- Grapevines under controlled field conditions were wounded (cut) at the trunk.
- Trunk wounding led to enhanced production of anthocyanins in grape berries by increasing sugar levels and delaying ripening.
- The grapevine hormone abscisic acid (ABA) was found to be involved in the response to wounding.
Wounding, such as pruning or animal bites, is known to affect grapevine physiology and berry composition, including anthocyanin content. However, the underlying mechanisms are not well understood. To shed light on this, a team of researchers conducted a controlled field study on grapevines (Vitis vinifera L. cv. Cabernet Sauvignon).
The researchers wounded grapevines by making a single cut at the trunk, simulating a typical pruning wound. They then compared the wounded vines to unwounded control vines. The results showed that wounding led to several changes in grapevine physiology and berry composition:
- Enhanced anthocyanin production: The most striking effect of wounding was the significant increase in anthocyanin content in grape berries. Anthocyanins are pigments that give red grapes their color. The wounded vines produced berries with deeper, more intense color compared to the unwounded vines.
- Increased sugar levels: Wounding also led to increased sugar levels in grape berries. This suggests that wounding may accelerate the process of sugar accumulation in the berries.
- Delayed ripening: The wounded vines showed delayed ripening compared to the unwounded vines. This was evident in several parameters, including berry color change and softening.
- Involvement of abscisic acid (ABA): The researchers found that wounding caused a significant increase in the levels of abscisic acid (ABA) in grapevine leaves. ABA is a plant hormone known to be involved in various stress responses. The increase in ABA levels suggests that this hormone may play a role in the grapevine's response to wounding and the subsequent changes in berry composition.
The study highlights the importance of wounding as a factor influencing grapevine physiology and berry composition, particularly in relation to anthocyanin content. Understanding the mechanisms underlying these effects can help grape growers manage their vineyards to achieve desired berry characteristics, such as enhanced color and flavor.
