Data from: Natural variation in stomata size contributes to the local adaptation of water-use efficiency in Arabidopsis thaliana

Stomata control gas exchanges between the plant and the atmosphere. How
natural variation in stomata size and density contributes to resolve
trade‐offs between carbon uptake and water‐loss in response to local
climatic variation is not yet understood. We developed an automated
confocal microscopy approach to characterize natural genetic variation in
stomatal patterning in 330 fully‐sequenced Arabidopsis thaliana accessions
collected throughout the European range of the species. We compared this
to variation in water‐use efficiency, measured as carbon isotope
discrimination (δ13C). We detect substantial genetic variation for stomata
size and density segregating within Arabidopsis thaliana. A positive
correlation between stomata size and δ13C further suggests that this
variation has consequences on water‐use efficiency. Genome‐wide
association analyses indicate a complex genetic architecture underlying
not only variation in stomata patterning but also to its co‐variation with
carbon uptake parameters. Yet, we report two novel QTL affecting δ13C
independently of stomata patterning. This suggests that, in A. thaliana,
both morphological and physiological variants contribute to genetic
variance in water‐use efficiency. Patterns of regional differentiation and
co‐variation with climatic parameters indicate that natural selection has
contributed to shape some of this variation, especially in Southern
Sweden, where water availability is more limited in spring relative to
summer. These conditions are expected to favor the evolution of drought
avoidance mechanisms over drought escape strategies.