Plant immunity: Endogenous danger peptides

Project team leader: Dr. Sebastian Bartels

Team members: Tim Hander, Mehdi Safaizadeh, Hendrik Schatowitz

Sensing of a threat is the key step in resistance to adverse conditions. In case of biological threats like potentially harmful microbes plants sense molecules called microbe-associated molecular patterns (MAMPs) which are tightly associated with microbial lifestyle. Detection of these MAMPs triggers a set of defense responses known as pattern-triggered immunity (PTI) and thus increases plant resistance to a broad variety of microbes.

PTI can also be triggered by endogenous molecules of the plant itself. These molecules can be of different chemical and cellular origin but due to their immunity inducing action are summarized as damage- or danger-associated molecular patterns (DAMPs).

We are interested in plant peptides (AtPeps) which trigger PTI and are thus regarded as DAMPs. Their function in plant immunity, however, is still not clear. Two models have been proposed, i) the amplifier model and ii) the damage model.

The amplifier model proposes that these peptides are released after the detection of MAMPs. In this way they amplify the PTI response and might even extent it to surrounding cells which did not get in contact with MAMPs, yet.

The damage model is based on a passive release of these peptides via mechanical damage like wounding. Wounding sites are ideal entry points for numerous plant pathogens. Release of these peptides and thus activation of PTI in the cells close to the wounding site would thus provide an ideal mechanism to induce immunity at the site of damage.