IDENTIFICATION OF MONOCROTALINE IN Crotalaria SPECIES AND THEIR ANTAGON ACTION TO PHYTONEMATODES

Abstract

Crotalaria species are widely used as crop rotation in agricultural systems, adding to the benefits of reducing the phytonematodes population, biological nitrogen fixation and the increase in soil organic matter content. Phytonematodes are the main causes of diseases in agricultural crops, especially soybeans, resulting in significant yield losses. Monocrotaline (MCT) is a pyrrolizidine alkaloid and has been described in plants belonging to the genus Crotalaria (Fabales: Fabaceae). The metabolite is attributed to antagonistic action, promoting the decrease and/or suppression of infectious species. The present work aimed to determine the presence of MCT in aqueous extract of leaves of C. juncea, C. spectabilis and C. ochroleuca species, and to correlate the results obtained with those presented in the literature. For MCT prospecting a target metabolomics approach was employed using UPLC-QToF-MSE with negative and positive electrospray ionization. Comparisons of mean intensity between the three species were made, with emphasis on C. spectabilis that presented higher intensity MCT among the other species. Aqueous extracts of C. juncea showed low intensity MCT peak and, in C. ochroleuca, was not detected under the conditions of study. When consulted in the literature, authors who used crotalaria extracts of both species that showed nematicidal and / or nematostatic activity attributed this effect to the monocrotaline metabolite. However, in our analysis the low incidence or absence of this pyrrolizidine alkaloid in the extracts of the species C. juncea and C. ochroleuca suggests that the adverse action to phytonematodes may not be attributed to monocrotaline, suggesting further investigations in the metabolite profile of plants of this crotalaria genus.