Traditional family production and nutritional-nutraceutical value of common beans (phaseolus vulgaris L.) in Southeast Mexico

In southeast Mexico, archaeobotanical and genetic evidence has been found regarding the origin, domestication and diversification of the common bean (Phaseolus vulgaris L.). The phaseolin and seed evidence found in the caves of Guila Naquitz,Oaxaca, Mexico, dates back to between 6220 and 6460 B.C., and since then, the common bean has remained an integral part of the crops and diets of farmers and their families. In this context, it is believed that there are hundreds of seed lots in the hands of farmers that have not been characterized in agronomic, genetic, biochemical and nurtritional terms, and there is limited research on the phenotypic, genetic and biochemical diversity of the common bean in its regions of origin. This chapter briefly documents the traditional production systems and the grain composition of traditional common bean varieties grown in southeast Mexico, based on our field and laboratory investigations, and complements this information with bibliographical references. In terms of the documented phenotypic diversity, two groups of bean growth types have been described: Type I and II determinate growth variations are generally used for crops sown in furrows and broadcast sowing, and type III and IV indeterminate growth variations are usually sown alongside maize and squash or in single-crop systems using trellises. The characteristics of the snap bean and dry grain vary significantly among native populations and sample origins. These differences are partly due to annual seed lot selection and diverse selection criteria, including adaptability to agroecological microniches that have a restrictive impact on the crop, growth types, yield in terms of the snap bean and dry grain, cooking time, flavor and a range of culinary aspects related to the preparation of specific dishes. All these factors influence the variability of the agronomic characteristics and grain composition. This influence is reflected in the differences found in bean populations with regard to their minerals, proteins, antinutritional compounds, polyphenols, flavonoids, anthocyanins and antioxidants, in both the seed coat and cotyledons. Grain composition differs among populations based on the region of origin of the gene pool, location cropping, and grain color. For example, flavonoid, polyphenol and antioxidant content was higher in seed coat than in cotyledons, and grains with light colors more frequently presented low values for the aformentioned compounds, including anthocyanins.