Plant Tissue Culture: Micropropagation Techniques

• Plant tissue culture is used in micropropagation for field, ornamental, and medicinal plants.
• Micropropagation allows for rapid clonal propagation, disease elimination, and genetic improvement across plant species.

Micropropagation Techniques

• Micropropagation involves in vitro regeneration of plants from small tissue pieces known as explants.
• The steps are: explant selection, sterilization, culture initiation, multiplication, rooting, and acclimatization.
• Explants can be shoot tips, buds, leaves, or single cells.
• Sterilization prevents microbial contamination for successful culture establishment.
• Culture media contains nutrients, vitamins, and plant growth regulators (PGRs).
• Auxins like IAA and NAA and cytokinins like BAP and kinetin are common PGRs used for shoot and root development.
• Multiplication involves repeated subculturing to increase the number of shoots or embryos.
• Rooting can occur in vitro or ex vitro, depending on the plant species and protocol.
• Acclimatization adapts plantlets to ex vitro conditions.
• Micropropagation methods:
  • Axillary bud proliferation enhances shoot production from axillary buds.
  • Adventitious shoot regeneration induces shoots from callus or explant surfaces.
  • Somatic embryogenesis produces embryos from somatic cells.
  • Suspension culture uses cells or cell aggregates in liquid media for mass propagation.
  • Bioreactors are large-scale culture vessels used for efficient micropropagation.

Field Plant Applications

• Micropropagation benefits field crops by:
  • Rapid propagation of elite genotypes, quickly multiplying high-yielding or disease-resistant varieties.
  • Disease elimination, producing pathogen-free planting material.
  • Providing Uniformity, ensuring genetic consistency for growth and yield.
• Examples of field crops propagated via tissue culture:
  • Banana: Cavendish bananas are mass-produced via micropropagation.
  • Potato: virus-free seed potatoes.
  • Sugarcane: disease-free and high-yielding varieties.
  • Rice: genetic improvement and hybrid seed production.
  • Cassava: rapid multiplication of improved lines.
• Advantages for field crops:
  • Faster breeding cycles which accelerates introduction of new varieties.
  • Year-round propagation is independent of seasonal constraints.
  • Conservation of germplasm to preserve rare or endangered varieties.
• Challenges in field plant micropropagation:
  • High cost for some crops.
  • somaclonal variation my cause Genetic instability.
  • Acclimatization issues where plantlets may struggle to adapt.

Ornamental Plant Culture

• Micropropagation has changed ornamental plant production by:
  • Rapid multiplication which quickly increases availability of desirable cultivars.
  • Production of disease-free plants which Ensures healthy stock.
  • Year-round availability to meets market demands regardless of season.
  • Preservation of rare species which conserves unique or threatened plants.
• Popular ornamental plants propagated via tissue culture:
  • Orchids: mass propagation of unique hybrids.
  • Roses: production of disease-resistant and novel varieties.
  • Gerbera: uniform and high-quality plants.
  • Carnations: disease-free and long-lasting flowers.
  • Lilies: rapid scaling up of production.
• Techniques in ornamental plant micropropagation:
  • Shoot tip culture for virus-free plants.
  • Nodal culture for efficient multiplication.
  • Callus culture for inducing somaclonal variation and new traits.
• Advantages for the ornamental plant industry:
  • Introduction of new cultivars that accelerates market entry.
  • Consistent quality which meets consumer expectations.
  • Lower production costs through efficient propagation.
• Challenges include:
  • Somaclonal variation affecting flower color, shape, or plant habit.
  • Maintaining genetic integrity with careful selection and monitoring.
  • Cost-effectiveness: balancing production costs with market value.

Medicinal Plant Culture

• Micropropagation is vital in medicinal plant conservation and production:
  • Multiplication of rare species prevents over-collection from wild populations.
  • Production of uniform plants ensures consistent secondary metabolite content.
  • Using Disease-free stock enhances plant health and metabolite yield.
• Important medicinal plants propagated via tissue culture:
  • Ginseng: production of high-quality roots with consistent ginsenoside levels.
  • Digitalis: uniform production of cardiac glycosides.
  • Artemisia: increased artemisinin production for malaria treatment.
  • Coleus: production of forskolin for pharmaceutical applications.
  • Stevia: mass propagation of high-stevioside lines for sweeteners.
• Techniques in medicinal plant micropropagation:
  • Hairy root culture enhances secondary metabolite production.
  • Cell suspension culture enables large-scale production of bioactive compounds.
  • Elicitation can increase metabolite synthesis.
• Advantages for the medicinal plant industry:
  • Sustainable supply reduces pressure on wild populations.
  • Consistent product quality ensures reliable medicinal properties.
  • Enhanced metabolite production to increases yields of desired compounds.
• Challenges in medicinal plant micropropagation:
  • Complex secondary metabolite pathways require optimization for in vitro production.
  • Maintaining Genetic stability ensures consistent metabolite profiles.
  • There are Regulatory issues regarding compliance with pharmaceutical standards.
• Micropropagation enhances conservation efforts for endangered medicinal plants.
• In vitro production of secondary metabolites reduces reliance on field cultivation.
• Optimization of culture conditions increases the yield of valuable compounds.
• Tissue culture contributes to drug discovery and development by providing a consistent source of plant-based compounds.