Biological control mechanisms of D-pinitol against powdery mildew in cucumber Chen, J. /Fernandez, Diana Wang, D. D. Chen, Y. J. Dai, G. H. Podosphaera xanthii Plant defense responses D-pinitol Cucumber D-pinitol is an effective agent for controlling powdery mildew (Podosphaera xanthii) in cucumber. In this study, we determined the mechanisms of D-pinitol in controlling powdery mildew in cucumber plants. We compared P. xanthii development on cucumber leaf surface treated with D-pinitol or water (2 mg ml(-1)) at different time points after inoculation. The germinating conidia, hyphae, and conidiophores of the pathogen were severely damaged by D-pinitol at any time of application tested. The highest level of suppression of fungal development was obtained at 3 days after inoculation. The contents of chlorophyll, total phenolics, flavonoid, and gallic acid and its derivatives (GAD); the activities of phenylalanine ammonialyase (PAL), polyphenoloxidase (PPO), peroxidase (POX), and superoxide dismutase (SOD); and the expression of the genes encoding for PR-1, peroxidase (POX), lipoxygenase (LOX1), chitinase (Chit1) were higher in the cucumber leaves treated with D-pinitol and inoculated than in the leaves either treated with D-pinitol or inoculated with the pathogen. These results suggest that D-pinitol triggers several plant defense responses in cucumber leading to pathogen suppression and resistance to powdery mildew. 2014 text https://www.documentation.ird.fr/hor/fdi:010063125 fdi:010063125 Chen J., Fernandez Diana, Wang D. D., Chen Y. J., Dai G. H.. Biological control mechanisms of D-pinitol against powdery mildew in cucumber. 2014, 88, 52-60 EN