Researchers evaluate promising biofungicide against Colletotrichum orbiculare

Chinese researchers have identified a natural compound with high antifungal potential against Colletotrichum orbiculare. The substance 9-methylstreptimidone is isolated from the bacteria Streptomyces sp. NEAU-S77.

In the study, its effectiveness was superior to fungicides carbendazim e thiram. The substance did not show toxic effects on the germination and growth of cucumber seedlings, even at high concentrations.

The application of the compound caused deformations in the fungal hyphae, rupture of the plasma membrane, loss of cell wall integrity and leakage of intracellular contents.

Biochemical analyses confirmed the inhibition of antioxidant enzymes, such as catalase and superoxide dismutase, in addition to the reduction in the activity of enzymes involved in cellular respiration, such as succinate dehydrogenase and ATPase.

Action in cellular processes

Transcriptomic analysis revealed that 9-methylstreptimidone interferes with central cellular processes of the pathogen, such as the citric acid cycle, oxidative phosphorylation and peroxisome biogenesis.

A total of 4868 genes were identified as differentially expressed after treatment, 2535 of which were repressed. Genes involved in acetyl-CoA production, the electron transport chain, and the maintenance of lipid metabolism were also affected.

The compound also showed broad-spectrum antifungal action against other phytopathogens, although its isolated structural analogs showed low activity against C. orbiculare.

9-methylstreptimidone is known for its antifungal and antiviral properties. However, according to scientists, this is the first time its action against Colletotrichum orbiculare is documented. According to the authors, the next steps involve evaluating the compound's efficacy under field conditions and identifying its specific molecular targets.

Further information at doi.org/10.1016/j.pestbp.2025.106683