Tissu Culture

Today, it is generally accepted that the term 'plant tissue culture' broadly refers to the cultivation in vitriol of all plant parts, whether a single cell, a tissue or an organ, under aseptic condition; although street has recommended a more restricted use of the term (20). Plant tissue culture is a technique which has great potential as a means of tentatively propagating economically important species; a potential which is being realized commercially at present. However, a tissue culture system is also very often a 'model' system which allows one to investigate physiological, biochemical, genetic and structural problems related  to plants and the technique is being used also as an adjunct to more traditional means in plant modification. Many of these approaches being used at present are described in succeeding chapters in this book. It is mainly in view of using tissue culture as a tool in basic and applied research that the requirements of a plant tissue culture facility will be examined in this chapter. 

The underlying principles involved in plant tissue culture are very simple. Firstly, it is necessary to isolate isolate a plant part form the intact plant and its inter-organ, inter-tissue and inter-cellular relationships. Secondly, it is necessary to provide the plant part with an appropriate environment  in which it can express its intrinsic or induced potential. This means that a suitable culture medium and proper culture conditions must be provided. Finally, the above must be carried out aseptically. In practice, this means that the culture must be free of bacterial, algal, fungal and other contaminants.Contamination by such microorganisms is a very peal problem in tissue culture and one which demands a great deal of skill, care and organization because the media used to support higher plant cell growth also supports the growth of these microorganisms. If their growth is not prevented, they may overgrow the plant cells, inhibit there development and interfere with the physiology and biochemistry of the system by the release of metabolic products. Secondly, we will see that much of the equipment used in a tissue culture laboratory is aimed at careful control of all the components pertaining to the physical (and to some extent as a consequence, to the physiological) environment of the system (e.g.media components, gaseous atmosphere, types of vessels used, light and temperature regimes, etc .) All this is aimed at ensuring that the system is as defined as possible. Nonetheless, It is important to realize the as De Sanford has pointed  out, it is very rare for any of us to attain optimal,fully defined, reproducible culture condition. No doubt a rational yet imaginative use of laboratory equipment coupled with a knowledge of which factors man or may not influence the system and how, plays an essential role toward achieving this somewhat elusive goal.The following topics are covered in this chapter: basic organization and facilities, glassware, instrument and miscellaneous equipment, controlled environments and liquid cultures.

Basic organization and facilities :

The cultivation of a plant tissue in vitro does not per require complex or expensive equipment. It has been said that all one really requires is a pressure cooker and few jam jars! The extent to which more sophisticated apparatuses are necessary depends on the nature of the research undertaken.For example, one may wish to investigate the ultra structural changes occurring in the course of the growth and different ion of a particular system. In that case an electron microscope and darkroom facilities will be required. Radiochemical student carried out on a tissue culture model system may necessitate the acquisition's of a high-speed centrifuge, a spectrophotometer, a freeze-dryer, etc. such requirements will not be reviewed here.

The basic organization and facilities of most tissue culture laboratories today can be summarized as follows.

Facilities

*** A general laboratory area with provisions for either Independent or common working spaces or both.      Some equipment and materials will necessarily be communal and should be easily accessible to all workers.

*** Large sinks (some lead-lined to resist acids and alkali) and draining areas. Washing machines to wash glassware in bulk and hot-air cabinets or ovens for drying washed glassware are useful in most cases.

*** Cabinet and shelf space for safe storage of chemical and dust-free storage space for clean glassware.

*** Transfer areas for aseptic manipulations. Such a facility can be provided in several ways and will   bee reviewed later.

*** An autoclave and / or oven for sterilizing media, solutions, water, culture vessels and instruments.

*** Culture rooms or incubators where cultures can incubated under controlled light, temperature, and if    possible, humidity  regimes.