Leymus racemosus: A Potential Species of Gene Pool Enrichment for Wheat Improvement

Abstract

Leymus racemosus is a wild species belonging to tribe Triticeae(Poaceae), which includes important cereal crops such as bread wheat andbarley. This perennial species grows along the coast and in dry lands,and is reportedly tolerant to various biotic and abiotic stresses.Although L. racemosus is evolutionarily distant from wheat (Triticumspp.) within the tribe, it has been successfully hybridized with wheat,and several wheat-L. racemosus chromosome introgression lines have beenselected from among the backcrossed progenies of the hybrid. L.racemosus is, therefore, a promising wild species for wheat improvement.The production of wheat, as one of the world's most important staplecereals, must increase to provide food for growing population, but wheatis threatened by the effects of climate change, especially increaseddrought and heat. In addition, depletion of natural resources makes thelikelihood of success for increasing future productivity unclear.Maximizing yield to help achieve food security under such challengingconditions will not be easy. Wheat productivity could be improved byenhancing tolerance to biotic and abiotic stress, and tolerance to soilmacro-and micronutrient deficiencies or toxicities. However, the geneticbase of variation available for most of these traits is very narrow inthe available elite germplasm. Wild relatives of wheat, including L.racemosus, are an important source of wheat genetic variation and havecontributed much to the improvement of wheat productivity. This reviewdescribes the potential of this wild wheat relative as a germplasm forwheat improvement, and the characteristics that affect its efficient usein breeding, including its chromosomes, traits, and some genes that havebeen identified and transferred from this species to common wheat.