Antibodies and antibody derived fragments are widely used for therapeutic and diagnostic purposes. My research focused on the production of antibodies recognising seed proteins of a model plant, Arabidopsis thaliana, for protein characterisation and localisation studies. Two antibody formats were analysed in-depth: VHHs (Nanobodies®) and the derived bivalent VHH-Fcs. In addition, the research also included a critical evaluation of three production platforms (the yeast P. pastoris and the plants A. thaliana and N. benthamiana) for the VHH-Fc antibody format.