Introduction of transgenic soybean

Introduction: in 1994, Roundup Ready soybeans (RR soybeans), a genetically modified herbicide resistant soybean launched by Monsanto, became the first genetically modified soybean variety approved for promotion Roundup is a non selective broad-spectrum herbicide Its active ingredient is glyphosate Since it was first registered in the United States in 1974, roundup has been registered and promoted in more than 100 countries in the world Nongda is less toxic and safer to the environment No carcinogenicity, teratogenicity or mutagenicity was found in the laboratory Animals can degrade glyphosate through their kidneys, and soil microorganisms can decompose glyphosate into carbon dioxide and inorganic salts The principle of killing weeds is to inhibit the activity of EPSP synthetase in plant essential fatty acid biosynthesis pathway, so as to kill weeds The chemical structure of EPSP synthetase in some bacteria is different from that in plants and other bacteria, and its activity is not easy to be inhibited The EPSP synthetase gene, which is not sensitive to glyphosate, was introduced into soybean to protect soybean from glyphosate This genetically modified soybean is called RR soybean In addition, Aventis has been approved to promote GM soybeans resistant to the broad-spectrum herbicide glufosinate; DuPont has been approved by the U.S Food and Drug Administration (FDA) in 1997 to promote GM soybeans with high oleic acid (70%); at present, low linolenic acid (2%), low palmitate (4%), high stearic acid (28%) and high palmitate (27%) are trans based soybeans Because the variety has been successfully cultivated in the United States Since the introduction of transgenic soybean, the planting area has expanded rapidly In 1996, the planting area of GM soybeans in Nongda was 500000 hectares, increased to 4.45 million hectares in 1997, 13 million hectares in 1998, and 16.2 million hectares in 1999, accounting for more than 50% of the total soybeans in the United States; Argentina produced nearly 20 million hectares of soybeans annually, 70% - 90% of which were GM soybeans The production cost of transgenic soybean is 30% - 35% lower than that of traditional soybean, and the yield is 15% - 20% higher The advantages of GM soybean with broad-spectrum herbicide resistance are that the amount of herbicide can be greatly reduced, the period of spraying pesticide is not restricted by the growth and development period of soybean, farmers only use drugs according to the occurrence of weeds; the number of times of application is reduced from 5-7 to 1-2, reducing energy consumption and water and soil loss The transgenic method can improve the properties of soybean, improve the nutritional value, oxidation stability and functionality of soybean oil, and help to improve the added value of oil products The development fields of transgenic soybean breeding include: first, continue to pay attention to the improvement of single traits such as herbicide resistance and insect resistance 2 Improvement of quality, agronomic and multiple characters 3 Tolerance to abiotic adversity such as drought, salinization, low temperature, ultraviolet radiation and adverse conditions The current focus areas are: (1) improve the composition of fatty acids, enhance functionality and meet market demand (2) improve the composition of amino acids and improve the nutritional value (3) reduce the content of phytate and phosphorus, improve the nutritional value of soybean to animals, and reduce the phosphorus emission of poultry to the environment (4) increase sucrose content and sweetness, reduce stachyose content, improve the digestibility and palatability of soybean (5) soybean was used as bioreactor to produce high-value protein drugs The methods of obtaining transgenic soybean are mainly Agrobacterium mediated method and gene gun method, the former is more commonly used; there are also successful cases of transferring foreign genes Agrobacterium mediated method: Agrobacterium, including Agrobacterium tumefaciens (containing Ti plasmid) and Agrobacterium rhizogenes (containing Ri plasmid), can integrate a single or a few copies of foreign genes, and can obtain a high transformation frequency when cultured with plant cells under certain conditions for a period of time It has become the first transformation method to be considered and widely used by researchers Gene gun method: gene gun relies on particles to accelerate the bombardment of embryogenic suspension cell lines and embryogenic tissues, and directly penetrates genes (generally plasmid DNA) into complete plant cells The bombarding materials can be callus, meristem, pollen and stem tip The key to the success of the technology is to be able to regenerate fertile plants from transformed cells, that is, the regeneration ability of the cell lines used Many studies have shown that immature embryo tissue is the best material Pollen tube pathway method: mediated genetic transformation is a direct transformation technology with the help of the egg cells or fertilized eggs of the plant's own germplasms as the transformation objects Exogenous genes or DNA can enter the fertilized embryo sac through pollen tube pathway, so it is called pollen tube pathway method Due to the characteristics of no genotype restriction and easy to achieve large-scale gene transformation, gene transfer can be achieved between flowering plants and different species, so that the receptor species can obtain new genotypes as well as new phenotypic characters expressed by transgenes The efficiency of transgenic breeding is limited by the low frequency of Agrobacterium in the regeneration and transformation of transgenic soybean Conventional breeding method is an indispensable means The transgenic plants obtained need to be crossed with the excellent varieties with good comprehensive characters, and the later is the recurrent parent backcross, which can be transformed into commercial varieties with good comprehensive characters and special transfer characters (author:) share to feed Weibo share to: