PHENOTYPICAL MODIFICATIONS OF MICROPROPAGATED GRAPEVINES

Abstract

Grapevine commercial micropropagation has been constrained by the possibility that the phenotype of the resulting plants may be modified. In this work, we observed the characteristics of self-rooted grapevine plants (cvs Moscato and Barbera), derived from micropropagation (MP) or from woody cuttings (C) over several years after they had been planted in the vineyard. Observations concerned phenology, vegetative growth, ampelography, production, and juice composition. For ampelometric description, the main parameters of adult leaves were measured by means of a computerised graphic digitizer, After some years in the vineyard, most differences in vegetative growth and production were not significant, with the exception of the yield in 'Barbera': MP plants produced more compared to C plants. No significant difference was observed in fertility, vegetative vigour and berry juice composition. On the contrary important morphological characters were still different among leaves of MP and C plants. MP plants often had smaller leaves, with deeper lateral sinuses and a more pronounced hairiness on the veins of the leaf lower side. In 'Barbera', lateral sinuses of MP plants had frequently an atypical form but the frequency of this feature lowered as plants grew older. Leaves of 'Moscato' plants had frequently 5 lobes instead of 3. Discriminant analysis was effective in separating leaf samples collected from plants obtained with different propagation systems, In grapevine, modifications in leaf features may lead to some problems in the ampelographic characterisation of clones. Such morphological modifications, resulting from in vitro culture of vines, are supposed to be due to the rejuvenation induced by this culture method, and to the fact that some juvenile characters could persist for some time after transfer to the vineyard.