Drought resistance in wild emmer wheat: Physiology, ecology, and genetics

Drought is the main environmental stress limiting crop productivity and yield stability worldwide. Improving drought resistance of crop plants is considered a sustainable and economically viable solution to increasing agricultural productivity under diminishing water availability. The implementation of this solution requires wide explorations of potential genetic resources and in-depth understanding of their adaptive mechanisms and responses to water deficit. In this minireview we summarize the physiological, ecological, and genetic aspects of drought resistance in wild emmer wheat [Triticum turgidum ssp. dicoccoides (Körn.) Thell.] and discuss their implications on wheat improvement. A comprehensive survey of wild emmer wheat populations, collected across the aridity gradient in Israel, revealed wide genetic diversity for drought responses, with a considerable number of wild accessions exhibiting an advantage over durum wheat cultivars. A variety of adaptive traits associated with improved performances under water-limited conditions, including phenology and water use efficiency, were identified in wild emmer wheat. The greatest allelic diversity, as well as the highest drought resistance capacity, were observed in wild emmer populations from intermediate aridity levels exposed to the greatest climatic fluctuations. It is concluded that the wild emmer wheat gene pool harbors a rich allelic repertoire for various morpho-physiological traits conferring drought resistance that are potentially useful for wheat improvement. An ongoing mapping study revealed numerous quantitative trait loci (QTLs) underlying the observed drought resistance that may serve as a starting point for introgression and marker-assisted breeding.