Wild emmer: genetic resources, gene mapping and potential for wheat improvement

Abstract

Wild emmer, Triticum dicoccoides, the progenitor of cultivated wheat, harbors rich genetic resources for wheat improvement. They include many agronomic traits such as abiotic stress tolerances (salt, drought and heat), biotic stress tolerances (powdery mildew, rusts, and Fusarium head blight), grain protein quality and quantity, and micronutrient concentrations (Zn, Fe, and Mn). In this review, we summarize (1) traits and controlling genes identiWed and mapped in T. dicoccoides; and (2) the genes transferred to cultivated wheat from T. dicoccoides. These genes, controlling important agronomic traits such as disease resistance, high protein and micronutrient content, should contribute to wheat production and food nutrition. However, most of the rich genetic reservoir in wild emmer remains untapped, highlighting the need for further exploration and utilization for long-term wheat breeding programs.

Nutritionally Enhanced Staple Food Crops

“…Wild and weedy relatives of common bean and wheat have shown large variability for seed-Fe and -Zn concentrations (Cakmak et al 2000;Guzman-Maldonado et al 2000;Chhuneja et al 2006;Acosta-Gallegos et al 2007;Xie and Nevo 2008). For example, the 75 wild and weedy common beans from Jalisco and Durango state of Mexico showed large variability for seed Ca (500-7470 mg k À1 ), iron (64-280 mg k À1 ), and zinc (11-33 mg k À1 ) concentrations (Guzman-Maldonado et al 2000) or nonprogenitor Aegilop species of wheat with large variability for grain Fe and Zn (Chhuneja et al 2006).…”

“…Wild emmer wheat germplasm harbors a rich allelic diversity, including for seed minerals (Xie and Nevo 2008). A major locus, Gpc-B1 (a 250-kb locus) mapped as a simple Mendelian locus (Distelfeld et al 2006), associated with increased seed-protein (38%), -Fe (18%), and -Zn (12%) concentrations from wild emmer wheat germplasm (Triticum dicoccoides), encodes a NAC transcription factor (NAM-B1) that accelerates senescence and increases nutrient remobilization from leaves to developing seeds (Uauy et al 2006;Distelfeld et al 2007).…”

Wheat Evolution, Domestication, and Improvement

“…Among the potential donors for improving wheat, wild emmer occupies a very important and unique position due to its direct ancestry of bread wheat and its rich and largely adaptive genetic diversity. This was fi rst suggested by Aaronsohn (1913) and later elaborated on by many authors (see Feldman 1977;Nevo 1983Nevo , 1995Nevo , 2001Nevo , 2006Xie and Nevo 2008).…”

“…Natural hybrids do occasionally form between cultivated tetraploid wheat and T. dicoccoides, so T. dicoccoides is sometimes ranked as the wild subspecies of the T. turgidum complex. Because of its central place in the evolution of cultivated wheat, wild emmer is among the best sources for obtaining insights into wheat evolution and improvement (Xie and Nevo 2008).…”

“…Studies on wild emmer (T. dicoccoides), the progenitor of most tetraploid and hexaploid wheats, have revealed rich genetic resources applicable to wheat improvement, given its diverse single-and multilocus adaptations to stressful abiotic and biotic environments (Xie and Nevo 2008). The available resources have been described (Zohary 1970;Feldman 1979;Lange and Jochemsen 1992;Grama et al, 1983;Nevo 1995Nevo , 2001Nevo et al, 2002) Quantitative trait loci (QTLs) and benefi cial cryptic, agronomically important alleles have now been extensively described.…”