Plants can Signal Microbial Friends for Help

Posted on October 19, 2008  Comments (1)

When under attack, plants can signal microbial friends for help

Researchers at the University of Delaware have discovered that when the leaf of a plant is under attack by a pathogen, it can send out an S.O.S. to the roots for help, and the roots will respond by secreting an acid that brings beneficial bacteria to the rescue.

In a series of laboratory experiments, the scientists infected the leaves of the small flowering plant Arabidopsis thaliana with a pathogenic bacterium, Pseudomonas syringae. Within a few days, the leaves of the infected plants began yellowing and showing other symptoms of disease.

However, the infected plants whose roots had been inoculated with the beneficial microbe Bacillus subtilis were perfectly healthy. Farmers often add B. subtilis to the soil to boost plant immunity. It forms a protective biofilm around plant roots and also has antimicrobial properties, according to Bais.

Using molecular biological tools, the scientists detected the transmission of a long-distance signal, a “call for help,” from the leaves to the roots in the plants that had Bacillus in the soil. The roots responded by secreting a carbon-rich chemical–malic acid.

All plants biosynthesize malic acid, Bais explains, but only under specific conditions and for a specific purpose–in this case, the chemical was actively secreted to attract Bacillus. Magnified images of the roots and leaves showed the ratcheted-up defense response provided by the beneficial microorganisms.

“Plants can’t move from where they are, so the only way they can accrue good neighbors is through chemistry,” Bais notes.

Related: Researchers Learn What Sparks Plant GrowthSecret Life of MicrobesSymbiotic relationship between ants and bacteriaBacterium Living with High Level Radiation

One Response to “Plants can Signal Microbial Friends for Help”

  1. Curious Cat Science and Engineering Blog » Promoting Bio-Literacy
    January 30th, 2009 @ 8:11 pm

    […] Plants can Signal Microbial Friends for Help – posts on plants – Rainforests – The Avocado by curiouscat   Tags: Life Science, […]

Leave a Reply