MYB59 is linked to natural variation of water use associated with warmer temperatures in Arabidopsis thaliana

Water-use contributes significantly to plant growth and productivity, yet the extent to which variation in water-use is a function of adaptive differentiation is unknown. Here, we studied natural variation of water use in Arabidopsis thaliana to understand how climatic history impacts water use strategies. We performed a survey of vegetative water use (VWU) and life-history traits across A. thaliana ecotypes in controlled and outdoor settings. Performance of select ecotypes in controlled experiments was reflective of performance in outdoor conditions. Through trait-climate and genome-wide association (GWAS) analyses, we tested for signals of environmental adaption in water use. Ecotypes from warmer environments were noted in displaying enhanced water use, independent of precipitation. GWAS identified MYB59 as a determiner of VWU. Functionally significant MYB59 SNPs showed associations with temperature, but not precipitation, and myb59 mutants demonstrated reduced water use under high temperatures. Our study suggests intraspecific variation in water-use can be explained in part by climatic history, where temperature is the most significant driver. MYB59 appears involved in this association and holds promise for study in crops.