Maize Lipoxygenase ZmLOX2 Modulates Jasmonate-Associated Antioxidant Defense and ROS Scavenging Under Osmotic Stress in Transgenic Arabidopsis
Drought stress is a major abiotic factor that adversely affects plant growth, development, and crop productivity. Lipoxygenases (LOXs) are key enzymes in the jasmonic acid (JA) biosynthetic pathway and play crucial roles in plant responses to environmental stresses. In this study, the ZmLOX2 gene was cloned from maize (Zea mays L.), and was found to encode a chloroplast-localized 13-lipoxygenase (13-LOX) protein. Expression analysis revealed that ZmLOX2 was predominantly expressed in leaves and was strongly induced under osmotic stress conditions. Compared with wild-type plants, transgenic Arabidopsis thaliana overexpressing ZmLOX2 exhibited significantly higher survival rates, enhanced growth performance, and improved root development under water deficit conditions. Physiological and biochemical analyses showed that the overexpression lines displayed higher activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), accompanied by significantly reduced malondialdehyde (MDA) content and reactive oxygen species (ROS) accumulation. Further investigation demonstrated that the expression levels of JA biosynthesis- and signaling-related genes, including ALLENE OXIDE SYNTHASE (AtAOS), 12-OXOPHYTODIENOATE REDUCTASE 3 (AtOPR3), MYC DOMAIN PROTEIN 2 (AtMYC2), and JASMONATE ZIM-DOMAIN 1 (AtJAZ1), were markedly upregulated in the transgenic lines. Protein–protein interaction analysis suggested that ZmLOX2 may interact with ALLENE OXIDE SYNTHASE 1 (AOS1), HYDROPEROXIDE LYASE 1 (HPL1), and ALPHA-DIOXYGENASE 1 (DOX1). Collectively, these results suggest that ZmLOX2 may contribute to plant adaptation to water limitation by regulating responses associated with JA, enhancing antioxidant defense, and maintaining ROS homeostasis.