Leaf morphoanatomy traits in white grapevine cultivars with distinct geographical origin

This study aims to compare the leaf morphoanatomical characteristics of seven Vitis vinifera subsp. vinifera white cultivars with different geographical origin, grown side by side at the same “terroir”. The leaf morphoanatomical traits analyzed under light and scanning electron microscopy (SEM) showed large variability among genotypes. Significant differences between cultivars were observed in single leaf area, specific leaf area, leaf density and in the thickness of cuticle, upper and lower epidermal cells and mesophyll. Leaf dry mass per area presented a significant positive correlation with leaf density but showed no correlation with leaf thickness, results that can be explained by the quite different mesophyll structure, epidermal cells and cuticle thickness. ‘Alvarinho’, ‘Encruzado’, ‘Macabeu’ and ‘Viosinho’ were the cultivars with the highest thickness of cuticle and mesophyll tissues. Under SEM magnification three types of stomata were identified: sunken, at the same level and raised above, with the same level type presenting the higher percentage in all cultivars. Stomata density presented significant differences between cultivars, with ‘Macabeu’ showing the highest value and ‘Alvarinho’ and ‘Arinto’ the lowest ones. The hairs on the lower surface presented a similar woolly aspect in all cultivars. Calcium oxalate crystals, raphids and druses were visible and widely distributed in the parenchyma tissues. The observed differences in leaf traits among genotypes suggest a major role of leaf anatomy in determining grapevine capacity for coping with different environmental conditions