The aim of this proposal is to substantiate proof of the existence and the operation of a new group of phytohormones, analogues of the fungal phytotoxin fusicoccin (FC). The programme envisages identifying FC and/or its analogues, assessing their distribution amongst and localization in the higher plants and ascertaining the signal transduction mechanism involved in the action of the FC. The analytical approaches will include GC/MS, radioimmuno assay (RIA) and radioreceptor assay.

Different approaches will be taken to identify the components of the signal transduction pathway. By means of co-reconstitution of the FC receptor and the plasma membrane located H+-ATPase in increasingly purified form in liposomes, it is expected to find the number of components necessary for successful reconstitution. In addition to this, enzymes co-purifying with the FC receptor will be further purified and tested for enzymatic activity. With the patch-clamp technique, using intact protoplasts in the whole-cell configuration, the outcome of the aforementioned experiments will be tested by introducing specific compounds to the cytoplasmic side of the plasma membrane.

The widespread occurrence of FC receptors as well as FC-related compounds in various plant taxa is highly indicative of their essential role for plant growth and development. It is hoped that the integrated approach will make it possible to reach a deeper understanding of this novel plant hormonal system.