Genetics of Barrel-Spoiling Bad Apples


Long before there were “life hacks,” there was folk wisdom. One classic kitchen tip was to put a ripe apple in a paper bag with a green banana to speed the banana’s ripening. Chemically, ethylene gas released by the ripe apple caused the banana to become yellow and delicious. A similar chemical reaction causes “one bad apple to spoil the whole bunch,” because a single piece of ripe fruit speeds up the ripening and subsequent rotting of its neighbors.

However, until now, the exact genetic mechanism behind this kitchen chemistry had been a mystery.

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Recent research discovered that etylene gas acts as a hormone to activate a particular gene in plants’ DNA, known as Ethylene Insensitive3 (EIN3). Ethylene’s effect on that gene then ripples out and causes a multitude of other chemical reactions in fruits and many other plants. The study was published online in eLife.

“I have been trying, for several decades, to understand how a simple gas—two carbons and four hydrogens—can cause such profound changes in a plant,” said study co-author Joseph R. Ecker of the Salk Institute for Biological Studies in a press release. “Now we can see that by altering the expression of one protein, ethylene produces cascading waves of gene activation that profoundly alters the biology of the plant.”


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Manipulating ethylenes effects on EIN3 could allow:

•    Breeding or engineering plants that slow down growth at specific times

•    Accelerating or slowing fruit ripening

•    Slowing rotting

•    Breeding crops resistant to certain diseases

The newly discovered ethylene effects on EIN3 influence all other plant hormone signaling.

“If ethylene tells a plant to stop growing, it has to control other hormones that are telling the plant to grow,” said Ecker. “Imagine you are in a recording studio and you have one of those tables in front of you that have all of those switches. If you start pushing up the dials for one sound effect, you probably turn down the dial for other sound.”

IMAGE: A rotten apple. (Kulmalukko, Wikimedia Commons)

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