Wheat Landraces: A mini review <br>

Abstract

Traditional farmers planted diverse assemblages of wheat landraces to lower the risk of failure and increase food security because they had limited capacity to control the spatially heterogeneous and temporally unpredictable environments. This practice led to the development of landrace meta-populations of wheat and the emergence of farmers' seed systems through which they accessed and exchanged diverse genetic material. During the last ~50 years, the introduction of high-yielding wheat varieties into, and the structural changes in wheat farming systems in developing countries, led to the loss of genetic diversity and fragmentation of metapopulation structures of wheat landraces from large parts of the Fertile Crescent, the center of origin and diversity of wheat landraces. However, the persistence cultivation of some wheat landraces attests to their continued value to farmers, or to their competitive agronomic or nutritional advantage relative to modern varieties. For farmers to continue to grow, select, and manage local wheat landraces, and to reverse the fragmentation of their meta-populations, especially in their center of diversity, and allow evolutionary processes that mold landrace diversity to continue, their value should be raised to approximate or exceed the social value of high-yielding wheat varieties. This review provides information on wheat domestication and the origin of wheat landraces; their dynamic on-farm conservation and utilization in improving modern wheat cultivars and reversing the genetic erosion of wheat genetic diversity.

How diverse a farmer-managed wheat landrace can be?

“…These populations were subjected to natural, and probably man-made, selection; were not subjected to modern improvement methods; and were managed by subsistence, resource-poor farmers in a marginal zone for wheat production (Al-Maskri et al, 2003;Al-Khanjary et al, 2007;Gebaur et al, 2010). We concluded that these landrace populations, similar to other landraces in the primary (Ali Deb et al, 1992;Karagö z and Zençirçi 2005;Ahmadizadeh et al, 2011;Jaradat, 2013) and secondary (Bechere et al, 1995;1996) centers of wheat diversity, can provide a largely unexplored diversity with great potential for broadening the genetic base of modern wheat cultivars.…”

“…The genetic erosion caused by the displacement of wheat landraces in developing countries (Van de Wouw et al, 2009), including Oman (Guarino, 1990;Gebauer et al, 2010), is a concern for wheat breeders because these genetic resources may be the most valuable sources for broadening the genetic bases for many traits in current and future wheat breeding and improvement programs. While the problem was globally addressed, to some extent, by international strategy of collecting, conserving and utilization of wheat landraces (Bradsley and Thomas, 2005;Goats and Bockelman, 2012), specific efforts to identify potentially new genetic variability for immediate use in breeding programs are still needed at local levels, especially in the developing world (Akram et al, 2012;Ahmad et al, 2013;Jaradat, 2013). Local landraces may provide new alleles for the improvement of commercially valuable traits in wheat, including quality traits and adaptation to biotic and abiotic stresses (Yedliay et al, 2011;Goats and Bockelman, 2102).…”

“…Appropriate forms of on-farm conservation need to be developed in relation to both local cultural values attributed to these genetic resources, and within the context of Oman's agricultural development objectives. However; the main difficulties of on-farm conservation of landraces are non-biological, but rather a complex of ethanoanthropological processes, involving legal, economic and social factors, superimposed on ecological and genetic processes (Jaradat, 2013). The Omani wheat landraces have been described (Zhang et al, 2006) as being quiet unique and different from those collected in other regions, while harboring a comparable level of genetic diversity.…”

“…In wheat, as a self-pollinated crop, the genotypes of the mixture are mostly homozygous. A wheat landrace being composed of a mixture of homozygous genotypes usually exhibits considerable genetic variation for developmental (i.e., phenological traits), qualitative and quantitative traits (Camacho-Villa et al, 2005;AlKhanjari et al, 2008;Jaradat, 2013).…”

“…Having evolved over many generations in a multitude of environments and local farming systems, wheat landraces have developed abundant patterns of variation and would represent a largely untapped reservoir of useful traits for adaptation to biotic and abiotic stresses (Ali Deb et al, 1992). Throughout their evolutionary history, wheat landraces have been shaped and molded mainly by farmers to meet diverse end uses (Zeven, 2000), cultural practices, and to respond to changing socio-economic and growing conditions (Brush and Meng, 1998;DeLacy et al, 2000;Jaradat, 2006).The development of new varieties from landrace populations is a viable strategy to improve landrace yield and yield stability, especially under stress and to combat future climate change (Moghaddam et al, 1997;Zaefyzadeh et al, 2009;Jaradat, 2013). Diversity of wheat landrace populations, when structured to build spatial and temporal heterogeneity into cropping systems will enhance resilience to climate change and the abiotic and biotic stresses associated with it.…”