Plants may have their own language that allows them to communicate with each other by sharing genetic information. This language could be what helps weeds when they take over other plants.

Jim Westwood at the Virginia Tech College of Agriculture and Life Sciences made this discovery. If confirmed, it could not only help us understand how plants communicate, but also give us better ideas on how to fight off weeds without the use of harmful chemicals.

Westwood studied a specific parasitic plant called a dodder on two specific other plants: Arabidopsis and tomatoes. Dodder attaches a part of itself to a host plant and penetrates it, which allows it to suck out nutrients. However, Westwood discovered that this interaction is more complex than that: when this occurs, genetic material gets passed between the two plants, which carries DNA information.

What makes this discovery particularly interesting is that messenger RNA, mRNA, actually sends messages within plant cells from the parasite to the host, basically telling it which proteins to code. This helps the parasite indulge in a little subterfuge, perhaps telling the host plant to let down its defenses so that it can quickly take over the other plant.

"The typical way that plants communicate is through chemicals that they release through their leaves and roots," says Westwood. "So to find out that there is an exchange of RNA" - the intermediary form of genetic information that fills the gap between DNA and proteins - "is a new concept that hasn't been explored at all."

This is remarkable because scientists previously thought that mRNA didn't last very long, especially for this kind of communication.

The implications of this discovery are important, particularly in agriculture. Currently, to control parasitic plants like dodder, farmers use pesticides. However, if we can understand more about the information passed from parasite to host, scientists could eliminate the need for pesticides and do something at the genetic level of a plant to block that communication or teach the host plant how to ignore it.

"Parasitic plants such as witchweed and broomrape are serious problems for legumes and other crops that help feed some of the poorest regions in Africa and elsewhere," says Julie Scholes, a professor at the University of Sheffield, U.K. "In addition to shedding new light on host-parasite communication, Westwood's findings have exciting implications for the design of novel control strategies based on disrupting the mRNA information that the parasite uses to reprogram the host."

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