Gene bank and plant conservation
Out of 2,50,000 different plant species, some are already lost and nearly 20,000 seed plants are threatened to extinction. Due to disappearing of natural resources at fast rate, genetic variabilities are being lost for ever, which will result a dangerous future. Therefore, to save the threatened and gradually vanishing species, and to meet the world demand of food, we would have to conserve the natural heritage. The gene bank (germplasm bank) has taken the challenge of conserving the gene pool of economically, medicinally, socially and ecologically important plant species.
In the first decade of 20th century a Russian scientist, N.I. Vavilov, was the first to realize the need of conservation of plant genetic resources. Later, in 1920, he established the first genetic resource center (GRC) of the world at Leningrad. Thereafter, a global concern was raised after the International Biological Programme in 1964. |
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World Genetic Resource Centers
During the last two decades, many regional and international GRCs have been set up in different countries. International Rice Research Institute, Manila (Philippines) has rice germplasm bank where 25,000 varieties of rice germplasm has been collected throughout the world. Similarly, maize germplasma have been stored at Maize and Wheat Improvement Center, Mexico (with more than 12,000 varieties), Institute Colombiano Agropecuario, Colombia (more than 2000 varieties), Instituto National de Investigations Agricolas, Mexico (with more than 7000 varieties), and potato germplasm at International Potato Center, Lima (Peru). A seed bank has been set up at the National Bureau of Plant Genetic Resources (NBPGR) (New Delhi) which is associated with a world network of gene resource centers coordinated by the International Bureau of Plant Genetic Resources of FAO.
Conservation and Storage
For the conservation of genetic materials, seeds pollen grains, vegetatively propagating parts, plant tissues or genome of plant cells is collected. These depend on (i) ease to handle, (ii) nature of crops, (iii) longevity, (iv) expertise, (v) methodologies available, (vi) space required, (vii) problems of genetic erosion of stocks, (viii) expenses. The seeds are compact and easy to handle; hence seed collection and preservation are commonly adopted. Seeds are stored in sealed hermetic containers, dried to a desired moisture level and maintained at desired low temperature.
Viability of pollen grains differs in different species; the species having maximum viability are selected. The families showing highest longevity of pollen grains are: Pinaceae, Primulaceae, Rosaceae and Saxifragaceae. The longest period of pollen storage recorded is 9 years at -20°C for apples.
The vegetatively propagating parts (corn, bulb, tubers, etc) of some plants such as Dioscorea, potato, sweet potato, etc are used for storage purposes.
In recent years, techniques have been developed to culture the plant cell, tissue, and organs. In vitro grown cultures (e.g. plantlet, apical meristem culture, etc.) are stored (see Cryobiology). Storage of in vitro grown cultures has many advantages over the others such as (i) requirement of less space, (ii) cheap in maintenance, (iii) high propagation potential, (iv) least problem of genetic erosion of stock, (v) maintenance of pathogen free stock.
