Plant Biotechnology – Preparation of Plant Rooting and Regeneration Media (Part 1)
The main purpose of Modern Agriculture’s Plant Biotechnology series is to explain and elaborate on… well… exactly what genetic engineering is and how it is accomplished. We’ll be explaining how to propagate peppermint plants using plant hormone regulators and the appropriate media.
The first part of this series is to get you acquainted with biotechnological terms, equipment, and plant rooting and regeneration media.
Plants can be regenerated in vitro (in test tubes) from various parts and tissues using defined growth media containing the appropriate salts, nutrients, and hormones (growth regulators). This technology has been successfully used as an alternative to producing plants from seeds for the rapid propagation of commercially important ornamental and crop plants. Other uses have been to “rescue” endangered species, improve agronomic traits in various crops, along with a multitude of other applications.
The Importance of Sterilization
In any lab setting, one must remember that when it comes to the handling of plant tissue, an aseptic technique must be used. This is to ensure that no bacteria, fungus, or pathogens of any sort can compromise our experiment and ruin the results, and thus your hard work. This can be achieved through using Laminar Flow Hoods (where powerful fans take in air and pass it through HEPA filters) or an autoclave (high pressure, high temperature container used for chemical reactions and/or sterilization).
Murashige and Skoog (MS) Media:
MS Media is commonly used for plant propagation and tissue culture. This medium contains the basic nutrients that a plant needs to grow. In order for plant propagation to occur, the medium must contain a number of macronutrients (elements needed in higher amounts) and micronutrients (elements needed in trace amounts). In addition to the nutrients, the medium also contains sugars, generally in the form of sucrose, and vitamins.
Plant hormones are also essential for the growth and development of plants. The two major types of plant growth regulators include auxins and cytokines. Auxins are compounds produced in apical and root meristems, young leaves, and developing seedlings. They elicit physiological responses in vivo and in vitro, including root initiation, cell elongation, cell division, and breaking dormancy. Cytokinins are produced in the same areas as auxins, and have been proven to elicit physiological responses including shoot initiation, bud formation, and cell division. A higher auxin/cytokinin ratio typically results in root induction, while a higher cytokinin/auxin ratio induces shoot formation. Thus, it is important to maintain the appropriate levels of both hormones when attempting any plant propagation.
It is also essential to adjust the pH of the media in accordance to the plant’s natural environment. For example, if the plant has adapted to acidic soil, the tissue culture media should be lower to stimulate the natural environment.
Finally, when all of the required nutrients and hormones are in place, the appropriate gelling agent must be added. This helps to solidify the media. Gelling agents are inert, as they do not interact with the media components, nor do they affect mineral availability.
Once all of the appropriate pieces are in place, we have the media required to root and regenerate our plants.
Our next article will explain in vitro propagation and genetic transformation in plants.