Ultrastructure, phenol content and peroxidase activity in developing leaves of Vitis vinifera (cv. Lambrusco salamino).

Ultrastrucural observations, assays of total poliphenol content and peroxidase activity were carried out in developing leaves of grape cv. Lambrusco salamino, to assess the morphological and physiological background related to ozone sensitivity. Specialized tannin cell layers were observed both in the leaf primordia and fully expanded leaves; vacuolar tannins appeared in different aggregation forms, at successive leaf ages, varying from globular compact to granular dispersed deposits. The transition in tannin ultrastructural morphology parallels the gradient of water-extractable polyphenols, that decrease from leaf primordia to expanded leaves. Minimum values of total polyphenols and of peroxidase activity in newly expanded leaves seem to be consistent with low tolerance to ozone displayed by these leaves.