Yang Yang, Qing-Yun Gu, Xiao-Han Wu, Shu-Yuan Zhang, Ming-Hui Xu, Chao Dai, Chuan-Chao Dai
With the popularization of upland rice cultivation and the intensification of global warming, drought tolerance in rice has become a critical agronomic challenge. Plant endophytes can establish symbiotic relationships with host plants and enhance plant stress tolerance. Previous studies have demonstrated that Phomopsis liquidambaris B3 (P. liquidambaris B3) can form a stable symbiosis with rice and improve plant disease resistance. However, whether this strain can enhance rice drought tolerance remains unclear. In this study, a 7-day water-withholding treatment was imposed on rice at the seedling, tillering, and booting stages. Physiological and biochemical indices related to drought tolerance were determined in plants inoculated with P. liquidambaris B3 and uninoculated control plants.The results showed that drought stress induced obvious leaf rolling in uninoculated rice, whereas no significant leaf rolling was observed in B3-inoculated plants. Under drought conditions, the relative water content, photosynthetic performance (chlorophyll content and net photosynthetic rate), osmotic adjustment substances (proline, soluble protein and soluble sugar), and antioxidant enzyme activities (superoxide dismutase, catalase and peroxidase) in B3-inoculated rice were significantly higher than those in the uninoculated control. Meanwhile, stomatal conductance and transpiration rate were markedly lower in the B3 inoculation group. In addition, plant growth performance and grain yield were significantly improved by B3 inoculation. P. liquidambaris B3 effectively promoted rice photosynthetic capacity under drought stress.Collectively, these findings indicate that P. liquidambaris B3 enhances rice drought tolerance by optimizing physiological performance, promoting plant growth, and ultimately increasing grain yield. This study provides a promising theoretical and application basis for improving drought tolerance in rice.