Brown breach

Fruits and vegetables that turn brown within minutes of being bruised or sliced may soon be guaranteed against discolouration, if ongoing field trials in The Netherlands and Australia on genetically-engineered potatoes succeed (New Scientist, Vol 145, No 1961)

The browning occurs because of an enzyme called polyphenol oxiclase (PPO) reacting with phenolic compounds, present in plant cells. In undamaged fruits and vegetables, membranes separate PPO and the phenolic compounds.

Simon Robinson at the CSIRO, Australia's national research body, isolated the gene for PPO and then prepared a reversed gene that can switch off the original gene.