A histochemical assay for polyphenolic profiling in cereal grains

Abstract

In different cell layers, cereal grains may accumulate various economically important polyphenols such as colored anthocyanins and melanins and colorless proanthocyanidins. To effectively create new cultivars with different combinations of these compounds, a simple, fast, and precise screening method is required. Here, a histochemical assay that includes a combination of hot ethanolic, acidic, alkaline, and ammoniacal silver treatments of grain cryosections followed by microscopy was successfully applied to distinguish these substances in cereal grains. Barley lines previously characterized chemically for the presence of anthocyanins, proanthocyanidins, and melanins in grains were used as a model. In black barley grains, this approach allowed to visually distinguish insoluble melanins that