An international research team led by Heribert Hirt from King Abdullah
University of Science and Technology (KAUST) has found the missing link in
the complex molecular pathway by which plants resist pathogens.

Using Arabidopsis, the team activated mitogen-activated protein kinases
(MAPKs) using a bacterial microbial-associated molecular patterns (MAMPs).
In a series of experiments, they searched for phophorylation events and
found that the final MAPK-MAPK in the chain which is MPK3, phosphorylates
the enzyme histone deacetylase (HD2B), which regulates DNA compaction into
chromatin.

The team showed that in Arabidopsis plants that lack MPK3 or HD2B, many
defense genes increased in activity, suggesting that HD2B represses gene
activity. When pathogens attack, MPK3's action on HD2B reverses this
repression.

Hirt said that kinase-triggered chromatin reprogramming is a widespread
mechanism, and considers possibilities for artificially stimulating this
process. "Once we better understand the mechanism of inducing pathogen
memory, we might be able to induce long-term resistance, similar to human
vaccination," he added.

[discovery.kaust.edu.sa]