Drought Tolerance Is Correlated with the Activity of Antioxidant Enzymes in Cerasus humilis Seedlings

Cerasus humilis, grown in the northern areas of China, may experience water deficit during their life cycle, which induces oxidative stress. Our present study was conducted to evaluate the role of oxidative stress management in the leaves of two C. humilis genotypes, HR (drought resistant) and ND4 (drought susceptible), when subjected to a long-term soil drought (WS). The HR plants maintained lower membrane injury due to low ROS and MDA accumulation compared to ND4 plants during a long-term WS. This is likely attributed to global increase in the activities of superoxide dismutase (SOD) isoenzymes and enzymes of the ascorbate-glutathione (AsA-GSH) cycle and maintenance of ascorbate (AsA) levels. Consistent closely with enzymes activities, the expression of cytosolic ascorbate peroxidase (cAPX) and dehydroascorbate reductase (DHAR) followed a significant upregulation, indicating that they were regulated at the transcriptional level for HR plants exposed to WS. In contrast, ND4 plants exhibited high ROS levels and poor antioxidant enzyme response, leading to enhanced membrane damage during WS conditions. The present study shows that genotypic differences in drought tolerance could be likely attributed to the ability of C. humilis plants to induce antioxidant defense under drought conditions.