Abstract
Sunburn is a physiological disorder that reduces grape quality and
vineyard yield. It is the result of excessive sunlight and high
temperatures. As climate change continues to increase air temperatures,
reports of sunburn damage in vineyards worldwide are becoming more
frequent. Grapes produce secondary metabolites (carotenoids, polyphenols
and aroma compounds) to counter photooxidative stress and acclimate to
higher radiation environments. This study evaluated changes in these
compounds in during ripening when grapes were exposed post-flowering
(ED) and at véraison (LD), and compared them to a nondefoliated control
(ND). ND contained more α-terpineol and violaxanthin, and the defoliated
treatments contained more zeaxanthin, β-carotene, C6
compounds and flavonoids. ED berries adapted better to higher-light
environments, displayed larger changes in secondary metabolite
concentrations and lower levels of sunburn damage than LD berries did.
The composition of berries with increasing sunburn damage was evaluated
for the first time. Berries with no damage had the lowest concentrations
of flavonoids and oxidized glutathione, and the highest concentrations
of chlorophyll and α-terpineol. As damage increased, destruction of
photosynthetic pigments, increase in polyphenols and loss of aroma
compounds were evidenced. A significant effect of temperature and
developmental stage on grape composition was also observed. This study
provides a holistic overview of changes in secondary metabolites
experienced by grape berries when exposed to excessive light, how these
vary along development and how they affect sunburn incidence.
Original language | English |
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Article number | 42 |
Number of pages | 23 |
Journal | Biomolecules |
Volume | 12 |
Issue number | 1 |
DOIs | |
Publication status | Published - Jan 2022 |