The pepper AP2 domain-containing transcription factor CaDRAT1 plays a negative role in response to dehydration stress

Abstract

APETALA2 (AP2) domain-containing transcription factors play critical regulatory roles in plant growth, development, and response to abiotic stresses, including dehydration stress. In Capsicum annuum (pepper), data are lacking regarding AP2 domain-containing transcription factors and their precise functions. Here, we identified six putative AP2 domain-containing transcription factors in pepper plants; the expression levels of these transcription factors were induced or repressed by dehydration stress. We named the gene having the highest fold change as Capsicum annuum Dehydration Responsive AP2 domain-containing Transcription factor 1 (CaDRAT1). CaDRAT1 belongs to the ERF subfamily B-4, but the roles of these ERF proteins in dehydration responses are not well known. CaDRAT1 transcript levels were significantly induced after exposure to abscisic acid (ABA), mannitol, low temperature, and H2O2. The acidic domain in the CaDRAT1 C-terminal region had a transactivation effect on the reporter gene in the yeast GAL4 system. CaDRATI-silenced pepper plants displayed a dehydration resistant phenotype characterized by enhanced stomatal closure and low levels of transpirational water loss. Moreover, under dehydration stress conditions, expression levels of stress-related genes including CaNCED3 were higher in CaDRAT1-silenced pepper plants than in control plants and ABA content was also higher. Taken together, our findings suggest that CaDRAT1 functions as a negative regulator of dehydration resistance through modulation of ABA biosynthesis and signaling.