PAMP Activity of Cerato-Platanin during Plant Interaction: An -Omic Approach.

Cerato-platanin (CP) is the founder of a fungal protein family consisting in non-catalytic secreted proteins, which work as virulence factors and/or as elicitors of defense responses and systemic resistance, thus acting as PAMPs (pathogen-associated molecular patterns). Moreover, CP has been defined an expansin-like protein showing the ability to weaken cellulose aggregates, like the canonical plant expansins do. Here, we deepen the knowledge on CP PAMP activity by the use of a multi-disciplinary approach: proteomic analysis, VOC (volatile organic compound) measurements, and gas exchange determination. The treatment of Arabidopsis with CP induces a differential profile either in protein expression or in VOC emission, as well changes in photosynthetic activity. In agreement with its role of defense activator, CP treatment induces down-expression of enzymes related to primary metabolism, such as RuBisCO, triosephosphate isomerase, and ATP-synthase, and reduces the photosynthesis rate. Conversely, CP increases expression of defense-related proteins and emission of some VOCs. Interestingly, CP exposure triggered the increase in enzymes involved in GSH metabolism and redox homeostasis (glutathione S-transferase, thioredoxin, Cys-peroxiredoxin, catalase) and in enzymes related to the "glucosinolate-myrosinase" system, which are the premise for synthesis of defence compounds, such as camalexin and some VOCs, respectively. The presented results are in agreement with the accepted role of CP as a PAMP and greatly increase the knowledge of plant primary defences induced by a purified fungal elicitor.