Plants have certain basic requirements that enable them to live, grow, and
The same is true for tissues and cells.
One of these requirements is a source
of energy, which for the intact plant, is light for photosynthesis.
restricted to cells and tissues that contain chlorophyll.
Hence, non-photosynthetic tissues
meet their energy requirements by cellular respiration of organic materials.
source, not only of energy but also of carbon, which is required for growth, is supplied to
non-photosynthetic tissues via transport systems.
Thus, cells throughout the plant body,
photosynthetic or not, rely on the energy of respiration to synthesize organic compounds.
Excised or cultured plant tissues retain their requirements for specific organic substances.
If the tissues in culture require only a general carbon and energy source, a simple
carbohydrate such as sucrose may be all that is necessary to be supplied in the culture
However, if the requirements are more specific, other organic substances may
be necessary; for example, vitamins, amino acids, growth regulators, and so on.
cultured tissues are unable to synthesize essential substances, these substances must be
supplied in the culture medium.
Bacteria and fungi, like cultured plant tissues, have many of the same basic requirements
However, microorganisms, unlike plant cells, multiple very rapidly, especially in
a culture medium containing sugars.
Their presence can have a deleterious effect on the
Therefore, special techniques, referred to as Aseptic Procedures, must be
used to eliminate and prevent microbial contamination.
Without the use of aseptic
techniques, plant tissue culture would be extremely difficult, if not impossible.
. Although the equipment for plant tissue culture may vary, there are certain
basic elements that are essential.
These basic items will be described.
The laboratory room is a major source of contamination.
Therefore, the working area must be further confined, preferably to a small, enclosed
chamber—the transfer hood.
Transfer hoods are generally “box-like” with a front
The hood that we are using in this class is known as a laminar flow hood.
blower is used to force air from the top or back to the front of the hood. The air passes
through a hepa-filter, which theoretically makes it free of bacteria and fungi.
is turned on before the hood is used and remains on while the hood is in operation.
contamination arises, this usually means that the user has not employed proper sterile
technique or that the filter needs to be changed.
In the past, a hood used to be equipped with an ultraviolet light that was turned on