Title: Schenk and Hildebrandt (SH) Medium: A Comprehensive Guide in Plant Tissue Culture
In the field of plant biotechnology, the development of refined tissue culture media has proven indispensable for the success of in vitro plant growth, propagation, and research. One such seminal medium is the Schenk and Hildebrandt (SH) Medium, which has been instrumental in advancing studies, particularly in promoting root and callus development in plant tissue cultures.
What is Schenk and Hildebrandt (SH) Medium?
Schenk and Hildebrandt (SH) medium was developed by Schenk and Hildebrandt in 1972 specifically for the culture of excised tissues such as callus formation, root, and cell suspension cultures. Primarily intended for dicot species, this medium is especially effective for the in-vitro cultivation of carrot, potato, and tobacco tissues, as well as other plant species that require enhanced supplementation for growth and differentiation processes.
Even today, SH Medium remains a popular choice for plant scientists due to its balanced macro and micronutrients and its relatively high concentration of potassium and phosphate, which play critical roles during cellular growth, tissue differentiation, and organogenesis.
Uses of Schenk and Hildebrandt (SH) Medium
Callus Induction: SH medium is frequently employed for promoting callus formation from explants. It is particularly effective when culturing cells or tissues with the aim of regenerating new plant material from undifferentiated cell masses.
Root Induction: This medium encourages the robust root development that is essential for the stabilization and in vitro acclimatization of plantlets during micropropagation.
Cell Suspension Cultures: SH Medium is often used in cell suspension cultures, facilitating the propagation of plant cells in a liquid environment, which is useful for secondary metabolite production and biotechnological work.
Genetic Transformation: SH medium serves as a growth foundation in a variety of plant genetic transformation studies, allowing transformed cells or tissues to recover and proliferate.
- Micropropagation: It is used for the rapid propagation and multiplication of plant species in controlled conditions, especially for species that require specific nutrient provisions to facilitate growth.
Composition of Schenk and Hildebrandt Medium (SH Medium)
The SH Medium contains a range of macronutrients, micronutrients, vitamins, and a carbon source, all crucial for plant growth in a synthetic environment. Given below is the classical formulation for Schenk and Hildebrandt medium on a per liter basis:
Macronutrients:
| Component | Concentration (mg/L) |
|---|---|
| Potassium Nitrate (KNO₃) | 2500.000 |
| Potassium Phosphate monobasic (KH₂PO₄) | 136.000 |
| Ammonium Sulfate ((NH₄)₂SO₄) | 134.000 |
| Magnesium Sulfate (MgSO₄∙7H₂O) | 370.000 |
| Calcium Chloride (CaCl₂∙2H₂O) | 148.000 |
Micronutrients:
| Component | Concentration (mg/L) |
|---|---|
| Boric Acid (H₃BO₃) | 6.200 |
| Cobalt Chloride (CoCl₂∙6H₂O) | 0.020 |
| Copper Sulfate (CuSO₄∙5H₂O) | 0.025 |
| Ferrous Sulfate (FeSO₄∙7H₂O) | 27.850 |
| Manganese Sulfate (MnSO₄∙H₂O) | 22.300 |
| Potassium Iodide (KI) | 0.830 |
| Sodium Molybdate (Na₂MoO₄∙2H₂O) | 0.250 |
| Zinc Sulfate (ZnSO₄∙7H₂O) | 8.600 |
| EDTA (Disodium salt) | 37.300 |
Vitamins:
| Component | Concentration (mg/L) |
|---|---|
| Thiamine-HCl | 10.000 |
| Myo-Inositol | 100.000 |
Carbon Source:
| Component | Concentration (g/L) |
|---|---|
| Sucrose | 30.000 |
pH: Although SH medium can be used at different pH levels depending on the plant species being cultured, it is typically adjusted to 5.8 before autoclaving.
Preparation of SH Medium
The preparation of SH medium begins with weighing out and dissolving the required macronutrients, followed by micronutrients, vitamins, and sucrose into distilled or deionized water. The pH is then adjusted to around 5.8 using either HCl or NaOH as necessary. Once completed, the total solution volume is made up to 1 liter. Afterward, the medium is sterilized by autoclaving at 121°C for 15-20 minutes.
If the inclusion of plant growth regulators (like auxins or cytokinins) is required for specific experimental protocols (e.g., callus induction or shoot regeneration), these are added after sterilization, once the medium has cooled down to an appropriate handling temperature (around 50°C).
Conclusion
Schenk and Hildebrandt medium has stood the test of time as one of the best multi-purpose growth media for the in vitro growth of various plant species. It offers a well-balanced nutrient composition that has been shown to foster effective callus induction, root development, and cell suspension cultures, making it indispensable in plant tissue culture laboratories around the world.
Whether you’re involved in commercial micropropagation efforts or conducting research in fundamental plant biology, incorporating SH Medium into your experimental designs can be the key to unlocking better and more reliable results.
References:
- Schenk, R.U., Hildebrandt, A. C. (1972). Medium and Techniques for Induction and Growth of Monocotyledonous and Dicotyledonous Plant Cell Cultures. Canadian Journal of Botany, 50(1): 199-204.