A method for synthesizing a protein of interest within a plant or a portion of a plant is provided. The method involves treating the plant to increase secondary leaf biomass production, followed by introducing one or more than one nucleic acid sequence encoding a protein of interest operatively linked with a regulatory region that is active in the plant, into the plant. The plant is then maintained under conditions that permit the nucleic acid sequence encoding the protein of interest to be expressed in the plant or the portion of the plant. Optionally, the plant or portion of the plant may be harvested and the protein of interest extracted.