Biotechnology
Biotechnology is any technique that uses living organisms or
substances derived from these organisms to make or modify a product, improve
plants or animals or develop microorganisms for specific uses” It ranges from
traditional biotechnology to most modern biotechnology
History
·
The person who should
be mentioned: Haberlandt, a plant physiologist, is the first person performing
the real plant tissue culture experiment, and the time was 1902.
·
Theory
·
Theory for plant cell
and tissue culture: the totipotency, which states that cells are autonomic, and
in principle, are capable of regenerating to give a complete plant.
·
Plant
tissue culture
·
Plant tissue culture
is defined as culture under sterile conditions, of plants, seeds, embryos,
organs, tissues, cells and protoplasts.
·
Characteristics of
Plant Tissue Culture Techniques
- Occur on a micro-scale.
- Environmental conditions
optimized
(nutrition, light, temperature, phytochemistry).
- All microbes (fungi,
bacteria, viruses, and nematodes are excluded).
- The normal pattern of plant
development breaks down giving rise to callus, adventitious roots, shoots,
and/or embryos.
- Ability to grow as single cells
(protoplasts, microspores, suspension cultures)
- Plant cells are totipotent
(e.g.: able to regenerate a whole plant).
Uses of Plant Cell and
Tissue Culture
·
Production of
pathogen free plants
·
Meristem Culture
·
Somatic
embryogenesis
·
Organ Culture
Callus Culture
·
Anther and
pollen grain Culture (Haploid production)
·
Protoplast
culture
·
Germplasm
preservation
Main Objectives
·
Elimination of
viruses from infected plants
·
Rapid
multiplication of clones
·
Vegetative
propagation of difficult to propagate species
·
All the year
round propagation of clones
·
Rapid
multiplication of seedlings (in cases where seed is hard to get
·
Virus Eradication
Tissue Culture
Methodology
·
Disinfest plant
material and culture buds;
·
Discard
contaminated field taken material /cultures and rear aseptic cultures until
they are small plants; or
·
Expose these field
taken material/aseptic plants to elevated temperatures (34-37 oC)
during incubation for various times.
·
Excise
small stem tips from these incubated plants and incubate in culture at 25°C;
·
Incubate until
each plant is quite large and test for presence of viruses;
·
If free of
detectable viruses, re-culture from this (or these) plant(s) and multiply to obtain
a population of virus-free clonal material.
Meristem Tip Culture
·
Meristem tip
refers to the region of shoot apex lying distal to the youngest leaf
primordial, whereas shoot apex includes Meristem tips plus a few sub adjacent
leaf primordial.
Micropropagation
·
Enhanced axillary
shoot proliferation
·
Node culture,
·
de novo
formation of adventitious shoot through shoot organogenesis,
·
Nonzygotic
embryogenesis.
Advantages of
Micropropagation
·
Plant material require
less attention between subcultures and there is no labour or material
requirement for watering, weeding, spraying, etc. Micropropagation is most
advantageous where costs is less than traditional methods of multiplication.
·
Certified virus free
plants can be produced in large number.
·
It is possible
to produce clones of same kinds of plants that are otherwise slow and difficult
to propagate vegetative.
·
Only limited space is
required to maintain and produce large number of plants.
·
Plants may acquire a
temporary vigor through micropropagation which makes them more desirable to the
grower than conventionally raised stock.
·
Production can
be continued all the year round and is independent of seasonal changes.
·
Plants may acquire
a temporary vigor through micropropagation which makes them more desirable to
the grower than conventionally raised stock.
·
Production can be
continued all the year round and is independent of seasonal changes.
·
Propagation is
ideally carried out under aseptic conditions, free from pathogens. Once culture
have been started there should be no loss through disease and the plantlets
finally produced should be free from bacteria, fungi and other microorganisms.
·
Somatic
Embryogenesis
·
Somatic embryogenesis
is the production of embryos from somatic or “non-germ” cells.
·
Not a common
micropropagation technique but is currently being used to produce superior
spruce seedlings here in B.C.
·
Usually involves
a callus intermediate stage which can result in variation among seedlings
·
Organogenesis
·
This is the production
of roots, shoots or leaves.
·
These organs may arise
out of pre-existing meristems or out of differentiated cells.
·
This, like
embryogenesis, may involve a callus intermediate but often occurs without
callus.
Somatic Embryogenesis
and Organogenesis
·
Both of these
technologies can be used as methods of micropropagation.
·
Not always
desirable because they may not always result in populations of identical
plants.
·
The most beneficial
use of somatic embryogenesis and organogenesis is in the production of whole
plants from a single cell (or a few cells).
Callus Culture
·
Callus is an
unorganized mass of cell which can be induce to re-differentiate on appropriate
medium to develop embryoids which directly develop into plantlets, eventually
giving rise to a whole viable plant.
Anther and Pollen Grain Culture
·
The culture of
immature anthers and pollen grains is done so as to induce the pollen grains to
develop into multicellular forms, particularly into embryos, with
half the normal number of chromosomes for the species.
·
When such
haploid embryos are treated with chromosome doubling agents, e.g.
colchicines, their normal chromosome number is restored (and thus their
fertility) and, in addition, the plants are pure lines.
Protoplast Culture
·
Enzymatic removal of
the mainly cellulose wall surrounding a plant cell results in a protoplast.
When these are cultured, a new wall is synthesized thus restoring the original
state of the plant cell. However, during the period that the protoplast is
wall-less, there is the possibility:-
·
Of adding
foreign genetic material to the protoplast,
·
Of fusing the
protoplasts of two cultivars or even species to form hybrid cells.
·
Germplasm
Conservation
·
The preservation of
Germplasm in vitro by tissue culture is an extension of
micropropagation techniques.
·
Simply it is
that by the micropropagation techniques scientists get plant materials to
be conserved. Then by the same techniques they make these materials grow slowly
in the culture room and keep their genetic characteristics stable
·
Banana
In Pakistan, experimental banana cultivation was started after
Independence, and soon after its success in Sindh the banana emerged as an
important fruit crop. It is now grown on 30.3,000 ha with a total annual
production of 139.5,000 metric tons.
Overview
Area (Pakistan)
= 30,300 hectare
Production
= 1,39,500 tones
Distribution
= Sindh (86.8%), Punjab (8.6%),
Balochistan(3.0%), NWFP (2.0%)
VARIETY
Locally called Bombay
Dwarf
Cavendish
(95%)
William
hybrid
(3%)
Setting up of Tissue Culture Laboratory
·
Media Preparation
Area/Room
·
Aseptic transfer
Chamber Area
·
Environmentally
Controlled Culture Room
·
Analytical Room and
Acclimatization Room
Conclusion
The application of tissue culture techniques has helped breeders
to improve varieties more efficiently, and the breeders are able to handle the
crops in such a new way that they were unable to do with conventional methods
only. For many agronomic and horticultural crops, tissue culture can accelerate
growth of seeds and seedlings which contributes directly to an improved
agricultural production.
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