EXPRESSION OF A 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID OXIDASE GENE FAMILY IN TABLE GRAPE CULTIVARS

During berry development, veraison is a key developmental stage in grapes as most of the compositional changes that determine quality are triggered in this stage. Recently, it was demonstrated that ethylene biosynthesis was up-regulated at veraison. In this work, we evaluated the expression of 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase genes that catalyze the last step in ethylene biosynthesis during berry development. Experiments were performed using three cultivars of table grapes (Vitis vinifera L.) that were sampled weekly, from the early stages of fruit development until commercial maturity. In all cultivars (‘Thompson Seedless’, ‘Crimson Seedless’ and ‘Red Globe’), VvACO1 accumulated at higher levels, in comparison to VvACO2 and VvACO3, and in all three cultivars the VvACO1 transcripts accumulated around the veraison stage, at levels four to five-fold higher than at the harvest stage. VvACO1 transcript peak at veraison was higher in ‘Thompson’ and ‘Crimson Seedless’ grapes and concomitant with the characteristic changes observed at veraison, especially in terms of the sugar accumulation rate. Therefore, further studies with a larger number of cultivars will confirm if VvACO1 expression is a suitable measurement for identifying veraison in table grape.