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

A technique has been developed for the study of the histochemical loca lization of anthocyanins in both seeded and seedless grapes (Vitis vin ifera) through the blotting of freeze/thawed tissue sections on nitroc ellulose membranes. After blotting, anthocyanins can be seen principal ly at the level of the hypodermal tissue before and after exposure to NH, vapours. This last treatment provokes the transition of the red an thocyanin flavylium ion to the corresponding blue anthocyanin anhydrob ase, this being characteristic of anthocyanin pigments. The reliabilit y of this technique in the histochemical localization of anthocyanins in grapes was confirmed by fractionation and determination of the anth ocyanin content in the different tissues.