1 Application status of plant genetic engineering in agriculture 1.1 Application of high-yield and comprehensive trait improvement breeding The main goal of genetic engineering breeding is high-quality, high-yield breeding. Before the 1990s, it was widely used in crops, and mainly to increase crop yields. Recently, it focused on improving quality. For example, American scientists increased potato starch content by 20%-40%, up to 40%-60%. At present, the genes and applications for improving the quality of crop products include: genes controlling fruit ripening; grain seed storage protein genes; controlling fat synthesis genes; and increasing crop yield genes. There are 43 varieties of crops in the world improved, such as rice, tomatoes, potatoes, melons, tobacco and so on. 1.2 Application of genetic engineering in resistance The development of genetic engineering has provided new means for the breeding of pest-resistant crops, thus opening up a new era of plant pest resistance breeding. Disease resistance gene engineering breeding is mainly to transplant the virus coat protein gene into crops so that the crops can resist the virus infection and cultivate new crop varieties such as antiviral tomato, antiviral tobacco and antiviral cucumber. The Biotechnology Research Center of the Chinese Academy of Agricultural Sciences cooperated with the Institute of Crops to introduce the bivalent genes of chitinase and glucanase into wheat, and to breed two-transgenic wheat with resistance to diseases such as scab, sheath blight and root rot. Sexual diseases. There are many kinds of genes that are resistant to plant pests. There are mainly three kinds of genes that are commonly used today. One is the Bacillus thuringiensis insecticidal crystal protein gene isolated from the microorganism Bacillus thuringiensis, or Dt gene for short; the second is the protease isolated from plants. Inhibitors, of which cowpea trypsin inhibitor gene (CpTI) is the most widely used; third, lectin gene. These transgenic crops can reduce the amount of insecticides and pesticides, reduce the pollution of insecticides and pesticides and their residues on the food chain and water, and thus help protect the ecological environment. 1.3 Application in Abiotic Stress Breeding With the development of biotechnology, it is now possible to cultivate herbicide-tolerant crop varieties through genetic engineering methods. The emergence of herbicide-tolerant transgenic plants not only extends the range of applications of existing herbicides, but also affects the design and use of new herbicides. At present, there are two main strategies for herbicide-tolerant genetic engineering: (1) modification of herbicide-target proteins to render them insensitive to herbicides, or to promote their overexpression so that plants can normally metabolize after receiving herbicides . (2) Introduction of enzymes or enzyme systems to degrade or detoxify herbicides before they occur. Both of these strategies have been successfully applied. The application of genetic engineering in drought resistance breeding provides new ideas for overcoming drought. Stanford University in the United States introduced cactus genes into wheat, soybean, and other crops, and developed new drought-resistant and resistant varieties. Research on the isolation, cloning, and transformation of stress-resistance genes in China has progressed. Salt- and alkali-resistant genes have been cloned, and 2% NaCL-tolerant tobaccos have been obtained through genetic transformation; and 1% Na-CL-resistant has been obtained. 0.8% NaCL resistant strawberry. 1.4 Application in Phyto-Pharmaceutical Genetic Engineering At present, the achievements in this area are mainly reflected in two aspects: one is the successful expression of antibodies in plants, and the second is the successful use of plants to produce certain animal vaccines. To date, more than 100 pharmaceutically active peptides and vaccines are being developed around the world. Among the polypeptide drugs are insulin, human growth hormone (HGH), interferon, interleukin, tissue plasminogen activator (TPA), immunoglobulin (Ig), and the like. The vaccine includes Leprosy vaccine, Meningococcal vaccine, Hepatitis B vaccine, Influenza vaccine and Human immunodeficiency virus vaccine. 2 The problems in the application of plant genetic engineering in agriculture 2.1 The development of genetic engineering itself The limitations of genetic engineering itself have technical problems that prevent them from being used quickly. These technical problems include low gene conversion rates, imperfect transformation systems, low ability to regulate foreign gene expression, and low genetic stability of transformed foreign genes. 2.2 Genetic engineering and protection of genetic diversity of agricultural resources Relying on plant genetic engineering technology, high light efficiency, resistance to pests and diseases, which can be designed and created in accordance with the wishes of humans, can grow in adversity, and high-quality "super varieties" are bound to become advantages in natural history. Species, thereby potentially exacerbating the genetic and genetic rarity of agricultural resources. Therefore, it is necessary to organically combine the development and utilization of target genes with the preservation of biological gene libraries. 2.3 Genetic engineering and pest resistance Drug resistance of pests and diseases is a major issue that plagues agricultural production. The genetic engineering operation will cause new pest resistance. 2.4 Genetic Engineering and Environmental Ecological Balance When people use plant genetic engineering to produce drought-resistant, salt-tolerant, and disease-resistant crops, they can also cause serious damage to biodiversity, and even extinction of some species. Biotechnology can also cause erosion and desertification in the earth. This result is due to the fact that biotechnology promotes the geographical expansion of crops that it has not adapted to, which may cause environmental and ecological problems. 2.5 Safety issues in genetic engineering The safety issues of genetically modified technologies include two aspects: safety to the human body and the environment. Genetically modified foods must be essentially the same as natural foods in terms of natural toxic substances, ingredients, anti-nutritional factors, allergens, etc. to be safe. For example, does a genetically modified product (such as a food product) have allergies, do they contain toxins, cause short-term or long-term damage to the human body, etc.; whether the genes of genetically modified crops will mutate or drift during natural growth, and whether they will change themselves or others? The genetic characteristics of the species, and so on. Transgenic plants are generally obtained by the transformation of antibiotic-labeled gene vectors. The genes that these antibiotics label will not harm the human body. So far, although there is no evidence that GM foods are unsafe, people's concerns about their safety will not be easily eliminated. 3 Application prospects of plant genetic engineering With the continuous development of transgenic technology, people recognize its good side, but also recognize its potential negative side, that is whether it will cause adverse effects on human health and ecological environment. When people realize the "two-sidedness" of GMO technology, how to take measures to use its advantages and overcome its potential harms will become an important issue for the further development of this technology.
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