Applications of Genetic Engineering in Agriculture | A-Level 生物：基因工程在农业中的应用

📚 Applications of Genetic Engineering in Agriculture | A-Level 生物：基因工程在农业中的应用

Genetic engineering, also known as genetic modification (GM), involves the direct manipulation of an organism’s genome using biotechnology. In agriculture, this technology has revolutionised crop improvement by enabling the transfer of desirable traits, such as pest resistance or enhanced nutrition, across species barriers that would be impossible through traditional breeding.

基因工程又称遗传修饰（GM），是指利用生物技术直接操纵生物体基因组的过程。在农业领域，这项技术通过跨越传统育种无法突破的物种界限，转移抗虫性或增强营养等优良性状，彻底改变了作物改良的方式。

1. Core Techniques in Plant Genetic Engineering | 植物基因工程的核心技术

Successful genetic modification of crops relies on a set of core techniques. The key steps include: isolation of the gene of interest using restriction endonucleases, insertion of the gene into a vector (usually the Ti plasmid of Agrobacterium tumefaciens), transformation of plant cells, and regeneration of whole plants via tissue culture.

作物遗传修饰的成功依赖于一系列核心技术。关键步骤包括：利用限制性内切酶分离目的基因，将基因插入载体（通常是根癌农杆菌的Ti质粒），转化植物细胞，并通过组织培养再生完整植株。

The Ti plasmid is particularly useful because it naturally transfers a segment of its DNA (T-DNA) into plant chromosomes. Scientists replace the tumour-inducing genes with the desired trait gene, allowing the plant to express new characteristics without forming tumours.

Ti质粒尤为有用，因为它能自然地将其DNA片段（T-DNA）转移到植物染色体中。科学家用所需性状基因替换致瘤基因，使植物在不形成肿瘤的情况下表达新性状。

Gene construct = Promoter + Coding sequence + Terminator + Selectable marker

基因构建体 = 启动子 + 编码序列 + 终止子 + 选择标记

The promoter drives expression of the transgene; a constitutive promoter like CaMV 35S ensures expression in all tissues.

启动子驱动转基因的表达；像CaMV 35S这样的组成型启动子确保基因在所有组织中表达。
A selectable marker gene (e.g. antibiotic resistance gene) allows transformed cells to survive on selective media.

选择标记基因（如抗生素抗性基因）使转化细胞能在选择培养基上存活。

2. Insect Resistance: Bt Crops | 抗虫性：Bt作物

One of the most widespread applications of genetic engineering in agriculture is the creation of insect-resistant crops using genes from the bacterium Bacillus thuringiensis. This bacterium produces a crystalline protein (Cry protein) that is toxic to specific insect pests, particularly lepidopteran larvae such as corn borers and cotton bollworms.

基因工程在农业中最广泛的应用之一，是利用苏云金芽孢杆菌的基因培育抗虫作物。这种细菌能产生晶体蛋白（Cry蛋白），对特定害虫有毒，尤其是玉米螟和棉铃虫等鳞翅目幼虫。

When an insect feeds on Bt crop tissue, the alkaline conditions in its gut solubilise the inactive protoxin. Proteases then cleave it into an active toxin that binds to midgut epithelial cell receptors, forming pores. This leads to cell lysis, cessation of feeding, and ultimately death of the pest. Importantly, the toxin only activates in the alkaline insect gut, so it remains harmless to mammals and other non-target organisms.

当害虫取食Bt作物组织时，其肠道内的碱性环境使无活性的前毒素溶解，蛋白酶将其切割为活性毒素。活性毒素与中肠上皮细胞受体结合并形成孔道，导致细胞裂解、停止取食，最终害虫死亡。重要的是，毒素仅在昆虫肠道的碱性环境中激活，因此对哺乳动物和其他非靶标生物无害。

Feature 特点	Benefit 益处
Target-specific toxicity 靶标特异性毒性	Reduces harm to beneficial insects 减少对益虫的伤害
Continuous protection 持续性保护	Bt toxin produced throughout plant growth 整个生长期持续产生Bt毒素
Reduced chemical pesticide use 减少化学农药使用	Lower environmental pollution 降低环境污染

3. Herbicide Tolerance | 耐除草剂性状

Herbicide-tolerant (HT) crops are engineered to withstand the application of specific broad-spectrum herbicides, such as glyphosate. This allows farmers to spray herbicides over the entire field, killing weeds while leaving the crop unharmed.

耐除草剂（HT）作物经过基因工程改造，能耐受草甘膦等特定广谱除草剂的施用。这使得农民可以在整个田间喷洒除草剂，杀死杂草而不伤害作物。

The most common strategy is to introduce a gene that encodes a herbicide-insensitive version of the target enzyme. For glyphosate, the target is EPSP synthase, an enzyme in the shikimate pathway essential for synthesising aromatic amino acids. The CP4 gene from Agrobacterium sp. strain CP4 encodes a glyphosate-resistant form of EPSP synthase, enabling the crop to survive glyphosate application.

最常见的策略是引入编码对除草剂不敏感的靶标酶基因。以草甘膦为例，其靶标是EPSP合酶，这是莽草酸途径中负责合成芳香族氨基酸的关键酶。来自农杆菌CP4菌株的CP4基因编码一种对草甘膦具有抗性的EPSP合酶，使作物在施用草甘膦后存活。

Glyphosate inhibits EPSP synthase → Shikimate pathway blocked → Plant dies

草甘膦抑制EPSP合酶 → 莽草酸途径受阻 → 植物死亡

HT crops enable no-till farming, reducing soil erosion and improving soil organic matter. However, over-reliance has led to the evolution of herbicide-resistant weeds, requiring integrated weed management strategies.

耐除草剂作物使得免耕种植成为可能，减少水土流失并改善土壤有机质。然而，过度依赖也导致抗性杂草的进化，因此需要综合杂草管理策略。

4. Enhanced Nutritional Content: Golden Rice | 增强营养含量：黄金大米

Golden Rice is a landmark example of genetic engineering aimed at improving human nutrition. It was developed to address vitamin A deficiency (VAD), which causes blindness and increased mortality in millions of children in developing countries.

黄金大米是基因工程改善人类营养的里程碑式案例。它旨在解决维生素A缺乏症（VAD），这种缺乏症导致发展中国家数百万儿童失明和死亡率上升。

Vitamin A is not synthesised by plants; humans obtain it from animal sources or convert β-carotene (provitamin A) from plants. Conventional rice does not accumulate β-carotene in the endosperm. Genetic engineers introduced three genes: psy (phytoene synthase) from daffodil or maize, crtI (phytoene desaturase) from Erwinia uredovora, and lyc (lycopene β-cyclase) from maize. These complete the biosynthetic pathway in the rice endosperm, enabling β-carotene production.

植物本身不合成维生素A，人类通过动物性食物摄取维生素A，或将植物中的β-胡萝卜素（维生素A原）转化而来。传统水稻的胚乳中不积累β-胡萝卜素。基因工程师引入了三个基因：来自水仙或玉米的psy（八氢番茄红素合酶基因）、来自欧文氏菌的crtI（八氢番茄红素脱氢酶基因）以及来自玉米的lyc（番茄红素β-环化酶基因）。这些基因在稻米胚乳中完整了生物合成通路，使β-胡萝卜素的产生成为可能。

The characteristic yellow colour of Golden Rice, due to β-carotene accumulation, gave the crop its name. A single bowl of Golden Rice can provide around 60% of the recommended daily intake of vitamin A for a child.

黄金大米因β-胡萝卜素积累呈现出特征性的黄色而得名。一碗黄金大米即可提供儿童每日推荐摄入量约60%的维生素A。

5. Disease Resistance | 抗病性

Plant diseases caused by viruses, fungi, and bacteria account for substantial crop losses worldwide. Genetic engineering offers several strategies to enhance disease resistance.

由病毒、真菌和细菌引起的植物病害在全球造成巨大的作物损失。基因工程提供了多种增强抗病性的策略。

For viral resistance, pathogen-derived resistance is commonly used. Introducing the viral coat protein gene into the plant genome triggers RNA interference (RNAi). When the virus infects the plant, the presence of homologous double-stranded RNA activates the RNAi pathway, leading to degradation of viral mRNA and suppressing viral replication.

针对病毒抗性，常采用病原体衍生抗性策略。将病毒外壳蛋白基因导入植物基因组可触发RNA干扰（RNAi）。当病毒感染植物时，同源双链RNA的存在激活RNAi通路，导致病毒mRNA降解并抑制病毒复制。

For fungal resistance, genes encoding pathogenesis-related (PR) proteins, such as chitinases and β-1,3-glucanases, are introduced. These enzymes degrade fungal cell wall components, weakening the pathogen’s ability to establish infection.

针对真菌抗性，通常会引入编码病程相关（PR）蛋白的基因，如几丁质酶和β-1,3-葡聚糖酶。这些酶能降解真菌细胞壁组分，削弱病原体建立感染的能力。

6. Abiotic Stress Tolerance | 非生物胁迫耐受性

Environmental stresses such as drought, salinity, and extreme temperatures severely limit agricultural productivity. Genetic engineering aims to improve crop tolerance to these abiotic stresses.

干旱、盐碱和极端温度等环境胁迫严重限制农业生产力。基因工程旨在提高作物对这些非生物胁迫的耐受性。

For drought tolerance, genes encoding osmoprotectants—such as trehalose, proline, and glycine betaine—are introduced. These compatible solutes help maintain cellular water balance and protect proteins and membranes from dehydration damage. Additionally, transcription factors like DREB1A regulate the expression of multiple stress-responsive genes, providing broader stress tolerance.

针对耐旱性，通常会引入编码渗透保护剂（如海藻糖、脯氨酸和甘氨酸甜菜碱）的基因。这些相容性溶质有助于维持细胞水分平衡，保护蛋白质和膜免受脱水损伤。此外，DREB1A等转录因子可调节多个胁迫响应基因的表达，提供更广泛的胁迫耐受性。

For salt tolerance, genes encoding vacuolar Na⁺/H⁺ antiporters are introduced. These transporters sequester excess sodium ions into the vacuole, preventing toxic accumulation in the cytoplasm and maintaining ionic homeostasis.

针对耐盐性，引入编码液泡Na⁺/H⁺逆向转运蛋白的基因。这些转运蛋白将多余的钠离子隔离到液泡中，防止其在细胞质中有害积累，维持离子稳态。

Stress tolerance involves multiple genes and complex regulatory networks

胁迫耐受涉及多基因和复杂的调控网络

7. Improved Shelf Life and Quality | 延长保质期和改善品质

Genetic modification can extend the shelf life of perishable produce by modifying genes involved in ripening. The most famous example is the Flavr Savr tomato, developed in the 1990s, which used antisense RNA technology to suppress the expression of the polygalacturonase (PG) gene.

基因修饰可通过改变与成熟相关的基因来延长易腐农产品的保质期。最著名的例子是1990年代开发的Flavr Savr番茄，它利用反义RNA技术抑制多聚半乳糖醛酸酶（PG）基因的表达。

PG is an enzyme that degrades pectin in the cell wall, causing fruit softening during ripening. By introducing an antisense copy of the PG gene, the mRNA of the native gene is targeted for degradation, reducing PG enzyme levels below 10% of normal. The tomatoes could be left on the vine longer for better flavour development while maintaining firmness during transport.

PG是一种降解细胞壁果胶的酶，在成熟过程中导致果实软化。通过引入PG基因的反义拷贝，内源基因的mRNA被靶向降解，使PG酶水平降至正常的10%以下。这些番茄可以在藤上停留更长时间以充分发展风味，同时在运输过程中保持坚实度。

8. Risk Assessment and Biosafety | 风险评估与生物安全

Despite the benefits of genetically modified crops, concerns about their environmental and health impacts have driven extensive risk assessment and biosafety regulation.

尽管转基因作物具有诸多益处，但对其环境和健康影响的担忧推动了广泛的风险评估和生物安全监管。

One key concern is gene flow—the transfer of transgenes from GM crops to wild relatives through pollen. This could create herbicide-resistant weeds or disrupt natural ecosystems. To mitigate this, strategies such as male sterility, chloroplast transformation (which prevents pollen-mediated gene flow), and geographic isolation are employed.

一个关键担忧是基因漂移，即转基因从GM作物通过花粉转移到野生近缘种。这可能导致抗除草剂杂草的出现或破坏自然生态系统。为缓解这一问题，采用雄性不育、叶绿体转化（阻止花粉介导的基因流）以及地理隔离等策略。

Another concern is the development of resistance in pest populations. Long-term planting of Bt crops exerts strong selection pressure on pests, favouring individuals with resistance mutations. The ‘refuge strategy’ addresses this by planting non-Bt refuges nearby, maintaining a susceptible pest population that dilutes resistance alleles through interbreeding.

另一个担忧是害虫种群抗性的发展。长期种植Bt作物对害虫施加强选择压力，有利于携带抗性突变的个体存活。’避难所策略’通过附近种植非Bt避难所来应对这一问题，维持易感害虫种群，通过与抗性个体交配稀释抗性等位基因。

9. Ethical and Socioeconomic Considerations | 伦理与社会经济考量

The deployment of GM crops raises important ethical and socioeconomic questions. Critics argue that large corporations control the seed supply and that farmers become dependent on proprietary seeds and associated agrochemicals.

转基因作物的推广引发了重要的伦理和社会经济问题。批评者认为，大公司控制着种子供应，农民变得依赖专有种子及配套的农用化学品。

Proponents counter that GM technology has helped smallholder farmers by reducing crop losses, improving yields, and decreasing pesticide exposure. The Cartagena Protocol on Biosafety provides an international framework for balancing the benefits of biotechnology with the need to protect biodiversity and human health.

支持者反驳说，GM技术通过减少作物损失、提高产量和降低农药接触，帮助了小农。卡塔赫纳生物安全议定书为平衡生物技术的益处与保护生物多样性和人类健康的需要提供了国际框架。

Transparency and informed choice are also crucial. Many countries require mandatory labelling of GM products, allowing consumers to make decisions based on their values and preferences, while maintaining scientific evidence as the foundation of regulatory decisions.

透明度和知情选择也至关重要。许多国家要求对转基因产品进行强制性标签标识，允许消费者根据自己的价值观和偏好做出决定，同时将科学证据作为监管决策的基础。

10. Future Directions | 未来发展方向

The future of genetic engineering in agriculture is increasingly focused on precision and sustainability. CRISPR-Cas9 gene editing technology enables scientists to make targeted modifications to an organism’s own genome without introducing foreign DNA, potentially addressing some public concerns about GMOs.

农业基因工程的未来日益侧重于精准和可持续性。CRISPR-Cas9基因编辑技术使科学家能够对生物体自身基因组进行靶向修饰，而不引入外源DNA，这可能解决公众对转基因生物的一些担忧。

Synthetic biology approaches are being explored to engineer entire metabolic pathways, such as nitrogen fixation in cereals, which could reduce dependence on synthetic fertilisers. Climate-resilient crops with enhanced carbon sequestration capacity are also under development.

合成生物学方法正被用于工程化完整的代谢途径，例如谷物的固氮能力，这可能减少对合成肥料的依赖。增强碳封存能力的气候韧性作物也在开发中。

As our understanding of plant genomics and molecular mechanisms deepens, genetic engineering will continue to play an increasingly important role in addressing global food security challenges in an environmentally sustainable manner.

随着我们对植物基因组学和分子机制的理解不断深入，基因工程将继续以环境可持续的方式在应对全球粮食安全挑战中发挥越来越重要的作用。

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Applications of Genetic Engineering in Agriculture | A-Level 生物：基因工程在农业中的应用