Hormone action was until recently mainly viewed as an organ-specific process. Based on
recent findings for auxins, gibberellins and brassinosteroids, we speculate that cell type
specificity plays a general role in hormone action mechanisms. In this project, cell type
specificity of ethylene action will be addressed by using cell type specific promoters driving EBF1 and EBF2 (EIN3 binding F-box 1 and 2), two regulators of the prevalence of the
EIN3/EIL1 proteins, positive regulators of ethylene signaling. First, cell type specificity will be investigated at the root level. The biological significance of the cell type specific ethylene response will be addressed by different response assays. For the most relevant cell type(s), the appropriate line(s) will be constructed with shoot specific promoters as well. As for roots, the biological significance of the cell type specific ethylene response in shoots will be addressed by ethylene response assays. Effects at the whole organ level will be studied at UGent; effects
at the level of root and shoot cell expansion will be studied at UA.