Biochemical Characterization of Building Block of Condensed Tannin in Faba Bean (Vicia faba L.).

Abstract

Despite being nutritionally rich, faba bean is not considered as commercial legume crop. One of the probable reasons for it, is the lesser acceptance due to high content of condensed tannins in seed coat. Condensed tannins are polymer of flavan-3-ols type monomers like catechin and/or epicatechin. The knowledge about these monomers is highly important to design strategies to modulate its content in target parts of the plant. In this study we first confirmed the presence of condensed tannin in seed and further its localization in seed coat by tannin specific reagent. The enzyme responsible for biosynthesis of catechin/epicatechin i.e. antocyanidin reductase, was purified from leaf extract. We further demonstrated the presence of epicatechin as monomer in seed extract of faba bean which was further confirmed by in-vitro anthocyanidin reductase catalyzed reaction using paper chromatography. The enzyme and/or gene responsible to synthesize epicatechin can now be an ideal target for reducing the amount of condensed tannin in seed coat, and hence can be useful for nutritional improvement of faba bean