mutation causes low leaf temperature under various abiotic stresses in .

Stomata are microscopic pores on epidermal cells of leaves and stems that regulate water loss and gas exchange between the plant and its environment. Constitutive photomorphogenic 1 (COP1) is an E3 ubiquitin ligase that is involved in plant growth and development and multiple abiotic stress responses by regulating the stability of various target proteins. However, little is known about how COP1 controls stomatal aperture and leaf temperature under various environmental conditions. Here, we show that COP1 participates in leaf temperature and stomatal closure regulation under normal and stress conditions in Arabidopsis. Leaf temperature of mutants was relatively lower than that of wild type (WT) under drought, salt, and heat stress and after abscisic acid (ABA), CaCl, and HO treatments. However, leaf temperature was generally higher in both WT and mutants after abiotic stress and chemical treatment than that of untreated WT and mutants. Stomatal aperture was wider in mutants than that in WT under all conditions tested, although the extent of stomatal closure varied between WT and mutants. Under dark conditions, leaf temperature was also lower in mutants than that in WT. Expression of the genes encoding ABA receptors, ABA biosynthesis proteins, positive regulators of stomatal closure and heat tolerance, and ABA-responsive proteins was lower in mutants that that in WT. In addition, expression of respiration-related genes was lower in mutants that that in WT. Taken together, the data provide evidence that mutations in lead to wider stomatal aperture and higher leaf temperature under normal and stress conditions, indicating that leaf temperature is highly correlated with stomatal aperture.