New histochemical observations of shot grapevine berries

Abstract

This paper describes the histological structure of normal grape berries and of different shot grape berries during the first growth period (the first month after fertilisation). We focused our observations on a specific zone during fertilisation, i.e. the septum of the grape berries, which was treated with different histochemical reagents to selectively reveal phenolic compounds and certain tissues; each sample was examined by visible and ultraviolet light. The septum of control grape berries was always cellulosic, whereas the septum of shot grape berries featured lignified (scar) tissue typical of a wound reaction and associated with significant accumulation of flavonoid pigments not seen in normal grape berries. The origins of this lignified tissue are discussed.