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Are Plants "Smart" Enough to Recruit Protection?

A study by researchers from the University of Delaware (UD) and Texas Tech University determined that plants are smart enough to use positive feedback mechanisms to recruit friendly neighbors to deter pathogens and pests and to fight pathogens by boosting their own innate resistance.

This research may change the way we perceive and use plants in everyday life and has potential applications in medicine. The results evolve our understanding of plants' immune systems and enable new fields of science or technology based on manipulation of those mechanisms to help fight infections.

While previous thinking held that infected plants were powerless to counter the spread of disease, this research found that plants can fight infection via chemical signaling.

Using the model plant system Arabidopsis thaliana and the model pathogen Pseudomonas syringae, Professor Harsh Bais' (UD) research team infected plants at the leaf surface to determine what would happen at the root level. The beneficial bacterium Bacillus subtilis bound to the plant's roots, and the plants secreted malic acid to signal the beneficial bacteria to come to the rescue. Next, the scientists added malic acid as a carbon supplement, and as they expected, the bacteria moved toward the roots more quickly.

The plants effectively recruited helpful bacteria using malic acid. When a plant was blocked from creating malic acid, the helpful bacteria did not attach to the roots, leaving the plant vulnerable to attack.


  • Biofilm
Biofilm formation by Bacillus subtilis on Arabidopsis root surface. Green in the image represents bacteria.
Thimmaraju Rudrappa and Delaware EPSCoR

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