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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)

 

 

 

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