Figure 2

Multiple functions of L-ascorbate in plants. During abiotic stress conditions, scavenging of ROS by APX increases MDA content in both apoplast and symplast. If the MDA is not rapidly reduced back to ascorbate by MDAR, spontaneously disproportionate into ascorbate and DHA. Cytoplasmic DHAR can reduce DHA back to ascorbate using GSH, and the resulting GSSG is regenerated back to GSH through the action of GR in a NADPH dependent reaction. Furthermore, during oxidative stress conditions, L-ascorbate acts as a cofactor for violaxanthin de-epoxidase for the formation of zeaxanthin and also involves in the regeneration of α-tocopherol from tocotrienoxyl radicals.