## 3 Transgenic Plants--Brief History and Potential Industrial Use
_rhizogenes_ have become an alternative for the production of secondary metabolites and have been the subject of intensive research for several decades. They are characterized not only by genetic stability but also by a fast growth rate, which translates into obtaining a large biomass in a short time. In addition, this process allows us to obtain biologically valuable compounds without destroying the entire plant and its habitat, which is extremely important in the era of environmental protection [16; 48; 49]. Transgenic plants can also represent a valuable industrial-scale source of bioactive secondary metabolites used in many fields of pharmacology or medicine [50]. Modern biotechnology has led to a revival of interest in obtaining new active therapeutic compounds from plant sources. In turn, metabolic engineering has proven to be an effective tool for manipulating biosynthetic pathways by increasing or decreasing selected gene expression [51; 52]. The advantage of transgenic plants over other expression systems makes them an attractive alternative for producing secondary metabolites or recombinant proteins [53; 54; 55]. The main advantages of transgenic plants are increased yields [56], resistance to diseases and pests, and the possibility for growth under stress conditions [57], including drought [58; 59; 60], heat [61], and frost [62]. In addition, foods can be given increased resistance for transport over long distances: the plants are harvested early and can ripen during transport, which ensures a longer shelf life. Even with extended shipping and storage periods, the product reaches its destination without spoiling. In addition, the producers of these crops promote them as the second \"green revolution\" in a world with an ever-increasing population [63]. In the pharmaceutical sphere, transgenic cultures are a platform for obtaining recombinant proteins and valuable secondary metabolites [50]. Unfortunately, transgenic plant production also has disadvantages. It has been suggested that the antibiotic resistance genes present in these crops result in the wider development of antibiotic resistance [62]. Another problem may be the emergence of super-pests and the loss of biodiversity if these plants are used in an uncontrolled manner [27; 64]. This situation is of course not possible in the case of closed and controlled in vitro cultures. Currently, transgenic plants are rationally used and have found versatile applications, particularly as bioreactors for the production of proteins and various biopharmaceuticals, such as erythropoietin--used in the treatment of anemia--and insulin--used in the treatment of diabetes [42; 65]. The issues related to the genetic modification of organisms described in the article obviously touch upon social and ethical problems. Arguments are often raised here about the potential threats to human health and the natural environment, traditional agricultural practices, or even corporate dominance from large biotechnology concerns. It is worth emphasizing that, when assessing the possible benefits and potential threats, each case should be assessed individually and holistically. It is important to bear in mind the significant benefits of genetically modified plants, such as pest resistance, increased levels of nutrients, and improved productivity. The arguments presented above are usually raised in the case of field cultivation of genetically modified crops. For the examples described in our article, many of these arguments are not justified because these cultures are kept strictly controlled and isolated from the environment in in vitro conditions. In such systems, the possibility of a significant increase in the productivity or synthesis of completely new compounds with a wide range of applications, including new and more effective therapies for many human diseases, is the best rationale for many skeptics.