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Genetic Diversity In Agriculture

Genetic Diversity In Agriculture


Genetic variation is the raw material for the plant breeder, who must
often select from primitive and wild plants, including wild species, in search
of new genes.   The appearance of new diseases, new pests, or new virulent forms
of disease causing organisms makes it imperative that the plant be preserved,
because it offers a potential for the presence of disease resistant genes not
present in cultivated varieties.   Also, there are demands for new characters--
for example, high protein, improved nutritional factors, and fertility
restoration.   As a result, plant breeders require a large and diverse gene pool
to meet ever changing needs.
A gene bank is a popular term that is used to describe repositories for
genes of living organisms.   It is commonly used in the context of plant breeding
as I described above, but it also applies to the freezing and the storage of
animal sperm and embryos for use in animal husbandry or artificial insemination.
An understanding of crop origins and variations is necessary in
assembling genetic diversity in plant crops.   In certain geographical areas
there has existed a rich source of variability in crop plants but the
encroachment of civilization has reduced the natural variability inherent in
primitive plant forms and related species of crop plants.   Agricultural process,
as a result of new breeding programs, has reduced rather than increased crop
variability as improved cultivars, or varieties, are planted in wider and wider
areas and old cultivars, which may contain valuable genes, are lost.   Crop
failures, which result in a smaller gene pool, have led to an increased
awareness of the need to preserve genetic diversity in plants.   Efforts are
under way to increase collections of plant materials in various forms.   Usually
these are preserved as seeds, but living plants, pollen, and cell cultures are
also used.   In most gene banks, seeds are usually preserved under conditions of
low temperature and...