In this article:
Fruit of the variegated grapevine mutant Bruce’s Sport is known to dry to a lighter colour than other seedless varieties.
The biochemical basis for this decreased browning capacity was investigated.
The activity of polyphenol oxidase (PPO( in mature berries of Bruce’s sport was 20-30% of that in Sultana H5.
The Bruce’s Sport grapes were variegated and the green regions of the skin had similar PPO activity to Sultana H5 while the white regions had very low activity.
The decreased browning in this grapevine mutant apparently results from decreased levels of PPO activity in the white regions of the berry, possibly arising from a disruption in the chloroplast development.
Characterisation of a Variegated Grapevine Mutant showing reduced Polyphenol Oxidase Activity
1992, Australian Journal of Plant Physiology, vol 19, pages 43-45