Do Colletotrichum gloeosporioides and Rhizopus stolonifer induce alkaloidal and antifungal responses in Annona muricata seedlings?

The benzylisoquinoline alkaloids of have been isolated, but their physiological or ecological role is unknown. The objective was to explore whether these secondary metabolites are involved in defense against phytopathogenic fungi. To do this, the alkaloidal response of 6-leaf seedlings of was analyzed, previously inoculated with and . Before and after inoculation, alkaloidal extracts of roots, stems, and leaves were obtained, and the antifungal activity was evaluated . The alkaloids anonaine, reticuline, nornuciferine, assimilobine, and coreximine were identified. caused variable increases in the production of anonaine, reticuline and nornuciferine (10-1200%), while only stimulated the increase of nornuciferin and anonaine (10%) in the stems and leaves. The alkaloidal extracts of inoculated seedlings increased the antifungal activity, both against the pathogen elicitor and against the second target pathogen. These findings suggest that the alkaloids participate in the antifungal defense mechanism.