Mechanisms of Cananga odorata essential oil in the control of black spot needle blight of Pinus sylvestris var. Mongolica Litv. (Pestalotiopsis neglecta): cell membrane integrity and permeability

Abstract

Cananga odorata essential oil (COEO) from Cananga odorata has medical uses but its antifungal against plant phytopathogenic fungi was unknown. In this study, COEO showed significant concentration-dependent inhibition of mycelial growth and spore germination in Pestalotiopsis neglecta (P. neglecta). Compared with the control groups, the contents of ergosterol and total lipids in P. neglecta decreased by 50.08% and 83.30% respectively after being treated with 0.516 µL/mL (EC₃₀) and 0.797 µL/mL (EC₅₀) of COEO. Subsequently, an overall upward trend was observed in the activity of superoxide dismutase (SOD), while downward trends appeared in the activities of catalase (CAT) and peroxidase (POD). Meanwhile, the contents of hydrogen peroxide (H₂O₂) and Malondialdehyde (MDA) increased. These alterations induced oxidative stress and aggravated the peroxidation state of cellular membrane lipids. Furthermore, the treatment of COEO was found to enhance the extracellular conductivity and the content of extracellular soluble protein in P. neglecta. The staining with Propidium iodide (PI) and Fluorescein diacetate (FDA) demonstrated that COEO induced the disruption of cell membrane integrity. Moreover, the activities of polygalacturonase (PG), pectin lyase (PL), and endoglucanase (EG) were observed to decrease in the control groups. In vivo, 120 µL/mL COEO inhibited black spot needle blight in Pinus sylvestris var. mongolica. COEO alters cell membrane, triggers stress, and affects P. neglecta growth and virulence, showing potential as a plant-derived pesticide for controlling this and other plant diseases.