The researchers discovered a group of five acids that collectively had the biggest effect on turning on the bacteria's T3SS: pyroglutamic, citric, shikimic, 4-hydroxybenzoic, and aspartic acids.
They found that the mutant has a much lower level of these cellular products on the surface of the plant than found in normal plants. Since the resistant plants don't have high levels of these acids, it stops the bacteria from unfurling the "syringe" in the presence of the plant. But when the combination of acids is introduced onto mkp1, it quickly becomes a target for infection.
"We know that microbes can disguise themselves by altering the proteins or molecules that the plant uses to recognize the bacteria, as a strategy for evading detection," said Peck, associate professor of biochemistry at the University of Missouri and lead author of the PNAS paper. "Our results now show that the plant can also disguise itself from pathogen recognition by removing the signals needed by the pathogen to become fully virulent."
While Peck's study focused on bacteria known mostly for damaging tomatoes, the findings also could have implications for people. The same molecular machinery employed by Pseudomonas syringae is also used by a host of microbes to cause diseases that afflict people, including salmonella, the plague, respiratory disease, and chlamydia.
On the energy front, the findings will help scientists grow plants that can serve as an energy source and are more resistant to infection. Also, a better understanding o
|Contact: Tom Rickey|
DOE/Pacific Northwest National Laboratory