Antifungal activity in winter squash fruit peel in relation to age related resistance to Phytophthora capsici

Age-related resistance (ARR), or ontogenic resistance, is associated with host developmental stages. Winter squash fruit (Cucurbita moschata) develops resistance to the oomycete plant pathogen, Phytophthora capsici, as they mature. ARR in winter squash to P. capsici could be exploited to assist growers in limiting crop loss due to fruit rot. The objective of this study was to determine whether preformed or pathogen-induced antifungal activity during fruit development is correlated with ARR. We examined fruit peel methanol/ethanol extracts of three cultivars of C. moschata at different developmental stages with and without P. capsici inoculation. Results indicated the presence of compounds with antifungal activity in all fruit ages tested, but the antifungal activity decreased with age indicating a lack of association between preformed antifungal activity and ARR in winter squash. In addition, no significant change was detected in the antifungal activity among fruit ages that were inoculated with P. capsici and examined at different times post inoculation, suggesting no association between the induced antifungal activity and ARR in winter squash.