Early transcription of defence-related genes in Platanus acerifolia leaves following treatment with cerato-platanin

The protein elicitor cerato-platanin (CP) is known to induce defence-related responses in various plants. Some of these responses occur very quickly. In the present work, the transcriptional changes caused by CP in leaves from Platanus acerifolia were studied during the first 24 hours. With a cDNA microarray 131 differentially regulated transcripts were identified as responsive to CP after 24 hours of treatment. Eighty-six of these were cold- or ozone-modulated transcripts from poplar, thus revealing a significant overlap between genes responsive to CP and to cold/ozone stress. The transcriptional changes caused by CP were compared with Pop1, a CP-orthologous protein, in a time-course analysis performed after 3, 6, 12 and 24 hours by real-time RT-PCR on five defence-related genes. CP and Pop1 were able to induce early transcriptional changes (WRKY was overexpressed after only 3 hours), although the two proteins acted differently on gene transcription.