( Two soil-dwelling strangers ?a friend a...)Plants respond similarly to signals from friends, enemies

In a new finding published in Proceedings of the National Academy of Sciences, researchers at North Carolina State University have found that the two strangers communicate with the plant in very similar ways. The plant's responses to both friend and foe are also remarkably similar.

Using high-tech microscopy and florescent imaging techniques that allow for real-time, three-dimensional study in living cells over time, the NC State researchers discovered that the model legume Lotus japonicus responded similarly to signals from both rhizobia, the friends that fix nitrogen for the plant, and root-knot nematodes, the parasitic foes that want to harm the plant. Signals from both outsiders induce rapid changes in distribution of the plant's cytoskeleton, which is part of a pathway that leads to a series of growth changes that include the formation of either nodules housing bacteria or giant cells from which the nematodes feed.

The scientists also discovered that, like rhizobia and contrary to popular belief, the root-knot nematode signals plants from a distance and therefore does not need to attach itself to the plant to elicit a response.

When the researchers studied L. japonicus plants missing the receptors that receive signals from other organisms ?certain genes in the plant were modified to accomplish this ?they discovered that the plants failed to respond to signals from both friend and foe, and therefore no changes were viewed in the plant's cytoskeleton.

"This exquisite system that plants have developed to allow beneficial interactions with other organisms like rhizobia is being exploited by nematodes," says Dr. David Bird, associate professor of plant pathology, co-director of NC State's Center fo
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Source:North Carolina State University