Murashige and Skoog medium  (or  MSO  or  MS0  (MS-zero) ) is the most popular plant growth medium  used   in laboratories worldwide for cultivating plant cell cultures  on agar . MS0  was invented in 1962 by plant scientists Toshio Murashige and Folke K. Skoog during Murashige's search for a new growth regulator.

A number after the letters  MS  indicates the sucrose content of the medium. For example,  MS0 contains  no sucrose,  while MS20  contains 20 g/L sucrose. Together with its modifications, it is the most commonly used medium for plant tissue culture experiments in the laboratory.

As Skoog's doctoral student, Murashige originally set out to search for a previously undiscovered growth hormone in tobacco sap. However, no such compound was found; instead, analyses of tobacco sap and tobacco ash revealed higher concentrations of certain minerals in plant tissue than previously known. A series of experiments showed that different concentrations of these inorganic nutrients significantly enhanced growth compared to existing formulations. Nitrogen, in particular, promoted tobacco growth in tissue cultures.

However, according to recent scientific findings,  MS  medium is not suitable as a nutrient solution for deep water culture or hydroponics , and organic compounds are not required for normal plant nutrition.

Important salts (macronutrients)

• Ammonium nitrate (NH  ₄  NO  ₃  ) 1650 mg/l
• Calcium chloride (CaCl  ₂  · 2H  ₂  O) 440 mg/l
• Magnesium sulfate (MgSO  ₄  7H  ₂  O) 180.7 mg/l
• Monopotassium phosphate (KH  ₂  PO  ₄  ) 170 mg/l
• Potassium nitrate (KNO  ₃  ) 1900 mg/l

Trace salts (micronutrients)

• Boric acid (H  ₃  BO  ₃  ) 6.2 mg/l
• Cobalt chloride (CoCl  ₂  6H  ₂  O) 0.025 mg/l
• Iron sulfate (FeSO  ₄  7H  ₂  O) 27.8 mg/l
• Manganese(II) sulfate (MnSO  ₄  · 4H  ₂  O) 22.3 mg/l
• Potassium iodide (KI) 0.83 mg/l
• Sodium molybdate (Na  ₂  MoO  ₄  · 2H  ₂  O) 0.25 mg/l
• Zinc sulfate (ZnSO  ₄  ·7H  ₂  O) 8.6 mg/l
• Ethylenediaminetetraacetic acid iron(III) sodium (FeNaEDTA) 36.70 mg/L
• Copper sulfate (CuSO  ₄  5H  ₂  O) 0.025 mg/l

Vitamins and organic compounds

• Myo-Inositol 100 mg/l
• Nicotinic acid 0.5 mg/l
• Pyridoxine HCl 0.5 mg/l
• Thiamine HCl 0.1 mg/l
• Glycine 2 mg/l
• Tryptone 1 g/l (optional)
• Indoleacetic acid 1-30 mg/l (optional)
• Kinetin 0.04–10 mg/l (optional)

Sources: https://en.wikipedia.org/wiki/Murashige_and_Skoog_medium, https://en.wikipedia.org/wiki/Toshio_Murashige

Image: By Juandev - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=47459533

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