**2. Synthetic biology applied to soybean crops**

Plant Synthetic Biology has a wide range of applications in agriculture and the pharmaceutical and energy industry. In agriculture, genetic engineering can be applied to develop new cultivars that are resistant to herbicides, bugs, illness, and drought and can be used to alter the nutritional profile of a cultivar of interest. In the energy and pharmaceutical industry, SynBio allows the production of plant biofabrics for different compounds like remedies, vaccines, biofuel, etc. The major defiance of the Synthetic Biology implementation in agriculture is the time and the extensive outgoing involved in the propagation, transformation, and screening of the superior plants. Although there is an impulse in the plant biotechnology, following the development of new technologies like genome editing based on CRISPR/Cas9 [26], speed breeding [27], key genomes sequencing [28–30], and the SynBio growth as a scientific field [31], the challenge goes on. For example, the huge size of the plant genomes

and their polyploidy (wheat, for example, has a hexaploidy genome >15Gb [29]) has so far limited the efficiency of the site-specific genetic manipulations. Besides that, plants usually have fewer direct homolog recombination mechanisms (HDR) than the microbial [32]. However, some works have shown the homolog recombination mechanism mediated by the CRISPR/Cas9 for obtaining genetically modified plants [33]. Thus, despite all prominent challenges for SynBio in Agriculture/Plant Biotechnology, new approaches have arisen to overcome the old problems.

Historically, the speed of productivity increase through classical breeding was not enough to meet the world's demand for food. This lack has required genetic improvement through biotechnology, thus by the 1980s, the development of molecular and plant transformation technologies delivered the first bioengineered genes into plant genomes. Limited yields due to climate stress, changes in pests and pathogens, heat waves, and other weather extremes − the new world reality due to global warming – forces biotechnology and molecular biology to evolve in a new disruptive and fast technology that allows the creation of a new productive and functional crop. Rapid crop improvement must influence naturally grown traits and transformative engineering driven by mechanistic understanding to produce the resilient production systems needed to secure future crops [34]– this will be the new Green Revolution. Currently, the most adopted genetically modified traits are herbicide and insect resistance in crops with large markets, such as soybean [35–37], canola [38] cotton [39], and corn [40, 41].

The challenges of modern agriculture are not restricted to the increment in production to attend to the huge world population growth. Therefore, actually, agriculture faces industry adaptations to digital and genetic technologies, carbon constraints, environmental and animal welfare legislation, the growing focus on "food as medicine" and their ethical production, risks associated with globalization and climate change, a global shift in diet and more discriminating customers in search of a wealthier world [30]. SynBio can overcome these obstacles, like the industry is a pioneer in the use of technological innovations, it is also the biggest beneficiary of advances in SynBio, but in recent years, primary sectors such as agriculture have benefited from this technological evolution.

According to the United States Department of Agriculture, most commercial releases of bioengineered soybeans aim to provide herbicide tolerance, biotic and abiotic factors, improved oil quality, improved yield, and growth (USDA, 2021; CTNBio, 2021). However, many other traits need to be explored, such as superior nutritional contents and the capacity of cultivars to act as biofabrics of industrial products. Primary industries such as agriculture, fisheries, and forestry have benefited directly from advances in genetic research. It is estimated that about half of the 1−3% annual increase in productivity in crops and livestock to date has been driven by improved genetics, with genetic gain rates predicted to more than double with the implementation of emerging molecular technologies [42].

Soybean [*Glycine max* (L.) Merr.], the most consumed legume in the world, originated and domesticated in North-Eastern Asian regions, especially China and Korea, its consumption has been disseminated worldwide since it arrived in American colonies in 1765 [31]. Growing demand for a nutritious, quality, low-cost, lowenvironment impact, source of protein to feed the growing human population turned soybean into one of the most important global agricultural commodities [43]. Because it is one of the major protein sources, such as food, for animal nutrition, including humans, livestock, pets, and fish, thus soybean seeds of commercial crops contain about 40% protein and about 20% oil [44]. In addition to being a source of protein,

*Soybean Functional Proteins and the Synthetic Biology DOI: http://dx.doi.org/10.5772/intechopen.104602*


**Table 1.**

*Roll some examples of engineered soybean crops with improved traits by synthetic biology. Based on [57].*

soy has recently been used to produce biofuels. Currently, the United States, Brazil, and Argentina together produce more than 80% of the world's soybean crop. On the other hand, China is the largest soybean importer in the world, consuming 30% of the world's soybean production [45]. Thus, the global soy market is governed by two major producers (the United States and Brazil, respectively), which produce around 68% of the world's crop, and a major consumer (China) [46].

The agriculture sector has a heavy history of fast improving new transformative techniques innovations, for example, in 2005−2006 the worldwide soybean production was 220.809 million tons, already in 2021−2022 the production reached 385.524 million tons (data from https://www.sopa.org/statistics/world-soybean-production), this increment can be attributed to the development of new disruptive genetic technologies. In the past, mutagenesis is presented as an alternative for classical plant breeding to increase genetic variation in soybean germplasm. Random mutagens techniques were normally used to introduce changes in genes aleatorily, including radiation (such as X-ray), fast neutrons, and gamma rays, chemicals (such as EMS (ethyl methanesulfonate)), and biological mutagenesis (such as T-DNA insertion and transposons) [47]. Although it is hereditary and stable, random mutagenesis demand intensive, specific, time-consuming, and expensive techniques to identify the intended phenotypes in the mutants [48], and in the most cases, it is impossible to locate and obtains the specific allele to determinate function due to the imprecision of the random mutation [43].

In this way, to solve this challenge, in the last 20 years, with the advent of the SynBio, new biotechnologies based on site-directed nucleases (SNDs) or site-specific nucleases (SSNs), such as Zinc Finger Nucleases (ZFNs) [49, 50]. Transcription Activator-Like Effector Nucleases (TALENs) [51, 52] or the Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR) [53, 54] has been developed for generation of site-specific mutagenesis and, as the multiple SDN platforms are a very useful tool, they have been integrated into the new and actual plant breeding programs[55, 56]. Thus, with the rise of the SynBio tools and techniques, there was an exponential acceleration in the speed, quality, and several launches of new commercially interesting crops and, on the other hand, a great reduction in costs and time spent. These new approaches also increased the scope and size of genetic variability available for crop improvement, allowing the creation of diverse new engineered soybean crops for a wider range of traits (**Table 1**).
