Alkaloid induction by the interaction between Annona purpurea Moc. & Sessé ex Dunal Curvularia lunata (Wakker) Boedijn and Rhizopus stolonifer Ehrenb. (Ex Fr.) Lind.

Annona purpurea is a species of the Annonaceae family that biosynthesizes more than 50 alkaloids, most of them with benzylisoquinoline structure. Some alkaloids perform defense functions and can be grouped from the ecological perspective as constitutive and induced metabolites. Induced metabolites are expressed in response to changes in abiotic or biotic conditions that trigger plant stress. Few studies have been conducted on alkaloid production as a function of biotic stress. In this work, the response of the alkaloid metabolism of A. purpurea seedlings to infection with fungi Curvularia lunata and Rhizopus stolonifer was analyzed. To determine the alkaloid profile, methanolic extracts were obtained from leaves, stems and roots of control and infected seedlings, which were analyzed by Gas Chromatography coupled to Mass Spectrometry. Chemical diversity was determined by the presence and organ-specific abundance and by means of the adapted ecological indices of Margalef, Shannon and Simpson. In addition, Principal Component Analysis (PCA), PERMANOVA and paired PERMANOVA were performed. Induced responses with C. lunata and especially with R. stolonifer were found. Results indicate that seedlings have an arsenal of available alkaloids, some of which respond according to the infecting phytopathogen.