Choose the right medium for your plant

Plant tissue culture media includes a variety of ingredients: inorganic salts, vitamins, amino acids, growth regulators, sugars, agar (or gellan gum), and water. All of these ingredients have at least one or more effects in plant tissue culture.

Mineral elements in plant tissue culture media are used to synthesize organic molecules or act as catalysts in enzymatic reactions after entering plant cells. Soluble salt ions play an important role as counter ions in the transport of plant ionized molecules, regulation of osmotic pressure and maintenance of the electrochemical potential of plants.

Nitrogen, sulfur and phosphorus are components of proteins and nucleic acids. Magnesium ions and many trace elements are essential components of many enzymes and organelles and therefore play an important catalytic role in a variety of reactions. Calcium and boric acid are mainly present in the cell wall of plants, especially calcium ions play an important role in maintaining biofilm stability. In contrast, potassium ions and chlorides play an important role in osmotic adjustment, participating in maintaining the balance of the electrochemical potential, and are also activators of many enzymes.

The following is an introduction to commonly used media:

MS medium, originally designed by Murashige and Skoog for tobacco cell culture in 1962, has been improved and can now be used for tissue culture of various plants, such as potatoes, carrots, cabbage, etc. Many researchers have different experimental needs. , has developed an improved MS medium including 1/2 large elements, containing 3 / 4 large elements, NaNO3 instead of NH4NO3, NH4NO3, 1/2NH4NO3 and KNO3, etc., generally need to be based on specific test materials Specific media are selected for the purpose of the test.

N6 medium, defined to improve the formation, growth and differentiation of rice pollen callus. The optimum range for NH4+ ion concentration is 7.0 mM (or 3.5 mM (NH4)2SO4)). High concentrations of ammonium salts significantly inhibit the growth and differentiation of rice pollen. The concentration of KNO3 and other ingredients in the medium does not affect the growth of pollen.

B5 medium was designed in 1968 by Gamborg et al. for the cultivation of soybean root cells, and dicotyledonous plants were more suitable for growth on B5 medium. The main feature of the B5 (Gamborg) medium is that it contains lower ammonium because ammonium may inhibit the growth of many cultures.

NB medium, a large amount of elements in N6 medium and a trace element and vitamin mixture of B5 medium.

The woody plant medium, also known as WPM medium, was designed by Lloyd and McCown for the tip culture of the mountain laurel in 1981. It was modified according to the MS medium. Compared with the MS medium, potassium sulfate was used instead of potassium nitrate. The content of ammonium nitrate is also reduced to 1/4 of that of MS medium. The nitrogen salt is also mainly supplied in the form of calcium nitrate, and is mainly used for tissue culture of woody plants.

Precautions for configuring the medium :

1. Adjust the pH. Use a dropper to absorb the amount of the substance in a 1 mol/L NaOH solution (generally the medium is just acidic), drip into the dissolved medium, and stir while dropping. The pH of the medium was measured at any time with a precision pH test paper (5.4 to 7.0) until the pH of the medium was 5.8 (the pH of the medium must be strictly controlled at 5.8). It should be noted here that many students have clearly adjusted the PH value to 5.8 when they are doing the medium but still do not coagulate. The reason may be:

a. First check the amount and quality of agar in the medium components.

b. If there is no problem with the agar, the sterilization time is too long, and it is generally difficult to coagulate after 0.15 MPa for more than 1 hour.

c. If all of the above are normal, we should also consider whether the weighing tool is accurate. Some weighing tools purchased in small markets are not very accurate. It is recommended that the weighing tools be purchased from regular manufacturers or professional stores.

2. The medium in which the medium is dissolved and dissolved should be hot-packed. Be careful not to let the medium get on the bottle mouth and the bottle wall, as it sticks to the bottle mouth and is easily contaminated.

3, the pH should not be adjusted to avoid the callback and affect the concentration of each ion in the medium.
4. Stir constantly to prevent the agar paste from burning.

5. Prepare in strict accordance with the medium formula.