**1. Introduction**

128 Soybean – Genetics and Novel Techniques for Yield Enhancement

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In recent years, genetically modified (GM) plants, whose DNA has been changed using genetic engineering techniques, are mainly used as foods for human and feeds and foods for farm animals. To date, a number of GM products have been approved for human consumption but concerns over safety persist, mainly as regards either the detection of transgenic plant genes and proteins in animal systems or allergenicity and toxicity of GM plants.

Since their commercial release in 1996, the global cultivation area dedicated to the production of GM plants has increased significantly (ISAAA, 2010). The majority of GM crops currently produced, like soybean, corn, cotton and canola, have been engineered to enhance agronomic performance by transformation with genes encoding herbicide tolerance and pest resistance. GM soybean has been rendered tolerant to the glyphosate family of herbicides through expression of transgenic DNA from the CP4 strain of *Agrobacterium tumefaciens* that encodes 5-enolpyruvylshikamate-3-phosphate synthase (CP4 EPSPS). Roundup Ready (RR) soybean have been grown commercially from 1996 and continued to be the principal biotech crop in 2010. Farm animals are currently fed soybean and soybean meal developed from genetic transformation as well as corn and corn products. The European Union imports soybean from USA, Brazil, and Argentina, the main users of biotech crops globally. About 90% of the compound feed produced in the EU contains GM soybean.

Although regulations with regard to GM plants have been developed primarily from the perspective of human consumption of GM food, it is generally assumed that these criteria are suitable for a risk assessment of the consumption of GM feed by livestock. The protocol for establishing "substantial equivalence" of GM plant compared to isogenic parental lines does not complete a nutritional safety assessment of a GM plant, rather, it provides a starting point for the overall assessment (FAO/WHO, 2000). Based on the European novel food and feed regulation, all foods and feeds containing or derived from approved GM products in amounts greater than a 0.9% threshold are subject to labelling rules (European Commission, 2003). Labelling of feeds containing GM ingredients gives farmers the choice of using such feed for their livestock. However, products such as milk, meat, and eggs, that are derived from livestock fed transgenic feeds are exempt from EU-labelling laws. Several studies have been conducted to evaluate the safety of GM crops, but there is still a debate on the risk of GM consumption and their potential passage into tissues.

Genetically Modified Soybean in Animal Nutrition 131

Farm animals are currently fed soybean and soybean meal developed from genetic transformation as well as corn and corn products such as corn gluten feed and meal. Europe is strongly dependent upon the American continent for its protein requirements amounting up to 90 to 95% for soybean, 40 to 60% for corn derivatives and partly for canola grain or

Traditionally, plants with desirable characteristics were chosen for food of the next generation. The desirable characteristics arose from naturally occurring variations in the genetic make-up of individual plants. Unlike conventional genetic modification that is carried out through time-tested conventional breeding of plants as combining genes from different organisms is known as recombinant DNA technology and the resulting organism is said to be genetically modified, or genetically engineered or transgenic (Pandey et al.,

Transgenic plant is one that has received a segment of DNA or genes from another organism (known as heterologous or foreign DNA) using recombinant DNA techniques. The foreign DNA is integrated through natural systems present in plant cells into the plant's genome. The newly introduced genes are subsequently inherited in a normal Mendelian manner through pollen and egg cells. The mainly process of introducing DNA into plants (called transformation) uses the *Agrobacterium* mediated method and it can be achieved both in monocotyledonous plants such as wheat, barley and rice and in dicotyledonous plants such

The soil bacterium *Agrobacterium tumefaciens* causes crown gall disease on some plants, in particular in dicotyledonous species. In causing crown gall disease *A. tumefaciens* transfers DNA (the transferred DNA or T-DNA) from the bacterium to the plant. In nature the transferred bacterial DNA cause the symptoms associated with crown gall disease. In the early 1980s scientists removed the disease causing genes from this bacterium and the T-DNA is now routinely used to transport foreign genes into plants. *Agrobacterium* cells carrying the foreign genes of interest are incubated with cultured cells of the recipient crop plant and transgenic plants are regenerated from them. Not all cells subjected to this process are successfully modified so it may be necessary to identify the modified cells using marker genes which are closely linked to the genetic material that is transferred. These selectable marker genes usually confer resistance to an antibiotic such as kanamycin or resistance to an

The genetically modified soybean (named RoundUp Ready, RR) has been rendered tolerant to the glyphosate family of herbicides through expression of transgenic DNA from *Agrobacterium tumefaciens* sp. strain CP4 that encodes 5-enolpyruvylshikamate-3-phosphate synthase (CP4 EPSPS). The CP4 EPSPS protein expressed in GE glyphosate tolerant plants is functionally equivalent to endogenous plant EPSPS enzymes with the exception that CP4 EPSPS displays reduced affinity for glyphosate (Franz et al. 1997). This soybean is, also, composed of a 35S promoter from cauliflower mosaic virus (CMV) and a NOS-terminator, a

According to the Center for Environmental Risk Assessment (2010), the 5 enolpyruvylshikimate-3-phosphate synthase (EPSPS: EC 2.5.1.19) family of enzymes is ubiquitous in plants and microorganisms. EPSPS enzymes have been isolated from both sources, and their properties have been extensively studied. EPSPS proteins catalyze the

meal (Aumaitre, 2004).

2010).

herbicide.

**3. Genetic modification of soybean** 

as soyabean, potato and tomato.

terminator of nopaline synthase gene.

Current researches suggest that the passage of plant DNA fragments across the intestinal barrier is a natural event, as demonstrated by the detection of endogenous, high copy number chloroplast genes from plants in several animal tissues and products. Low copy endogenous and transgenic DNA in animal tissues have been detected but to a lesser extent than high copy genes.

For several years, no direct evidence that GM food may represent a possible danger for health has been reported and the scientific literature in this field is still quite poor, especially as to the possible effect of a diet involving a significant amount of GM plants. More recently, a number of papers have been published and controversial results have been obtained. However, some have found significant modifications in some nuclear features in mice fed GM soybean and, more recently, it has been reported that the activity of some enzymes was altered in rabbit and goats fed GM soybean, as confirmed also by histochemistry which showed a widespread distribution of enzyme activity in myocytes, myocardiocytes, epithelial cells of renal tubules and hepatocytes. These observations suggest that the risk of genetically modified crops cannot be ignored and requires further investigations in order to identify possible long-term effects of GM plants on both livestock and human consumption. The main focus of this chapter concerns the genetically engineered soybean, its effects on

human and animal health, the productivity of this GM crop and the outcome for environment.
