Characterization of the secondary metabolites in the seeds of nine native bean varieties (Phaseolus vulgaris and P. Coccineus) from Querétaro, Mexico

Abstract

Background: Beans (Phaseolus spp.) are one of the most important legumes due to their high nutritional value. The type and amount of beans’ secondary metabolites varies according to their domestication status, species, and the site where they are grown. In the sate of Querétaro, the most commonly cultivated species are P. vulgaris L. and P. coccineus L., both of which can also be found in wild and disturbed areas. Hypothesis: The aim of this project was to characterize the secondary metabolites in the seeds of the aforementioned species of Phaseolus with different domestication stages and from different geographical areas. The hypothesis is that wild beans collected in Mexican Plateau will have higher concentrations of secondary metabolites. Study site and period of research: The seeds of six samples of domesticated P. vulgaris and three of wild and weedy P. coccineus populations were collected from the Mexican Plateau and the Sierra Madre Oriental in Querétaro, between 2013 and 2016. Methods: It was an experiment with one factor and two levels (bean species) sampled randomized. The experimental unit was each sample, which was studied to obtain 17 chemical parameters, mainly secondary metabolites. From each sample 5 g were selected, minced and parameters were measured twice employing spectrophotometry and high performance liquid chromatography. Data was analyzed using a bootstrap method, discriminant analysis and by establishing simple correlations. Results: The content of secondary metabolites from cultivated P. vulgaris seeds was higher, probably due to its favorable growth environmental and domestication status. Also, beans from the Mexican Plateau had a higher content of secondary metabolites than those from the Sierra Gorda. The analysis of these metabolites allowed for the identification of bean samples with the highest gallic, ellagic, ferulic and p-coumaric acids and vainillin content. Conclusion: The studied samples had different metabolite content according to their species, domestication status and site of growth.