Scientists from Salk Institute for Biological Sciences reported an unusual plat immune response to bacterial infection. The result of their study is published in Nature Communications.

Figure: This cartoon depicts a leaf with areas of damage (brown spots) caused by the plant’s innate immune response. The superimposed schematic shows SOBER1’s three-dimensional structure. Credit: Salk Institute

"There are a lot of losses in crop yields due to bacteria that kill plants…With this work, we set out to understand the underlying mechanism of how resistance works, and to see how general it is," said Joanne Chory, senior author of the study and a 2018 recipient of the Breakthrough Prize in Life Sciences. The research team studied a protein (SOBER1) in Arabidopsis thaliana, which was previously reported to impede the plant's immune response to a bacterial protein (AvrBsT). The researchers perceived that studying immune suppression may lead to more information about infection resistance.

They studied the amino acid sequence of SOBER1 and found that it can be classified as part of a vast protein superfamily of alpha/beta hydrolases. It was very similar to a cancer-pathway-related human enzyme. Further tests suggested that SOBER1 is a deacetylase, removing acetyl groups added by bacterial proteins. Without the acetyl groups tagging proteins, the plant didn't recognize them as foreign and thus didn't mount a cell-killing immune response. The researchers were surprised that SOBER's function is to keep infected tissue alive, putting the plant at risk. Chory said that they are just beginning to understand such mechanisms and they think that there are conditions where the actions of SOBER1 is helpful for the plant.

Further tests showed that the activity and function of SOBER1 are not restricted to Arabidopsis, but also exists in oilseed rape demonstrating that the findings of Chory's lab could be applied to agricultural crops and biofuel resources.

Read the news release from Salk for more details.