Murashige and Skoog’s medium is the most widely used tissue culture medium, of which many variations have been developed. The medium originates from White’s medium and was originally developed for the cultivation of Nicotiana tabacum calli. Compared to the white medium, the concentration of all ingredients is increased. An increase to 50-60 mM nitrogen significantly stimulated the growth of Nicotiana cells, however, a concentration of 80 mM and higher was clearly disadvantageous to the cells.
The increase in all other elements, especially the macroelements, also stimulated the growth of calluses. Due to the high concentration of minerals, the MS medium is a very rich and saline medium and may be too salty for certain plant species. To avoid this problem, DM is often used with the microelements at full concentration, but with the macro elements at half or three-quarters concentration, respectively, as originally described by the authors. Sometimes the original MS vitamins are replaced by the vitamins from the Linsmaier and Gamborg B5 medium due to the higher concentration of Thiamine in relation to the requirement of this vitamin by the plants.
Instructions for use:
Dissolve 4.54 g of dehydrated medium in 600 ml of distilled or deionized water at room temperature (15-30°C). Rinse the media vial with a small amount of distilled water to remove energy debris. Add desired heat-stable supplements prior to autoclaving. Continue stirring until the powder has dissolved. Sometimes media will not completely dissolve unless the pH is lowered. For these, lower the pH to around 3.0 to make it easier to dissolve the media. The pH of the medium is adjusted using 1N HCl/ 1N NaOH/ 1NKOH.
Make up the final volume to 1000 ml with distilled water. Mix gently, heat and swirl between intervals until the solution becomes clear. Do not boil, reheat and allow to cool below 50°C during dispensing. Dispense the medium into suitable containers, stopper or lid, then autoclave at 15 pso (121*C) for 15 minutes, using a slow exhaust cycle. Higher temperatures and/or longer times are not recommended. Cool the autoclaved culture vessels containing the medium to 45-50*C and aseptically add the desired sterile heat labile substrate.
Note: Media must be prepared according to the formula listed on the label; however, it is recommended to use one full container at a time. Heat-sensitive substrates should be added after autoclaving.
Storage and shelf life:
Dehydrated plant tissue culture media are hygroscopic and must be protected from sunlight and moisture. Store the prepared medium at 2-8*C away from direct light. The medium must be used before the expiration date. The entire volume of each bottle should be used immediately after opening or the unused portion should be stored in desiccators and refrigerated at 2-8°C.