4 Most SAQ’s of Biotechnology and its Applications Chapter in Inter 2nd Year Botany (TS/AP)

4 Marks

SAQ-1 : List out the beneficial aspects of transgenic plants.

Introduction

Transgenic plants, also known as genetically modified (GM) plants, are engineered to possess certain traits that enhance their productivity, nutritional value, and resistance to pests and diseases. The beneficial aspects of transgenic plants include:

1. Resistance to Pests and Diseases: Transgenic plants can be engineered to have increased resistance to pests and diseases. Examples include Bt cotton, resistant to insects, and transgenic papaya, resistant to papaya ring spot virus. This resistance reduces the need for chemical pesticides, leading to more sustainable agriculture and safer food products.
2. Improved Nutritional Content: Certain transgenic plants have been modified to have increased nutritional value. An example is Golden Rice, engineered to produce beta-carotene, a precursor of Vitamin A. This can help prevent Vitamin A deficiency, a major public health concern in some countries.
3. Improved Food Processing Qualities: Transgenic plants can also have improved food processing qualities. For instance, the transgenic tomato variety “Flavr Savr” has been engineered for delayed ripening, which makes it bruise resistant and extends its shelf life, facilitating storage and transport.
4. Facilitating Hybrid Seed Production: Transgenic technology can be used to produce male sterile plants, which can facilitate the production of hybrid seeds. This can eliminate the need for manual emasculation and reduce the cost of hybrid seed production.
5. Tolerance to Abiotic Stresses: Transgenic plants can be engineered to be more tolerant to abiotic stresses, such as cold, drought, salt, and heat. They can also be designed to be resistant to certain chemicals, enabling them to survive in conditions where non-GM plants cannot. An example is Roundup Ready soybean, resistant to the herbicide glyphosate.

Summary

In summary, transgenic plants offer many potential benefits, from increasing agricultural productivity and sustainability, to improving food nutrition and quality, to facilitating the production of hybrid seeds. These advantages highlight the significant potential of GM technology in addressing some of the world’s major agricultural and nutritional challenges.

---

SAQ-2 : What are some bio-safety issues concerned with genetically modified crops?

Introduction

Genetically Modified (GM) crops, while offering significant benefits like improved crop yields and pest resistance, also present several bio-safety concerns. These concerns are related to potential risks to human health, biodiversity, and the environment. Below are some key issues:

1. Allergenicity and Toxicity: A primary concern with GM crops is the potential to create new allergens or toxins. There is a fear that inserting genes into plants might lead to unexpected allergic reactions in susceptible individuals or increase the levels of naturally occurring toxins in the crops.
2. Impact on Non-Target Organisms: GM crops designed for pest resistance might harm non-target organisms, such as beneficial insects or soil microbes. This could disrupt ecosystems and reduce biodiversity.
3. Gene Flow: Gene flow from GM crops to non-GM crops or wild relatives is a concern. This cross-pollination could create ‘superweeds’ resistant to herbicides or pests, posing threats to biodiversity and complicating weed management.
4. Unintended Effects on Crop Traits: The genetic modification process could unintentionally alter other crop traits, like nutritional content, taste, or resistance to certain environmental conditions.
5. Impact on Agricultural Practices: GM crops could contribute to the intensification of monoculture farming, increasing vulnerability to pests and diseases and reducing biodiversity.
6. Evolutionary Changes: There is concern that the widespread use of GM crops could accelerate the evolution of pests and diseases resistant to the engineered traits. This might necessitate further genetic modifications or additional pesticide use.

Summary

In conclusion, while GM crops offer many potential benefits, it is crucial to carefully address these bio-safety issues. Rigorous testing and regulatory oversight are essential to mitigate risks and ensure the safety of GM crops for human consumption and the environment.

---

SAQ-3 : Give a brief account of Bt cotton.

Introduction

Bacillus thuringiensis (Bt) cotton is a transgenic cotton variety with a gene from the bacterium Bacillus thuringiensis integrated into its genome. This genetic modification enables Bt cotton to produce an insecticide toxic to various insects, providing inherent protection against certain pests.

1. Origin: Bt cotton derives its name from Bacillus thuringiensis, a bacterium naturally producing a toxin lethal to certain insects. Scientists identified and inserted the gene responsible for this toxin into the cotton plant’s genome using genetic engineering techniques.
2. Toxin Production: Bt cotton plants produce the Bt toxin throughout their tissues as an inactive protoxin, which is harmless to the plant.
3. Pest Control: When pests like the cotton bollworm consume Bt cotton, they ingest the protoxin. The alkaline pH in the insect’s gut activates the toxin, forming pores in the insect’s gut cell membranes and leading to the insect’s death. The Bt toxin, encoded by genes such as Cry I Ac and Cry II Ab, is insect-group specific and effective against cotton bollworms, while Cry I Ab targets corn borers.
4. Benefits: Bt cotton has significantly reduced the need for chemical pesticides in cotton farming, leading to cost savings for farmers and a reduced environmental impact. It effectively controls insects, including those resistant to sprayed insecticides.
5. Widespread Adoption: Bt cotton is widely adopted globally, with millions of farmers in countries like India, China, and the United States cultivating this GMO variety.

Summary

Despite its benefits, Bt cotton has also raised concerns about potential impacts on non-target organisms, the development of Bt-resistant pests, and socio-economic issues for farmers. Hence, the cultivation of Bt cotton should be carefully managed within an integrated pest management strategy.

---

SAQ-4 : Give a brief account of pest resistant plants.

Introduction

Pest-resistant plants, developed using advanced biotechnology methods, aim to enhance agricultural output and reduce dependency on chemical pesticides. A key technique in creating pest-resistant plants is RNA interference (RNAi), which hinders the translation of specific mRNAs.

1. Need for Pest-Resistant Plants: Various pests, including insects, bacteria, viruses, and nematodes, can significantly damage agricultural crops. An example is the nematode Meloidogyne incognitia, which infects tobacco plant roots, reducing tobacco production.
2. Role of Biotechnology: Biotechnology provides tools for genetically engineering plants to be resistant to these pests. Introducing specific genes into plants enables them to counteract or repel the targeted pest.
3. RNAi Technique: RNAi is a cellular defense mechanism that silences specific mRNA molecules, preventing protein translation. This approach is used to create pest-resistant plants, such as transgenic tobacco plants resistant to nematodes using Agrobacterium vectors.
4. Process of RNAi: In transgenic plants, introduced DNA produces both sense and antisense RNAs. These complementary RNAs form a double-stranded RNA (dsRNA), initiating the RNAi process. The corresponding specific mRNA is then degraded or its translation inhibited, silencing the gene.
5. Pest Control: RNAi silences the genes of the nematode within the host plant, hindering the nematode’s survival and reproduction. This resistance enhances the plant’s growth and yield in the presence of pests.
6. Outcome: Pest-resistant plants contribute to sustainable agriculture by reducing the need for chemical pesticides, decreasing environmental pollution, and increasing crop yields.

Summary

While pest-resistant plants, developed through techniques like RNAi, offer promising solutions for sustainable agriculture, there are concerns about their environmental impact and the potential for pests to develop resistance. Thus, these techniques should be part of broader pest management strategies.