THE HISTOCHEMICAL-LOCALIZATION OF ANTHOCYANINS IN SEEDED AND SEEDLESS GRAPES (VITIS-VINIFERA)

A technique has been developed for the study of the histochemical localization of anthocyanins in both seeded and seedless grapes (Vitis vinifera) through the blotting of freeze/thawed tissue sections on nitrocellulose membranes. After blotting, anthocyanins can be seen principally at the level of the hypodermal tissue before and after exposure to NH, vapours. This last treatment provokes the transition of the red anthocyanin flavylium ion to the corresponding blue anthocyanin anhydrobase, this being characteristic of anthocyanin pigments. The reliability of this technique in the histochemical localization of anthocyanins in grapes was confirmed by fractionation and determination of the anthocyanin content in the different tissues.