Genomic basis of drought resistance in Fagus sylvatica by PoolGWAS

In the course of global climate change, central Europe is experiencing more frequent and prolonged periods of drought. The 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 SNPs throughout the genome. Most affected genes were previously implicated in drought reaction of plants. Non-synonymous substitutions led either to a functional amino acid exchange or premature termination. A SNP-assay with 70 loci allowed the prediction of drought phenotype in 98.6% in a validation sample of 92 trees. Drought resistance in European beech is a moderately polygenic trait that should respond well to natural selection, selective management, and breeding.

在全球气候变化的背景下，中欧正经历愈发频繁且持续时间更长的干旱事件。2018年与2019年的干旱对欧洲山毛榉（Fagus sylvatica L.）的影响存在显著差异：即便在同一林分中，受旱植株与健康植株比邻而生，这表明该差异的成因是基因型而非环境。我们借助这一天然实验体系，采用混合池全基因组关联分析（Pool-GWAS）探究欧洲山毛榉抗旱性的基因组基础。通过对比两类极端表型，我们在全基因组范围内筛选得到106个显著关联的单核苷酸多态性（Single Nucleotide Polymorphism, SNPs）位点。多数受影响的基因此前已被证实参与植物的干旱响应调控。非同义替换（Non-synonymous substitution）要么引发氨基酸发生功能性替换，要么导致翻译过程提前终止。基于70个位点的SNP分型检测体系，可在包含92株植株的验证样本中以98.6%的准确率预测植株的抗旱表型。欧洲山毛榉的抗旱性属于中度多基因调控性状，可对自然选择、定向管理与育种手段产生良好响应。