Tissue culture
Tissue culture (especially plant tissue culture) is a laboratory technique where cells, tissues, or organs are grown on a nutrient medium under sterile conditions. It is widely used in agriculture, biotechnology, and research.
🌱 Explant
- Explant is the small piece of plant tissue used to start the culture.
- It can come from leaf, stem, root, bud, or meristem.
- The explant must be healthy and disease-free so the culture grows properly.
- The explant should be young, healthy, and disease-free.
- Before culturing, it is surface sterilized to remove microorganisms.
🧪 Nutrient Medium
- A nutrient medium supplies food and minerals required for growth.
- Commonly used medium: Murashige and Skoog (MS) medium.
- It contains:
- Macronutrients – nitrogen, phosphorus, potassium, calcium
- Micronutrients – iron, zinc, manganese, boron
- Vitamins
- Sugar (sucrose) for energy
- Agar to solidify the medium
- The pH of medium is usually around 5.6–5.8.
🌿 Plant Growth Regulators
- Plant hormones regulate cell growth and differentiation.
- Important hormones used in tissue culture:
- Auxins – stimulate root formation and callus growth
- Cytokinins – stimulate shoot formation
- Gibberellins – help in stem elongation
- Abscisic acid – regulates dormancy
- The ratio of auxin to cytokinin determines whether roots or shoots develop.
🧼 Sterile (Aseptic) Conditions
- Tissue culture requires complete sterility to avoid contamination.
- Common sterilization methods:
- Autoclave – sterilizes media and equipment
- Alcohol or sodium hypochlorite – sterilizes explants
- Laminar airflow cabinet – provides sterile working area
- Workers usually wear gloves, masks, and lab coats.
🧫 Culture Vessels
- Culture vessels are containers where plant tissues are grown.
- They must be clean and sterilized.
- Common vessels include:
- Test tubes
- Petri dishes
- Culture bottles
- Glass jars or flasks
- Workers usually wear gloves, masks, and lab coats.
🌡️ Controlled Environmental Conditions
- Tissue cultures grow best under controlled conditions:
- Temperature: 20–27°C
- Light intensity: 1000–3000 lux
- Photoperiod: about 16 hours light / 8 hours dark
- Humidity: around 50–70%
