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2024+Plant+Tissue+Culture+and+Propagation

Culture of Horticultural Plants In Vitro Propagation

  • In vitro propagation of plant parts (cells, tissues, organs) is used in ornamental nurseries (e.g., orchids, African violets).

  • Tissue culture applications include:

    • Potato seed certification for healthy stocks

    • Production of virus-free strawberries

    • Panama disease-free banana plants

  • Commonly cultured plants: Begonia, Rosa, Chrysanthemum, Grapevine.

Micropropagation

  • Definition: Clonal in vitro propagation from cells/tissues/organs in a controlled environment.

  • Terms:

    • Clone: Population from a single cell/plant via mitosis.

    • In vitro: Biological processes outside the living organism.

Macropropagation vs Micropropagation

  • Macropropagation: Photoautotrophic growth, larger propagules, non-aseptic conditions.

  • Micropropagation: Heterotrophic growth, smaller propagules, aseptic conditions.

Plant Tissue Culture

  • Definition: "Preparation of isolated somatic cells growing in vitro, functioning normally" - P.R. White.

History of Plant Tissue Culture

  • Gottlieb Haberlandt (1902): Proposed that plant cells can grow/divide with proper nutrients; concept of totipotency.

  • Early attempts: cells grew but did not divide; growth stimuli were later linked to phytohormones.

    • Key discoveries:

      • Auxin (Fritz Went & Kenneth Thimann, 1937)

      • Coconut milk for callus formation (J. van Overbeek, 1941)

      • Kinetin (Carlos Miller & Folke Skoog, 1955)

      • MS media (Toshio Murashige & Folke K. Skoog, 1962).

Plant Growth Regulators (PGRs)

  • Common PGRs:

    • Auxin: Promotes growth/division, root formation.

    • Cytokinin: Promotes cell division, shoot formation.

    • Gibberellin: Stimulates division, flowering, growth post-seed germination.

  • High concentrations of auxin (IBA) and cytokinin (Zeatin) lead to callus formation (undifferentiated cells).

  • Somaclonal Variation: Variations due to rapid cell division increase mutation chances.

Media Requirements for Tissue Culture

  • Essential components: Water, essential minerals (N, P, K...), carbon source (sucrose), vitamins, PGRs, gelling substances (e.g., agar).

Main Steps in Plant Tissue Culture

  1. Maintain stock plants for explant material.

  2. Prepare and sterilize media and explant material.

  3. Culture plant material in defined media under suitable conditions.

  4. Transfer plantlets to potting mix, acclimate for planting.

Explant Material

  • Taken from young, actively growing donor plants (leaves, shoots, meristems).

Sterilization Measures

  • Media: Autoclave at 121°C for 15-20 min.

  • Plant Material: Surface sterilized (diluted bleach, alcohol).

  • Culture Facility: Use laminar flow hoods for sterile conditions.

Four Stages of Micropropagation

  1. Donor plant selection and preparation.

  2. Establish aseptic culture through surface sterilization.

  3. Propagule multiplication.

  4. Rooting and acclimatization of plantlets.

Micropropagation Systems

  • Types: leaf/petiole segment culture, axillary shoot culture, somatic embryogenesis, etc.

Tissue Culture Applications

  • Germplasm conservation, rapid clonal propagation, genetic transformation, production of important plant compounds.

Meristem Culture

  • Isolating and growing meristems for virus-free stock resulting in genetically stable plants.

Advantages and Disadvantages of Micropropagation

  • Advantages: Rapid multiplication, disease-free material, long-term storage, continuous propagation.

  • Disadvantages: High start-up costs, contamination risk, specialized facilities needed, difficulty in propagating some plants via tissue culture.