Aegilops sharonensis: Origin, genetics, diversity, and potential for wheat improvement

Aegilops sharonensis Eig (Sharon goatgrass; section Sitopsis) is an annual diploid grass species growing endemically in the coastal plains of Israel and southern Lebanon. It is a wild relative of wheat, with a genome closely related to the B genome of cultivated bread wheat. With the most limited distribution of any species in the genus Aegilops, Ae. sharonensis is rapidly losing its habitats, owing to the combined effects of modern agricultural intensification and expansion of urban and industrial areas. Aegilops sharonensis is known to be a rich source of genes providing resistance to important wheat diseases and abiotic stresses, but it has not been widely exploited. The presence of gametocidal genes that control preferential transmission of chromosome 4S ^sh increases the difficulty of introgressing genes from Ae. sharonensis into wheat. However, successful introgression of the genes for resistance to leaf rust, stripe rust, and powdery mildew has been achieved. Studies on genetic and phenotypic diversity indicated that Ae. sharonensis is a highly diverse species, comparable with others that have a wider geographic distribution and more variable environments. Targeting the regions and sites with the highest diversity in Ae. sharonensis will facilitate the capture of the greatest variability and also the identification of novel and diverse genes for wheat improvement.