- IntroductionBiotechnology, according to the Convention on Biological Diversity (CBD), is defined as “any technology that is applied to living organisms to make them more valuable to people” (CBD, 2008). Modern biotechnology involves technologies such as tissue culture, genomics, marker-assisted breeding, diagnostics and genetic engineering. Biotechnology is often used as a complementary tool to conventional plant breeding to develop improved crop cultivars. Crops developed using biotechnologicaL methods are often referred to as genetically modified (GM), genetically engineered (GE) or transgenic crops. This website will generally use the term genetically modified (GM) crops.
A few more terms used in this section are defined below. For additional definitions, please see the Glossary link.
involves “sexually crossing” related plants with the aim of combining the favorable traits from both parent plants to produce a new and better plant
variety. The progeny resulting from the crosses inherit a mixture of genes from both parents which can include both favorable and unfavorable traits. Plant
breeders select among progeny for ones with the most positive traits and least negative traits. Various types of crossing and selection are alternated over
many generations to achieve an improved combination of genes and traits. In some cases additional technologies may be utilized to introduce additional
valuable traits. For example, if the two parents are not closely related (i.e., one parent may be a wild or exotic relative of the crop), then techniques
such as embryo rescue may be required to produce the progeny. Another method used to develop new varieties through conventional breeding is irradiation and
chemical treatment to cause change in plant gene properties by a process known as mutation.
: A gene is a basic unit of inheritance. It consists of a sequence of deoxyribose nucleic acid (DNA) that occupies a specific location in an organism’s
genome and determines a particular characteristic/trait.
Genetic engineering (GE)
is used to develop transgenic plants with added traits using recombinant DNA techniques. Genetic engineering allows individual gene(s) responsible for
desired traits to be moved from one organism to another.
is the complete set of genes in an organism.
is the study of genes and their functions; it is used to describe the genetic make-up (all the hereditary material) of an organism, and understand how
molecular systems interact to result in expression of a trait.
is used track specific genes to speed up selection during conventional breeding. It is a tool used to identify chromosome regions or genes responsible for
particular traits. Identified sequences of DNA known as molecular markers have been used to develop genetic maps of great detail and accuracy for many crop
species. They have also been used to analyze the inheritance of complex traits like plant productivity and stress tolerance. The molecular markers are
being employed to develop improved varieties as a tool to assist conventional breeding.
is an enzyme produced by certain bacteria, having property of cleaving DNA molecules at or near a specific sequence of bases.Recombinant DNA
(rDNA) refers to a DNA that is formed by joining (recombining) genetic materials from different sources.
includes a collection of techniques that allow for the production of new plants from plant parts. These techniques can allow for rapid or large-scale plant
multiplication. They are frequently used for vegetatively propagated plants, plants with long generation times, or to provide disease-free planting
materials. They can also be used as a tool of conventional breeding, to help make crosses between more distantly related plant relatives by removing and
culturing the developing embryo. In addition, tissue culture is used in conjunction with gene introduction by genetic engineering to produce plants with
- The advent of GM organisms and their regulation
Several discoveries were the vital precursors for the emergence of the field of genetic engineering in the 20th century; 1)The landmark discovery of DNA as the genetic material in 1943 by Oswald Avery and coworkers (Avery et. Al., 1944); 2) the discovery of the structure of DNA and its hereditary implications by Watson and Crick in 1953 (Watson and Crick, 1953a; 1953b); 3) the laboratory synthesis of DNA by using DNA polymerase which was isolated by Arthur Kornberg in 1956 (Kornberg, 1960); and 4) the report on the semi-conservative nature of DNA replication by Meselson and Stahl in 1958 (Meselson and Stahl, 1958). These discoveries were followed by the isolation of restriction enzymes by the research groups of Mathew Meselson and Hamilton Smith towards the end of 1960s (Meselson and Yuan, 1968; Smith and Wilcox, 1970) and the use of these enzymes for specific cleavage of DNA at specific sites by Daniel Nathans in 1971 (Danna and Nathans, 1971). Janet Mertz and Ronald Davis developed the techniques for joining cohesive ends of DNA fragments cut by restriction enzymes (Mertz and Davis, 1972) and Paul Berg and co-workers were the first to successfully introduce‘new information into DNA’ of a virus in 1972 (Jackson et al., 1972). All these advancements culminated in the production of the first genetically modified bacteria by Stanley Cohen, Herbert Boyer and co-workers in 1973 (Cohen, 1973).The first transgenic plant cell was reported in 1983 (Fraley et al., 1983) and the first commercial GM crop, a tomato modified to extend its shelf life, was approved in 1994. Genetically modified crops have been cultivated since 1996.
The year 1973 marks both the first report of a GM organism and a call by scientists for guidelines to oversee work involving ‘DNA hybrid molecules’ (Singer and Dieter, 1973). In 1974, prominent scientists in the USA working on recombinant DNA (rDNA) made pronouncements for a voluntary moratorium on certain types of experiments involving rDNA and requested the US National Institute of Health to establish an advisory committee to oversee the evaluation of potential hazards of rDNA molecules and develop procedures to minimize hazards (Berg et al., 1974).The scientists also called for an international conference to deliberate on ways to mitigate the potential hazards of generating rDNA molecules (Berg et al., 1974). The famous Asilomar Conference on rDNA molecules was held in 1975 and made important recommendations in order to match evel of containment with the potential level of hazards posed by different types of rDNA molecules, setting off an era of formal regulation of work involving GM organisms (Berg et al., 1975). These regulations were meant to direct the safe production of GM plants in the laboratory, while another set of protocols were developed for the safe testing of GM plants outside the the laboratory
These are described below.
- Comparison of Genetic Engineering with Conventional BreedingHumans have been improving crops for yield and other characteristics since the advent of agriculture. In conventional breeding, all of the genes from the two parents (including both favorable (e.g., disease resistance) and unfavorable (e.g., poor yield) traits) are mixed to try to obtain a better combination of desired traits. In genetic engineering, a specific desirable gene is selected and inserted directly into cells of the crop species of interest. The resultant GM plant is then used for crossing by conventional techniques to develop the finished variety.
Genetic engineering techniques are one way to enable gene transfer between species that would not naturally cross. Thus genetic engineering allows breeders to use genes from unrelated plant species and sometimes other organisms to develop a new variety. This means breeders have access to a broader range of genetic resources for developing new plant varieties. For example, a rice gene responsible for defense against a disease-causing fungus can be transferred to a banana susceptible to that disease. The intent is to protect the GM banana from that disease and thereby reduce yield loss and/or number of fungicide applications.
- Safety Testing of GM CropsBefore any GM crop is commercially released, it undergoes extensive evaluation for a number of years, to assess performance in a range of growing conditions and environments, as would a conventionally bred variety. In addition, a GM crop undergoes further testing to ensure that it meets safety criteria. For further description of safety testing, please see the Environmental Safety Assessment and Food Safety Assessment links. Performance and safety testing occurs in the laboratory, contained greenhouse or screenhouse, and confined field trials. The first environmental release is in small-scale field trials with precautionary measures taken to isolate the GM plants from the wider environment (confined field testing). Initial performance and safety assessments are conducted at this stage. If the accumulated evidence supports the view that it performs well and is safe to the environment, the crop proceeds to multi-locational testing to establish its agronomic performance in different conditions and to perform further food and environment safety testing. After commercialization, there is a requirement in some countries for continued monitoring of the GM crop, for a specified period.
- Overview of Genetically Engineered crops – International Service for the Acquisition of Agri-biotech Applications (ISAAA)
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