Transgenic Science in Plant Improvement
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Questions and Answers

What is the most commonly used promoter in plant transformation?

The CaMV 35S promoter from cauliflower mosaic virus.

What role do selectable markers play in the process of plant transformation?

Selectable markers help identify successfully transformed cells by allowing them to survive in the presence of antibiotics or herbicides.

Which tissue types are commonly used for transformation in plants?

Immature embryos, leaf disks, and apical meristems.

Name one method used for introducing a gene construct into plant cells.

<p>Agrobacterium mediated transformation.</p> Signup and view all the answers

What happens to plant cells lacking the selectable marker gene during transformation?

<p>They get killed or their growth is arrested.</p> Signup and view all the answers

What hormone is primarily responsible for initiating rooting in cultured transformed cells?

<p>Auxin is primarily responsible for initiating rooting.</p> Signup and view all the answers

What is the significance of auxin/cytokinin ratio in the regeneration of transformants?

<p>The auxin/cytokinin ratio is crucial for promoting the growth and regeneration of cultured transformed plant cells.</p> Signup and view all the answers

During the selection of transformants, what kind of media do the seeds of infiltrated plants get plated on?

<p>Agar containing kanamycin.</p> Signup and view all the answers

Which method is used to study gene expression by detecting mRNA in a plant sample?

<p>Northern blot is used to study gene expression by detecting mRNA.</p> Signup and view all the answers

What is the significance of isolating and cloning the gene of interest in transgenic plant development?

<p>It is a crucial first step that requires extensive resources to identify and develop genes important for agriculture.</p> Signup and view all the answers

What is the purpose of using the nopaline synthase gene in plant transformations?

<p>It is commonly used as a terminator sequence.</p> Signup and view all the answers

What are some traits that can be engineered using the plastid genome?

<p>Traits like herbicide resistance, insect resistance, and antibiotic resistance can be engineered.</p> Signup and view all the answers

Which evaluation is crucial for ensuring the safety of transgenic plants as food or feed?

<p>Evaluation for food or feed safety is crucial.</p> Signup and view all the answers

How do Bt genes contribute to insect resistance in crops?

<p>Bt genes encode for cry proteins that produce toxins, leading to cell lysis in the gut of the insect, causing their death.</p> Signup and view all the answers

What is the main action of the cry protein in the digestive tract of insects?

<p>The cry protein forms pores in the cell membrane of the insect gut, leading to cell lysis and the insect's death.</p> Signup and view all the answers

What type of stress can chloroplast engineering help plants withstand?

<p>Chloroplast engineering can help plants withstand abiotic stresses like drought and salinity.</p> Signup and view all the answers

What role do promoters and 5' UTR elements play in the expression of transgenic genes?

<p>They regulate the level of gene expression, determining how efficiently the transgenic traits are expressed in the plant.</p> Signup and view all the answers

What type of bacteria produces the cry protein used for biopesticides?

<p><em>Bacillus thuringiensis</em> produces the cry protein, which is toxic to various insect groups.</p> Signup and view all the answers

What is the role of proteolysis concerning the cry protein and insect gut?

<p>Proteolysis of the cry protein crystals in the insect gut converts them into a soluble form, releasing the active toxin.</p> Signup and view all the answers

What is a truncated cry gene's purpose in transgenic crops?

<p>It is used to produce insect-resistant crops by encoding a modified version of the cry protein.</p> Signup and view all the answers

Which insect orders are affected by the toxicity of the Cry protein?

<p>The Cry protein is toxic to Lepidoptera, Coleoptera, Hymenoptera, Diptera, and Nematode orders.</p> Signup and view all the answers

What effect does the over-expression of enzymes required for GlyBet biosynthesis have on transgenic plants?

<p>It improves tolerance to various abiotic stresses.</p> Signup and view all the answers

Which enzyme catalyzes the conversion of choline into betaine aldehyde?

<p>Choline monooxygenase (BvCMO).</p> Signup and view all the answers

What type of plants were developed to express betaine aldehyde dehydrogenase for salt tolerance?

<p>Transplastomic carrot plants.</p> Signup and view all the answers

What is one application of chloroplast engineering in agriculture mentioned?

<p>Production of biopharmaceutical proteins.</p> Signup and view all the answers

Which promoter is used in the expression of the 'Human serum Albumin' gene in chloroplast transformation?

<p>Prrn and PpabA.</p> Signup and view all the answers

Name one vaccine antigen expressed via chloroplast transformation.

<p>Cholera toxin (ctxB).</p> Signup and view all the answers

How does chloroplast engineering compare to conventional nuclear transgene expression?

<p>It represents an attractive alternative for metabolic engineering.</p> Signup and view all the answers

What is the site of integration for the 'Interferon gamma' gene in chloroplast transformation?

<p>rbcL/accD.</p> Signup and view all the answers

Which gene is used for expressing an antimicrobial peptide in chloroplast engineering?

<p>MSI-99.</p> Signup and view all the answers

What are the 5'/3' regulatory elements associated with the 'Tetanus toxin' gene?

<p>T7 gene 10, atpB/Trbcl.</p> Signup and view all the answers

Study Notes

Transgenic Science in Plant Improvement

  • Transgenic plants are created by transferring or modifying genes from another organism using physical, chemical, or biological methods.
  • Genes are introduced into the plant genome using vectors to develop new traits.
  • Recombinant DNA technology is employed to produce genetically modified plants, enhancing pest, disease, and stress resistance or quality.
  • Conventional breeding can also be used if the desired traits are present in close relatives. If not, transgenesis is the only viable option.
  • Genetic engineering bypasses limitations of conventional breeding, such as large space requirements, time consumption, and uncertainty of outcomes.
  • Rational decision-making is guided by the flow chart provided in Figure 6-1.2.1, which determines if the trait is naturally present in related varieties.

Gene Identification and Cloning

  • Identifying and cloning the target gene is a crucial initial step in transgenic development.
  • Locating, characterizing, and cloning agriculturally important genes is a substantial undertaking requiring significant resources.
  • The early development of insect-resistant crops using transgenic technology was a significant advancement.
  • The Bt gene (or cry gene), encoding a protein found in the bacterium Bacillus thuringiensis (Bt), was a key discovery leading to insect-resistant crops.
  • Spores of Bt contain a crystal protein (6-endotoxin) which, when ingested by insects, disrupts their gut lining, leading to insect death.
  • Figure 6-1.2.2.2 illustrates the structure of the truncated cry gene.

Gene Expression Control

  • Gene expression levels are controlled by regulatory sequences (e.g., promoters).
  • The CaMV 35S promoter, originating from cauliflower mosaic virus, is a common constitutive promoter.
  • The nopaline synthase (nos) gene from Agrobacterium tumefaciens is frequently used as a terminator sequence.
  • Selectable markers are used for identifying which plant cells have taken up the desired gene during transformation.

Plant Transformation Methods

  • Different methods are used to introduce genes into plant cells (transformation).
  • Agrobacterium-mediated transformation is a common approach.
  • Other methods include agro-infection, chloroplast transformation, indirect gene transfer, electroporation, biolistic (gene gun) method, chemical methods, microinjection, pollen transformation, and direct uptake by mature zygotic embryos.

Selection of Transformed Plants

  • Transformation success is confirmed using various methods like media containing antibiotics in transformed cells/tissues.
  • Selectable marker genes (e.g., conferring antibiotic resistance) help to identify cells that successfully incorporated the gene.

Transgenic Plant Regeneration

  • Through tissue culture, regenerated whole plants with inserted genes are produced.
  • Appropriate conditions, like the auxin/cytokinin ratio, are crucial for regeneration.

Transgenic Plant Confirmation

  • Phenotype observation is used to confirm the presence and activity of the introduced gene.
  • Techniques such as Southern blotting, Northern blotting, and Western blotting are used to study gene expression.
  • Evaluation of the transformed plant's response to various environmental factors like food and feed safety, and basic containment levels are also conducted.

Plant Trait Improvement

  • Modifying the plastid genome can enhance traits such as herbicide resistance, insect resistance, and antibiotic resistance.
  • Expression of insect resistance genes can be successfully introduced without modifications to codon usage.

Abiotic Stress Tolerance

  • Chloroplast engineering can be used to enhance abiotic stress tolerance in plants by producing enzymes like choline monooxygenase.

Biopharmaceutical Production

  • Chloroplast engineering can be used to produce biopharmaceuticals like proteins and antigens.

Metabolic Pathway Engineering

  • Chloroplast engineering can be an effective alternative to nuclear methods for metabolic engineering.
  • Examples include the synthesis of polyhydroxybutyrate (PHB), a bioplastic.

Examples of GM Crops

  • Specific examples, like Sorghum, Sunflower, Canola, Wheat, Sugar Beet, and Alfalfa, are provided with their respective trait enhancements and wild relatives.

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Description

Explore the principles and techniques of transgenic science in plant improvement. This quiz covers the processes of genetic engineering, gene identification, and how these methods enhance plant traits. Test your knowledge on the applications and benefits of recombinant DNA technology in agriculture.

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