The antagonistic activity of Streptomyces scopuliridis (No. HS1) against of poplar canker pathogen Botryosphaeria dothidea

Abstract Background Poplar canker caused by Botryosphaeria dothidea is one of the most severe plant disease that is also associated with death of poplars worldwide. In this study, the biocontrol efficacy and mechanisms of action of Streptomyces scopuliridis (No. HS1), which was previously isolated from soil, was determined against B. dothidea. In vitro, S. scopuliridis and fermentation broth supernatant (FBS) significantly suppressed mycelium growth and biomass accumulation and also disrupted the mycelium morphology of B. dothidea. Results On the 3rd day after treatment, the inhibition rates of colony growth and dry weight were 80.72% and 52.53%, respectively. In addition, FBS treatment damaged the plasma membrane of B. dothidea based on increased electrical conductivity in the culture medium and malondialdehyde content in B. dothidea hyphae. Notably, analysis of key enzymes in glycolysis pathway showed that the activity of hexokinase, phosphofructokinase, and pyruvate kinase increased after FBS treatment. Moreover, the activity of Ca2+Mg2+-ATPase increased, which considerably affected the accumulation of nutrients and energy in pathogenic cells. Meanwhile, the significant reduction in glucose contents and increase in pyruvate contents in B. dothidea treated with FBS further confirmed that FBS may accelerate glycolysis in B. dothidea, which accelerated energy consumption and reduced nutrients accumulation r in B. dothidea. Conclusions In summary, the inhibitory mechanism of FBS on B. dothidea was a complex process, which was reflected in multiple levels of mycelium growth, cell membrane structure, material and energy metabolism. Therefore, S. scopuliridis (No. HS1) FBS represents an ecofriendly biocontrol alternatives for poplar canker with good antifungal effect, which provides an alternative approach to biological control strategies.