Sulphur-Rich Protein Gene Modification for Optimized Expression in Transgenic White Clover

A gene encoding the sulphur-rich pea seed storage protein pea albumin I (PAI), transcriptionally fused to the CaMV 35S promoter has been introduced into Nicotiana Iabacum and white clover (Trifolium repens L.) using Agrobacterium-mediated transformation. PA I mRNA expression has been confirmed in transgenic tobacco and white clover plants. However, PAI protein accumulation, as assessed by ELISA using an anti-PAI monoclonal antibody, is either low or the antibody does not have the required avidity or titre. Strategies for improved accumulation and immunological surveillance of this protein in leaf tissue are described, including the construction of PA I translational fusions designed to target the PA I protein to alternative intracellular compartments and the epitope tagging of PAI.