Isolation of differentially expressed transcripts after treatment of Platanus acerifolia leaves with cerato-platanin, a multi-functional protein from Ceratocystis fimbriata f. sp. platani

The Ascomycete Ceratocystis platani (Walter) Engelbrecht et Harrington comb. et stat. nov. (Cep) is the causal agent of the canker stain of the plane trees that causes severe consequents on plane trees growing in many European areas. In consequence of the absence of control methods it is very important to improve the knowledge of the factors involved in the pathogen-host interaction. A 120 amino acids protein (cerato-platanin, CP), isolated from Cep culture filtrates, has been hypothesised as a signal molecule involved in the induction of plant defence mechanisms. Pre-treatments of leaves with CP and subsequent inoculation with Cep showed the inhibition of Cep conidia germination and hyphal lengthening, showing the ability of CP in the induction of localized resistance. We have applied the suppression-subtractive hybridisation (SSH) methodology for the isolation and characterisation of genes induced after a 48 hours CP treatment and for the constitution of reverse and forward clones. Sequence analysis of forward clones showed that many genes are positively regulated, the most part of which code for DNA/RNA synthesis and metabolism, and for proteins involved in: i) the protein synthesis/turnover, ii) cell primary metabolism, iii) energy, iv) signalling pathways and v) defence and/or stress related. We have analysed some of them by relative PCR using total RNA from leaves treated with CP and Cep conidia at different times after the treatment. The results showed the involvement of CP in the stimulation of plant defence responses