Application of Shoot-tip or Meristem Culture
1. Virus Elimination:
Plants are often infected with more than one type of virus, including some even not known. A general term virus- free is used by commercial horticulturist for plants freed of any type of virus.
2. Micro Propagation:
A sexual or vegetative propagation of whole plants using tissue culture techniques referred to as micropropagation. Shoot tip or meristem culture of many plant species can successfully be used for micro propagation.
3. Storage of Genetic Resources:
Many plants produce seeds that are highly heterozygous in nature or that is recalcitrant. Such seeds are not accepted for storing genetic resources. So , the meristem from such plants can be stored in vitro. The materials are preserved at 196 0 C for the long term preservation of germplasm.
4. Use in Plant Breeding:
In many plant breeding experiments the hybrid plants produce abortive seeds or non viable seeds. As a result, it makes a barrier to crossibility in plants where non-viable seeds are unable to develop into mature plants. Shoot-tip or meristem from such hybrid plant can be cultured to speed up breeding programme.
5. Propagation of Haploid Plants:
Haploid plants derived from anther or pollen culture always remain sterile unless and until they are made homozygous diploid. Meristem or shoot-tip culture of haploid plants can be used for their propagation from which detailed genetic analysis can be done on the basis of morphologically character and biochemical assay.
There are some regulations concerning the international movement of vegetative plant material. After thoroughly checking, the plant materials may be rejected by quarantine authority if the plant material carries some diseases. Plantlets derived from shoot-tip or meristem cultures are easily accepted by the quarantine authority for international exchange without any checking. Therefore, using this technique , crop plants can be easily exchanged in crop improvement programmes that are based on materials from different parts of the world.
Limitation of Tissue Culture in Plant Disease Elimination:
The overall operation involving the production, multiplication and maintenance of the in vitro regenerated plants required a good knowledge of pathology. Viruses can be transmitted either mechanically , through an insect vector or through other biological agents. The advantages of the tissue culture technique in raising disease free plants can be offset by increased susceptibility of these plants to attack from more severe viruses and fungi. One of the reason for this increased susceptibility maybe the altered nutritional and physiological state of the tissue culture derived plants as a result of pathogen eradication.
It is also essential to have a good knowledge of greenhouse maintenance to control the reinfection of disease free plants.