Natures wonders: how parasitic plants pounce (Introduction)

by David Turell @, Friday, July 31, 2015, 14:46 (1271 days ago) @ David Turell

Many parasitic plants leave seeds in the soil that will germinate and attach to host plant roots for a free ride. A genetic change accomplished this method:

"'In the simplest terms, these are plants that eat other plants," said David Nelson, co-author of the paper and assistant professor of genetics in UGA's Franklin College of Arts and Sciences. "The seeds of some parasitic plants, like witchweed for example, can lie dormant in soil for more than a decade, waiting to grow until they detect the presence of a host. We wanted to understand how the parasites know other plants are nearby so we could develop new ways of combating them."

"As plant roots grow, they release hormones called strigolactones into the soil. This is a signal that normally helps fungi form a beneficial connection to the plant, in which they each trade nutrients. But the seeds of parasitic plants also possess the ability to sense strigolactones, which prompt them to germinate, attach to the host root and syphon off nutrients.

"'It's kind of like root radar," said Nelson, who is also a member of UGA's Plant Center. "But the incredible thing is that this strigolactone detection system seems to have evolved from plant genes that normally control a seed's ability to detect fire."

"When a forest burns, compounds in the smoke and ash leach into the soil. Many plants have evolved the ability to detect these compounds, which signal that their competition--large shady trees or dense ground cover--has been destroyed and it might be an opportune time to grow.

"Nelson and his colleagues found that during the evolution of parasitic plants, the smoke detector gene duplicated and some copies switched to become strigolactone detectors. This critical switch is what allows the parasites to recognize and attack nearby hosts."

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