Pepper JAZ Protein CaJAZ1-06 Negatively Regulates Drought Stress and Abscisic Acid Signaling.

Abstract

JASMONATE ZIM-DOMAIN (JAZ) proteins are well-known key JA signaling repressors that play a crucial role in regulating various abiotic stresses, such as drought, salinity, and cold. However, their functional involvement in response to drought stress in pepper plants remains elusive. Here, we isolated a novel JAZ protein, namely, CaJAZ1-06 (Capsicum annuum JAZ1 from chromosome 06), from pepper plants and analyzed the expression of CaJAZ1-06 under drought stress conditions. Our results showed that its expression significantly increased compared with that of other pepper JAZ proteins, including its homologous gene CaJAZ1-03, a negative regulator of drought stress and ABA signaling. We also investigated the biological role of CaJAZ1-06 by silencing its expression in pepper plants through virus-induced gene silencing and by overexpressing it in Arabidopsis thaliana transgenic plants. In response to drought stress, CaJAZ1-06-silenced pepper plants showed enhanced tolerance, accompanied by a reduced transpirational water loss and increased expression of stress-responsive genes compared with the control plants. Conversely, the CaJAZ1-06 overexpressing Arabidopsis plants exhibited reduced drought tolerance, with increased transpirational water loss relative to the control plants. Furthermore, CaJAZ1-06 overexpression resulted in ABA insensitivity during seedling and adult stages. Therefore, our findings suggest that CaJAZ1-06 acts as a negative regulator of drought stress responses and ABA signaling.