Differential role of Capsicum annuum FANTASTIC FOUR-like gene CaFAF1 on drought and salt stress responses

Abstract

As sessile organisms, plants are potentially susceptible to diverse environmental stresses, including drought, salt, and extreme temperatures. To adapt and survive under these adverse conditions, plants have evolved sophisticated defense mechanisms. Here, we isolated the FANTASTIC FOUR-like gene CaFAF1 (Capsicum annuum Fantastic Four 1) from pepper and functionally characterized this gene with respect to its responses to drought and salt stresses. We found that CaFAF1 expression was relatively abundant in all examined pepper tissues and was significantly induced by drought and salt stress. Compared with control plants, CaFAF1-silenced pepper plants exhibited enhanced drought tolerance, accompanied by a high expression of stress-related genes and enhanced abscisic acid-mediated stomatal closure. In contrast, CaFAF1-silenced pepper plants were sensitive to salt stress, with high electrolyte leakage and lipid peroxidation. CaFAF1 overexpression in Arabidopsis resulted in a phenotype that is the opposite of that after CaFAF1 silencing in pepper. A cell-free degradation assay using leaf crude extracts from drought- or salt-stressed pepper plants revealed that CaFAF1 degradation was promoted by drought and delayed by salt stress. Thus, we suggest that CaFAF1 plays negative and positive roles in response to drought and salt stresses, respectively, possibly via modulation of its protein stability. © 2022 Elsevier B.V.