Little is known about adaptive within-species thermotolerance variation in wild plants despite its likely role in functional adaptation at range limits and in predicting response to climate change. In a new study published in AoB PLANTS, Zhang et al. focused on identifying the adaptive variation in response to high-temperature stress across an elevation gradient in natural Arabidopsis thaliana populations. The authors found that the accumulation of Hsp101, an important heat shock protein known to be essential for acquired thermotolerance, was positively associated with seedling survival and post-stress root growth. Pre-acclimation significantly increased thermotolerance at 45°C but not 42°C. Both Hsp101 and thermotolerance were correlated with the climate variation of home sites. The study contributes to growing knowledge on abiotic stress responses in natural plant populations.