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Why do leaves fall from trees in fall--and can they keep hanging on?

Researchers say that they have pinpointed chemical signals that cause leaves, flowers, and fruit to fall from plants – and that, if blocked, might allow them to hang on forever.

Scientists already knew there were cells in the tissue linking stems and branches that release chemicals that break down plant cells, causing leaves, et al, to fall off. But they in the dark about what triggered the release of these chemicals.

Now University of Missouri plant biologist John Walker says he and colleagues have identified a group of compounds in Arabidopsis thaliana that prompt production of the proteins that cause plants to shed their petals. By blocking these chemicals, they succeeded in keeping petals intact, according to their paper published today in the Proceedings of the National Academy of Sciences.
 
Walker believes that the process is the same one that causes trees to lose their leaves. "We're presuming that those molecular components are conserved across the evolution of plants," he says.

Understanding how plants discard parts could come in handy.  Plant scientists might be able to prevent or beef up production of the signaling chemicals to create new breeds of plants – or stop, say, a diseased fruit tree from dropping its fruit to conserve energy to fight off the infection.

And then there's always the commercial appeal:  Imagine a Christmas tree that doesn't shed pine needles all over the living room floor.

(Image from iStockphoto/Matthew Dixon)

 

 

 

Tags: leaf, petal, leaves, fall, plant, arabidopsis, abscission
More News Blog: Next: Medical studies about drugs may be victims of spin, says report Previous: Hobbled LHC shuttered for repairs; 'No big deal' say scientists

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  1. 1. MeSoTrashed 09:35 PM 9/22/08

    this may help out more then you would think. We could keep leaves on trees to increase the amount of carbon absorption. we could also help rebuild bee populations by keeping flowers for longer.

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  2. 2. way2ec 11:57 PM 9/22/08

    As there are who knows how many reasons for the leaves to fall, fruit to drop, and after how many millions of years of evolutionary success, we just come along and decide to keep the leaves, flowers and fruits on the plant?

    But they in the dark about...(editor please see above text), I be in the dark about benefits let alone the consequences. Flowers for the bees? Will we need another chemical to prompt the flower to continue to make nectar, and another to prevent fruit and seed development? Birth control for flowers? And sorry for my confusion, but how does keeping its fruit help a diseased tree conserve energy? Wouldn't the fruit continue to use energy? Doesn't the dropping of the fruit free up the energy to be used elsewhere?

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  3. 3. yanghuansailing 05:19 AM 9/23/08

    These kinds of chemicals, which are capable of controlling the defoliation, seem to have been pinpointed for a long time . I am a little bit confused about they published something new on P.N.A.S.. Actually speaking ,what they find will help us have a better control over the plants, which may bring very detrimental consequences,e.g. on the one hand , we can keep the beautiful leaves and flowers on the plants for a long time, on the other hand, plants' physiological laws will be tremendously disturbed by anthropogenic activities. However, no matter this new discovery will benefit nature or not ,it is rewarding and attracting to us all.

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  4. 4. way2ec in reply to yanghuansailing 12:47 PM 9/23/08

    yanghuansailing I like your perspective and appreciate your comment.

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  5. 5. asatlin 06:49 PM 11/26/11

    We had a good demonstration of this effect this year in the US Northeast, where a freak late October snowstorm, while the leaves were still on the trees, left many tree branches broken and dangling from the trees. Over the next weeks, as the leaves fell from the trees, the dead leaves on the broken branches did not fall, presumably because the hormone signals triggered by the shortened daylight could not get to these branches and the leaves on them. Throughout my neighborhood, one can now look through the tree branches and see the sky, except where the clumps of dead leaves on the broken branches block the view.

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