Growth and Development of higher plants

In the past P1D, P5 and EU1 have published work on hormone signalling and elongation. The greater part of hormone signalling related to root development is covered and summarized in WP3. As gravitropic bending has been included in several approaches to the study of the elongation phenomenon, its link to the more general background of hormone signal interactions is highlighted here. Unequivocal evidence for auxin being a mobile signal transported via the lateral root cap and root epidermis in the control of gravitropic response has recently been established. Ethylene also has been implicated in this process, possible modulating the rate of differential auxin accumulation. A number of lines that aberrantly express F-box proteins implicated in hormonal responses (as those for ethylene, gibberellins, or auxins) in a cell-type specific manner (epidermis, cortex, endodermis) will be created under WP3 (P1D in collaboration with EU1). The gravitropic response of these lines will be studied using time lapse imaging (P1C), and will be compared with the wild type. In addition, mutant target lines will be crossed with reporter lines specific for other hormones. Alterations in expression patterns upon gravistimulation will be investigated (collaboration P1D – EU1).