Protection of conservation of genetic resources (i.e., all the various types of genes present in the different varieties of a species which have been, are being or likely to be used in the improvement of domesticated plants) is called genetic conservation
Biological or bio-diversity is the occurrence of a large number of different species and their biotypes adapted to specific area and woven in webs of biotic relationships. Genetic diversity is the occurrence of a large number of varieties, biotypes, variations and alleles. There are 12 centres of diversity / megadiversity. India is one of the 12 megadiversity regions of the world with 8% of global genetic resource and some 45000 species of plants. Vavilov (1926) proposed that different crop plants originated in different areas where their wild relatives are present and genetic diversity is maximum with temperature fluctuations and UV radiation’s. Vavilov proposed 11 centres. Australia is the 12th centre. New World was discovered by Christopher Columbus in 1492 when he landed on island of Bahmas in Caribbean Sea. Cotton has developed in both old and new worlds.
Due to intra and interspecific variations in variety of genes (genetic diversity), improvement of crop plants takes place. But simultaneously as a result of genetic erosion, there is loss of genes from gene pool (totality of genes in a species or population), which leads to reduction in genetic variability. Deforestation, shifting cultivation, urban expansion, disturbances in ecosystems and use of some specific plant varieties are some of the causes of genetic erosion.
There are four basic methods of genetic conservation :
(1) In Situ Conservation : It is maintenance of biological diversity in natural habitats like forests and nature preserves by setting national parks, wildlife sanctuaries and biosphere reserves.
(2) Ex Situ Conservation : It is conservation of selected rare plants / animals in places outside their natural homes. Ex situ conservation includes offsite collections and gene banks but it is often restricted to channeling the selected organisms into trade for nature lovers, agriculturists and horticulturists. Ginkgobiloba (Ginkgo Tree), once in the list of endangered species, is now flourishing in gardens.
(3) Offsite Collections : They are live collections of wild and domesticated species in botanical gardens, zoos, arboreta ( = arboretums = arbouretums), etc.
(4) Gene Banks : They are institutes that maintain stocks of viable seeds (seed banks), live growing plants (orchards), tissue culture and frozen germplasm with the whole range of genetic variability
(i) Seed Bank : In gene bank storage is done either in the form of seeds or vegetative materials, but best and convenient way is storage of seeds. Storage of dry seeds is done at low temperature (–10 to –20°C), because under these conditions, their metabolic activities are minimum which check their germination. Seeds are of two types :
(a) Orthodox seeds are those which are not killed or damaged as a result of decrease in moisture contents and temperature. These can even live upto –196°C, e.g., seeds of wheat, rice maize, oat, barley (cereals) and also different pulses or legumes.
(b) Recalcitrant seeds are those which are killed or damaged as a result of drying and decrease in temperature. These can be stored for a short span, e.g., seeds of rubber, tea, coconut, jack fruit (Artocarpus), litchi, oil palm (Elaies), etc. Conservation of crops with this type of seeds can be made by in situ conservation method and also by tissue culture method.
(ii) Orchards : Plants with recacitrant seeds are grown in orchards where all possible strains and varieties are maintained, e.g., litchi, oil palm, rubber tree, etc.
(iii) Tissue Culture : It is carried out through callus formation, embryoids, pollen grain culture and shoot tip culture for those plants which are either seedless, have recalcitrant seeds, variable seed progeny or where clone is to be maintained. The method is useful in maintaining a large number of genotypes in small area, rapid multiplication of even endangered species and for hybrid rescue. Shoot tip culture maintains virus free plants. It is used for international exchange of germplasm in vegetatively multiplied cultivars, e.g., Banana, Potato.
(iv) Cryopreservation : Dry, freezed storage of germplasm (at –196°C) is called cryopreservation. Under these conditions, there is near stoppage of all biological activities and further there are no chances of genetic changes. This method is not used for plant germplasm.
(v) Germplasm : It is the genetic material contained in organisms especially in their reproductive / germ cells. The first germplasm centre of the world was established by Vavilov in Leningrad, now known as Vavilov All Union Institute of Plant Industry.
It is very important to conserve wild species of plants as these are highly resistant of insects, pests, diseases and unfavourable growth conditions, which are necessary for survival of plants. The loss of wild plants will reduce the genetic variability and will be a great loss to gene pool. Potato and sugarcane have been improved by use of germplasm of wild species having many defensive characters like disease resistance and resistance to environmental stresses.
Harnessing Genetic Variability
(1) Coloured Cotton : Genes present in Gossypium arboreum, G. hirsutum, G. barbadense have been found to cause colouration of cotton fibres like grey, cream, brown and green. Central Institute of Cotton Research (CICR) Nagpur is engaged in bringing about varieties with different coloured fibres so as to overcome the need for artificial colouration.
(2) Improvement in Wheat : Dwarfing gene Norin – 10 was noticed in Japan. It was picked up by American breeders. In 1963, Borlaug was able to breed high yielding triple dwarf or Mexican wheats (Nobel Prize in 1970) which were resistant to lodging, common pathogens and pests. Two of these, Sonora – 64 and Lerma Rojo were brought to India and modified to form basis for Green Revolution.
(3) Improvement of Sugarcane : Resistance to red rot disease was introduced in sugarcane at Sugarcane Breeding Institute of Coimbatore by crossing it with its wild relative Saccharum spontaneum (Thatch Grass). It gave rise to Co – varieties.
(4) Improvement in Rice : In rice, considerable increase in yield has been made by introducing genes for resistance to ‘grassy shoot virus’ from wild rice (Oryza nivara) found in central India. Similarly, introduction of dwarfing genes from a variety of Taiwan, Dee-geo-woo-gen has produced many improved varieties in rice. IR-36 variety of rice has been developed at IRRI, Manila (Philippines) by using wild species Oryza nivara, which is high yielding and has solved food problem in Asia by increasing rice production by 5 million tons per year.
(5) Improvement In Potato : In potato (Solanum tuberosum), genes for resistance to potato virus-X and potato leaf roll virus have been obtained from a wild species Solanum ocaule; resistance to wilt fungus (Fusarium) and cyst nematode (Globodera) has been introduced from Solanum spegazzani; resistance to potato virus-Y has been introduced from S. stoloniferum and resistance to late blight of potato (caused by Phytophthora infestans) has been derived from S. demissum.
Botanical Gardens
(1) Royal Botanical Garden, Edinburg. Spread over 50 acres.
(2) Royal Botanical Garden, Kew (London). Spread over an area of 300 acres. It has world’s largest herbarium with about 6.5 million specimens. Museum of Natural History Paris has an almost equal number of specimens.
(3) Bundes Garden, Vienna. It is spread over an area of 400 acres.
(4) Main Botanical Garden, Moscow. Largest, spread over an area of 900 acres.
(5) Botanical Garden Berlin-Dahlem. Spread over 103 acres. It has a botanical museum and herbarium arranged by Engler.
(6) Arnold Arboretum, Boston (U.S.A.). Spread over an area of 265 acres, it has a large number of bonsai trees and green houses.
(7) Kebun Raya (Botanical Garden) Bogor, Java. It is spread in an area of 200 acres. There is a section with virgin rain forest.
(8) Indian Botanical Garden, Sibpur, Calcutta. Largest botanical garden of India (Asia) spread in an area of 273 acres. It has the biggest herbarium in India/Asia. It also has the head-quarters of Botanical Survey of India (BSI).
(9) National Botanical Garden, Lucknow. Spread in an area of 70 acres. It has a good herbarium.
(10) Lloyd Botanical Garden, Darjeeling. It is spread in an area of 40 acres.
(11) Garden of Forest Research Institute, Dehradun. Small garden in an area of 20 acres. Has a good herbarium.
(12) Garden of Indian Agricultural Research Institute, New Delhi. 60 acres. Mainly for experimentation.
Table : 10.6-1
Important Herbaria of World (Holmgren et al 1981)
Herbaria of RBG (Royal Botanic Gardens), Kew (london) abbreviated as K, presently it is the largest herbarium of the world, otherwise Berlin Gotanical Museum Herbarium was largest but it was destroyed in II world War.
Estd 1841
Over 6500000 (6.5 million) specimen sheets
Herbaria of the Komarov Botanical Society of Academy of sciences of USSR, Leninguard (Russia), abbreviated as
Herbaria of Royal Botanic Garden, Edinburgh (Scotland)
1761
2.5 million
Central National Herbarium (CNH) of Indian – Botanical Gardens, Sibpur (Distt. Howrah), Kolkata, Under BSI
1793
2.5 million
Herbarium of Forest Research Institute (FRI), Dehradun (Uttranchal)
1816
0.3 million
Herbarium of National Botanical Garden (NBG) Lucknow (UP)
1948
1 lakh
Kanjilal Herbarium of Botanical Survey of India, Eastern Circle, Shillong
1956
1 lakh
Madras Harbarium, Southern Circle, BSI
1874
2 lakh
New Crops
Out of about 3,50,000 known plants at this time, a few i.e., about 100. Scientists are in search of less known and underutilized crop plants, which can be used for food and other purposes and thus exploitation of traditional plants can be reduced. Such under-utilized and under-exploited plants are known as new crops.
Some of these new and underutilized crops are as follows :
(1) Triticale: Triticale is the first man made cereal or crop, which has been produced by intergeneric hybridization between common wheat (Triticum aestivum) and European rye (Secalecereale) with a view to combine characters of these two parent plants. Triticale is hexaploid, i.e, 2n = 6x = 42 (tetraploid Durum wheat × diploid Rye) or octaploid, i.e., 2n = 8x = 56 (hexaploid Bread wheat × diploid Rye). Triticale is the first new man-made plant to join the rank of cereals which have long evolutionary plants are being used for fulfilling man’s daily requirements history. Triticale or triticosecale is not suitable for purpose of bread making due to low gluten content, but it is a good forge crop. Triticale is grown all over world, mainly in USSR.
(2) Winged bean (Psophocarpus tetragonolobus family Leguminosae) : This is a herbaceous plant, which has capacity of nitrogen fixation. The tuberous roots, leaves, shoots, long pods with prominent wings and seeds are highly nutritious due to rich source of proteins and edible for humans as well as livestock. When green, the pods, leaves and shoots are used as vegetables, unripe seeds may be used as soups and ripe seeds can be roasted. The ripe seeds contain about 34% proteins and 18% oils (similar to soybean). Further this plant can be used as a green-manure plant, fodder plant and also as a cover crop.
(3) Jojoba or Hohoba (Simmondsia chinensis) : This is a shrub, which is native of Mexican deserts. It is important drought desert plant, because it can survive under poor soil and low moisture conditions and hence is being grown in deserts. The seeds of this plant contain about 50% liquid wax, which is similar to sperm whale oil (spermaceti). This liquid wax was originally used in cosmetics, but now is also being used in high performance lubricants.
(4) Guayule (= Wayule, Parthenium argentatum family Asteraceae) : It is commonly known as carrot grass or congress grass. This is native of America and nowadays it is most troublesome terrestrial weed in India and is present in almost all states of India. The roots of this plant secret transcinnamic acid, which inhibits the growth of other plants (allelopathy). This is a shrub and can grow on poor desert soils. This plant is nowadays used in obtaining rubber, which is called guayule rubber, which is similar to para rubber or hevea rubber. The body of this plant contains caotchouc granules, which are ingredient of rubber. The plant contains 12- 20% rubber on dry wt. basis. This plant can be a natural source of rubber in future.
(5) Leucaena or Subabul/Loo-See-na/Loo-kee-na (Leucaena leucocephala family Leguminosae) : This is a fast growing small tree and is native of central America. This plant is nowadays being planted on a large scale under social-forestry. These plants are used as wind breaks, fire breaks, cover plant for deforested tropical regions, leaves as fodder, wood as fuel and in charcoal formation, paper pulp, rayon and timber. It is also used as shade and cover plant in coffee, tea and rubber plantations. Leucaena is a nitrogen fixing plant and leaves are good sources of green manure. It can grow on poor and worn out marginal lands.
(6) Oil plant : Some potential oil yielding plants are there, which provide edible and non-edible oils after suitable treatments. Some potential oil plants are as follows :
(i) Margosa or Neem:Azadirachta indica (family Meliaceae). It is native of Burma (Myanmar) and is widely grown tree in India. Seeds are source of margosa or neem oil with bitter taste, used in soap making.
(ii) Indrayan or colocynth: Citrullus colocynthis (family Cucurbitaceae). It is a perennial trailer area with medicinal. Roots used in curing jaundice and urinary disease. Fruit pulp is used medicinally as purgative and bacteriocidal. Seeds have oil.
(iii) Mahua:Madhuca indica, seeds give oil used in soap making and also in cooking purposes.
(iv) Buffalo or Wild gourd :Cucurbita foetidissima, it can tolerate heat and drought. Its fruit is employed as a soap substitute. The seeds are oily and edible. The underground storage roots of the plant are source of industrial starch.
(v) Mustard tree or Kharjal:Salvadora perisca, seeds provide oil which is used commercially.
(vi) Sal : Shorea robusta, trunk yields oleoresin, which is source of ‘chua oil’ on distillation, which is used in perfumes.
(7) Fodder trees : Some important fodder trees are :
(i) Kikar or Babul (Acacia nilotica) : Foliage and pods are widely used for feeding goats and sheeps in arid regions of India. Leaves and twigs of A. senegal provide fodder also.
(ii) Siris (Albizzia lebbeck) : Young foliage contain about 20% protein and are fed to livestock
(iii) Peepal (Ficus religiosa) : The leaves are lopped for elephant and cattle fodder.
(iv) White mulberry (Morus alba) : The leaves which are avidly browsed by goats, cattle and sheep are deliberately lopped for fodder.
(v) Basna (Sesbania grandiflora) : Cattle relish the fleshy, feathery leaves and long pods in the tropical parts of India.
(8) Non-alcoholic beverages (Less-known) : Generally, non-alcoholic beverages are obtained from coffee, tea and cocoa, but there are other sources of less known beverages plants. Some of them are :
(i) Caltha edulis or Arabian tea: A decoction from its leaves known as khat. Leaves and buds on chewing have stimulating effect.
(ii) Cola nitida or Cola: A beverage ‘cola’ is obtained from seeds in Africa.
(iii) Ilex paraguariensis(Mate) : It is source of Paraguay tea.
(iv) Paullinia cupana or Guarana (Yaco) : Guarana seeds used as beverage in South America.
? Useful plants. Some 3000 plants can yield food, out of which 150 are commercialised. However, most of the agriculture is based on only 12 species.
? IBPGR. International Board of Plant Genetic Resources (Established 1971).
? Primary Introduction. Exotic variety directly used for cultivation.
? Cultigens. Cultivated plants without wild form and fully dependent on humans for their survival.
? National Bureau of Plant Genetic Resources (Established 1976). Keeps control on plant introductions.
? Secondary Introduction. Exotic variety first reared in selected areas. It is introduced to other areas only after selection or hybridisation.
? World food Day. 16th October.
? Ex-situ conservation means the cultivation of rate varieties of plants in gardens and protection of rare wild animals in home.
? Alianthus excelsa (tree of heaven) is a fast growing timber tree suitable for wind breaks and shelter belts. Young branches are cut to feed goats.
? Salvadora oleoides is botanical name for barihath pilu (bara pilu)
Genetic Conservation
Post-Vavilov megadiversity centre is
(a) Australia (b) Siberia
(c) Andamans (d) Tibet
The number of centres of origin of crop plants recognised by Vavilov is
(a) 8 (b) 11
(c) 7 (d) 21
Potato famine of Ireland was caused by the attack of fungus
Assertion : Paraguay tea is obtained from Paullinia cupana.
Reason : Tea is obtained from Camelliasinensis.
Assertion : Cola contains caffeine and kolanin.
Reason : It is obtained from the powdered seeds of Cola nitida.
Assertion : Winged bean is widely cultivated in India.
Reason : Seeds of winged bean has low protein contents. [AIIMS 1996]
Genetic Conservation
1
a
2
b
3
d
4
c
5
d
6
d
7
a
8
b
9
c
10
c
11
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d
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c
14
b
15
d
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b
17
d
18
a
19
c
20
d
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d
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d
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d
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d
25
a
26
a
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c
28
a
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a
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d
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a
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a
33
b
34
c
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d
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b
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b
39
d
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c
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a
42
a
New Crops
1
a
2
c
3
b
4
b
5
b
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c
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a
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d
9
c
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c
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b
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d
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d
14
c
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d
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b
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d
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c
19
a
20
c
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d
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c
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c
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a
25
d
Critical Thinking Questions
1
c
2
c
3
a
4
b
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a
6
d
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a
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a
9
b
Assertion and Reason
1
b
2
b
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a
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b
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c
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b
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c
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a
9
b
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e
11
b
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c
Genetic Conservation
(b) Vavilov (1926) proposed 11 centers of origin of plants.
(c) Late Blight of potato (caused by Phytophthorainfestans) has been derived from S. demissum.
(d) In situ conservation is maintenance of biological diversity in natural habitats like forest and nature preserves by setting national parks, wildlife sanctuaries, Biosphere reserves.
(a) Gene banks institutes that maintain stocks of viable seed (seed banks), live growing plants (orchards), tissue culture and frozen germplasm with the whole range of genetic variability.
(b) Orthodox seeds which can be partially dried (upto 5% moisture) and can be stored indefinitely at low temperature (–10° to –20°C) e.g., cereals.
(c) Dwarfing gene Norin –10 of wheat was noticed in Japan.
(c) Cryopreservation at –196°C (liquid nitrogen) can maintain tissue culture embryo etc.
(b) Resistance to red rot disease was introduced in sugarcane at sugarcane breeding institute of Coimbatore by crossing with Saccharum spontaneum.
(c) Germplasm is the genetic material contained in organism especially in their reproductive / germ cell.
(d) In 1963, Borlaug evolved dwarf wheats. He got Nobel prize in 1970.
(d) Shoot tip culture maintains virus free plants. It used for international exchange of germplasm in vegetativily multiplied cultivars e.g., Banana, patato.
(a) Ex situ conservation of selected rare plants / animals in place outside their natural home. Ginkgo biloba, once in the list of endangered species is now flourishing in gardens.
(a) Dry, freezed storage of germplasm at –196°C is called cryopreservation.
(d) Indian Botanical Garden, Sibpur, Culcutta is largest botanical garden of India (Asia)
(a) Royal Botanical Garden Kew (London) spread over an area of 300 acres. It has world largest herbarium.
New Crops
(a) Simmondsia chinensis (Jojoba) seed have 50% liquid wax. Which can be used as high performance lubricant for michinery involving pressure but not temperature changes.
(c) Margosa / Neem / Azadirachta indica is under utilized oil crop. Its oil obtained from seed.
(b) Triticale is man made cereal of two types
(i) Hexaploid – tetraploid wheat cross with diploid Rye.
(ii) Octaploid – hexaploid wheat cross with diploid Rye.
(b) Triticale used as forage crope flour does not form chapatis.
(c) Jojoba plant seeds contain 50% liquid wax, which is similar to spermaceti. This was originally used in cosmetic and high performance lubricants.
(b) Jojoba (Simmondsia chinensis) is shrub, which is native of Mexican deserts.
(d) Winged been / Psophocarpus tetragonolobus plants having tuberous root for nitorgen fixing, seed contain 34%. Protein and 13% oil similar to Soybean. It is new potent crop.
(b) Leucaena plants having tuberous root for the nitrogen fixation and plants used as a good green manure.
(c) Jojoba seeds contain liquid wax which is similar to sperm whale oil and used in cosmetics and lubricants.
(c) This plant is nowadays being planted on a large scale under social – forestry. They used as a wind breaks, fire breaks fodder etc.
Critical Thinking Questions
(c) Guarana (Paullinia cupana) is beverage plant it is rich in caffeine.
(a) Ex situ conservation includes offsite collections and gene banks.
(b) Gurdev S. Khush crossed 13 varieties of rice from Oryza nivara to develop IR – 36 which was resistant to grassy stunt virus.
(a) Potato and tomato originated in the new world.
Assertion and Reason
(b) In modern era a high yielding variety developed at one place is immediately distributed to all parts of the globe. Naturally the low yielding local varieties or wild varieties are discarded. The discarded wild varieties automatically disappear. However unless different types of genes are available in the gene pool, newer varieties cannot be produced.
(b) In situ conservation is the maintenance of genetic diversity in natural habitats like forests. It is important because growing populations, economic activity and soil erosion are eating up our forests.
In situ conservation ensures genetic diversity and provides genetic material for improvement of crop plants because the wild germplasm has genes to combat environmental stresses, diseases are pests.
(a) Wild plants grow themselves. Their seeds do not get spoiled during unfavourable periods. Plant breeders are always on the look out of the defensive traits in the wild relatives of the crop plants. The traits are introduced into crop plants through selective hybridization.
(b) Ex situ conservation is the conservation of rare plants and animals by feeding them into trade for nature lovers, horticulturists and agriculturists. For example Gingko tree was once on the list of endangered species. It is now thriving in almost all the places because its cultivation has been taken up by gardeners.
(c) Some seeds are capable of withstanding exposure to low temperature (-10°C to –20°C). Some of properly dried seeds can withstand low temperature of even liquid nitrogen (– 196°C). This reduces respiration and enzymatic activity to bare minimum which is required for sustaining the living of the seeds. Samples of the seeds are periodically tested for germination ability.
(b) The seeds of some economically important trees and shrubs get killed on drying and freezing. They are called recalcitrant seed, g., Jack fruit, litchi, coconut, rubber etc. The recalcitrant seeds may be stored for short duration in undehydrated condition after treatment with fungicides and with access to oxygen. Therefore the plant having recalcitrant seeds must either be kept in special orchards or maintained through tissue culture.
(c) Winged bean is a nitrogen fixing herbaceous plant found in tropical Asia. All parts of the plant are edible and rich in protein. Ripe seeds are roasted and eaten like peanuts. They contain 34-40% protein and 18% oil. Their nutritive value is similar to that of soyabeans.
(a) Jojoba seeds contain upto 50% liquid wax. Jojoba oil can penetrate outer layers of human skin. Like sperm whale oil, jojoba oil has the ability to function as high perfomance lubricant for fine machinery, which can tolerate extreme pressures. The stems and roots of Guayule contain latex. Latex of Guayule produces natural rubber and it is resistant to temperature changes and abrasion.
(b) Leucaena is a fast growing leguminous shrub or small tree. It enriches the soil with nitrogenous chemicals. The leaves being rich in nitrogenous compounds, are a good green manure. The plant is capable of growing on poor, marginal soils. It is planted on roadsides, as wind breaks, fire breaks, ornamentation and for revegetating deforested tropical areas.
(e) Paraguay tea is obtained from leaves of evergreen tree Ilex All the leaves are used. Tea is obtained from the leaves of Camelliasinensis of family Theaceae.
(b) The seeds of Cola nitida are used in Africa and other countries for beverage purpose.
The drink is prepared by powdering the cola nuts (seeds). Cola is rich in caffeine and heart stimulant glycoside called kolanin.
(c) Winged bean is nitrogen fixing legume. It has high amount of protein in seeds. It is widely cultivated in India.
(a) Aseptate and multinucleate (b) Septate and multinucleate (c) Aseptate and uninucleate (d) Septate and uninucleate Answer. (b) The mycelium of Aspergillus consist of branch septate hyphae. Cells of hyphae are multinucleate. (184)
(a) Parenchyma (b) Chlorenchyma (c) Plectenchyma (d) Collenchyma Answer. (c) Plectenchyma (Pseudoparenchyma) is nothing but the interwoven mass of fungal mycelium which in cross-section look like parenchyma. (104)
(a) Colletotrichum falcatum (b) Phytophthora infestans (c) Potato mosiac virus (d) Alternaria solani Answer. (b) Late blight of potato is a seed born disease which is caused by Phytophthora infestans. The disease is characterised by brownish to blackish dead areas …
