Gene Negatively Regulates Salt and Osmotic Stress Responses in L.

Salt and osmotic stress seriously restrict the growth, development, and productivity of horticultural crops in the greenhouse. The papain-like cysteine proteases (PLCPs) participate in multi-stress responses in plants. We previously demonstrated that salt and osmotic stress affect cysteine protease 15 of pepper ( L.) (); however, the role of in salt and osmotic stress responses is unknown. Here, the function of in regulating pepper salt and osmotic stress resistance was explored. Pepper plants were subjected to abiotic (sodium chloride, mannitol, salicylic acid, ethrel, methyl jasmonate, etc.) and biotic stress ( inoculation). The was silenced through the virus-induced gene silencing (VIGS) and transiently overexpressed in pepper plants. The full-length fragment is 1568 bp, with an open reading frame of 1032 bp, encoding a 343 amino acid protein. CaCP15 is a senescence-associated gene 12 (SAG12) subfamily member containing two highly conserved domains, Inhibitor 129 and Peptidase_C1. expression was the highest in the stems of pepper plants. The expression was induced by salicylic acid, ethrel, methyl jasmonate, and was infected by inoculation. Furthermore, was upregulated under salt and osmotic stress, and silencing in pepper enhanced salt and mannitol stress resistance. Conversely, transient overexpression of increased the sensitivity to salt and osmotic stress by reducing the antioxidant enzyme activities and negatively regulating the stress-related genes. This study indicates that negatively regulates salt and osmotic stress resistance in pepper via the ROS-scavenging.