ETHYLENE PRODUCTION DURING GRAPE BERRY DEVELOPMENT AND EXPRESSION OF GENES INVOLVED IN ETHYLENE BIOSYNTHESIS AND RESPONSE

The evidence is compelling that ethylene plays a role in grapevine berry ripening. An endogenous ethylene peak has been observed in ‘Cabernet Sauvignon’ (Vitis vinifera L.) just before véraison and treatments with exogenous ethylene were shown to influence the onset of ripening and some of the related processes such as anthocyanin accumulation. We also observed a small ethylene peak just before véraison in berries of ‘Pinot Noir’. To better understand the importance of ethylene signalling during berry development and ripening, we studied the expression of genes involved in ethylene biosynthesis and response. Expression profiles were determined for all the grape ACC synthase (ACS) and ACC oxidase (ACO) gene sequences and four ethylene responsive factor (ERF) gene sequences identified in the grape genome. The results highlighted an isogene-specific expression of these gene families, as only ACS1, 2, 4 and 6 and ACO 1, 2 and 4 were detected in the berries. Gene modulation was highly related to the berry developmental stage, too. In particular two ERF genes showed a peak of expression at véraison, while the other two showed a minimum at this developmental phase.