MS Medium: Plant Tissue Culture

• Murashige and Skoog (MS) medium is a plant tissue culture medium that is widely used.
• It provides a balanced mix of nutrients for plant growth in vitro.

Components of MS Medium

• Macronutrients are essential elements needed in relatively large amounts.
• Examples of macronutrients include potassium nitrate (KNO3), ammonium nitrate (NH4NO3), calcium chloride (CaCl2), magnesium sulfate (MgSO4), and potassium phosphate monobasic (KH2PO4).
• Micronutrients are trace elements vital for enzyme function and metabolism.
• Examples of micronutrients include manganese sulfate (MnSO4), zinc sulfate (ZnSO4), copper sulfate (CuSO4), boric acid (H3BO3), and potassium iodide (KI).
• Vitamins act as coenzymes in metabolic processes.
• Examples of vitamins include myo-inositol, nicotinic acid, thiamine HCl, and pyridoxine HCl.
• Phytohormones, or Growth Regulators, influence plant growth and development.
• Auxins promote root formation and cell elongation.
• Cytokinins stimulate cell division and shoot formation.
• Sucrose serves as a carbon source.
• Agar solidifies the medium.

MS Medium Composition (per liter)

• Macronutrients (10x) Stock solution I includes 1650 mg/l NH4NO3, 1900 mg/l KNO3, 370 mg/l MgSO4.7H2O, and 170 mg/l KH2PO4 with 100 ml of medium.
• Macronutrient (10x) Stock solution II includes 440 mg/l CaCl2 2H2O with 100 ml of medium.
• Micronutrients (100x) Stock solution III includes 6.2 mg/l H3BO3, 22.3 mg/l MnSO4. 4H2O, 8.6 mg/l ZnSO4.7H2O, 0.83 mg/l KI, 0.25 mg/l Na2MOO4.2H2O, 0.025 mg/l CuSO45H2O and 0.025 mg/l CoCl2. 6H2O with 10 ml of medium.
• Iron source: 40 mg/l Fe EDTA Na salt (added fresh)
• Vitamins: 0.5 mg/l Nicotinic acid, 0.1 mg/l Thiamine HCl, and 0.5 mg/l Pyridoxine HCl (1 ml, 0.2 ml, and 1 ml respectively of 50 mg/100 ml stock), and 100 mg/l Myo-inositol (added fresh).
• Others: 2.0 mg/l Glycine (4 ml of 50 mg/100 ml stock), 30,000 mg/l Sucrose (added fresh), and 8000 mg/l Agar (added fresh)
• pH is adjusted to 5.8.

Preparation Steps for MS Medium

• Weigh each component accurately using a precision balance.
• Dissolve chemicals in high-quality distilled or deionized water, following a specific order to prevent precipitation.
• Use a magnetic stirrer for thorough mixing.
• Adjust the pH to 5.7-5.8 using HCl or KOH, using a calibrated pH meter.
• Add agar and heat to dissolve it completely.
• Bring the medium to the final volume, then dispense into culture vessels.
• Autoclave at 121°C and 15 psi for 15-20 minutes.
• Heat-liable items should be filter sterilized and added after the media has cooled.

Important Considerations

• Maintain sterility to prevent contamination by using aseptic techniques.
• Use high-grade chemicals to ensure chemical purity.
• Utilize distilled or deionized water to ensure water quality.
• Store stock solutions and prepared media properly.
• Handle chemicals with care for safety.