Uncoupling differential water usage from drought resistance in a dwarf Arabidopsis mutant

Understanding the molecular and physiological mechanisms of how plants respond to drought is paramount to breeding more drought resistant crops. Certain mutations or allelic variations result in plants with altered water-use requirements. To correctly identify genetic differences which confer a drought phenotype, plants with different genotypes must therefore be subjected to equal levels of drought stress. Many reports of advantageous mutations conferring drought resistance do not control for soil water content variations across genotypes and may therefore need to be re-examined. Here, we reassessed the drought phenotype of the Arabidopsis thaliana dwarf mutant, chiquita1-1 (also called cost1), by growing mutant seedlings together with the wild type to ensure uniform soil water availability across genotypes. Our results demonstrate that the dwarf phenotype conferred by loss of CHIQ1 function results in constitutively lower water usage, but not increased drought resistance.