Polygenic basis of strong and rapid flowering time response to environment perturbations in wild Arabidopsis thaliana population

Despite the importance in understanding the impact of climate change, the genetics of rapid response to changing environments and its role in adaptive evolution remains elusive. Here, we studied flowering time response to environment changes using 514 Arabidopsis thaliana worldwide accessions with re-sequencing genomes and flowering time measurements from ten unique environments with variable temperature, drought, daylight and competition stresses. We revealed a polygenic basis of flowering time mean and plasticity, underpinned by 52 mean and plasticity QTL. Widespread interaction between mean QTL, polygenic background and surrounding environments considerably altered the amount of additive genetic variance and allelic effects of detected QTL. This caused variability in phenotype plasticity and across environment variation in genetic variance, resulting in rapid flowering time response to environment perturbations. In addition, the plastic alleles showed a higher correlation with the environment factors than that from randomly sampled alleles, suggesting a potential role in climate adaptation. We therefore proposed a polygenic interaction model, whereby large effect QTL and polygenic background simultaneously interacted with the surrounding environment, underlying rapid response to changing environments. Results from our study thus provided deeper insights into the genetics of plasticity, with potential benefit in genomic selection of crops in heterogeneous environments and predicting changes in species distribution and the evolutionary trajectory of wild populations.