Physiological mechanism beneath the inhibition of Cleome spinosa against the morphology and reproduction of Fusarium oxysporum

Fusarium oxysporum is a soil-borne plant pathogen that can cause various plant diseases including cucumber wilt. An experiment was conducted to explore the physiological mechanism underlying the inhibitory activity of Cleome spinosa against the morphology and reproduction of F. oxysporum. Different concentrations of C. spinosa extracts.−0 (Z0), 5 (Z5), 15 (Z15), 30 (Z30), 45 (Z45), and 60 (Z60) mg·mL−1 were applied to F. oxysporum. Cleome spinosa extract significantly reduced the colony diameter (89.7 %) and dry mass (78.9 %) of F. oxysporum under the Z45 treatment. Moreover, spore formation was also significantly inhibited by C. spinosa extract. The spore number and germination rate decreased by 73.5 % and 83.0 %, respectively, under the Z45 treatment. The number of mycelia in the unit field of view was significantly reduced, and the mycelia were wizened with rough surfaces and more bends under the Z45 treatment. Hence, C. spinosa extracts severely damaged the morphology of F. oxysporum mycelia. Additionally, F. oxysporum could not adjust to the osmotic changes caused by C. spinosa extract, leading to membrane injury and electrolyte leakage. Finally, they impaired the antioxidant system in F. oxysporum, resulting in cell membrane injury.