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What determines the type of opine found in crown galls?
Nopaline strains contain two T-DNA regions of different sizes.
False
What are the two types of opine mentioned in the content?
Nopaline and Octopine
The bacteria used in the study is called __________.
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Match the following strains with their respective opine:
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What is the main function of VirA?
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Viable bacteria are no longer necessary for tumor growth beyond how many days post-inoculation?
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VirB is responsible for processing T-DNA in the plant nucleus.
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Tumors can form if the tissue is incubated at room temperature for at least one day before heat-killing the bacteria.
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What was the temperature used to kill the bacteria in the experiments?
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Which Vir gene is involved in cutting the T-DNA at the borders?
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VirF is thought to degrade host cell factors during ______.
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Match the following Vir genes with their functions:
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What triggers the induction of vir genes in Agrobacterium?
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The T-DNA transferred to the plant cell is a double-stranded molecule.
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What are the two main border regions flanking the T-DNA in Agrobacterium?
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What is the primary purpose of Agrobacterium tumefaciens in plant cells?
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During T-DNA processing, the _____ protein is responsible for auto-phosphorylation.
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Match the following Agrobacterium components with their roles:
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Agrobacterium tumefaciens can transform fungi, but not non-plant species.
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What two virulence loci on the Ti plasmid are mentioned as determining the range of plant species that can be transformed?
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The dominant selection marker system widely used in fungi is the _____ gene, which confers resistance to hygromycin.
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Match the following terms with their descriptions:
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Which gene is commonly associated with kanamycin resistance in plant systems?
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Plant-active selectable marker genes are typically associated with herbicide resistance only.
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What is the function of the CaMV-35S promoter in plant transformation?
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The ____ gene is used as a reporter system in plant transformation, allowing for detection of transformed tissues.
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Match the following elements with their correct descriptions:
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What is typically used as a carbon source to eliminate E.coli from Agrobacterium cultures?
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The transient expression of T-DNA can occur within the first 12 hours after agroinfiltration.
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What is one primary characteristic of T-DNA Binary vectors?
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Study Notes
Opines and Crown Galls
- Opines are specialized compounds produced in crown galls, a result of Agrobacterium tumefaciens infection.
- The type of opine produced is dictated by the specific strain of bacterium, with notable examples being octopine and nopaline.
T-DNA Characteristics
- Nopaline strains feature a single T-DNA region, approximately 20kb in size.
- Octopine strains contain two T-DNA regions (T1 and TR), sized around 14kb and 17kb, respectively.
Tumor Independence
- Tumors can become independent from the bacteria a few days post-inoculation, as bacteria alter host cells by transferring DNA.
- A lag exists between infection and tumor growth, as demonstrated by experiments with inoculated periwinkle stems.
Agrobacterium Gene Transfer
- Agrobacterium tumefaciens transfers DNA into plant cell genomes, prompting cells to divide and produce opines for bacterial sustenance.
- Virulence (vir) loci on the Ti plasmid, such as virC and virF, impact the range of plant species that can develop crown gall tumors.
Agrobacterium-Mediated Transformation in Fungi
- In 1995, successful transformation of Saccharomyces cerevisiae using Agrobacterium tumefaciens-mediated transformation (ATMT) was reported.
- More than 125 fungal species have been transformed, often using the hygromycin phosphotransferase gene as a selection marker.
Broad Host Range of ATMT
- Agrobacterium tumefaciens can transform a wide range of plant species, including monocots and dicots, as well as non-host organisms like fungi and algae.
- It facilitates both transient and stable transformation methods in plants.
Virulence Genes (Vir Genes)
- VirA: Senses plant phenolic compounds induced by wounding.
- VirG: Functions as a cytoplasmic response element for transcription of other vir genes.
- VirB: Comprises 11 proteins essential for T-DNA substrate transfer and T-pilus formation.
- VirD: Processes T-DNA through five genes, with virD2 acting as an endonuclease/integrase.
- VirE: Includes virE1 (chaperone) and virE2 (forms channels in membranes for T-DNA).
- VirF: Aids in the breakdown of host cell factors during infection and assists T-DNA release.
T-DNA Integration Process
- The T-strand, a single-stranded molecule, is transferred into the plant cell, rather than a double-stranded DNA molecule.
- VirA activates VirG, leading to the induction of other vir genes in the presence of phenolic signals.
Marker Genes and Reporter Systems in Plants
- Selection markers like neomycin phosphotransferase (NPTII) and hygromycin phosphotransferase (HPT) are utilized for resistance.
- Reporter systems include β-D-glucuronidase (GUS), various luciferases (LUC), and green fluorescent protein (GFP).
Characteristics of T-DNA Binary Vectors
- Include left and right border repeat sequences to ensure only T-DNA is integrated.
- Contain plant-active selectable marker genes, typically for antibiotic or herbicide resistance.
- Feature restriction sites for gene-of-interest insertion and origins of replication for maintenance in both E. coli and Agrobacterium.
Transient Transformation
- Non-integrated T-DNA can persist in the nucleus, allowing transient gene expression.
- Expression of transgenes can occur within 3–5 days post-inoculation, often reaching high levels within 2-4 days in species like lettuce and tobacco.
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Description
Explore the fascinating world of plant pathology with a focus on opines found in crown galls. This quiz dives into the types of opines and their significance in plant biology. Test your knowledge and deepen your understanding of plant diseases.