A Critical Review of the Concept of Transgenic Plants: Insights into Pharmaceutical Biotechnology and..

Using transgenic plants for the production of high-value recombinant proteins for industrial and clinical applications has become a promising alternative to using conventional bioproduction systems, such as bacteria, yeast, and cultured insect and animal cells. This novel system offers several advantages over conventional systems in terms of safety, scale, cost-effectiveness, and the ease of distribution and storage. Currently, plant systems are being utilised as recombinant bio-factories for the expression of various proteins, including potential vaccines and pharmaceuticals, through employing several adaptations of recombinant processes and utilizing the most suitable tools and strategies. The level of protein expression is a critical factor in plant molecular farming, and this level fluctuates according to the plant species and the organs involved. The production of recombinant native and engineered proteins is a complicated procedure that requires an interand multi-disciplinary effort involving a wide variety of scientific and technological disciplines, ranging from basic biotechnology, biochemistry, and cell biology to advanced production systems. This review considers important plant resources, affecting factors, and the recombinant-protein expression techniques relevant to the plant molecular farming process. Introduction Currently, critical challenges in soil and water resources, as well as climate change, have resulted in the human population outpacing the available agricultural products. Thus, scientists are attempting to find various ways to increase the qual i ty and quanti ty of the food, pharmaceutical and the industrial products of plants within limited arable spaces (De La Fuente et al., 2013). Phenotypic selection was the first action taken by humans to establish plant breeding as a reliable classical approach to this problem. Indeed, the history of plant breeding can be traced to the dawn of civilization,10,000 years ago, when early societies began to shift from being huntergatherers to being members of agrarian communities (Tilman et al., 2002). Gregor Mendel reached the first milestone in modern plant breeding. The results of his plant-breeding investigations led to the discovery of genetic functions through focusing on DNA as the basis of trait heredity (Acquaah, 2009). Although, conventional plant breeding has been used to overcome the lack of sufficient food or feed (Lopes et al., 2012), the success of this method is largely dependent on the breeder's experience and on phenotypic selection; consequently, inaccurate predictions can be made and low-efficiency breeding can occur (Mewett et al., 2007). Moreover, other limiting factors, such as the method being time consuming, the difficulty in finding the most related parents of a new generation of plants, selecting the best crossing method according to the plant traits desired, the high number of back-crosses required and the difficulties in increasing the expression of the favoured traits are the main concerns in plant breeding (De La Fuente et al., 2013). Genetic modification (GM) is a new method that researchers have been using to increase the yield of plant products by improving certain traits, including the responses of herbs to abiotic and biotic stresses (Tait, 1999; Ashraf et al., 2008). Background genetic transformation is the most significant application of GM; in this process various methods are utilized to introduce desirable traits into the host genome while concentrating on preserving the individual characteristics of the plant (Ziemienowicz, 2013). The most important plants that have been successfully subjected to gene transformation programs are industrial plants, cereal crops, legumes, root plants, vegetables, turf grasses, tropic plants, woody species, medicinal and ornamental plants, as well as fruit plants (Wang, 2006a; Wang, 2006b). These plants and their related species have been presented in Table 1. In gene transformation processes, the gene(s) of interest of donor plants, bacteria or viruses are transferred to host Curr. Issues Mol. Biol. 18: 21-42. horizonpress.com/cimb !21 A Critical Review of the Concept of Transgenic Plants: Insights into Pharmaceutical Biotechnology and