Dissecting the genetic basis of drought escape across multiple traits in colonizing Arabidopsis thaliana lineages

Drought response in plants is complex, involving integration across a range of physiological processes. However, our knowledge of how different aspects of drought response are linked at the genetic level is limited. We investigated multi-trait adaptation in Arabidopsis thaliana from the Cape Verde Islands (CVI). Using a high-throughput phenotyping platform that minimizes spatial heterogeneity, we measured variation in rosette area, growth rate, leaf color, water-use efficiency (WUE), and stomatal patterning under precisely controlled water conditions. Relative to the Moroccan outgroup, CVI populations evolved to be smaller rosette size with faster growth and reduced WUE, consistent with drought escape adaptation.

Genome-wide association mapping revealed evidence for pleiotropy involving MPK12 (WUE, rosette area, growth rate, and leaf color), NHL26 (WUE and leaf color), SUVH4 (stomatal patterning, rosette area, and leaf color), and FRI (WUE and leaf color), along with an enrichment of signals in ABA response. This study advances our knowledge of the genetic mechanisms driving plant adaptation to novel precipitation environments. By identifying key genetic components and their contributions to multi-trait adaptation, our findings offer insights into how plants respond to environmental challenges and contribute to predicting plant responses to future climate change.