The current research is focused on the communication between the scion and rootstock of grafted grapevine both locally at the graft interface and at distance in the shoot apex. Sarah Cookson has employed a range of techniques to study this communication, from gene expression to growth and biomass accumulation analysis. The skills and experience that she acquired before her recruitment (e.g. ecophysiology and molecular biology) have helped her integrate into the EGFV and she hopes that her experience can strengthen the research skills of the EGFV. In the future, Sarah intends to focus her research activities on studying grapevine responses to phosphate nutrition as part of a collaborative grant shared amongst herself, Virginie LAUVERGEAT and Philippe VIVIN of the EGFV and Alain MOLLIER (UMR 1391 Interactions Sol-Plante-Atmosphère, INRA Bordeaux), and also on studying graft union development at the cellular level in collaboration with Lysiane BROCARD (Bordeaux Imaging Center). This HDR thesis gives a brief overview of her professional activities to date including her research experience, supervision experience, grant writing skills and her network of collaborators. The thesis is divided into four main sections: curriculum vitae, previous research activities (from her Ph.D. and two postdocs), her current and future research activities (since her recruitment at INRA) and five of her publications. Sarah has been fortunate to have had experience of working for three years in three different European countries during her early career; this has not only given her the opportunity to learn different languages but she has been able to experience working in three different scientific cultures.