Hexaploid Wheat: Evolution, Domestication

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Hexaploid Wheat: Evolution, Domestication, Dissemination, US commercialization, and Molecular characterization

Wheat is one of the major food crops in the world, which provides 532 kcal/capita/day (http://faostat.fao.org). World production of wheat is about 670 M tonnes, which is only behind maize (872 M tonnes) and rice (720 M tonnes) (http://faostat.fao.org) whereas the US is the third largest wheat producer in the world (http://faostat.fao.org). Wheat group comprise of 13 diploid and 18 allopolyploid species (12 tetra and 6 hexa) (Feldman et al. 2012), where hexaploid wheat is the most cultivated class throughout the world (Faris 2014). Hexaploid wheat (bread wheat) is known as the allohexaploid (2n=6x=42, BBAADD), because it is derived from the diploid species via convergent evolution (Faris 2014 and Feldman et al. 2012). Hexaploid wheat consist of winter and spring wheat, which mainly differed by vernalization governed by vrn (vrn1, vrn2) genes (Taiz and Zeiger 2002, Doebley et al. 2006).

Wheat has 21 pairs of homologous chromosomes and seven homoeologous chromosome group, which possess high level of similarity (Feldman et al. 2012). There are various genetic changes such as elimination of low or high copy DNA sequences, elimination …show more content…

2007; Peng et al. 2011). Tough glume do not allow free – threshing. However, two genes Tg22BTg12Dassociated with the tenacity of the glume has been reported (Faris 2014). Till now there is no Tg gene has been reported on the A genome. The single recessive gene sog has been reported, which confines the soft glume trait in the free- threshing mutant of domesticated einkorn wheat T.sinskajae (2AmS) (Taenzler et al. 2002; Sood et al. 2009; Faris 2014) .Exact relationship between the tg/ sog is not well defined yet (Faris 2014). Studies performed by Nalam et al. (2007) indicates that possibility of two paralogous regions on chromosome 2DS for

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