Functional Analysis of Cucumis melo CmXTH11 in Regulating Drought Stress Tolerance in Arabidopsis thaliana

The <i>CmXTH11</i> gene, a member of the <i>XTH</i> (xyloglucan endotransglycosylase/hydrolase) family, plays a crucial role in plant responses to environmental stress. In this study, we heterologously expressed the melon gene <i>CmXTH11</i> in <i>Arabidopsis</i> to generate overexpressing transgenic lines, thereby elucidating the regulatory role of <i>CmXTH11</i> in water stress tolerance. Using these lines of <i>CmXTH11</i> (OE1 and OE2) and wild-type (WT) <i>Arabidopsis</i> as experimental materials, we applied water stress treatments (including osmotic stress and soil drought) and rewatering treatments to investigate the response mechanisms of melon <i>CmXTH11</i> in <i>Arabidopsis</i> under drought stress from a physiological and biochemical perspective. Overexpression of <i>CmXTH11</i> significantly improved root growth under water stress conditions. The OE lines exhibited longer roots and a higher number of lateral roots compared to WT plants. The enhanced root system contributed to better water uptake and retention. Under osmotic and drought stress, the OE lines showed improved survival rates and less wilting compared to WT plants. Biochemical analyses revealed that <i>CmXTH11</i> overexpression led to lower levels of malondialdehyde (MDA) and reduced electrolyte leakage, indicating decreased oxidative damage. The activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), were significantly higher in OE lines, suggesting enhanced oxidative stress tolerance. The <i>CmXTH11</i> gene positively regulates water stress tolerance in <i>Arabidopsis</i> by enhancing root growth, improving water uptake, and reducing oxidative damage. Overexpression of <i>CmXTH11</i> increases the activities of antioxidant enzymes, thereby mitigating oxidative stress and maintaining cellular integrity under water deficit conditions. These findings suggest that <i>CmXTH11</i> is a potential candidate for genetic improvement of drought resistance in crops.