Phytochromes influence stomatal conductance plasticity in Arabidopsis thaliana

The ability to sense and respond effectively to drought stress can be important for plant fitness. Here, phytochrome loss-of-function mutants were grown in dry and moist conditions to examine the role of three photoreceptors (phyA, phyB, and phyE) in stomatal conductance (g (ST)) and abscisic acid (ABA) concentration. Overall, drought treatment plants had lower g (ST) than moist treatment plants. However, the wild-type Landsberg erecta line had a less pronounced conductance response to drought treatment than the phytochrome mutants, suggesting a role for phytochrome in suppressing drought tolerance. Phytochrome gene effects were potentially additive for g (ST); however, PHYB and PHYE effects were nonadditive for ABA concentration.