The demand for recombinant proteins in terms of quality, quantity, and diversity is increasing steadily, which is attracting global attention for the development of new recombinant protein production technologies and the engineering of conventional established expression systems based on bacteria or mammalian cell cultures. Since the advancements of plant genetic engineering in the 1980s, plants have been used for the production of economically valuable, biologically active non-native proteins or biopharmaceuticals, the concept termed as plant molecular farming (PMF). PMF is considered as a cost-effective technology that has grown and advanced tremendously over the past two decades. The development and improvement of the transient expression system has significantly reduced the protein production timeline and greatly improved the protein yield in plants. The major factors that drive the plant-based platform towards potential competitors for the conventional expression system are cost-effectiveness, scalability, flexibility, versatility, and robustness of the system. Many biopharmaceuticals including recombinant vaccine antigens, monoclonal antibodies, and other commercially viable proteins are produced in plants, some of which are in the pre-clinical and clinical pipeline. In this review, we consider the importance of a plant- based production system for recombinant protein production, and its potential to produce biopharmaceuticals is discussed.

• Growth factors play a crucial role in tissue repair and wound healing. • Recombinant human epidermal growth factor was produced in N. benthamiana by agroinfiltration. • Expression conditions were optimized and the recombinant protein was purified. • Plant-produced hEGF facilitate the HaCaT cell proliferation and cell migration in vitro. • Plant-produced hEGF can potentially be exploited for their application in tissue engineering.

Keywords | Nicotiana benthamiana ; Nucleocapsid protein; Plant-produced protein; Porcine reproductive and respiratory syndrome virus; Transient expression