A Grape is a Non-Climacteric Fruit

After reading Remi Cohen's article in the November/December 2013 issue of Vineyard & Winery Management and blogging about it in Abscisic Acid and Grapevine Dormancy, my curiosity was peaked regarding abscisic acid's role in grape ripening. One thing that I learned while digging into this topic is that grapes are a non-climacteric fruit. I had no idea! Grapes, along with citrus fruits and strawberries are non-climacteric fruits, meaning that they ripen without ethylene and respiration bursts. Fruits that are climacteric include apples, bananas, tomatoes, some melons and apricots.¹
So, the question is, what is the trigger for non-climacteric fruit ripening. The French call the onset of ripening in the grape, veraison, this is when the skins in red grape varieties begin to turn from green to red and the berries begin to soften. Still, this does not address the question of the trigger and chemistry of ripening in grapes. I found a freely available publication online called Fruit ripening in Vitis vinifera: spatiotemporal relationships among turgor, sugar accumulation, and anthocyanin biosynthesis researched and written by Simone D. Castellarin1, Greg A. Gambetta, Hiroshi Wada, Ken A. Shackel and Mark A. Matthews.
The onset of ripening results in²:

• Berry softening
• Sugar accumulation
• Increase in abscisic acid (ABA)

The increase in abscisic acid is accompanied by a decrease in cell turgor (P). Research into the ripening process has found that exogenous sugar and ABA is enough to result in berry softening and anthocyanin accumulation. But other hormones such as auxins, brassinosteroids, as well as ethylene also play a role in grape ripening. Auxin has been found to be a negative regulator in grape ripening and brassinosteroids are postive regulators.³
I'm still reading about the chemistry of grape ripening. Will report with more info later.
References:
1. Wikipedia: Climacteric_botany.
2. Simone D. Castellarin1, Greg A. Gambetta, Hiroshi Wada, Ken A. Shackel and Mark A. Matthews, Fruit ripening in Vitis vinifera: spatiotemporal relationships among turgor, sugar accumulation, and anthocyanin biosynthesis, J. Exp. Bot., (2011) 62 (12): 4345-4354.
3. Marzia Giribaldi, Laurence Gény, Serge Delrot and Andrea Schubert, Proteomic analysis of the effects of ABA treatments on ripening Vitis vinifera berries, J. Exp. Bot., (2010) 61 (9): 2447-2458.