In the course of global climate change, Central Europe is experiencing more frequent and prolonged periods of drought.The here drought years 2018 and 2019 affected European beeches (Fagus sylvatica L.) differently: even in the same stand, drought-damaged trees neighboured healthy trees, suggesting that the genotype rather than the environment was responsible for this conspicuous pattern.We used this natural experiment to study the genomic basis of drought resistance with Pool-GWAS.Contrasting the extreme phenotypes identified 106 significantly associated single-nucleotide polymorphisms (SNPs) throughout the genome.
Most annotated genes with associated SNPs (>70%) were previously implicated in the drought reaction of plants.Non-synonymous substitutions led either to a functional amino acid exchange or peperomia double duty premature termination.A non-parametric machine learning approach on 98 validation samples yielded 20 informative loci which allowed an 88% prediction probability of the drought phenotype.Drought resistance in European beech is a moderately polygenic trait that should respond well to natural selection, selective management, and breeding.