Principal investigator:

Schaller, Andreas, Prof. Dr.,
Universität Hohenheim (HOH)

Institut für Physiologie und Biotechnologie der Pflanzen (IPPB)

Emil-Wolff-Str. 23

70593 Stuttgart

Phone: 49 711 459 22197

E-mail: andreas.schallerspam prevention@uni-hohenheim.de

Summary:

Systemin was the first hormone-like signaling peptide identified in plants. Initially conceived as the long-distance signal mediating systemic defense responses after herbivore attack, it was later shown to act locally at the site of wounding, where it amplifies the production of jasmonates as mobile signals for defense gene activation in distal tissues. It is unclear how the activity of systemin as a paracrine signal for immune-modulation differs from that of microbe-associated molecular patterns which act through similar LRR-RLK-type receptors. The specific output of systemin signaling at the plasma membrane will be determined by comparing systemin and MAMP responses by phospho-proteomics in a systemin-responsive cell culture and in cells lacking the systemin receptor. The relevance of specific systemin targets for wound signaling will be confirmed by targeted mutagenesis in tomato. A second part of the project addresses signal biogenesis. Processing of the systemin precursor and the specificity of the processing proteases are analysed in a current DFG project (SCHA 591/8-1). Here we will continue to determine the subcellular site of systemin maturation and its mode of secretion. Lacking a signal peptide for targeting to the secretory pathway, secretion is mediated by the pro-part of prosystemin. The molecular determinants of secretion will be identified, the subcellular localization of prosystemin and the site of prosystemin processing will be characterized to gain insight into non-canonical secretion of peptide signals.