By: Krishnakumar, V.G
This article is meant for familiarizing tissue culture to common man and hence, complicated terms and terminologies are least used. Technology is also elaborated to simplicity so that a layman can have an understanding of this developing technology.
Tissue culture is the synonym for scientific asexual regeneration of living organisms as far as modern agriculturists and the whole world of biologists. Technically, tissue culture is a form of vegetative propagation. It is the science of artificial replication of a living plant or animal from a single cell or group of cells- tissue. Tissue culture is also known as micro propagation.
Indian epics have very well exposed to this science in the very past. Agasthyamuni, the founder of Sidhavydya (a branch of Ayurveda) was born in a pot. When Varuna Maharshi saw Urvashi and Rambha, the resultant semen was collected in pot. Biologically, Agasthyamuni was thus haploid! (half of the chromosome numbers in cell nucleus. Normal living being developed through sexual regeneration- union of sperm and ovum which are haploid- is diploid. Human sperm and ovum have 23 chromosomes and a human being’s cell will have 46 chromosomes)
There is energy in every living cell which has of certain life. Before the expiry of the lifespan of the cell, if it is stimulated it can reproduce the next generation having original characteristics of the donor organism. Unlike animal cells which can reproduce that particular cells (a cell of skin can produce only skin tissue, a liver cell can produce only liver tissue) when stimulated, plant cells have a phenomenon, totipotency (the ability of a single cell to divide and produce all of the differentiated cells in an organism- Wikipedia)
In our garden, we used to regenerate flowering plants like rose, etc. using the branch cuttings and planting in filled-in pots. Within few days, new plant establishes. Likewise, if we plant a live branch of a mango tree and dip the cut end in rooting hormone and plant, another mango sapling, exactly having the qualities of the mother tree, will start establishing. The tissues of cut end of the plant stem are stimulated by the hormone to produce roots and thus whole plant system is generated.
Process of plant tissue culture.
Father of plant tissue culture is Mr. Gottlieb Haberlandt, the German scientist of Academy of Science. It was in 1902 on his experiments on the culture of single cell the first true cultures were obtained by Gautheret from cambial tissue of great maple tree.
Tissue culture process is having two stages, viz., in vitro process (inside lab) and ex vitro (in natural condition) process
In vitro process
Cell from any part of a plant can be developed to a full-fledged plant. This can be done in a highly suitable environment. The process is given below:
The growing part of the ideal mother plant is cut (explants), cleaned and sterilized to free from all impurities, pathogens and microbes under various sterilizing process. This part is cut to smaller parts and then kept in growth media borne vessel. Growth media is the compound of various minerals, salts vitamins and plant hormones prepared in a highly protected hygienic environment. This vessel is kept for a fixed period in the growth room which is having a maximum of 25oC and minimum 18oC and 12 hours lighting. During this process, the cells undergo uncontrolled and undefined division (exactly similar to cancer growth) and result in callus formation. This callus is later multiplied under sterile atmosphere. Normally, shoot development is done initially and later when there is sufficient quantity of cultures are ready, rooting initiation is done. After establishing roots, the culture plants are transferred to further process under Ex Vitro process, i.e, outside the laboratory. The laboratory manager can decide the development of shoots or roots in culture as it is done by adding the concerned hormone in the culture media.
Ex vitro process
The cultures received from the laboratory are washed off the media and then split. The split culture plants are separated and planted in wet cocopeat-filled portrays (similar to the egg-packing case) and kept in poly houses which has high humidity and temperature range of 26-30o C in daytime and 25-28o C in night time and humidity of 80%. During these conditions, the real root formation and normal function of plant develops. After 2 weeks, these plants are taken out, and dead ones are removed. The survived plants are then transferred to fresh protrays filled with wet cocopeat and regular watering is done. After 90 days of such poly house life, the plants are transferred to shade net house, where the plants will get in touch with real soil in nursery bed and finally to poly bags or root trainers for sales.
The need for tissue culture
As already stated, tissue culture is a sort of photocopying! We can produce the exact offspring’s of a plant as much as we require from a small portion of that plant. When there is a heavy demand for a particular plant and seed availability would be inadequate, tissue culture is the answer. When there was gregarious flowering of bamboos in Northeast India and regeneration was in docks, Government of India resorted to tissue culture of bamboos to meet the need of planting materials by setting up a Tissue Culture Laboratory for bamboo propagation in Nagaon Paper Mill, Jagi Road, Assam, under Government of India owned Hindustan Paper Corporation. This tissue culture lab facility can produce one billion plantlets of various bamboo species annually.
In India, banana is widely produced under tissue culture method and thus profit making.
Tissue culture can ensure plant purity. The costs are high in in vitro stage, where costly organic chemicals are used and high cost for lab establishments are also to be met with. Skilled technicians are required for this delicate work. Hygiene is of high priority to establish success in tissue culture. Uncontrolled contamination in culture at any stage can result in heavy loss.
Tissue culture facility can be developed for just 1000 plants to even billions of plants per month. It can be established in a building having an area of 800 square feet! Government of India is providing financial and technical support to new entrepreneurs. Details can be available in the websites of department of biotechnology or national horticulture mission.
Tissue culture is the most updating field of technology and success lies with the customization of technology for the requirement of plants and its demand. In our country, this technology can transform the agriculture scenario by increased output, by incorporating the genetic engineering methods. As every biotechnology ventures are having high risk for want of adequate technology and technicians, less entrants are in the field. Tissue culture should be introduced as a subject in the Vocational Higher Secondary syllabus to prepare technicians in the field.
About Author: Well experienced Forestry personnel in all fields of forestry in paper industry. Raising plantations of pulpwood like eucalyptus, acacia, bamboo etc. Experience in Tissue Culture laboratory (from the installation to production stage), extraction works and storage. Well experienced in public activities like Farm forestry. His Specialties: Forestry- plantation, tissue culture, extraction and community forestry.