Economic Botany: Origin of cultivated plants

This is a part of Core Course VI : Economic Botany: Crop domestication and loss of genetic diversity; crop introduction

1. Economic Botany Core Course VI Unit1:Lecture2: Origin of cultivated plants Crop domestication and loss of genetic Diversity; Examples of major plant introductions; Importance of Germplasm diversity Ref :A Text Book of Botany Volume IV; Bhattacharya, Ghosh & Hait Plant Breeding, P.Satya Dr Rita Som Paul Associate Professor Botany Department Siliguri College

2. Crop domestication and loss of genetic Diversity Domestication is selection for desirable characters like higher yield,non -shattering type of grain and elimination of undesirable characters of wild species through several generations Mere cultivation of crop does not qualify for domestication Thus, domestication is a form of plant breeding

3. Domestication of plants is as old as domestication of animals about 14,000 years BP(Before present). Rice was the earliest domesticated crop. Sl No Crop Evidence of domestication (years BP) Place 1 Rice 15,000-13,000 Korea, Indo-China 2 Eikorn wheat 10,000 Near East 3 Maize 6300 Central Mexico 4 Bottle gourd 12,000 Asia and Africa 5 Squash 10,000 Central Mexico 6 Pearl Millet 3000 Central Africa 7 8 Barley Fig 10,000 10,000 Near East Near East

4. Pollination cross-pollinated self-pollinated

5. Consequences of domestication Loss of genetic diversity- loss of divergent alleles in a species-genetic erosion Genetic pollution-invasive species, transgenes Dependence of the species on human interference/help for survival- loss of fitness-non-competitive Loss of species diversity – out of 13 million plant species, only 7000 plant species are cultivated and only 30 supply most of human needs for food.

6. Loss of genetic diversity Two types of genes 1. directly controlling the traits selected by the humans (seed size, seed number, fruit colour ) directly influenced by selection – variability at these loci is drastically reduced 2. do not directly control the traits under selection - variability reduced to a lower extent ( Eg.embryo size) --  Bottleneck effect; narrowing of genetic base

7. Examples of major Plant Introductions Introduction - Transfer of genotype of crop plants either singly or in groups from one place of cultivation to a totally different new area for the purpose of cultivation . The main target is to Method:Import of germplasm Indian Agencies : NBPGR (National Bureau of Plant Genetic Resources) BSI (Botanical Survey of India) FRI(Forest Research Institute)

8. Plant Introduction Primary Introduction : the variety os well-adapted and can be cultivated without any genotype changes Eg Rice -IR8 ( fromPhillipines ) and IR36; wheat – Lerma Roja and Sonara 64 (from Mexico) Secondary Introduction –variety introduced is initially subject to selection and /or hybridization Eg Sonalika and Kalyan Sona of wheat are selected from Mexican varieties

9. Examples of primary introductions Sl No Crop Variety 1 2 Wheat Rice Lerma Rojo-64;Sonora-64(Mexico) IR8;IR50( Phillipines ) 3 4 Sunflower Groundnut Peredovik (USSR) M13(USA) 5 6 Soybean Pea Lee(USA) Harbhajan (Portugal) 7 8 Tomato FrenchBean Labonita (USA); FireBall (Canada) Kentucky Wonder(USA) 9 10 Water Melon Apple SugarBaby (USA) Delicious-II(USA)

10. Examples of secondary introductions Sl No Crop Variety 1 Cowpea Rituraj 2 Cauliflower Pusa SnowBall-1 3 Tomato Pusa Ruby 4 Water Melon Akra Manik

11. Importance of Germplasm Diversity Germplasm - total genetic resource of an organism (usually of a species) OR - a collection of living tissues (usually a species) from which new plant can be grown (seed, piece of stem or the whole plant etc)- it contains the information for the total species genetic makeup

12. Importance of Germplasm Diversity PGR (Plant Genetic Resources)/Plant Biodiversity Usable (direct use) value – germplasm of crop plants especially is important for survival of humans. 1.Some gene may be present in wild relative that might be useful at some stage for the plant breeder 2.Plants used for clothes, furniture, medicine Non-use (indirect use) value – support to evolution; balancing of ecosystem ; aesthetic value; CO2/O2 balance;

13. Importance of Germplasm Diversity 1. Population (a group of individuals of same species) with large gene pool has a better chance of survival 2.To improve the existing plants and form new varieties 3. Reduction of incidents of unfavourable traits being inherited (inbreeding depression reduction)

14. Gene banks- means to preserve germplasm (mainly crop plants) Sl No Gene bank Country No of accessions held 1 National Seed storage Laboratory USA 268,000 2 Institute of Crop Germplasm China 300,000 3 Vavilov Institute of Plant Industry Russia 177,680 4 National Bureau of Plant Genetic Resources India 343,000 5 National Institute of Agrobiological Research Japan 146,000