contributing only a very small effect to the phenotype. While this genetic architecture is highly interesting from an evolutionary point of view, it is disappointing from an agricultural perspective, because (at least in the utilized mapping population) no major resistance genes are present that could be exploited for marker-assisted selection or by other means in breeding programmes of crucifer crops to improve resistance against Myzus persicae in a sustainable manner.