Klauser, Dominik Roman. An endogenous danger detection system in "Arabidopsis thaliana": the AtPep peptides and their receptors. 2014, PhD Thesis, University of Basel, Faculty of Science.
Official URL: http://edoc.unibas.ch/diss/DissB_10685
More recently, a family of eight peptides has been discovered in Arabidopsis, named Arabidopsis thaliana danger peptides (AtPeps) 1-8. These AtPeps have been shown to be capable of inducing PTI-like responses and to be expressed upon the detection of various biotic stresses, therefore being considered as DAMPs. Moreover, two PRRs, named Pep-Receptor 1 (PEPR1) and Pep-Receptor 2 (PEPR2) have been identified to perceive AtPeps and to induce defense responses upon receptor-ligand interaction. Despite of eliciting PTI responses and being expressed upon the detection of biotic stress, no direct beneficial involvement of the AtPep-PEPR system to plant defense against attackers has been described so far.
Taking advantage of a mutant deficient in both PEPRs and thus fully impaired in AtPep-PEPR signaling, we investigated the potential contribution of a functional AtPep-PEPR system to plant defense responses.
In a first approach, we investigated the potential interplay between MAMP and DAMP signaling, especially in the context of DAMPs being believed to act as endogenous amplifiers of MAMP-induced PTI. Doing so, we identified that the AtPep-triggered production of reactive oxygen species (ROS) is strongly enhanced upon previous MAMP detection, indeed indicating a role of the AtPep-PEPR signaling system as an enhancer of MAMP-triggered defense signaling.
In a second approach, we compared the AtPep-PEPR system to systemins – well described DAMPs in tomato with generally similar molecular features to AtPeps. Following up the lead that systemins are important mediators of defense responses against herbivorous insects, we checked whether a similar role would apply to the AtPep-PEPR system. Here, we could show that the AtPep-PEPR system is indeed induced by herbivore feeding and strongly interacts with the plant hormone jasmonic acid (JA) to orchestrate defense responses. Accordingly, mutants deficient in AtPep-PEPR signaling are strongly impaired in defense responses against the generalist herbivore Spodoptera littoralis, underlining the importance of AtPep signaling in plant defense against herbivores.
Thirdly, we followed up a lead that the expression of some AtPeps as well as both PEPRs is induced upon virus infection. Assessing the potential contribution of the AtPep-PEPR system to plant defense against viruses, we could not observe an increased susceptibility of plants deficient in both PEPRs. However, mutants in BAK1 (BRI1 Associated Kinase 1), a co-receptor required for full-strength AtPep-triggered signaling and many other PRRs, showed a clearly increased susceptibility to all viruses tested. Therefore, we established a first potential line of evidence for a role of PTI in plant defense against viruses.
All in all, we provide several lines of evidence that show the contribution of a functional AtPep-PEPR signaling system to plant defense. Therefore, we underline the pivotal importance of DAMP signaling to plant immunity against a plethora of biotic invaders.
|Committee Members:||Felix, Georg|
|Faculties and Departments:||05 Faculty of Science > Departement Umweltwissenschaften > Botanisches Institut > Pflanzenphysiologie Pathogenabwehr (Boller)|
|Bibsysno:||Link to catalogue|
|Number of Pages:||161 S.|
|Last Modified:||30 Jun 2016 10:55|
|Deposited On:||27 Mar 2014 14:14|
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