ZmPOD5 positively regulates drought tolerance by modulating ROS production.

Drought stress is an important abiotic stress affecting maize (Zea mays L.) growth and productivity. Class III peroxidases (PODs) are plant-specific enzymes that play crucial roles in plant growth, development, and responses to abiotic stress. However, only a few studies have been conducted on the responses of PODs to drought stress in maize. In the present study, we identified a maize POD gene, ZmPOD5, whose expression was prominently upregulated by drought stress. ZmPOD5 overexpression lines showed enhanced drought tolerance, as evidenced by the improved survival rates and increased relative water content (RWC), alleviating water loss rate, malondialdehyde (MDA) content, relative electrical conductivity (REC), O• content, and reactive oxygen species (ROS) accumulation, whereas enhancing the activities of ROS-scavenging/antioxidant enzymes such as superoxide dismutase (SOD) and peroxidase (POD). In contrast, ZmPOD5-KO and ems3-06a97c mutants displayed opposite phenotypic and physiological responses under drought stress. Transcriptome sequencing analysis further revealed that drought stress substantially altered the expression patterns of genes involved in the stimulus response and oxidation-reduction processes in ZmPOD5-OE lines and ZmPOD5-KO mutants. These results demonstrated that ZmPOD5 functions as a positive regulator of maize response to drought stress. This study will provide new insights into the role of PODs in regulating drought tolerance in maize.