Ethylene triggers the ripening of fruit for many plant species but does not seem to play an important role for the ripening of grapes. Scientists hypothesized that the trigger for the ripening of grape fruits is abscisic acid (ABA). They sprayed unripe Cabernet Sauvignon grapes with different concentrations of ABA and tracked several fruit characteristics over time: percent of fruits that are purple, concentration of anthocyanin (a purple pigment) per fruit, weight of each fruit, and total soluble solids per fruit as measured by °Brix. °Brix measurements indicate the amount of sugar in the fruit, and determine how much alcohol a wine will have. Higher values of each measurement indicate a greater degree of ripening. The scientists' results are shown in these four graphs.
Source: Wheeler, S., Loveys, B., Ford, C., & Davies, C. (2009). The relationship between the expression of abscisic acid biosynthesis genes, accumulation of abscisic acid and the promotion of Vitis vinifera L. berry ripening by abscisic acid. Australian Journal of Grape and Wine Research, 15(3), 195-204.
-Should the wine industry recommend the use of ABA to speed up ripening of grapes for wine making?
A) No, because any early increases in fruit sugars as a result of ABA addition decreases as ripening progresses.
B) No, because there is no difference in the trajectory of ripening when ABA is added compared to when it is not.
C) Yes, because colored, full-sized fruit can be produced earlier when ABA is added.
D) Yes, because more fruit sugars will be present earlier in fruits sprayed with ABA compared to fruits that are not.

Question

Ethylene triggers the ripening of fruit for many plant species but does not seem to play an important role for the ripening of grapes. Scientists hypothesized that the trigger for the ripening of grape fruits is abscisic acid (ABA). They sprayed unripe Cabernet Sauvignon grapes with different concentrations of ABA and tracked several fruit characteristics over time: percent of fruits that are purple, concentration of anthocyanin (a purple pigment) per fruit, weight of each fruit, and total soluble solids per fruit as measured by °Brix. °Brix measurements indicate the amount of sugar in the fruit, and determine how much alcohol a wine will have. Higher values of each measurement indicate a greater degree of ripening. The scientists' results are shown in these four graphs.
  Source: Wheeler, S., Loveys, B., Ford, C., & Davies, C. (2009). The relationship between the expression of abscisic acid biosynthesis genes, accumulation of abscisic acid and the promotion of Vitis vinifera L. berry ripening by abscisic acid. Australian Journal of Grape and Wine Research, 15(3), 195-204.
-Should the wine industry recommend the use of ABA to speed up ripening of grapes for wine making?
A) No, because any early increases in fruit sugars as a result of ABA addition decreases as ripening progresses. 
B) No, because there is no difference in the trajectory of ripening when ABA is added compared to when it is not. 
C) Yes, because colored, full-sized fruit can be produced earlier when ABA is added. 
D) Yes, because more fruit sugars will be present earlier in fruits sprayed with ABA compared to fruits that are not.

Quizplus · Accepted Answer

The results of the study show that while ABA does lead to an initial increase in fruit sugars, this effect decreases as ripening progresses. Therefore, it is not advisable for the wine industry to recommend the use of ABA to speed up ripening of grapes for wine making.

Ethylene Triggers the Ripening of Fruit for Many Plant Species