Plant Pathology: Opines in Crown Galls
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Questions and Answers

What determines the type of opine found in crown galls?

  • The environmental conditions
  • The plant species
  • The size of the tumor
  • The bacterium (correct)

    • 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 __________.

    <p>Agrobacterium tumefaciens</p> Signup and view all the answers

    Match the following strains with their respective opine:

    <p>Octopine-utilizing strain = Octopine Nopaline-utilizing strain = Nopaline</p> Signup and view all the answers

    What is the main function of VirA?

    <p>Senses plant phenolic compounds</p> Signup and view all the answers

    Viable bacteria are no longer necessary for tumor growth beyond how many days post-inoculation?

    <p>Two days</p> Signup and view all the answers

    VirB is responsible for processing T-DNA in the plant nucleus.

    <p>False</p> Signup and view all the answers

    Tumors can form if the tissue is incubated at room temperature for at least one day before heat-killing the bacteria.

    <p>False</p> Signup and view all the answers

    What was the temperature used to kill the bacteria in the experiments?

    <p>47°C</p> Signup and view all the answers

    Which Vir gene is involved in cutting the T-DNA at the borders?

    <p>VirD2</p> Signup and view all the answers

    VirF is thought to degrade host cell factors during ______.

    <p>infection</p> Signup and view all the answers

    Match the following Vir genes with their functions:

    <p>VirA = Senses plant phenolic compounds VirB = Forms the T-pilus for substrate transfer VirD2 = Cuts T-DNA at the borders VirE2 = Binds to T-DNA</p> Signup and view all the answers

    What triggers the induction of vir genes in Agrobacterium?

    <p>Presence of sugars and phenolics</p> Signup and view all the answers

    The T-DNA transferred to the plant cell is a double-stranded molecule.

    <p>False</p> Signup and view all the answers

    What are the two main border regions flanking the T-DNA in Agrobacterium?

    <p>Left Border (LB) and Right Border (RB)</p> Signup and view all the answers

    What is the primary purpose of Agrobacterium tumefaciens in plant cells?

    <p>To reprogram plant cells to divide and produce opines</p> Signup and view all the answers

    During T-DNA processing, the _____ protein is responsible for auto-phosphorylation.

    <p>VirA</p> Signup and view all the answers

    Match the following Agrobacterium components with their roles:

    <p>VirA = Signal detection and transduction VirG = Regulation of virulence gene expression Ti Plasmid = Carries T-DNA and virulence genes T-DNA = Integrates into the host genome</p> Signup and view all the answers

    Agrobacterium tumefaciens can transform fungi, but not non-plant species.

    <p>False</p> Signup and view all the answers

    What two virulence loci on the Ti plasmid are mentioned as determining the range of plant species that can be transformed?

    <p>virC and virF</p> Signup and view all the answers

    The dominant selection marker system widely used in fungi is the _____ gene, which confers resistance to hygromycin.

    <p>hygromycin phosphotransferase</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Agrobacterium tumefaciens = Natural plant pathogen that transfers DNA to plant cells Opines = Chemicals produced by transformed plant cells Saccharomyces cerevisiae = A commonly transformed fungal species using ATMT hygromycin phosphotransferase = Gene that provides antibiotic resistance in fungi</p> Signup and view all the answers

    Which gene is commonly associated with kanamycin resistance in plant systems?

    <p>neomycin phosphotransferase (NPTII)</p> Signup and view all the answers

    Plant-active selectable marker genes are typically associated with herbicide resistance only.

    <p>False</p> Signup and view all the answers

    What is the function of the CaMV-35S promoter in plant transformation?

    <p>To control the expression of transgenes</p> Signup and view all the answers

    The ____ gene is used as a reporter system in plant transformation, allowing for detection of transformed tissues.

    <p>GUS</p> Signup and view all the answers

    Match the following elements with their correct descriptions:

    <p>NPTII = Gene for kanamycin resistance HPT = Gene for hygromycin resistance GUS = Reporter for gene expression GFP = Fluorescent protein used as a reporter</p> Signup and view all the answers

    What is typically used as a carbon source to eliminate E.coli from Agrobacterium cultures?

    <p>Sucrose</p> Signup and view all the answers

    The transient expression of T-DNA can occur within the first 12 hours after agroinfiltration.

    <p>True</p> Signup and view all the answers

    What is one primary characteristic of T-DNA Binary vectors?

    <p>Contains left and right border repeat sequences</p> Signup and view all the answers

    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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    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.

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