Fruit-mediated Autoallelopathic Effects on Seed Germination of Pilosocereus catingicola subsp. salvadorensis

Abstract Autoallelopathy refers to the inhibitory effect of plant-derived compounds on seeds or seedlings of the same species and may influence germination and early establishment. In this study, we evaluated the potential autoallelopathic effect of the funicular pulp of Pilosocereus catingicola subsp. salvadorensis on the germination of its own seeds. We collected fruits from 20 individuals belonging to Caatinga and Restinga populations during the dry and rainy seasons. We characterized the polar and nonpolar metabolic profiles of the funicular pulp by GC-MS and prepared extracts using hexane, ethyl acetate, methanol, and water. We then evaluated the potential autoallelopathic effects of these extracts through germination bioassays using seeds of the same species. We annotated 74 metabolites polar and 52 nonpolar. We found that seasonality was the main factor structuring both metabolic fractions, whereas differences between populations were weaker and were not supported by robust model validation. During the rainy season, population differences in the polar fraction were mainly associated with carbohydrate metabolism, central carbon metabolism, and amino acid metabolism. After FDR correction, we detected no significantly different metabolic pathways between populations during the dry season. The hexane and ethyl acetate reduced germination capacity, speed, and synchrony and delayed germination in a concentration-dependent manner. At concentrations of 1.0 and 2.0 mg mL − 1 , these extracts completely inhibited the germination of seeds produced during the rainy season. Under controlled laboratory conditions, our results demonstrate that seasonality influences both the metabolic profile of the funicular pulp and the magnitude of its inhibitory effect on germination.