Impact of potato StuPPO9 gene overexpression on drought resistance in Nicotiana benthamiana

To investigate the role of the potato polyphenol oxidase gene <italic>StuPPO9</italic> in response to drought stress, we utilized the overexpression of the <italic>StuPPO9</italic> gene in <italic>Nicotiana benthamiana</italic> through <italic>Agrobacterium</italic>-mediated transformation as the experimental material. Pot experiments were conducted to simulate natural drought stress, and various physiological indicators including growth morphology, chlorophyll content, malondialdehyde and proline levels, antioxidant enzyme activity, and expression of related resistance genes were compared and measured in transgenic and wild-type tobacco plants under drought stress for 0, 3, 6, 9 and 12 days. The results revealed that following the drought treatment, the transgenic strains exhibited significantly higher relative water content, chlorophyll content, proline levels, and superoxide dismutase (SOD) and peroxidase (POD) activities compared to the wild-type plants. Conversely, the malondialdehyde content was significantly lower in the transgenic strains compared to the wild-type. RT-qPCR analysis demonstrated a significant upregulation of expression levels in ROS scavenging system genes (<italic>SOD</italic>,<italic> POX</italic>), ABA biosynthesis genes (<italic>NCED</italic>, <italic>RD29A</italic>), proline biosynthesis gene (<italic>P5CS</italic>), and other stress response genes (<italic>LEA</italic>, <italic>ADC</italic>, <italic>SAMDC</italic>). These findings suggest that the overexpression of the <italic>StuPPO9</italic> gene enhances drought tolerance in tobacco plants, providing a theoretical foundation for further exploration of <italic>StuPPO9</italic>’s role in regulating drought stress response.