The role of the plant’s pores in defense against invading bacteria has been redefined by a new look at the behavior of one the plant’s first lines of defense against disease.
Pores called stomata are like tiny mouths that open and close during photosynthesis, exchanging gases. In sunshine, the stomata open. In darkness, they close to conserve water.
It has been assumed that these tiny ports were busy with their photosynthesis business and were merely unwitting doorways to invading bacteria but recent discoveries show that stomata are an intricate part of the plant’s immune system that can sense danger and respond by shutting down.
It appears those plant-based bacteria produce a phytotoxin, a chemical called coronatine, to force the pores back open. For bacteria, entry is crucial to causing disease and probably survival. They could die if left lingering on the surface. Animal-based bacteria do not produce coronatine.
“Now that we know a key step in bacteria’s attack, we have something we can learn to interfere with,” Melotto said. “From this we can learn about disease resistance.”