Antifungal Action by <i>Streptomyces globisporus</i> Strain WB03 Against <i>Fusarium cugenangense</i> Causing <i>Gastrodia elata</i> Tuber Rot Disease

Tuber rot caused by <i>Fusarium cugenangense</i> is a serious problem in the cultivation and postharvest preservation of <i>Gastrodia</i>. It is essential to explore effective biocontrol methods to control this disease. In this work, we investigated the biocontrol efficiency and defense responses of an endophytic <i>Streptomyces globisporus</i> strain (WB03) isolated from the coralloid roots of <i>Cycas panzhihuaensis</i> against <i>Gastrodia</i> tuber rot disease. <i>S</i>. <i>globisporus</i> WB03 can secrete extracellular hydrolases that produce active compounds. Treatment with WB03 damaged the cell membranes of <i>F</i>. <i>cugenangense</i> and increased the leakage of cell contents from the pathogen's mycelia. In addition, WB03 produced phytohormones involved in root development in <i>Arabidopsis</i>. Spraying WB03 on <i>Arabidopsis</i> leaves upregulated the expression of resistance genes <i>PR1</i>, <i>PR5</i>, and <i>PDF1.2</i> and downregulated the transcription factor genes <i>WRKY38</i> and <i>WRKY64</i>. In addition, WB03 also enhanced the activity of the antioxidant enzymes superoxide dismutase and peroxidase, reduced the symptoms of rot disease, and reduced the size of the lesion in <i>Gastrodia</i> tubers. This study suggests that endophytic <i>S</i>. <i>globisporus</i> WB03 may be effective in controlling tuber rot disease in <i>Gastrodia</i>.