In vitro and in vivo study of the antifungal activity of extracellular products of cyanobacterium Neowestiellopsis persica strain A1387 against Fusarium wilt disease of cucumber.

Fusarium wilt of cucumber, caused by the fungus Fusarium oxysporum, is a major plant disease that causes significant economic losses. The extensive use of chemical fungicides for its control poses environmental and health risks. Due to growing concerns about the detrimental effects of chemical fungicides, finding safe and effective bio-based alternatives for plant disease control is of high importance. In this study, the potential of Neowestiellopsis persica A1387 cyanobacterial metabolites as a promising substitute for chemical fungicides in controlling this disease was investigated. The antifungal activity of N. persica A1387 cyanobacterial exopolysaccharide (EPS) extract was evaluated against F. oxysporum under in vitro and in vivo conditions. Cucumber plants infected with the fungus were treated with cyanobacterial EPS extract and then assessed for disease severity, antioxidant enzyme activity, and growth parameters. Both biomass and EPS extracts of N. persica A1387 cyanobacteria significantly increased the diameter of the F. oxysporum growth inhibition zone under in vitro conditions. Treatment with cyanobacterial EPS extract resulted in increased dry and fresh weight of stem and roots, and a significant reduction in disease severity and percentage in F. oxysporum-infected plants. Peroxidase, superoxide dismutase (SOD), and catalase enzyme activities in fungus-infected plants treated with cyanobacterial EPS extract were significantly lower on day 42 of infection compared to untreated and infected control plants. These findings demonstrate the potential of N. persica A1387 cyanobacterial extracts as natural and safe alternatives to chemical fungicides for controlling cucumber Fusarium wilt disease.