Transcript PRT 2008
PRT 2008 Lecture 8 Genetic resources Genetic resources Genetic material of actual or potential value Germplasm The term to describe DNA of an organism. Genetic material Any material or plant, animal or microbial containing functional unit of heredity Biodiversity Variability among living organism. It contains 3 aspects – habitat biodiversity, genetic biodiversity, species biodiversity Significance of biodiversity • It supports the healthy function of the earth’s ecosystem • Without biologically viable world human will not exist • Biodiversity provides services that maintains life on the earth • Biodiversity provides human with esthetic benefit Economic benefit • Crops • Domestic animals • Medicine • Natural products – wild life, fish, timber • Some 10,000 species of plants and animals are exploited industrially Importance of genetic resource • Genetics as units of inheritance control characters in biological organism • It help increase agricultural production by altering genetic constitution. Rice, barley, wheat cotton and sugarcane double. Tomato and rubber triple. Corn, sorghum and potato quadruple. Cont. Pest resistance. To maintain productivity requires constant input of new genetic material to overcome crop losses to pest that become pesticide resistant. Cont. Overall crop breeding programs add billions to world agricultural production Cont. Related to green revolution. Norman Borlaug (Nobel Laureate) speculated that by breeding genes we can increase productivity. Types of genetic resources • Wild relatives – other species from the same genus of plant/animal • Weedy relative – bridge between wild relatives and crop • Primitive – local type • Modern cultivars • Advanced breeding lines Where are the genetic resources? • Available in areas of diversity – places where many types of biological organism exist • This is called diversity centers or Diversity hot spots (25 in the world) Diversity hot spots • North and central America • South America • Europe and central Asia • Africa • Mainland Asia • Asia Pacific Center of Plant Origin/Diversity In an area where high diversity of a particular plant type existed, that area could be the origin of that particular plant. There are 8 centers. Chinese Center Soybean, Orange, tea Indian Center Paddy, egg plant, cucumber, pepper, coco yam, banana, coconut Central Asiatic Center Wheat, pea, carrot, apple Near Eastern Center Wheat, barley, melon, grape Mediterranean Center Wheat, cabbage, broad bean Abyssinian Center Wheat, barley and coffee South Mexican and Central America Center Corn, chili, pumpkin South American Center Sweet potato, tomato, potato, papaya, tobacco, tapioca, groundnut, rubber, cocoa, pineapple The demise of the centers of origin • Do not always occupy a limited area • Do not always coincide • There are secondary centers due to long history of continuous cultivation, ecological diversity, human diversity and introgression with wild relatives The need for conservation • • • • All genetic variation originates from vegetation Mutation are random Genetic variation is essential for evolution Large amount of variation present in natural population Species • 1.7 million identified • I million are animals • 250,000 are plants • 69,000 and fungi • About 750,000 of the animals are insects • Each species is given a name – corn (Zea mays) New species About 10,000 are discovered every year Species diversity Species are not evenly distributed. It increases as you moved towards the Equator Threat to diversity Species are dying due to multiple causes Causes • Natural extinction due to competition and • • • natural disasters Human intervention causes habitat destruction Invaded by exotic weeds Use of modern varieties lead to reduction in diversity Techniques to conserve genetic resources • In situ – conservation of important genetic • resources in wild population. It is often associated with traditional subsistence agriculture. Ex situ – conservation of genetic resources offsite in gene bank, often in long-term storage as seed.