Wheat evolution

a brief review about history and evolution wheat

1. History and Evolution of Wheat BY OMER MUMTAZ

2. CONTENTS INTRODUCTION IMPORTANCE HISTORY EVOLUTION

3. INTRODUCTION Triticum aestivum L . Hexaploid Specie (AABBDD) having 2n=6x=42 Self pollinated Wheat supplies about 20% of the food calories for about 2 Billion people (36% Worlds Population) The per capita wheat consumption of the country (130 kg per year) & is among the highest rankings in the world.

4. Importance Wheat is the second most produced cereal in the world. Provides a large fraction of the dietary protein and total food supply, and is grown all throughout the world. Wheat occupies a supreme position in the food grains of Pakistan it covers 66% of the total area under food grains and contributes 74% of the total food grain production.

5. Cont … Wheat alone contributes 13.8% to the value added in agriculture and 3.4% towards GDP of Pakitsan . A large variety of food that include bread, chapaties , cakes, noodles, crackers, biscuits, macronies and many other items are prepared from wheat.

6. Wheat Statistic: 2015-2016 Location Area (000, Ha) Production (000, tons) Yield (Kg/Ha) Pakistan 9260 4920 4301 KPK 470.9 914.8 1943 Source: PBS., 2016

7. History Cultivation and repeated harvesting and sowing of the grains of wild grasses led to the creation of domestic strains, as mutant forms of wheat were preferentially chosen by farmers. In domesticated wheat, grains are larger, and the seeds (inside the spikelets ) remain attached to the spike by a toughened rachis during harvesting. Cultivation of wheat began to spread beyond the Fertile Crescent after about 8000 BCE.

8. Cont … Jared Diamond traces the spread of cultivated emmer wheat starting in the Fertile Crescent sometime before 8800 BCE. Archaeological analysis of wild emmer indicates that it was first cultivated in the southern Levant with finds dating back as far as 9600 BCE. Genetic analysis of wild einkorn wheat suggests that it was first grown the in southeastern Turkey.

9. Cont …. Dated archeological remains of einkorn wheat in settlement sites near this region, including those at Abu Hureyra in Syria, suggest the domestication of einkorn near the eastern Turkey. The cultivation of emmer reached Greece, Cyprus and India by 6500 BCE. In Egypt shortly after 6000 BCE. Germany and Spain by 5000 BCE.

10. Cont … By 3000 BCE, wheat had reached the British islands and Denmark, Norway and Sweden. A millennium later it reached China. The oldest evidence for hexaploid wheat has been confirmed through DNA analysis of wheat seeds, dating to around 6400-6200 BCE, recovered from southern Anatolia. From Asia, wheat continued to spread throughout Europe.

11. Evolution Einkorn wheat (T. monococcum) is diploid (AA, two complements of seven chromosomes, 2n=14). Most tetraploid wheats (e.g. emmer and durum wheat) are derived from wild emmer, T. dicoccoides. Wild emmer is itself the result of a hybridization between two diploid wild grasses.

12. Cont … The hybridization that formed wild emmer (AABB) occurred in the wild, long before domestication and was driven by natural selection. Hexaploid wheats evolved in farmers' fields. Either domesticated emmer or durum wheat hybridized with yet another wild diploid grass ( Aegilops tauschii ) to make the hexaploid wheats, spelt wheat and bread wheat. These have three sets of paired chromosomes, three times as many as in diploid wheat.