Exploration of Drought Tolerant PGPR and Their role in Regulating Antioxidant Enzymes in Maize (Zea mays L.)

Maize in water-deficient regions faces growth challenges due to drought stress, disrupting water relations and nutrient absorption. This study aims to evaluate the potential of isolated plant growth-promoting rhizobacteria (PGPR) in alleviating drought stress effects and regulating antioxidant enzymes in maize. In an in vitro study, eight rhizobacterial isolates were assessed for drought tolerance. Among these isolates, three PGPR strains, namely Pseudomonas fluorescence (MZ723944): PKR1, Bacillus subtilis (MZ960306): PKR5, and Achromobacter xylosoxidans (OK272512): PKR6, were identified. These strains were exposed to 20% (w/v) PEG stress levels to simulate drought conditions, and their impact on maize germination and antioxidant enzyme activity was evaluated. The three isolated PGPR strains demonstrated resistance to 20% (w/v) PEG stress, resulting in a notable improvement of 40-50% in maize germination under stress conditions. Furthermore, these PGPR strains positively influenced the activity of antioxidant enzymes in maize seedlings. They enhanced superoxide dismutase and catalase activity, thereby regulating plant defence mechanisms. Additionally, enzymes such as peroxidases and glutathione reductases were found to reduce oxidative damage and enhance stress tolerance in maize plants. This study demonstrates that specific PGPR strains can mitigate drought stress and regulate antioxidant enzymes in maize, providing a sustainable approach to agriculture.