Plant Tissue Culture, Micropropagation and Objectives of Tissue Culture

Plant tissue culture comprises a set of in vitro techniques, methods and strategies that are part of the group of technologies called plant biotechnology. Tissue culture has been exploited to create genetic variability from which crop plants can be improved, to improve the state of health of the planted material and to increase the number of desirable germplasms available to the plant breeder.

Tissue-culture protocols are available for most crop species, although continued optimization is still required for many crops, especially cereals and woody plants. Tissue- culture techniques, in combination with molecular techniques, have been successfully used to incorporate specific traits through gene transfer. In vitro techniques for the culture of protoplasts, anthers, microspores, ovules and embryos have been used to create new genetic variation in the breeding lines, often via haploid production. Cell culture has also produced somaclonal and gametoclonal variants with crop-improvement potential.

The culture of single cells and meristems can be effectively used to eradicate pathogens from planting material and thereby dramatically improve the yield of established cultivars. Large-scale Micropropagation laboratories are providing millions of plants for the commercial ornamental market and the agricultural, clonally-propagated crop market. With selected laboratory material typically taking one or two decades to reach the commercial market through plant breeding, this technology can be expected to have an ever increasing impact on crop improvement as we approach the new millennium. Key words: Breeding, embryo culture, haploids, micropropagation, rotoplasts, synthetic seed, transformation, wide hybridization. Tissue culture is a term that is used to refer to the growth of plants or plant parts in sterile culture. Micropropagation is a method of propagating plants that uses very small parts of plants that are grown in sterile culture. Micropropagation is only one of a number of uses for plant tissue culture that are used in horticulture.

Horticultural uses for plant tissue culture

1. Clonal mass propagation: The important point here is that extremely large numbers of plants can be produced. Rather than getting 10000 plants per year from an initial cutting, one can obtain upwards of 1,000,000 plants per year from one initial explant.

2. Difficult or slow to propagate plants: Micropropagation enables growers to increase the production of plants that normally propagate very slowly such as narcissus and other bulbous crops.

3. Introduction of new cultivars. eg. Dutch iris, Get 5 daughter bulbs annually. Takes 10 years for commercial quantities of new cultivars to be built up. Can get 100-1000 bulbs per stem section.

4. Vegetative propagation of sterile hybrids used as parent plants for seed production. Eg. Cabbage.

5. Pathology: Eliminate viruses, bacteria, fungi etc. Use heat treatment and meristem culture. Used routinely for potatoes, carnation, mum, geranium, garlic, gypsophila.

6. Storage of germplasms: Generally the only successful method to date is  keeping them in refrigerator. Slows down, but does not eliminate, alterations in genotype.