Applications And achievements of Post harvest Biotechnology of flowers and
ornamentals
INTRODUCTION: -
Flowers by nature attract every
human being. In India commercial growing of
flowers are presently confined to Karnataka, Tamilnadu, Andhar Pradesh, West
Bengal, Maharashtra, Rajasthan, Uttar Pradesh, Delhi, Harayana. The major flowers grown in India are
marigold, aster, roses, tuberous, gladiolus, jasmine, crossandra in open field. while gerbera, carnation, roses, anthurium,
orchids etc. are grown in green house condition. The export of cut flowers from India
is of Rs 253 million. India ranks 23rd among world
exporters of floriculture products and its share in the world exports are
negligible at around 0.38% (US$ 47 million) (2004). It is estimated that fresh cut flowers
worth Rs. 100 crores are being exported annually from India. On the other hand the losses are
estimated to be more than30-35%. Factors at pre harvest stage including genetic
or inherent, climatic or environmental and management harvest factors like
stage, method and time of harvesting. Post-harvest factors such as watering,
dehydration, precooling, storage environment, packaging techniques and
micro-organisms influence the post harvest quality and longevity cut flowers.
WHAT IS BIOTECHNOLOGY:-
Science of
utilizing the properties and uses of micro organisms or to exploit cells and
the cell constituents at different level for generating useful products
essential to life and human welfare
Need of
Biotechnology
q Floriculture helps in enriching the
quality of life and development of our society.
q There is a global concern for
environmental improvement such as reduction of pollution and noise, energy use
minimization, prevention of erosion and flood, biodiversity and nature
conservation, therapeutic and economic benefits of our environment.
q It is well recognized that there is
need to conserve biological diversity in both native and cultivated plant
species.
q For Genetic resource characterization
DNA marker polymerization are
advantageous.
q DNA finger printing techniques exhibit a great
potential.
q Application of Biotechnology to the
development of new varieties of Flowers has been considered.
q The Genetic engineering Technology
has opened up possibilities for manipulation of flower senescence, Colour
pigments, plant height, flower shape, floral scent; and development of
transgenic plants.
q The changing scenario in
international trade in ornamental crops which provide unlimited export
potentialities, Demand perfection in post harvest technology to offer quality
plant products to the people around the world, all the year round.
q Biotechnology reduces
q Post harvest loses By making
Flower crops resistant to biotic and
a biotic stresses.
Flowers with new colors. Flowers with improved size, shape and
floral scent.
Flowers having long vase life.
Genetic
Engineering for biotic stress
•
Identification of genes that control general agronomic traits – disease
and insect resistance.
•
Insect control protein genes from Bt – increased resistance to
lepidopteran larvae (Fischhoff et al., 1987 biotech :5)
•
Expression of cowpea trypsin inhibitor gene in transgenic tobacco –
increased resistance to herbivorous insect pests (Hilder et al., 1988 Nature:
330)
•
The chrysanthemum cultivar 'Shuho-no-chikara' was transformed with modified
delta-endotoxin gene, modified cry1Ab (mcbt) of Bacillus thuringiensis.
•
which displays a specific biological activity against lepidopteran
insects into chrysanthemum.
(Shinoyama.H et al., Breeding science
53(4), 2003)
Genetic engineering of plants to virus resistance:
•
Coat protein mediated- resistance.
•
Expression of coat protein gene of Tobacco Mosaic Virus in transgenic
tomato – resistance to infection by TMV (Abel et al., 1986)
•
Similar approach for alfalfa mosaic virus, cucumber and mosaic virus
(Tumer et al., 1987)
•
Availability of cloned and sequenced plant viruses – use in protection of
flower crops (William R.Woodson 1991)
•
Transgenic chrysanthemum showing resistance against chrysanthemum stunt
viroid (CSVd) .
•
Double-stranded RNA-specific ribonuclease gene (pacl) derived from
Schizosaccharomyces probe using an Agrobacterium mediated transformation
(OgawaToshiya et al.,
Breeding science 55(1),2004)
Genetic
engineering for fungal resistance:
•
Limited success in area of fungal resistance through genetic engineering.
•
Chitinase – protein hydrolyses Chitin – component of fungal cell wall –
defense mechanism of plant.
•
This enzyme has been shown to inhibit fungal growth in vitro
(Broekart et
al., 1989 Science: 245)
Transgenic
carnation with fungal resistance:
To obtain
fungal resistance, transgenic carnation with osmotin, PR-1 and/or chitinase
genes were generated
A high
level of resistance in these transgenes to a major carnation pathogen (Fusarium
oxysporum f. sp. Dianthi) was demonstrated in greenhouse tests.
(A.Zuker
et al., 2005 Acta Horticulturae:560
Genetic
Engineering for a biotic stress
•
Identification of genes that provides freezing tolerance.
•
Down-regulating
α-Galctosidase in petunia results in an increase in freezing tolerance at the
whole-plant level in nonacclimated and cold-acclimated plants.
•
whereas
overexpression of the α-Gal gene caused a decrease in endogenous raffinose and
impaired freezing tolerance.
•
These results suggest that engineering
raffinose metabolism by transformation with α-Gal provides an additional method
for improving the freezing tolerance of plants.
•
Genetic engineering for flower color
Floriculture industry driven by
availability of novel flower crops. Because of this desire for novel
flower, tremendous interest in genetic engineering to introduce genes for new
flower colors. Particularly for rare shades of blue
and purple Flavanoids are one of the main
determinants of flower colors. Flavonoid compounds are produced by
the phenylpropanoid pathway. When two or more flavanoid pigments
are present , it will be possible to increase the level of one, sometimes at
the expense of the other , to result in change in colour.
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