Plants form protective networks

plantsform systems--constant and temporary--to defend themselves from herbivores. A new study from the Netherlands says temporary systems like production of protective chemicals work better in the short term. Such systems conserve energy, which plants use for several things, including reproduction. Permanent structures like thorns and leathery leaves use up a lot of energy. Such structures are a waste in the event of no herbivore attack.

The system works because plants have a unique system of communicating with each other, say researchers. For the study, they exposed Trifolium repens, a widely cultivated fodder crop, to caterpillars in phases. The researchers found when the plant sensed the caterpillar the first time, it communicated the "danger" to other plants in the vicinity and prepared themselves for another attack. They grew more leaves so that the caterpillar left the horizontal stems alone, ensuring regeneration later.

The study suggests that plants could be evolving induced temporary resistance to save more energy. The study was published in the October 2007 issue of the journal Oecologia.