David Wm. Reed,
Tissue culture (often called micropropagation) is a special type of asexual propagation where a very small piece of tissue (shoot apex, leaf section, or even an individual cell) is excised (cut-out) and placed in sterile (aseptic) culture in a test tube, petri dish or tissue culture container containing a special culture medium.
The culture medium contains a gel (agar) with the proper mixture of nutrients, sugars, vitamins and hormones, which causes the plant part to grow at very rapid rates to produce new plantlets. It has been estimated that one chrysanthemum apex placed in tissue culture could produce up to 1,000,000 new plantlets in one year. Thus, tissue culture is used for rapid multiplication of plants. A very specialized laboratory is required for tissue culture. All the procedures are done in a laboratory and special ventilated cabinet that is as sterile as an operating room.
Overview of the Tissue Culture Process
Steps in Tissue Culture
(images courtesy of Dr. Dan Lineberger, aggie-horticulture.tamu.edu/tisscult/microprop/microprop.html)
Explant: Cut-out Plant Tissue and Place in Tissue Culture Container
The first step is to obtain what is called and explant. This means to simply cut-out a very small piece of leaf or stem tissue, or even isolate individual cells, and place them in a tissue culture container. The tissue has to be sterilized so it will not have any contaminating bacteria or fungus. It is then placed inside the tissue culture contain on a gel called agar. In the agar is dissolved all the sugar, nutrients and hormones the plant needs.
Explants can be pieces of any part of the plant (leaves, stems, flowers, etc.),
or even individual isolated cells.
Multiplication: Tissue Grows and Produces Small Plants
The tissue will begin to grow. It may make a big blob of tissue called callus, or it may make new shoots directly from the explant tissue that was inserted in the container.
A mass of callus tissue is formed that is just starting to make new plantlets.
New plantlets (shoots with leaves) are forming.
If the conditions are right a small "forest" of plants
will develop in the tissue culture container.
Rapid Multiplication by Transfer of Cultures
Once the plantlets start developing, some can be removed and placed in new tissue culture containers. Thus, another "forest"' of plants is produced. This results in a rapid multiplication of the cultures and many thousand of plants can be produced in a few months.
Some of the small plantlets can be removed and transferred to new tissue culture
containers. These will produce more shoots and fill the container.
When the plantlets are large enough, they can be removed from the tissue culture container and transferred into pots with potting soil. The young plants are growth in a greenhouse just like you would any young seedling or cutting.
When the small plant clones are removed from the culture containers, they must be transplanted into some type of acclimation container or kept under a mist system until the acclimate to the ambient environment.
After acclimation, the young plants can be transplanted
and grown in pots in a greenhouse to produce new plants.
TAKE HOME LESSONS
1) To become familiar with how plants can be cloned from very small pieces of leaf, stem or other plant tissue.
2) To transfer plants out of a tissue culture container into a new tissue culture container.
3) Bring the new tissue culture clone home and transplant it into soil in a pot when it gets large enough.
Plantlets in a tissue culture container ready to be transferred.
Tissue culture lab and transfer hood.
Tissue culture container with fresh tissue culture medium.
View a Video on Cloning with Tissue Culture and Observe a Variety of Tissue Cultures
The class go to a tissue culture lab and view a video on tissue culture.
The class will view a variety of tissue culture containers with cloned plantlets.
Transfer Cloned Plantlets to Fresh Tissue Culture Container
The class will be instructed on the proper procedure to:
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