Anthocyanin Levels and Expression Analysis of Biosy nthesis- related Genes during Ripening of Sicilian and Inter national Grape Berries Subjected to Leaf Removal and Water De ficit

Abstract

The imposition of managed water deficit and early l eaf removal are strategies used to improve the grapes quality in terms of anthocyanin content. The aim of our work was to evaluate the change in total anthocyanin levels dur ing the ripening of the Sicilian grapes (Nero d'Avola and Frappato) and of the internationa l variety of Cabernet Sauvignon, subjected to two different levels of water deficit, 0% (NI) and 30% (I) of estimated crop evapotranspiration, and subjected to Early Leaf Rem oval (ELR) or Not (NLR). The expression of genes involved in anthocyanin biosynt hesis, such as Phenylalanine Ammonia Lyase (PAL) and UDP-glucose-Flavonoid-Gluco syl Transferase (UFGT), was also monitored. Our results indicate that the amoun t of anthocyanin during the ripening process can be regulated by the application of the aforementioned agronomic practises. The anthocyanin content of Cabernet Sauvignon may b e risen either by the simultaneous application of Early Leaf Removal and in water rest itution regime (ELR-I) or by the association of water deficit and absence of defolia tion (NLR-NI). The analysis of the total content of anthocyanin in Frappato variety has glob ally revealed that the maximum value in the levels of pigments is reached later than in the other autochthonous Nero d'Avola variety. This finding is of considerable interest s ince both the harvest time and product processing might be differentiated among varieties. Conversely, the variety Nero d'Avola was not affected by the experimental conditions and showed the highest level of pigments at fully ripe time. Keywords: Anthocyanin, Early leaf removal, PAL, UFGT, Vitis vinifera , Water deficit.