Expression of a transcription factor (FsERF1) involved in ethylene signalling during the breaking of dormancy in Fagus sylvatica seeds

By means of reverse transcriptase‐polymerase chain reaction, using degenerate oligonucleotides conserved among ethylene‐responsive transcription factors, we have isolated and characterized a cDNA clone encoding a protein involved in ethylene signalling during the breaking of dormancy in Fagus sylvatica L. seeds. This clone, named FsERF1, exhibits high homology to ethylene‐responsive factors (ERFs) from several plant species. The expression of FsERF1 as a fusion protein in Escherichia coli confirmed that it was able to bind to the GCC box, a cis element present in the promoters of several ethylene‐responsive genes, corroborating its role as a DNA‐binding protein. Northern analysis showed that the transcript levels increased when dormancy was broken by ethephon (an ethylene‐releasing compound), or by moist prechilling pretreatment at restricted water content, and were almost undetectable when seeds remained dormant by the addition of abscisic acid, aminooxyacetic acid (an ethylene biosynthesis inhibitor) or warm pretreatment, and when seeds were artificially dried, suggesting that FsERF1 function may be more closely related with the transition from seed dormancy to germination than with responses to drought stress mediated by ethylene.