Heat Tolerance in Arabidopsis thaliana By Genome-Wide Association Mapping of Leaf Growth and Chlorophyll Fluorescence Traits

Heat tolerance in crops will be more and more important with the progression of climate change because the frequency and intensity of heat waves is predicted to increase in Central Europe. These heat waves may affect several cop species at different stages of development, from small seedlings to maturity and could lead to yield reduction or total crop failure.

Therefore, there is a need for breeding crops which are more resistant against such extreme temperature conditions. This could be done, for example, by marker-assisted selection (MAS) if genes or genome regions which are associated with a positive plant response to the heat stress condition are known. The aim of this study was the identification of candidate genes which are up- or downregulated during heat stress conditions by a genome-wide association study (GWAS) to avoid the negative effects of such extreme stress events. As a model plant extensive genomic resources are available for Arabidopsis thaliana. Thus, the vast array of genome resources could be used to identify such candidate genes first in A. thaliana and afterwards use this knowledge to other crop species. We selected 80 Arabidopsis ecotypes from the 1001 genome project for high throughput phenotyping using RGB and fluorescence camera systems in automated climate chambers under control as well as heat stress conditions. In a GWAS with 250K SNPs, we observed based on Bonferroni threshold several associations for the 22 examined traits which were different between the control and the heat stress conditions.