All plants require nutrients to grow. In addition to oxygen, carbon dioxide, and water, plants require at least 14 mineral elements for adequate nutrition.
Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S) are called macronutrients and are required by plants in comparatively large amounts. These elements play an essential role in proper plant development and growth since their major functions range from being structural units to redox-sensitive agents.
Moreover, micronutrients (or trace minerals) include iron (Fe), boron (B), chlorine (Cl), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), and nickel (Ni). Micronutrients are essential components that are required in small quantities for plant growth and development.
Macro and micronutrients perform different nutritional functions in plants. Macronutrients, such as nitrogen, help to enhance seed and fruit production along with better leaf development, high quality forage in crops, and rapid plant growth. Phosphorous is known as an essential constituent of the plant cell membrane, where it exists as phosphate and is an essential constituent of adenosine triphosphate, ribonucleic acid, and deoxyribose nucleic acid.
Micronutrients such as manganese play a role in the electron transport chain in photosynthesis and act as enzyme activators involved in the citric acid cycle, phosphorous reactions, carbohydrate metabolism, carboxylation processes, and oxidation reactions. For instance, when zinc is incorporated as a component of proteins, it acts as a functional, structural, or regulatory cofactor of many enzymes. Furthermore, recent studies associate zinc with plant defense (Cabot et al., 2019).
Both macro and micronutrients remain in the soil as salts so plants absorb these elements as ions. Since plants cannot move, they cannot go shopping for food; therefore, they must absorb what is found available in the surrounding soil.
This situation changes when working with plant tissue culture. Any plant tissue used in vitro (also called explant) acts as a diner, or is heterotrophic, meaning you have to provide the food for growth—you become a chef preparing the menu for plants!
In cell culture, there are different options to provide a nutrient. For example, potassium can be provided as potassium nitrate (KNO3) and potassium dihydrogen phosphate (KH2PO4). A balance of the other nutrients being added in parallel, such N and P, is required in the recipe.
Besides macro and micronutrients, a carbon source must be provided in the in vitro process since it is the energy source for plants. It is usually added as sucrose (C12H22O11) or glucose (C6H12O6).
Also, vitamins such as myo-inositol, nicotinic acid, pyridoxine, thiamine, and glycine can be added in the medium to improve plant growth.
Plant growth regulators (that mimic naturally-occurring plant hormones) promote major growth changes in very small concentrations and are usually added to in vitro culture media. These growth regulators play important functions in vitro by affecting flowering, aging, root growth, organ formation, among others. The main groups of plant growth-regulating compounds include cytokinins, auxins, gibberellins, ethylene, and abscisic acid (ABA).
In general, each group contains both naturally-occurring hormones and synthetic substances. Growth regulators usually represent the most expensive input when preparing the menu.
At GoldBio we provide high-quality and low-price reagents of cytokinins such as 6-Benzylaminopurine (6-BAP), zeatin; auxins including Indole-3-Acetic Acid (IAA), Indole-3-butyric acid (IBA); giberellins such as Gibberellic Acid (GA3), and finally Abscisic acid (ABA). If you want to know more about plant hormones, please visit this link.
Now then, what are the strategies to prepare a plant cell culture medium?
Strategy 1. Picking the menu ingredients.
A way to start preparing a culture medium is by manually preparing each salt. In an in vitro process, there are at least 14 salts to prepare. Each salt can be concentrated, diluted, or removed from the final recipe.
This strategy has disadvantages and advantages. It is time-consuming since you are optimizing individual nutrients for culture. However, it facilitates adjusting individual nutrients when you have a deeper level of knowledge of the requirements of your culture.
Strategy 2. The salt cocktail.
A second strategy is to use commercially available salt reagents. In tissue culture, there are several traditionally used “standard formulation media,” which contain all of the main salts in balanced concentrations required by plants.
MS, DKW, Gamborg’s B-5, and White’s Basal salt mixtures are some examples. They differ regarding the components of chemical macronutrients or minor minerals.
MS, for example, is a nitrogen-rich medium. The basal salt mixture significantly facilitates the task by reducing the preparation time of the tissue culture.
Researchers also experiment with the basal medium by adding whole, half, or ¼ dose in the final preparation. This is the most used strategy in cell culture studies. Below a comparative table of the media.
Table 1. Comparison of commonly used plant cell culture media
Strategy 3. From the soil to the recipe.
It consists of conducting an analysis of the soil in which your target plant grows in order to extrapolate the concentration of the mineral salts present in the soil and adjust these in the culture medium.
Sometimes, the soil analysis is made available, yet, other times you must pay for it. Several papers report good results, and the assumption is that, although plants can grow in a nutrient-rich soil, they only take what they need from soil. It is a personalized menu for the plant!
At GoldBio, we have the most inexpensive ingredients (growth regulators) used in the tissue culture media preparation at very low cost to help you prepare your plant recipe. Just order what you need, salt as needed, and enjoy!
Brown, P. H., Cakmak, I., & Zhang, Q. (1993). Form and Function of Zinc Plants. Zinc in Soils and Plants, 93–106.
Cabot, C., Martos, S., Llugany, M., Gallego, B., Tolrà, R., & Poschenrieder, C. (2019). A Role for Zinc in Plant Defense Against Pathogens and Herbivores. Frontiers in Plant Science, 10(October), 1–15.
Etienne, P., Diquelou, S., Prudent, M., Salon, C., Maillard, A., & Ourry, A. (2018). Macro and micronutrient storage in plants and their remobilization when facing scarcity: The case of drought. Agriculture (Switzerland), 8(1).
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Singh, A. Tissue Culture Medium: Types and 5 Steps of Selection. Plant cell technology. URL: https://www.plantcelltechnology.com/pct-blog/tissue-culture-medium-types-and-5-steps-of-selection/. Accessed on 10 February 2021.
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