An epidermal peel shows that bacteria (green) that make coronatine (left) make it through stomata.
HE/ELSEVIER
Stomata are the plant's version of a window—an opening in the leaf epidermis where photosynthetic gas exchange occurs. This pore is a perfect way in for bacteria, which cannot themselves penetrate the epidermis. But the new findings show that, upon sensing bacterial proteins, the two guard cells that form the pore close the window.
Closure depends on signaling pathways activated by plant hormones, including salicylic acid and abscisic acid. A bacterial strain that successfully invades Arabidopsis overrides the closure and reopens stomata. This bypass requires a bacterial compound called coronatine, which antagonizes salicylic acid and abscisic acid, possibly by mimicking...
