Genetically modified plant
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Genetically modified plants have been engineered for scientific research, to create new colours in plants, deliver vaccines, and to create enhanced crops. 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 can be taken advantage of by genetic engineers; by selecting for cells that have been successfully transformed in an adult plant a new plant can then be grown that contains the transgene in every cell through a process known as tissue culture.
Much of the advances in the field genetic engineering has come from experimentation with tobacco. Major advances in tissue culture and plant cellular mechanisms for a wide range of plants has originated from systems developed in tobacco. It was the first plant to be genetically engineered and is considered a model organism for not only genetic engineering, but a range of other fields. As such the transgenic tools and procedures are well established making it one of the easiest plants to transform. Another major model organism relevant to genetic engineering is Arabidopsis thaliana. Its small genome and short life cycle makes it easy to manipulate and it contains many homolgs to important crop species. It was the first plant sequenced, has abundant bioinformatic resources and can be transformed by simply dipping a flower in a transformed Agrobacterium solution.
In research, plants are engineered to help discover the functions of certain genes. The simplest way to do this is to remove the gene and see what phenotype develops compared to the wild type form. Any differences are possibly the result of the missing gene. Unlike mutagenisis, genetic engineering allows targeted removal without disrupting other genes in the organism. Some genes are only expressed in certain tissue, so reporter genes, like GUS, can be attached to the gene of interest allowing visualisation of the location. Other ways to test a gene is to alter it slightly and then return it to the plant and see if it still has the same effect on phenotype. Other strategies include attaching the gene to a strong promoter and see what happens when it is over expressed, forcing a gene to be expressed in a different location or at different developmental stages.
Some genetically modified plants are purely ornamental. They are modified for lower color, fragrance, flower shape and plant architecture. The first genetically modified ornamentals commercialised altered colour. Carnations were released in 1997, with the most popular genetically modified organism, a blue rose (actually lavender or mauve) created in 2004. The roses are sold in Japan, the United States, and Canada. Other genetically modified ornamentals include Chrysanthemum and Petunia. As well as increasing aesthetic value there are plans to develop ornamentals that use less water or are resistant to the cold, which would allow them to be grown outside their natural environments.
It has been proposed to genetically modify some plant species threatened by extinction to be resistant invasive plants and diseases, such as the emerald ash borer in North American and the fungal disease, Ceratocystis platani, in European plane trees. The papaya ringspot virus (PRSV) devastated papaya trees in Hawaii in the twentieth century until transgenic papaya plants were given pathogen-derived resistance. However, genetic modification for conservation in plants remains mainly speculative. A unique concern is that a transgenic species may no longer bear enough resemblance to the original species to truly claim that the original species is being conserved. Instead, the transgenic species may be genetically different enough to be considered a new species, thus diminishing the conservation worth of genetic modification.
Genetically modified crops are genetically modified plants that are used in agriculture. The first crops provided are used for animal or human food and provide resistance to certain pests, diseases, environmental conditions, spoilage or chemical treatments (e.g. resistance to a herbicide). The second generation of crops aimed to improve the quality, often by altering the nutrient profile. Third generation genetically modified crops can be used for non-food purposes, including the production of pharmaceutical agents, biofuels, and other industrially useful goods, as well as for bioremediation.
There are three main aims to agricultural advancement; increased production, improved conditions for agricultural workers and sustainability. GM crops contribute by improving harvests through reducing insect pressure, increasing nutrient value and tolerating different abiotic stresses. Despite this potential, as of 2018, the commercialised crops are limited mostly to cash crops like cotton, soybean, maize and canola and the vast majority of the introduced traits provide either herbicide tolerance or insect resistance. Soybeans accounted for half of all genetically modified crops planted in 2014. Adoption by farmers has been rapid, between 1996 and 2013, the total surface area of land cultivated with GM crops increased by a factor of 100, from 17,000 square kilometers (4,200,000 acres) to 1,750,000 km2 (432 million acres). Geographically though the spread has been very uneven, with strong growth in the Americas and parts of Asia and little in Europe and Africa. Its socioeconomic spread has been more even, with approximately 54% of worldwide GM crops grown in developing countries in 2013.
The majority of GM crops have been modified to be resistant to selected herbicides, usually a glyphosate or glufosinate based one. Genetically modified crops engineered to resist herbicides are now more available than conventionally bred resistant varieties; in the USA 93% of soybeans and most of the GM maize grown is glyphosate tolerant. Most currently available genes used to engineer insect resistance come from the Bacillus thuringiensis bacterium. Most are in the form of delta endotoxin genes known as cry proteins, while a few use the genes that encode for vegetative insecticidal proteins. The only gene commercially used to provide insect protection that does not originate from B. thuringiensis is the Cowpea trypsin inhibitor (CpTI). CpTI was first approved for use cotton in 1999 and is currently undergoing trials in rice. Less than one percent of GM crops contained other traits, which include providing virus resistance, delaying senescence, modifying flower colour and altering the plants composition. Golden rice is the most well known GM crop that is aimed at increasing nutrient value. It has been engineered with three genes that biosynthesise beta-carotene, a precursor of vitamin A, in the edible parts of rice. It is intended to produce a fortified food to be grown and consumed in areas with a shortage of dietary vitamin A. a deficiency which each year is estimated to kill 670,000 children under the age of 5 and cause an additional 500,000 cases of irreversible childhood blindness. The original golden rice produced 1.6μg/g of the carotenoids, with further development increasing this 23 times. In 2018 it gained its first approvals for use as food.
Plants and plant cells have been genetically engineered for production of biopharmaceuticals in bioreactors, a process known as Pharming. Work has been done with duckweed Lemna minor, the algae Chlamydomonas reinhardtii and the moss Physcomitrella patens. Biopharmaceuticals produced include cytokines, hormones, antibodies, enzymes and vaccines, most of which are accumulated in the plant seeds. Many drugs also contain natural plant ingredients and the pathways that lead to their production have been genetically altered or transferred to other plant species to produce greater volume and better products. Other options for bioreactors are biopolymers and biofuels. Unlike bacteria, plants can modify the proteins post-translationally, allowing them to make more complex molecules.They also pose less risk of being contaminated. Therapeutics have been cultured in transgenic carrot and tobacco cells, including a drug treatment for Gaucher's disease.
Vaccine production and storage has great potential in transgenic plants. Vaccines are expensive to produce, transport and administer, so having a system that could produce them locally would allow greater access to poorer and developing areas. As well as purifying vaccines expressed in plants it is also possible to produce edible vaccines in plants. Edible vaccines stimulate the immune system when ingested to protect against certain diseases. Being stored in plants reduces the long-term cost as they can be disseminated without the need for cold storage, don't need to be purified and have long term stability. Also being housed within plant cells provides some protection from the gut acids upon digestion. However the cost of developing, regulating and containing transgenic plants is high, leading to most current plant-based vaccine development being applied to veterinary medicine, where the controls are not as strict.
- Walter P, Roberts K, Raff M, Lewis J, Johnson A, Alberts B (2002). "Studying Gene Expression and Function". Molecular Biology of the Cell (4th ed.).
- Ganapathi TR, Suprasanna P, Rao PS, Bapat VA (2004). "Tobacco (Nicotiana tabacum L.) — A Model System for Tissue Culture Interventions and Genetic Engineering". Indian Journal of Biotechnology. 3: 171–184.
- Koszowski B, Goniewicz ML, Czogała J, Sobczak A (2007). "Genetycznie modyfikowany tytoń – szansa czy zagrozenie dla palaczy?" [Genetically modified tobacco--chance or threat for smokers?] (PDF). Przeglad Lekarski (in Polish). 64 (10): 908–12. PMID 18409340.
- Mou B, Scorza R (2011-06-15). Transgenic Horticultural Crops: Challenges and Opportunities. CRC Press. p. 104. ISBN 978-1-4200-9379-7.
- Gepstein S, Horwitz BA (1995). "The impact of Arabidopsis research on plant biotechnology". Biotechnology Advances. 13 (3): 403–14. doi:10.1016/0734-9750(95)02003-L. PMID 14536094.
- Holland CK, Jez JM (October 2018). "Arabidopsis: the original plant chassis organism". Plant Cell Reports. 37 (10): 1359–1366. doi:10.1007/s00299-018-2286-5. PMID 29663032.
- Jefferson RA, Kavanagh TA, Bevan MW (December 1987). "GUS fusions: beta-glucuronidase as a sensitive and versatile gene fusion marker in higher plants". The EMBO Journal. 6 (13): 3901–7. doi:10.1002/j.1460-2075.1987.tb02730.x. PMC 553867. PMID 3327686.
- "Biotechnology in Ornamental Plants - Pocket K". www.isaaa.org. Retrieved 2018-12-17.
- Chandler SF, Sanchez C (October 2012). "Genetic modification; the development of transgenic ornamental plant varieties". Plant Biotechnology Journal. 10 (8): 891–903. doi:10.1111/j.1467-7652.2012.00693.x. PMID 22537268.
- Nosowitz D (15 September 2011). "Suntory Creates Mythical Blue (Or, Um, Lavender-ish) Rose". Popular Science. Retrieved 30 August 2012.
- "Suntory to sell blue roses overseas". The Japan Times. 11 September 2011. Archived from the original on 22 November 2012. Retrieved 30 August 2012.
- "World's First 'Blue' Rose Soon Available in U.S". Wired. 14 September 2011.
- "Green genetic engineering now conquers the ornamental plant market as well". www.biooekonomie-bw.de. Retrieved 2018-12-17.
- Adams JM, Piovesan G, Strauss S, Brown S (2002-08-01). "The Case for Genetic Engineering of Native and Landscape Trees against Introduced Pests and Diseases". Conservation Biology. 16 (4): 874–79. doi:10.1046/j.1523-1739.2002.00523.x.
- Tripathi S, Suzuki J, Gonsalves D (2007). "Development of genetically engineered resistant papaya for papaya ringspot virus in a timely manner: a comprehensive and successful approach". Methods in Molecular Biology. 354: 197–240. doi:10.1385/1-59259-966-4:197. ISBN 978-1-59259-966-0. PMID 17172756.
- Qaim, Matin (2016-04-29). "Introduction". Genetically Modified Crops and Agricultural Development. Springer. pp. 1–10. ISBN 9781137405722.
- "Global Status of Commercialized Biotech/GM Crops: 2014 - ISAAA Brief 49-2014". ISAAA.org. Retrieved 2016-09-15.
- ISAAA 2013 Annual Report Executive Summary, Global Status of Commercialized Biotech/GM Crops: 2013 ISAAA Brief 46-2013, Retrieved 6 August 2014
- Darmency H (August 2013). "Pleiotropic effects of herbicide-resistance genes on crop yield: a review". Pest Management Science. 69 (8): 897–904. doi:10.1002/ps.3522. PMID 23457026.
- Green JM (September 2014). "Current state of herbicides in herbicide-resistant crops". Pest Management Science. 70 (9): 1351–7. doi:10.1002/ps.3727. PMID 24446395.
- Fleischer SJ, Hutchison WD, Naranjo SE (2014). "Sustainable Management of Insect-Resistant Crops". Plant Biotechnology. pp. 115–127. doi:10.1007/978-3-319-06892-3_10. ISBN 978-3-319-06891-6.
- "SGK321". GM Approval Database. ISAAA.org. Retrieved 2017-04-27.
- Qiu J (October 2008). "Is China ready for GM rice?". Nature. 455 (7215): 850–2. doi:10.1038/455850a. PMID 18923484.
- Ye X, Al-Babili S, Klöti A, Zhang J, Lucca P, Beyer P, Potrykus I (January 2000). "Engineering the provitamin A (beta-carotene) biosynthetic pathway into (carotenoid-free) rice endosperm". Science. 287 (5451): 303–5. Bibcode:2000Sci...287..303Y. doi:10.1126/science.287.5451.303. PMID 10634784.
- Frist B (21 November 2006). "'Green revolution' hero". Washington Times.
One existing crop, genetically engineered "golden rice" that produces vitamin A, already holds enormous promise for reducing blindness and dwarfism that result from a vitamin-A deficient diet.
- Black RE, Allen LH, Bhutta ZA, Caulfield LE, de Onis M, Ezzati M, Mathers C, Rivera J (January 2008). "Maternal and child undernutrition: global and regional exposures and health consequences". Lancet. 371 (9608): 243–60. doi:10.1016/S0140-6736(07)61690-0. PMID 18207566.
- Humphrey JH, West KP, Sommer A (1992). "Vitamin A deficiency and attributable mortality among under-5-year-olds". Bulletin of the World Health Organization. 70 (2): 225–32. PMC 2393289. PMID 1600583.
- Paine JA, Shipton CA, Chaggar S, Howells RM, Kennedy MJ, Vernon G, Wright SY, Hinchliffe E, Adams JL, Silverstone AL, Drake R (April 2005). "Improving the nutritional value of Golden Rice through increased pro-vitamin A content". Nature Biotechnology. 23 (4): 482–7. doi:10.1038/nbt1082. PMID 15793573.
- "US FDA approves GMO Golden Rice as safe to eat". Genetic Literacy Project. 2018-05-29. Retrieved 2018-05-30.
- Gasdaska JR, Spencer D, Dickey L (March 2003). "Advantages of Therapeutic Protein Production in the Aquatic Plant Lemna". BioProcessing Journal: 49–56.
- (10 December 2012) "Engineering algae to make complex anti-cancer 'designer' drug" PhysOrg, Retrieved 15 April 2013
- Büttner-Mainik A, Parsons J, Jérôme H, Hartmann A, Lamer S, Schaaf A, Schlosser A, Zipfel PF, Reski R, Decker EL (April 2011). "Production of biologically active recombinant human factor H in Physcomitrella". Plant Biotechnology Journal. 9 (3): 373–83. doi:10.1111/j.1467-7652.2010.00552.x. PMID 20723134.
- Baur A, Reski R, Gorr G (May 2005). "Enhanced recovery of a secreted recombinant human growth factor using stabilizing additives and by co-expression of human serum albumin in the moss Physcomitrella patens". Plant Biotechnology Journal. 3 (3): 331–40. doi:10.1111/j.1467-7652.2005.00127.x. PMID 17129315.
- Hammond J, McGarvey P, Yusibov V (2012-12-06). Plant Biotechnology: New Products and Applications. Springer Science & Business Media. pp. 7–8. ISBN 9783642602344.
- Börnke F, Broer I (June 2010). "Tailoring plant metabolism for the production of novel polymers and platform chemicals". Current Opinion in Plant Biology. 13 (3): 354–62. doi:10.1016/j.pbi.2010.01.005. PMID 20171137.
- Lehr F, Posten C (June 2009). "Closed photo-bioreactors as tools for biofuel production". Current Opinion in Biotechnology. 20 (3): 280–5. doi:10.1016/j.copbio.2009.04.004. PMID 19501503.
- "UNL's AgBiosafety for Educators". agbiosafety.unl.edu. Retrieved 2018-12-18.
- Protalix technology platform Archived 27 October 2012 at the Wayback Machine
- Gali Weinreb and Koby Yeshayahou for Globes 2 May 2012. "FDA approves Protalix Gaucher treatment Archived 29 May 2013 at the Wayback Machine"
- Concha C, Cañas R, Macuer J, Torres MJ, Herrada AA, Jamett F, Ibáñez C (May 2017). "Disease Prevention: An Opportunity to Expand Edible Plant-Based Vaccines?". Vaccines. 5 (2): 14. doi:10.3390/vaccines5020014. PMC 5492011. PMID 28556800.