The pepper phosphatidyl ethanolamine-binding proteins CaMFT02 and CaMFT03 have distinct roles in responses to drought and salt stresses

Abstract

Plants have established defense systems to overcome diverse environmental threats. Abscisic acid (ABA) is one of the representative phytohormones that involves in stress response. Here, we isolated and verified the function of pepper CaMFT (Capsicum annuum Mother of FT and TFL1) genes, which negatively modulate ABA-mediated drought and salt tolerance. MFT is part of the phosphatidyl ethanolamine-binding protein (PEBP) family, which also contains the flowering locus T (FT) and terminal flower 1 (TFL1) subfamilies. While FT and TFL1 have been identified as regulators of flowering time in Arabidopsis, the biological function of MFT is largely unknown. To elucidate how CaMFT02 acts in ABA signaling, along with drought and salt stress responses, we conducted loss-of-function and gain-of-function assays with pepper and Arabidopsis, respectively. CaMFT02-silenced pepper exhibited increased ABA sensitivity and drought tolerance, whereas CaMFT02-overexpressing Arabidopsis showed ABA hyposensitivity and drought hypersensitivity. Silencing of CaMFT03, a CaMFT02 homolog, improved salt stress tolerance in pepper, and this negative regulatory role of CaMFT03 in salt stress tolerance was also observed in CaMFT03-overexpressing Arabidopsis. Taken together, our findings indicate that CaMFT02 negatively regulates drought stress tolerance via ABA signaling in pepper by modulating ABA signaling and suggest that CaMFT03 plays a similar negative regulatory role in salt stress tolerance.