Plant genetics

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An image of multiple chromosomes, taken from many cells Genome gradient.jpg
An image of multiple chromosomes, taken from many cells

Plant genetics is the study of genes, genetic variation, and heredity specifically in plants. [1] [2] It is generally considered a field of biology and botany, but intersects frequently with many other life sciences and is strongly linked with the study of information systems. Plant genetics is similar in many ways to animal genetics but differs in a few key areas.

Contents

The discoverer of genetics was Gregor Mendel, a late 19th-century scientist and Augustinian friar. Mendel studied "trait inheritance", patterns in the way traits are handed down from parents to offspring. He observed that organisms (most famously pea plants) inherit traits by way of discrete "units of inheritance". This term, still used today, is a somewhat ambiguous definition of what is referred to as a gene. Much of Mendel's work with plants still forms the basis for modern plant genetics.

Plants, like all known organisms, use DNA to pass on their traits. Animal genetics often focuses on parentage and lineage, but this can sometimes be difficult in plant genetics due to the fact that plants can, unlike most animals, be self-fertile. Speciation can be easier in many plants due to unique genetic abilities, such as being well adapted to polyploidy. Plants are unique in that they are able to produce energy-dense carbohydrates via photosynthesis, a process which is achieved by use of chloroplasts. Chloroplasts, like the superficially similar mitochondria, possess their own DNA. Chloroplasts thus provide an additional reservoir for genes and genetic diversity, and an extra layer of genetic complexity not found in animals.

The study of plant genetics has major economic impacts: many staple crops are genetically modified to increase yields, confer pest and disease resistance, provide resistance to herbicides, or to increase their nutritional value.

History

The earliest evidence of plant domestication found has been dated to 11,000 years before present in ancestral wheat. While initially selection may have happened unintentionally, it is very likely that by 5,000 years ago farmers had a basic understanding of heredity and inheritance. [3] This selection over time gave rise to new crop species and varieties that are the basis of the crops we grow, eat and research today.

Gregor Mendel, the "Father of genetics" Gregor Mendel oval.jpg
Gregor Mendel, the "Father of genetics"

The field of plant genetics began with the work of Gregor Johann Mendel, who is often called the "father of genetics". He was an Augustinian priest and scientist born on 20 July 1822 in Austria-Hungary. He worked at the Abbey of St. Thomas in Brünn (now Brno, Czech Republic), where his organism of choice for studying inheritance and traits was the pea plant. Mendel's work tracked many phenotypic traits of pea plants, such as their height, flower color, and seed characteristics. Mendel showed that the inheritance of these traits follows two particular laws, which were later named after him. His seminal work on genetics, “Versuche über Pflanzen-Hybriden” (Experiments on Plant Hybrids), was published in 1866, but went almost entirely unnoticed until 1900 when prominent botanists in the UK, like Sir Gavin de Beer, recognized its importance and re-published an English translation. [4] Mendel died in 1884. The significance of Mendel's work was not recognized until the turn of the 20th century. Its rediscovery prompted the foundation of modern genetics. His discoveries, deduction of segregation ratios, and subsequent laws have not only been used in research to gain a better understanding of plant genetics, but also play a large role in plant breeding. [3] Mendel's works along with the works of Charles Darwin and Alfred Wallace on selection provided the basis for much of genetics as a discipline.

In the early 1900s, botanists and statisticians began to examine the segregation ratios put forth by Mendel. W.E. Castle discovered that while individual traits may segregate and change over time with selection, that when selection is stopped and environmental effects are taken into account, the genetic ratio stops changing and reach a sort of stasis, the foundation of Population Genetics. [5] This was independently discovered by G. H. Hardy and W. Weinberg, which ultimately gave rise to the concept of Hardy–Weinberg equilibrium published in 1908. [6]

Around this same time, genetic and plant breeding experiments in maize began. Maize that has been self-pollinated experiences a phenomenon called inbreeding depression. Researchers, like Nils Heribert-Nilsson, recognized that by crossing plants and forming hybrids, they were not only able to combine traits from two desirable parents, but the crop also experienced heterosis or hybrid vigor. This was the beginning of identifying gene interactions or epistasis. By the early 1920s, Donald Forsha Jones had invented a method that led to the first hybrid maize seed that were available commercially. [7] The large demand for hybrid seed in the U.S. Corn Belt by the mid 1930s led to a rapid growth in the seed production industry and ultimately seed research. The strict requirements for producing hybrid seed led to the development of careful population and inbred line maintenance, keeping plants isolated and unable to out-cross, which produced plants that better allowed researchers to tease out different genetic concepts. The structure of these populations allowed scientist such a T. Dobzhansky, S. Wright, and R.A. Fisher to develop evolutionary biology concepts as well as explore speciation over time and the statistics underlying plant genetics. [8] [9] [10] Their work laid the foundations for future genetic discoveries such as linkage disequilibrium in 1960. [11]

While breeding experiments were taking place, other scientists such as Nikolai Vavilov [12] were interested in wild progenitor species of modern crop plants. Botanists between the 1920s and 1960s often would travel to regions of high plant diversity and seek out wild species that had given rise to domesticated species after selection. Determining how crops changed over time with selection was initially based on morphological features. It developed over time to chromosomal analysis, then genetic marker analysis, and eventual genomic analysis. Identifying traits and their underlying genetics allowed for transferring useful genes and the traits they controlled from either wild or mutant plants to crop plants. Understanding and manipulating of plant genetics was in its heyday during the Green Revolution brought about by Norman Borlaug. During this time, the molecule of heredity, DNA, was also discovered, which allowed scientists to actually examine and manipulate genetic information directly.

DNA

The structure of part of a DNA double helix DNA Overview.png
The structure of part of a DNA double helix

Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information. DNA is often compared to a set of blueprints or a recipe, or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA segments that carry this genetic information are called genes, and their location within the genome are referred to as genetic loci, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information.

Geneticists, including plant geneticists, use this sequence of DNA to their advantage to better find and understand the role of different genes within a given genome. Through research and plant breeding, manipulation of different plant genes and loci encoded by the DNA sequence of the plant chromosomes by various methods can be done to produce different or desired genotypes that result in different or desired phenotypes. [13]

Meiosis

During plant meiosis, double-strand breaks are introduced into the DNA genome and these breaks can be repaired by a recombination process employing gene products RAD51 and DMC1 that are homologous to recombinases employed by eukaryotes generally. [14] Central elements of eukaryotic meiosis are pairing of homologous chromosomes, double-strand break formation and homologous recombinational repair. [15] These processes appear to be optimized for repairing DNA damage in the germline. [15]

Plant Specific Genetics

Plants, like all other known living organisms, pass on their traits using DNA. Plants however are unique from other living organisms in the fact that they have chloroplasts. Like mitochondria, chloroplasts have their own DNA. Like animals, plants experience somatic mutations regularly, but these mutations can contribute to the germ line with ease, since flowers develop at the ends of branches composed of somatic cells. People have known of this for centuries, and mutant branches are called "sports". If the fruit on the sport is economically desirable, a new cultivar may be obtained.

Some plant species are capable of self-fertilization, and some are nearly exclusively self-fertilizers. This means that a plant can be both mother and father to its offspring, a rare occurrence in animals. Scientists and hobbyists attempting to make crosses between different plants must take special measures to prevent the plants from self-fertilizing. In plant breeding, people create hybrids between plant species for economic and aesthetic reasons. For example, the yield of Corn has increased nearly five-fold in the past century due in part to the discovery and proliferation of hybrid corn varieties. [16] Plant genetics can be used to predict which combination of plants may produce a plant with Hybrid vigor, or conversely many discoveries in Plant genetics have come from studying the effects of hybridization.

Plants are generally more capable of surviving, and indeed flourishing, as polyploids. Polyploid organisms have more than two sets of homologous chromosomes. For example, humans have two sets of homologous chromosomes, meaning that a typical human will have 2 copies each of 23 different chromosomes, for a total of 46. Wheat on the other hand, while having only 7 distinct chromosomes, is considered a hexaploid and has 6 copies of each chromosome, for a total of 42. [17] In animals, inheritable germline polyploidy is less common, and spontaneous chromosome increases may not even survive past fertilization. In plants however this is less of a problem. Polyploid individuals are created frequently by a variety of processes; however, once created, they usually cannot cross back to the parental type. Polyploid individuals that are capable of self-fertilizing can give rise to a new, genetically distinct lineage, which can be the start of a new species. This is often called "instant speciation". Polyploids generally have larger fruit, an economically desirable trait, and many human food crops, including wheat, maize, potatoes, peanuts, [18] strawberries and tobacco, are either accidentally or deliberately created polyploids.

Arabidopsis thaliana, growing from between a crack in a sidewalk; it is considered a key model organism in plant genetics. Arabidopsis thaliana.jpg
Arabidopsis thaliana, growing from between a crack in a sidewalk; it is considered a key model organism in plant genetics.

Model organisms

Arabidopsis thaliana

Arabidopsis thaliana , also known as thale cress, has been the model organism for the study of plant genetics. As Drosophila, a species of fruit fly, was to the understanding of early genetics, so has been A. thaliana to the understanding of plant genetics. It was the first plant to ever have its genome sequenced in the year 2000. It has a small genome, making the initial sequencing more attainable. It has a genome size of 125 Mbp that encodes about 25,000 genes. [19] Because an incredible amount of research has been done on the plant, a database called The Arabidopsis Information Resource (TAIR) has been established as a repository for multiple data sets and information on the species. Information housed in TAIR include the complete genome sequence along with gene structure, gene product information, gene expression, DNA and seed stocks, genome maps, genetic and physical markers, publications, and information about the A. thaliana research community. [20] Many natural inbred accessions of A. thaliana (often referred to as "ecotypes") are available and have been useful in genetic research. This natural variation has been used to identify loci important in both biotic and abiotic stress resistance. [21]

Brachypodium distachyon

Brachypodium distachyon is an experimental model grass that has many attributes that make it an excellent model for temperate cereals. Unlike wheat, a tetra or hexaploid species, brachypodium is diploid with a relatively small genome (~355 Mbp) with a short life-cycle, making genomic studies on it simpler.

Nicotiana benthamiana

Nicotiana benthamiana is a popular model organism for both plant-pathogen and transgenic studies. Because its broad leaves are easily transiently transformed with Agrobacterium tumefaciens , it is used to study both the expression of pathogen genes introduced into a plant or test new genetic cassette effects.

Other model plants

Other models include the alga Chlamydomonas reinhardtii , the moss Physcomitrella patens , the clover Medicago truncatula , Antirrhinum majus (snapdragon), the C4 grass Setaria viridis , and maize (corn).

Genetically modified crops

Genetically modified (GM) foods are produced from organisms that have had changes introduced into their DNA using the methods of genetic engineering. Genetic engineering techniques allow for the introduction of new traits as well as greater control over traits than previous methods such as selective breeding and mutation breeding. [22]

Genetically modifying plants is an important economic activity: in 2017, 89% of corn, 94% of soybeans, and 91% of cotton produced in the US were from genetically modified strains. [23] Since the introduction of GM crops, yields have increased by 22%, and profits have increased to farmers, especially in the developing world, by 68%. An important side effect of GM crops has been decreased land requirements, [24]

Commercial sale of genetically modified foods began in 1994, when Calgene first marketed its unsuccessful Flavr Savr delayed-ripening tomato. [25] [26] Most food modifications have primarily focused on cash crops in high demand by farmers such as soybean, corn, canola, and cotton. Genetically modified crops have been engineered for resistance to pathogens and herbicides and for better nutrient profiles. [27] Other such crops include the economically important GM papaya which are resistant to the highly destructive Papaya ringspot virus, and the nutritionally improved golden rice (it is however still in development). [28]

There is a scientific consensus [29] [30] [31] [32] that currently available food derived from GM crops poses no greater risk to human health than conventional food, [33] [34] [35] [36] [37] but that each GM food needs to be tested on a case-by-case basis before introduction. [38] [39] Nonetheless, members of the public are much less likely than scientists to perceive GM foods as safe. [40] [41] [42] [43] The legal and regulatory status of GM foods varies by country, with some nations banning or restricting them, and others permitting them with widely differing degrees of regulation. [44] [45] [46] [47] There are still ongoing public concerns related to food safety, regulation, labeling, environmental impact, research methods, and the fact that some GM seeds are subject to intellectual property rights owned by corporations. [48]

Modern ways to genetically modify plants

Genetic modification has been the cause for much research into modern plant genetics, and has also led to the sequencing of many plant genomes. Today there are two predominant procedures of transforming genes in organisms: the "Gene gun" method and the Agrobacterium method.

"Gene gun" method

The gene gun method is also referred to as "biolistics" (ballistics using biological components). This technique is used for in vivo (within a living organism) transformation and has been especially useful in monocot species like corn and rice. This approach literally shoots genes into plant cells and plant cell chloroplasts. DNA is coated onto small particles of gold or tungsten approximately two micrometers in diameter. The particles are placed in a vacuum chamber and the plant tissue to be engineered is placed below the chamber. The particles are propelled at high velocity using a short pulse of high pressure helium gas, and hit a fine mesh baffle placed above the tissue while the DNA coating continues into any target cell or tissue.

Agrobacterium method

Transformation via Agrobacterium has been successfully practiced in dicots, i.e. broadleaf plants, such as soybeans and tomatoes, for many years. Recently it has been adapted and is now effective in monocots like grasses, including corn and rice. In general, the Agrobacterium method is considered preferable to the gene gun, because of a greater frequency of single-site insertions of the foreign DNA, which allows for easier monitoring. In this method, the tumor inducing (Ti) region is removed from the T-DNA (transfer DNA) and replaced with the desired gene and a marker, which is then inserted into the organism. This may involve direct inoculation of the tissue with a culture of transformed Agrobacterium, or inoculation following treatment with micro-projectile bombardment, which wounds the tissue. [49] Wounding of the target tissue causes the release of phenolic compounds by the plant, which induces invasion of the tissue by Agrobacterium. Because of this, microprojectile bombardment often increases the efficiency of infection with Agrobacterium. The marker is used to find the organism which has successfully taken up the desired gene. Tissues of the organism are then transferred to a medium containing an antibiotic or herbicide, depending on which marker was used. The Agrobacterium present is also killed by the antibiotic. Only tissues expressing the marker will survive and possess the gene of interest. Thus, subsequent steps in the process will only use these surviving plants. In order to obtain whole plants from these tissues, they are grown under controlled environmental conditions in tissue culture. This is a process of a series of media, each containing nutrients and hormones. Once the plants are grown and produce seed, the process of evaluating the progeny begins. This process entails selection of the seeds with the desired traits and then retesting and growing to make sure that the entire process has been completed successfully with the desired results.

See also

Related Research Articles

<span class="mw-page-title-main">Biotechnology</span> Use of living systems and organisms to develop or make useful products

Biotechnology is a multidisciplinary field that involves the integration of natural sciences and engineering sciences in order to achieve the application of organisms and parts thereof for products and services.

<span class="mw-page-title-main">Genetically modified maize</span> Genetically modified crop

Genetically modified maize (corn) is a genetically modified crop. Specific maize strains have been genetically engineered to express agriculturally-desirable traits, including resistance to pests and to herbicides. Maize strains with both traits are now in use in multiple countries. GM maize has also caused controversy with respect to possible health effects, impact on other insects and impact on other plants via gene flow. One strain, called Starlink, was approved only for animal feed in the US but was found in food, leading to a series of recalls starting in 2000.

<span class="mw-page-title-main">Genetics</span> Science of genes, heredity, and variation in living organisms

Genetics is the study of genes, genetic variation, and heredity in organisms. It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar working in the 19th century in Brno, was the first to study genetics scientifically. Mendel studied "trait inheritance", patterns in the way traits are handed down from parents to offspring over time. He observed that organisms inherit traits by way of discrete "units of inheritance". This term, still used today, is a somewhat ambiguous definition of what is referred to as a gene.

<span class="mw-page-title-main">Genetically modified organism</span> Organisms whose genetic material has been altered using genetic engineering methods

A genetically modified organism (GMO) is any organism whose genetic material has been altered using genetic engineering techniques. The exact definition of a genetically modified organism and what constitutes genetic engineering varies, with the most common being an organism altered in a way that "does not occur naturally by mating and/or natural recombination". A wide variety of organisms have been genetically modified (GM), including animals, plants, and microorganisms.

<span class="mw-page-title-main">Genetic engineering</span> Manipulation of an organisms genome

Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including the transfer of genes within and across species boundaries to produce improved or novel organisms.

<span class="mw-page-title-main">Polyploidy</span> Condition where cells of an organism have more than two paired sets of chromosomes

Polyploidy is a condition in which the cells of an organism have more than one pair of (homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two complete sets of chromosomes, one from each of two parents; each set contains the same number of chromosomes, and the chromosomes are joined in pairs of homologous chromosomes. However, some organisms are polyploid. Polyploidy is especially common in plants. Most eukaryotes have diploid somatic cells, but produce haploid gametes by meiosis. A monoploid has only one set of chromosomes, and the term is usually only applied to cells or organisms that are normally diploid. Males of bees and other Hymenoptera, for example, are monoploid. Unlike animals, plants and multicellular algae have life cycles with two alternating multicellular generations. The gametophyte generation is haploid, and produces gametes by mitosis; the sporophyte generation is diploid and produces spores by meiosis.

Agricultural biotechnology, also known as agritech, is an area of agricultural science involving the use of scientific tools and techniques, including genetic engineering, molecular markers, molecular diagnostics, vaccines, and tissue culture, to modify living organisms: plants, animals, and microorganisms. Crop biotechnology is one aspect of agricultural biotechnology which has been greatly developed upon in recent times. Desired trait are exported from a particular species of Crop to an entirely different species. These transgene crops possess desirable characteristics in terms of flavor, color of flowers, growth rate, size of harvested products and resistance to diseases and pests.

<span class="mw-page-title-main">Genetically modified food</span> Foods produced from organisms that have had changes introduced into their DNA

Genetically modified foods, also known as genetically engineered foods, or bioengineered foods are foods produced from organisms that have had changes introduced into their DNA using various methods of genetic engineering. Genetic engineering techniques allow for the introduction of new traits as well as greater control over traits when compared to previous methods, such as selective breeding and mutation breeding.

<i>Agrobacterium</i> Genus of bacteria

Agrobacterium is a genus of Gram-negative bacteria established by H. J. Conn that uses horizontal gene transfer to cause tumors in plants. Agrobacterium tumefaciens is the most commonly studied species in this genus. Agrobacterium is well known for its ability to transfer DNA between itself and plants, and for this reason it has become an important tool for genetic engineering.

The term modifications in genetics refers to both naturally occurring and engineered changes in DNA. Incidental, or natural mutations occur through errors during replication and repair, either spontaneously or due to environmental stressors. Intentional modifications are done in a laboratory for various purposes, developing hardier seeds and plants, and increasingly to treat human disease. The use of gene editing technology remains controversial.

<span class="mw-page-title-main">Transfer DNA</span> Type of DNA in bacterial genomes

The transfer DNA is the transferred DNA of the tumor-inducing (Ti) plasmid of some species of bacteria such as Agrobacterium tumefaciens and Agrobacterium rhizogenes . The T-DNA is transferred from bacterium into the host plant's nuclear DNA genome. The capability of this specialized tumor-inducing (Ti) plasmid is attributed to two essential regions required for DNA transfer to the host cell. The T-DNA is bordered by 25-base-pair repeats on each end. Transfer is initiated at the right border and terminated at the left border and requires the vir genes of the Ti plasmid.

<span class="mw-page-title-main">Genetically modified crops</span> Plants used in agriculture

Genetically modified crops are plants used in agriculture, the DNA of which has been modified using genetic engineering methods. Plant genomes can be engineered by physical methods or by use of Agrobacterium for the delivery of sequences hosted in T-DNA binary vectors. In most cases, the aim is to introduce a new trait to the plant which does not occur naturally in the species. Examples in food crops include resistance to certain pests, diseases, environmental conditions, reduction of spoilage, resistance to chemical treatments, or improving the nutrient profile of the crop. Examples in non-food crops include production of pharmaceutical agents, biofuels, and other industrially useful goods, as well as for bioremediation.

<span class="mw-page-title-main">Genetic analysis</span>

Genetic analysis is the overall process of studying and researching in fields of science that involve genetics and molecular biology. There are a number of applications that are developed from this research, and these are also considered parts of the process. The base system of analysis revolves around general genetics. Basic studies include identification of genes and inherited disorders. This research has been conducted for centuries on both a large-scale physical observation basis and on a more microscopic scale. Genetic analysis can be used generally to describe methods both used in and resulting from the sciences of genetics and molecular biology, or to applications resulting from this research.

A transgene is a gene that has been transferred naturally, or by any of a number of genetic engineering techniques, from one organism to another. The introduction of a transgene, in a process known as transgenesis, has the potential to change the phenotype of an organism. Transgene describes a segment of DNA containing a gene sequence that has been isolated from one organism and is introduced into a different organism. This non-native segment of DNA may either retain the ability to produce RNA or protein in the transgenic organism or alter the normal function of the transgenic organism's genetic code. In general, the DNA is incorporated into the organism's germ line. For example, in higher vertebrates this can be accomplished by injecting the foreign DNA into the nucleus of a fertilized ovum. This technique is routinely used to introduce human disease genes or other genes of interest into strains of laboratory mice to study the function or pathology involved with that particular gene.

<span class="mw-page-title-main">Genetically modified food controversies</span>

Genetically modified food controversies are disputes over the use of foods and other goods derived from genetically modified crops instead of conventional crops, and other uses of genetic engineering in food production. The disputes involve consumers, farmers, biotechnology companies, governmental regulators, non-governmental organizations, and scientists. The key areas of controversy related to genetically modified food are whether such food should be labeled, the role of government regulators, the objectivity of scientific research and publication, the effect of genetically modified crops on health and the environment, the effect on pesticide resistance, the impact of such crops for farmers, and the role of the crops in feeding the world population. In addition, products derived from GMO organisms play a role in the production of ethanol fuels and pharmaceuticals.

<span class="mw-page-title-main">Gene targeting</span> Genetic technique that uses homologous recombination to change an endogenous gene

Gene targeting is a biotechnological tool used to change the DNA sequence of an organism. It is based on the natural DNA-repair mechanism of Homology Directed Repair (HDR), including Homologous Recombination. Gene targeting can be used to make a range of sizes of DNA edits, from larger DNA edits such as inserting entire new genes into an organism, through to much smaller changes to the existing DNA such as a single base-pair change. Gene targeting relies on the presence of a repair template to introduce the user-defined edits to the DNA. The user will design the repair template to contain the desired edit, flanked by DNA sequence corresponding (homologous) to the region of DNA that the user wants to edit; hence the edit is targeted to a particular genomic region. In this way Gene Targeting is distinct from natural homology-directed repair, during which the ‘natural’ DNA repair template of the sister chromatid is used to repair broken DNA. The alteration of DNA sequence in an organism can be useful in both a research context – for example to understand the biological role of a gene – and in biotechnology, for example to alter the traits of an organism.

<span class="mw-page-title-main">Genetically modified plant</span> Plants with human-introduced genes from other organisms

Genetically modified plants have been engineered for scientific research, to create new colours in plants, deliver vaccines, and to create enhanced crops. Plant genomes can be engineered by physical methods or by use of Agrobacterium for the delivery of sequences hosted in T-DNA binary vectors. Many plant cells are pluripotent, meaning that a single cell from a mature plant can be harvested and then under the right conditions form a new plant. This ability is most often taken advantage by genetic engineers through selecting cells that can successfully be transformed into an adult plant which can then be grown into multiple new plants containing transgene in every cell through a process known as tissue culture.

Genetically modified canola is a genetically modified crop. The first strain, Roundup Ready canola, was developed by Monsanto for tolerance to glyphosate, the active ingredient in the commonly used herbicide Roundup.

<span class="mw-page-title-main">History of genetic engineering</span>

Genetic engineering is the science of manipulating genetic material of an organism. The concept of genetic engineering was first proposed by Nikolay Timofeev-Ressovsky in 1934. The first artificial genetic modification accomplished using biotechnology was transgenesis, the process of transferring genes from one organism to another, first accomplished by Herbert Boyer and Stanley Cohen in 1973. It was the result of a series of advancements in techniques that allowed the direct modification of the genome. Important advances included the discovery of restriction enzymes and DNA ligases, the ability to design plasmids and technologies like polymerase chain reaction and sequencing. Transformation of the DNA into a host organism was accomplished with the invention of biolistics, Agrobacterium-mediated recombination and microinjection. The first genetically modified animal was a mouse created in 1974 by Rudolf Jaenisch. In 1976 the technology was commercialised, with the advent of genetically modified bacteria that produced somatostatin, followed by insulin in 1978. In 1983 an antibiotic resistant gene was inserted into tobacco, leading to the first genetically engineered plant. Advances followed that allowed scientists to manipulate and add genes to a variety of different organisms and induce a range of different effects. Plants were first commercialized with virus resistant tobacco released in China in 1992. The first genetically modified food was the Flavr Savr tomato marketed in 1994. By 2010, 29 countries had planted commercialized biotech crops. In 2000 a paper published in Science introduced golden rice, the first food developed with increased nutrient value.

<span class="mw-page-title-main">Genetic engineering techniques</span> Methods used to change the DNA of organisms

Genetic engineering techniques allow the modification of animal and plant genomes. Techniques have been devised to insert, delete, and modify DNA at multiple levels, ranging from a specific base pair in a specific gene to entire genes. There are a number of steps that are followed before a genetically modified organism (GMO) is created. Genetic engineers must first choose what gene they wish to insert, modify, or delete. The gene must then be isolated and incorporated, along with other genetic elements, into a suitable vector. This vector is then used to insert the gene into the host genome, creating a transgenic or edited organism.

References

  1. ↑ Griffiths, Anthony J. F.; Miller, Jeffrey H.; Suzuki, David T.; Lewontin, Richard C.; Gelbart, eds. (2000). "Genetics and the Organism: Introduction". An Introduction to Genetic Analysis (7th ed.). New York: W. H. Freeman. ISBN   978-0-7167-3520-5.
  2. ↑ Hartl D, Jones E (2005)
  3. 1 2 Allard, Robert W. (December 1999). "History of Plant Population Genetics". Annual Review of Genetics. 33 (1): 1–27. doi:10.1146/annurev.genet.33.1.1. ISSN   0066-4197. PMID   10690402.
  4. ↑ "1. Gregor Mendel: Versuche über Pflanzen-Hybriden". www.bshs.org.uk. Retrieved 2018-07-11.
  5. ↑ Castle, W. E. (1903). "The Laws of Heredity of Galton and Mendel, and Some Laws Governing Race Improvement by Selection". Proceedings of the American Academy of Arts and Sciences. 39 (8): 223–242. doi:10.2307/20021870. hdl: 2027/hvd.32044106445109 . JSTOR   20021870.
  6. ↑ Hardy, G. H. (1908-07-10). "Mendelian Proportions in a Mixed Population". Science. 28 (706): 49–50. Bibcode:1908Sci....28...49H. doi:10.1126/science.28.706.49. ISSN   0036-8075. PMC   2582692 . PMID   17779291.
  7. ↑ "Improving Corn". USDA Agricultural Research Service. Retrieved 2018-07-11.
  8. ↑ "CAB Direct". www.cabdirect.org. Retrieved 2018-07-11.
  9. ↑ Wright, Sewall (May 1940). "Breeding Structure of Populations in Relation to Speciation". The American Naturalist. 74 (752): 232–248. doi:10.1086/280891. ISSN   0003-0147. S2CID   84048953.
  10. ↑ Dobzhansky, Theodosius (1970). Genetics of the Evolutionary Process. Columbia University Press. ISBN   9780231083065.
  11. ↑ Lewontin, R. C.; Kojima, Ken-ichi (December 1960). "The Evolutionary Dynamics of Complex Polymorphisms". Evolution. 14 (4): 458–472. doi:10.1111/j.1558-5646.1960.tb03113.x. ISSN   0014-3820. S2CID   221734239.
  12. ↑ Vavilov, N. I. (1926). "Studies on the Origin of Cultivated Plants". Nature. 118 (2967): 392–393. Bibcode:1926Natur.118..392T. doi: 10.1038/118392a0 . S2CID   4122968.
  13. ↑ Dudley, J. W. (1993-07-08). "Molecular Markers in Plant Improvement: Manipulation of Genes Affecting Quantitative Traits". Crop Science. 33 (4): 660–668. doi:10.2135/cropsci1993.0011183X003300040003x. ISSN   0011-183X.
  14. ↑ Emmenecker, Côme; Mézard, Christine; Kumar, Rajeev (March 2023). "Repair of DNA double-strand breaks in plant meiosis: role of eukaryotic RecA recombinases and their modulators". Plant Reproduction. 36 (1): 17–41. doi:10.1007/s00497-022-00443-6.
  15. 1 2 Mirzaghaderi, Ghader; Hörandl, Elvira (14 September 2016). "The evolution of meiotic sex and its alternatives". Proceedings of the Royal Society B: Biological Sciences. 283 (1838): 20161221. doi:10.1098/rspb.2016.1221. PMC   5031655 .
  16. ↑ "Plant and Soil Sciences eLibrary". passel.unl.edu. Retrieved 2018-06-20.
  17. ↑ "Why is the Wheat Genome So Complicated? | Colorado Wheat". coloradowheat.org. Retrieved 2018-06-20.
  18. ↑ Banjara, Manoj; Zhu, Longfu; Shen, Guoxin; Payton, Paxton; Zhang, Hong (2012-01-01). "Expression of an Arabidopsis sodium/proton antiporter gene (AtNHX1) in peanut to improve salt tolerance - Springer". Plant Biotechnology Reports. 6: 59–67. doi:10.1007/s11816-011-0200-5. S2CID   12025029.
  19. ↑ The Arabidopsis Genome Initiative (December 2000). "Analysis of the genome sequence of the flowering plant Arabidopsis thaliana" (PDF). Nature. 408 (6814). The Arabidopsis Genome Initiative: 796–815. Bibcode:2000Natur.408..796T. doi: 10.1038/35048692 . ISSN   0028-0836. PMID   11130711.
  20. ↑ "TAIR - Home Page". www.arabidopsis.org. Retrieved 2018-07-11.
  21. ↑ Alonso-Blanco, Carlos; Koornneef, Maarten (2000-01-01). "Naturally occurring variation in Arabidopsis: an underexploited resource for plant genetics". Trends in Plant Science. 5 (1): 22–29. doi:10.1016/S1360-1385(99)01510-1. ISSN   1360-1385. PMID   10637658.
  22. ↑ GM Science Review First Report Archived October 16, 2013, at the Wayback Machine , Prepared by the UK GM Science Review panel (July 2003). Chairman Professor Sir David King, Chief Scientific Advisor to the UK Government, P 9
  23. ↑ "USDA ERS - Recent Trends in GE Adoption". www.ers.usda.gov. Retrieved 2018-06-20.
  24. ↑ "GMO crops have been increasing yield for 20 years, with more progress ahead - Alliance for Science". Alliance for Science. Retrieved 2018-06-21.
  25. ↑ James, Clive (1996). "Global Review of the Field Testing and Commercialization of Transgenic Plants: 1986 to 1995" (PDF). The International Service for the Acquisition of Agri-biotech Applications. Retrieved 17 July 2010.
  26. ↑ Weasel, Lisa H. 2009. Food Fray. Amacom Publishing
  27. ↑ "Consumer Q&A". Fda.gov. 2009-03-06. Retrieved 2012-12-29.
  28. ↑ "Genetically modified Golden Rice falls short on lifesaving promises | The Source | Washington University in St. Louis". The Source. 2016-06-02. Retrieved 2018-06-21.
  29. ↑ Nicolia, Alessandro; Manzo, Alberto; Veronesi, Fabio; Rosellini, Daniele (2013). "An overview of the last 10 years of genetically engineered crop safety research" (PDF). Critical Reviews in Biotechnology. 34 (1): 77–88. doi:10.3109/07388551.2013.823595. PMID   24041244. S2CID   9836802. Archived from the original (PDF) on 2016-09-17. Retrieved 2017-03-29.
  30. ↑ "State of Food and Agriculture 2003–2004. Agricultural Biotechnology: Meeting the Needs of the Poor. Health and environmental impacts of transgenic crops". Food and Agriculture Organization of the United Nations. Retrieved February 8, 2016.
  31. ↑ Ronald, Pamela (May 5, 2011). "Plant Genetics, Sustainable Agriculture and Global Food Security". Genetics. 188 (1): 11–20. doi:10.1534/genetics.111.128553. PMC   3120150 . PMID   21546547.
  32. ↑ But see also:

    Domingo, José L.; Bordonaba, Jordi Giné (2011). "A literature review on the safety assessment of genetically modified plants" (PDF). Environment International. 37 (4): 734–742. Bibcode:2011EnInt..37..734D. doi:10.1016/j.envint.2011.01.003. PMID   21296423.

    Krimsky, Sheldon (2015). "An Illusory Consensus behind GMO Health Assessment" (PDF). Science, Technology, & Human Values. 40 (6): 883–914. doi:10.1177/0162243915598381. S2CID   40855100. Archived from the original (PDF) on 2016-02-07. Retrieved 2017-03-29.

    And contrast:

    Panchin, Alexander Y.; Tuzhikov, Alexander I. (January 14, 2016). "Published GMO studies find no evidence of harm when corrected for multiple comparisons". Critical Reviews in Biotechnology. 37 (2): 213–217. doi:10.3109/07388551.2015.1130684. PMID   26767435. S2CID   11786594.

    and

    Yang, Y.T.; Chen, B. (2016). "Governing GMOs in the USA: science, law and public health". Journal of the Science of Food and Agriculture. 96 (6): 1851–1855. Bibcode:2016JSFA...96.1851Y. doi:10.1002/jsfa.7523. PMID   26536836.

  33. ↑ "Statement by the AAAS Board of Directors On Labeling of Genetically Modified Foods" (PDF). American Association for the Advancement of Science. October 20, 2012. Retrieved February 8, 2016.

    Pinholster, Ginger (October 25, 2012). "AAAS Board of Directors: Legally Mandating GM Food Labels Could "Mislead and Falsely Alarm Consumers"". American Association for the Advancement of Science. Retrieved February 8, 2016.

  34. ↑ European Commission. Directorate-General for Research (2010). A decade of EU-funded GMO research (2001–2010) (PDF). Directorate-General for Research and Innovation. Biotechnologies, Agriculture, Food. European Commission, European Union. doi:10.2777/97784. ISBN   978-92-79-16344-9 . Retrieved February 8, 2016.
  35. ↑ "AMA Report on Genetically Modified Crops and Foods (online summary)" (PDF). American Medical Association. January 2001. Archived from the original on September 7, 2012. Retrieved March 19, 2016.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  36. ↑ "Restrictions on Genetically Modified Organisms: United States. Public and Scholarly Opinion". Library of Congress. June 9, 2015. Retrieved February 8, 2016.
  37. ↑ National Academies Of Sciences, Engineering; Division on Earth Life Studies; Board on Agriculture Natural Resources; Committee on Genetically Engineered Crops: Past Experience Future Prospects (2016). Genetically Engineered Crops: Experiences and Prospects. The National Academies of Sciences, Engineering, and Medicine (US). p. 149. doi:10.17226/23395. ISBN   978-0-309-43738-7. PMID   28230933 . Retrieved May 19, 2016.
  38. ↑ "Frequently asked questions on genetically modified foods". World Health Organization. Retrieved February 8, 2016.
  39. ↑ Haslberger, Alexander G. (2003). "Codex guidelines for GM foods include the analysis of unintended effects". Nature Biotechnology. 21 (7): 739–741. doi:10.1038/nbt0703-739. PMID   12833088. S2CID   2533628.
  40. ↑ Funk, Cary; Rainie, Lee (January 29, 2015). "Public and Scientists' Views on Science and Society". Pew Research Center. Retrieved February 24, 2016.
  41. ↑ Marris, Claire (2001). "Public views on GMOs: deconstructing the myths". EMBO Reports. 2 (7): 545–548. doi:10.1093/embo-reports/kve142. PMC   1083956 . PMID   11463731.
  42. ↑ Final Report of the PABE research project (December 2001). "Public Perceptions of Agricultural Biotechnologies in Europe". Commission of European Communities. Retrieved February 24, 2016.
  43. ↑ Scott, Sydney E.; Inbar, Yoel; Rozin, Paul (2016). "Evidence for Absolute Moral Opposition to Genetically Modified Food in the United States" (PDF). Perspectives on Psychological Science. 11 (3): 315–324. doi:10.1177/1745691615621275. PMID   27217243. S2CID   261060.
  44. ↑ "Restrictions on Genetically Modified Organisms". Library of Congress. June 9, 2015. Retrieved February 24, 2016.
  45. ↑ Bashshur, Ramona (February 2013). "FDA and Regulation of GMOs". American Bar Association. Archived from the original on June 21, 2018. Retrieved February 24, 2016.
  46. ↑ Sifferlin, Alexandra (October 3, 2015). "Over Half of E.U. Countries Are Opting Out of GMOs". Time.
  47. ↑ Lynch, Diahanna; Vogel, David (April 5, 2001). "The Regulation of GMOs in Europe and the United States: A Case-Study of Contemporary European Regulatory Politics". Council on Foreign Relations. Archived from the original on September 29, 2016. Retrieved February 24, 2016.
  48. ↑ Cowan, Tadlock (18 Jun 2011). "Agricultural Biotechnology: Background and Recent Issues" (PDF). Congressional Research Service (Library of Congress). pp. 33–38. Retrieved 27 September 2015.
  49. ↑ Bidney, D; Scelonge, C; Martich, J; Burrus, M; Sims, L; Huffman, G (January 1992). "Microprojectile bombardment of plant tissues increases transformation frequency by Agrobacterium tumefaciens". Plant Mol. Biol. 18 (2): 301–13. doi:10.1007/bf00034957. PMID   1310058. S2CID   24995834.
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