Tissue
Culture: Application Micropropagation
Roy Reynolds
Introduction
Tissue culture is the growing and development of plant cells, tissues or organs in an aseptic environment on a nutrient rich medium. Plant tissues are maintained on the medium for a specified period of time, before they are transferred to fresh medium. This fresh medium may be exactly the same as the previous one or be different, which will alter the development of the explants. Micropropagation is the application of tissue culture to produce countless clones of a plant in a very short time.
The Process of Micropropagation
A small piece of the plant to be cloned (the explant) is removed and surface sterilized. The source of the explant will vary by species, but usually are shoot tip, leaf, stem, lateral bud, and flower tissues. The sterilized explant is rinsed with sterile water, and placed in an aseptic container on a specially formulated medium. The explant may produce shoots or callus. The growth pattern is determined by the auxin and cytokinin concentration in the medium. Most cultures are established in 1 to 3 months depending on the species and in some instances, the cultivar. Once the explant is established, it is divided and placed on a new medium for continued callus formation or shoot formation. A shoot proliferating culture is one which can be divided to produce divisions which will continue rapid multiplication. Rates of multiplication vary by the source of the explant and are affected by many factors, but the production of thousands or millions of plants a year is possible.
Key Equipment Required for Commercial Micropropagation
·
Laminar air flow cabinets: These
are commercially available cabinets that produce a sterile environment where
transferring and dividing of the explant is done.
· Autoclave: This is a commercially available piece of equipment, similar to a pressure cooker, used for sterilization.
· Oven: An oven is useful for sterilization of scalpels and glass-ware and other pieces of equipment.
· Equipment for sterilization by filtration: This is equipment that is used to sterilize the medium by aseptic filtration, which is a method of sterilizing that reduces the break down of less stable material in the medium.
· Water distillation apparatus or pure water demineralizer: This is equipment used to obtain water that is free of any salts.
Micropropagation Media
Micropropagation is done on a media that may or may not contain agar (a jelling substance made from seaweed), a carbon energy source (some form of sugar), plant hormones (auxins and cytokinins), and a variety of vitamins and mineral salts. The culture medium differs from species to species or even cultivar to cultivar, because plants respond differently to the concentrations of the hormones, vitamins, and minerals in the medium.
Stages of Micropropagation
Stages of Micropropagation
Done in an Aseptic Environment
There are three stages of micropropagation done in an aseptic environment which are:
STAGE I
is the initiation phase. It involves the establishment of plant tissue in an
aseptic environment by surface sterilizing the material and initiating it into
the cultural medium.
STAGE II
is the multiplication phase. This stage involves dividing the plant material
and placing it in a medium with plant growth regulators that induce the
proliferation of multiple shoots. This process is repeated until the number of
plants desired is reached.
STAGE III is
the root formation phase. It involves the introduction of hormones to induce
rooting and the formation of complete plantlets.
Stage of Micropropagation Done Outside of the Aseptic Environment
STAGE IV is the acclimization phase. This stage involves the transfer of the rooted shoots into pasteurized potting medium to harden off and grow on. In this stage the humidity, light, and temperature must be constantly monitored to allow the plantlet to get adapted to the outside environment gradually.
Advantages and Disadvantages of Micropropagation
The advantages of micropropagation are:
The disadvantages are:
Conclusion
The
application of tissue culture for the use of micropropagation
has only been really researched for the past 15 years, yet micropropagation
has had an impact of the nursery industry.
By being able to mass produce plants, new varieties have been able to be
released sooner than ever expected. Micropropagation has also allowed certified disease free
plant material to be developed and used for propagation. In conclusion, I think that micropropagation will be used more in the future for mass
producing plants for market; it has already had an impact in the availability
of orchids.
Works Cited
“Chapter 5: Equipment
and Facilities.” Accessed
<http://www.fao.org/docrep/t0831e/t0831e06.htm#5.1>
“Getting Started in Plant Tissue Culture.”
Accessed
<http://www.jmu.edu/biology/pctc/tcstart.htm>
Hartmen, Hudson T., et al. Hartman and Kestler’s Plant Propagation: Principles and Practices.
Lineberger, R. Daniel. “Care and Handling of Micropropagated
Plants.” Accessed
<http://aggie-horticulture.tamu.edu/tisscult/microprop/micropro.html>
“Tisssue
Culture/ Micropropagation.” Accessed
<http://oregonstate.edu/dept/hort/faculty/Proebsting/Web/14_Microprop.pdf>
“Tissue Culture
Technology: Cashing in on Cloning” Accessed
<http://www.agriforestbiotech.com/tissueculture.htm>
