In the latest work, involving the testing of more than 1,000 plants, the researchers shed more light on the relationship. They show that B. subtilis uses a secreted peptide to suppress the immune response in plants. It is known that plants synthesize several antimicrobial compounds to ward off bacteria, Bais says.
The team also shows that when plant leaves were treated with a foliar MAMP flagellin, a structural protein in the flagellum, the tail-like appendage that bacteria use like a propeller it triggered the recruitment of beneficial bacteria to the plant roots.
"The ability of beneficial bacteria to suppress plant immunity may facilitate efficient colonization of rhizobacteria on the roots," Bais says. Rhizobacteria form an important symbiotic relationship with the plant, fostering its growth by converting nitrogen in the air into a nutrient form the plant can use.
"We don't know how long beneficial bacteria could suppress the plant immune response, but we do know there is a very strong warfare under way underground," Bais says, noting that his lab is continuing to explore these interesting questions. "We are just beginning to understand this interaction between plants and beneficial soil bacteria."
|Contact: Andrea Boyle Tippett|
University of Delaware