1. Plant tissue culture
• Broadly refers to technique of growing plant cells, tissues,
organs, seeds or other plant parts in a sterile environment
on a nutrient medium
Plant tissue culture • The first commercial use of plant propagation on artificial
a.k.a. micropropagation media was in the germination and growth of orchid plants
in the 1920’s
• It was only after the development
of a reliable artificial medium by
Murashige & Skoog in 1962 that
plant tissue culture really took off
commercially
Why do plant tissue culture? History
• Fast commercial propagation of new cultivars • First attempted by Haberlandt (1902) - grew palisade cells
– Cost of culture (orchid price decrease) from leaves of various plants but they did not divide
• Agriculture • 1934 - White generated continuously growing culture of
– Fast selection for crop improvement – nutritional value, meristematic cells of tomato on medium containing salts,
pest control, hardiness yeast extract and sucrose and 3 vit B (pyridoxine,
thiamine, nicotinic acid) – established the importance of
– Cultivation virus free plants additives
• Pharmaceuticals – ginseng and taxol • 1953 Miller and Skoog, University of Wisconsin – Madison
• Cloning of rare and endangered plants discovered kinetin, a cytokine that plays an active role in
• Plant cultures in approved media are easier and safer to organogenesis
export
Further progress Basis for the cell culture
• 1958-60 Morel cultured orchids and dahlias freed them • Plant cells are totipotent
from a viral disease • Have the ability to develop into whole plants or plant
• 1962 Murashige and Skoog published recipe for M&S organs in vitro when given the correct conditions
medium • Not all plant cells are totipotent. However, there are a
• 60’s and 70’s Murashige cloned plants in vitro sufficient number of totipotent cells in the plant (e.g. in
– raised haploid plants from pollen grains the pith)
– used protoplast fusion to hybridize 2 species of tobacco
into one plant contained 4N • Differentiated cells have to be dedifferentiated into callus
• 70’s and 80’S beginning of genetic engineering and redifferentiated back to somatic embryo that will
regenerate the entire plant
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2. Culturing (micropropagating) plant
Callus tissue - the steps
• Is a natural response of the plant tissue to wounding • Selection of the plant tissue (explant) from a healthy
• A mass of actively dividing undifferentiated cells produced vigorous ‘mother plant’ - this is often the apical bud, but
by plant tissue explant can be other tissue
• Cells are totipotent • Establishment of the explant in a culture medium - the
• Callus can be medium sustains plant cells growth and encourages cell
division
– Resuspended in liquid media to create a susupension
culture of single totipotent cells – Each plant species (and sometimes the variety within a
species) has particular medium requirements that must
– Or differentiated into plant with the appropriate be established by trial and error
manipulations of culture conditions
• Multiplication - the explant gives rise to a callus
• Differentiation and organogenesis
What is needed? Plant tissue culture media
• Explant (some tissues culture better than others) • Mineralals (17 essential elements)
• A suitable growth medium • Energy and carbon source - sucrose is preferred
• Aseptic conditions, as microorganisms grow much more • Growth regulators – auxins and cytokinins
quickly than plant and animal tissue (phytohormones)
• Growth regulators - in plants, both auxins & cytokinins • Vitamins
• Frequent subculturing to ensure adequate nutrition and to • Organic compounds
avoid the build up of waste metabolites • Water
• Usually 5.0-5.7
Vitamins Growth regulators
• Thiamine Auxins and cytokinins
• Pyridoxin • Auxins stimulate cell division in explants
• Nicotinic acid – Used for callus induction and growth
• Biotin • High concentration suppresses the organized growth and
• Citric acid promotes formation of meristem-like cells
• Ascorbic acid • IAA, indole-3-acetic acid a light sensitive, natural auxin
• Inositol
• Cytokinins
• Promote cell division and regeneration possibly through
the effects on protein synthesis
• Zeatin – natural cytokine that induces morphogenesis
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3. Homework
• In your notebook write a detailed content of a selected
plant culture medium. It has to have concentrations of all
ingredients!
• Make sure you understand what is in it and why. Again,
there will be a question about it on the first exam.
• Find a name of the plant that is grown on that medium
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