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 and barley. 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 (Triticum spp.) within the tribe, it has been successfully hybridized with wheat, and several wheat–L. racemosus chromosome introgression lines have been selected 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 staple cereals, must increase to provide food for growing population, but wheat is threatened by the effects of climate change, especially increased drought and heat. In addition, depletion of natural resources makes the likelihood of success for increasing future productivity unclear. Maximizing yield to help achieve food security under such challenging conditions will not be easy. Wheat productivity could be improved by enhancing tolerance to biotic and abiotic stress, and tolerance to soil macro- and micronutrient deficiencies or toxicities. However, the genetic base of variation available for most of these traits is very narrow in the available elite germplasm. Wild relatives of wheat, including L. racemosus, are an important source of wheat genetic variation and have contributed much to the improvement of wheat productivity. This review describes the potential of this wild wheat relative as a germplasm for wheat improvement, and the characteristics that affect its efficient use in breeding, including its chromosomes, traits, and some genes that have been identified and transferred from this species to common wheat.