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Title: The vanishing wheat landraces of the Fertile Crescent

item Jaradat, Abdullah

Submitted to: Emirates Journal of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/4/2013
Publication Date: 1/1/2014
Citation: Jaradat, A.A. 2014. The vanishing wheat landraces of the Fertile Crescent. Emirates Journal of Food and Agriculture. 26(2):203-217.

Interpretive Summary: Wheat farming communities in the Fertile Crescent contributed for thousands of years to the development and conservation of wheat landraces. They developed efficient seed exchange systems to ensure the continued evolution and diversification of these landraces to meet their needs and to provide reliable sustenance and a sustainable food source to local communities. The present genetic structure of, and the changes within, these landraces were largely shaped and determined by traditional cultures and local cropping systems. The combined effects of natural and farmer selection have led to landraces with combinations of traits, such as growth habit, cold, heat or drought tolerance, early growth vigor, competition with weeds, disease tolerance, water and nutrient use efficiency, time to heading and maturity, seed filling duration, and quality traits suited for diverse sustenance objectives and local food preferences. Historically, traditional management of wheat landraces contributed more to the conservation of a general level of diversity than to the conservation of genetically stable and distinct populations. Therefore, a wheat landrace is far from being a stable, distinct, and uniform; its diversity is linked to the diversity of other landraces grown in its immediate geographical area, and to the level and frequency of seed exchange among farmers. The landraces identified as threatened by genetic erosion in this study are valuable sources of traits for adaptation to marginal wheat-growing parts of the world with high temperature and salinity, and may have specific traits to combat climate change.

Technical Abstract: Genetic diversity of wheat landraces constituted a sizable portion of the mega diversity in the Fertile Crescent as a center of origin and of diversity of major crop plants. Following wheat domestication in the Fertile Crescent, early farmers developed diverse wheat landraces, and contributed to their evolution, enrichment, on-farm conservation and developed efficient seed exchange systems, and ensured the continued evolution and diversification of these landraces. For millennia, wheat landraces served as staples for food production in the Fertile Crescent and beyond; however, their use dramatically declined in the 2nd half of the last century and they were replaced by modern high-yielding cultivars. Wheat landraces are facing the risk of genetic pollution, and genetic erosion and extinction due to anthropogenic and natural causes, including climate change. Monitoring and reversing genetic erosion in wheat landraces are scientifically challenging, technically and logistically difficult, and require long-term dedication and extensive efforts of farmers and the public sector. This paper presents in-depth assessment of the status of the "vanishing" wheat landraces of the Fertile Crescent, their vulnerability to predicted climate change, and proposes a strategy to give evolution a second chance to engage in reversing this trend and restoring the allelic richness of these landraces.