Histochemical approach of the mobilization of reserve compounds in germinating coffee seeds

Abstract

The endosperm of coffee beans is an important structure which is composed of different reserve compounds. In the present study, we followed anatomical features during the reserve mobilization of Coffea arabica L. cv ‘Catuaí’ seed samples, harvested at 20 different sites, after 0, 3, 6, 12, 24, 30 and 4days of imbibition. Seed samples were properly stored for enzyme activity assessment and fixed in FAA solution (formaldehyde, acetic acid and ethanol, 1; 18) and kept in ethanol 70% solution, for histochemical analysis. Alternatively, samples for phenolic compounds histochemical test were fixed in Ferrousulfate in formalin. Fixed samples were cross-sectioned for detection of starch, lipids, essential oils, oleoresins, proteins, phenolic compounds, neutrapolysaccharides, alkaloids, β-1,3 and β-1,4 glucans, and lignin. Overall, based on histochemical tests and enzyme activity, seed reserve mobilization wasimilar among the evaluated altitudes and mountainsides. During soaking, there is an intense consumption of reserve compounds, starting at the regioclose to the embryo. Reserve mobilization intensifies after root protrusion, from 12 days of soaking. The intensification of the reserve consumption con-comitant with an increased activity of MDH is observed at the first 12 days, whereas SOD showed higher expression after 30 days of soaking. At the 30 day, little reserve is observed in the endosperm. At 45th day, cotyledon leaves are expanded, and the root system, constituted by the taproot and lateraroots, is well established.