Plants Teach Humans a Thing or Two About Fighting Diseases

Avoiding germs to prevent sickness is commonplace for people. Wash hands often. Sneeze into your elbow. Those are among the tips humans learn. But plants, which are also vulnerable to pathogens, have to fend it alone. They grow where planted, in an environment teeming with microbes and other substances ready to attack, scientists note. Now, researchers are learning from plants' immune response new information that could help them understand more about humans' ability to ward off sickness and avoid autoimmune diseases.

This week's journal Science reports findings by Texas AgriLife Research scientists of a "unique regulatory circuit" that controls how a plant turns on and off its immune sensor.

"Plants and animals live out their lives mostly in good health, though they may have been subjected to a lot of pathogenic microbes," says Dr. Libo Shan, AgriLife Research plant molecular biologist and lead author for the journal article. "Scientists all around the world have been interested in how a healthy host can fend off invasions of pathogens and turn off the defense responses promptly once the intruder risk factors are decreasing."

The research team found a "unique regulatory circuit" in which BAK1, a protein involved with cell death control and growth hormone regulation, recruits two enzymes -- PUB12 and PUB13 -- to the immune sensory complex and fine-tunes immune responses.

Basically, the surface of plant cells has sensors that sense microbial invasion. One of the best understood plant receptors is FLS2, found in the common laboratory plant Arabidopsis.

FLS2 could sense the bacterial flagellin, which is a part of the flagellum, or tail-like projection on cells which help it to move. When FLS2 perceives flagellin, a series of "evolutionary conserved immune responses" is activated to fend off bacterial attack, Shan said.