Antifungal Action by Streptomyces globisporus Strain WB03 Against Fusarium cugenangense Causing Gastrodia elata Tuber Rot Disease.

Tuber rot caused by Fusarium cugenangense is a serious problem in the cultivation and postharvest preservation of Gastrodia. 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 Streptomyces globisporus strain (WB03) isolated from the coralloid roots of Cycas panzhihuaensis against Gastrodia tuber rot disease. S. globisporus WB03 can secrete extracellular hydrolases that produce active compounds. Treatment with WB03 damaged the cell membranes of F. cugenangense and increased the leakage of cell contents from the pathogen's mycelia. In addition, WB03 produced phytohormones involved in root development in Arabidopsis. Spraying WB03 on Arabidopsis leaves upregulated the expression of resistance genes PR1, PR5, and PDF1.2 and downregulated the transcription factor genes WRKY38 and WRKY64. 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 Gastrodia tubers. This study suggests that endophytic S. globisporus WB03 may be effective in controlling tuber rot disease in Gastrodia.