Cerato-platanin treated plane leaves restrict Ceratocystis platani growth and overexpress defence-related genes.

Cerato-platanin (CP) is a small protein of 120 amino acids, produced by the ascomycete Ceratocystis platani (Walter) Engelbrecht et Harrington (Cep), the agent of plane canker stain. CP is located in the cell walls of the conidia, hyphae and ascospores of Cep, is able to self-aggregate, and is released into the culture medium in the first growth stages of in vitro culture. CP is the founder member of the CP family, a group of proteins involved in the interaction between the producing microbe and the host cell. Leaves of Cep-susceptible Platanus acerifolia react to treatments with CP in a resistance-like manner, producing extracellular and intracellular phenolic compounds and undergoing cell plasmolysis and/or death. The present study provides evidence that in plane-leaves the CP-activated defence-related events are strictly correlated with the inhibition of Cep growth on the leaves and with a high level of transcripts of 78 differentially expressed genes. Of the transcripts, 19.2% regarded as genes coding for defence and/or stress related proteins. The other genes concerned DNA/RNA synthesis and metabolism, protein synthesis/turnover, energy, primary cellular metabolism and the signahg pathways. The results demonstrated that after treatment of the plane leaves with CP, a substantial network of regulatory interaction and coordmation was formed, as well as other defence-related molecular events.