Postharvest darkening of seed coat in common bean: Paths towards breeding for better marketability

Postharvest darkening (PHD) of seed coat, resulting from the oxidation of proanthocyanidins, is a critical challenge to the marketability of common bean since this characteristic is associated with long cooking time by consumers, thus lowering market values of darkened seed. Extensive research has been done to elucidate the phenotypic, biochemical, genetic, and genomic bases of PHD in several market class beans from many regions of the world. However, little or no information is available on the PHD status in the sub-Saharan Africa (SSA) bean germplasm under local environmental conditions . Therefore, the current review aims at systematically revisiting the available scientific information regarding the control of seed coat PHD from the reported studies to better guide future breeding efforts in sub-Sahara Africa. We investigated avenues for improving the trait in SSA in the context of a multi-trait and multi-environment paradigm basing our proposed approaches on the state-of-art standards. Keywords: Color, market classes, Phaseolus vulgaris, Proanthocyanidins