Maize Peroxidase ZmPrx25 Modulates Apoplastic ROS Homeostasis and Promotes Seed Germination and Growth Under Osmotic and Drought Stresses.

Drought is one of the major abiotic stresses threatening maize production globally. Under drought stress, maize plants produce excessive reactive oxygen species (ROS), leading to oxidative damage. The apoplast, as the site of substance and signal exchange between plant cells and the external environment, is an important location for the production of ROS under drought stress. Elucidating the ROS scavenging mechanisms in the apoplast is crucial for understanding plant stress responses. However, there is still a lack of research on the ROS scavenging enzymes in maize apoplast and their mediated signaling pathways. We verified that maize peroxidase Prx25 (ZmPrx25) is localized in the apoplast, it scan scavenge hydrogen peroxide (H₂O₂), and we systematically investigated the responses of the apoplastic ZmPrx25-ROS system to osmotic stress. ROS accumulate in the apoplast of maize mesocotyl in response to osmotic stress and transmit the external osmotic stress signals from the apoplast to the inner cellular compartments. The expression of ZmPrx25 is highly upregulated in the meristematic regions of maize seedlings under osmotic and oxidative stress. Overexpression of ZmPrx25 in Arabidopsis promoted seed germination and plant growth, significantly enhancing tolerance to osmotic and oxidative stress. This study provides a new perspective on the role of Prx25 in scavenging ROS under drought stress.