Control of Key Biochemical Processes for Quality Fruits and Vegetables

In nature, fruits and vegetables are allowed to mature on the plant before they are picked for consumption. This allows the synchrony of appropriate enzymes and biochemical controls for proper ripening that gives fruits their characteristic aroma and flavor. Research scientists have deciphered ethylene to be the biochemical control for ripening early on. Delayed ripening tomatoes that contain the antisense of the gene responsible for ethylene synthesis was later developed through biotechnology. However, Harry Klee, a biochemist from the University of Florida explained that the delay in the ripening also slowed down the flavor biosynthesis, thus consumers may perceive that biotech tomato may not taste as good as conventional ones.

In order to study the intricacies in making a tastier tomato, Klee started to tabulate tomato flavor volatiles. He found out that the biggest component of tomato aroma is cis-3-hexenal, a fatty-acid-derived volatile present at 12,000 parts per billion (ppb) in a garden-fresh tomato. The second most important volatile is β-ionone, an apocarotenoid present at only 4 ppb. The low concentration of this volatile is compensated by our incredible ability to sense it. Fruits and vegetables have their characteristic aroma depending on the organic compounds  produced during maturity and ripening.

Further studies have to deal with ripening switches, biosynthesis of ripening hormones, delay in ripening, and prevention of spoilage. Plant biologists believe that whatever knowledge that can be derived from these studies will provide traditional breeders with genetic markers they can use to check whether their new varieties contain the genes necessary to obtain quality fruits and vegetables.

For details, see the news article at: http://pubs.acs.org/cen/coverstory/85/8544cover.html