The Problem of the Origin of Subgenomes B, A, D of Bread Wheat<i> Triticum</i> <i>aestivum</i> L.: Old Facts and New Evidences

Abstract

Bread wheat (Triticum aestivum L.) belongs to the wheat tribe, which includes representatives of the genera Triticum, Aegilops, Secale, Hordeum, etc. The genera Aegilops and Triticum in the process of evolution have repeatedly hybridized with each other, including with the formation of polyploid forms that have the status of species and belong to the so-called Triticum–Aegilops alliance. As the methodological possibilities developed, various approaches were used to determine the ancestors of certain species of this alliance, ranging directly from interspecific crosses and cytogenetic methods to whole genome sequencing of non-nuclear and nuclear genomes. It has been established that the genome of bread wheat T. aestivum, one of the main food crops in the world, consists of three related subgenomes, which received the symbols A, B, D. At present, only the donor of the D subgenome, which is Aegilops tauschii Coss., is reliably known. The ancestor of subgenome A is presumably considered to be T. urartu Thum. ex Gandil. Information about the donor of the B subgenome is less clear, but most likely it is Ae. speltoides Tausch. or a species close to it. This review is devoted to the consideration of some old data on the putative donors of bread wheat, which, taking into account the maternal form, the BBAADD genome, and the refinement of some phylogenetic relationships in the Triticum–Aegilops alliance in the light of new information obtained as a result of whole genome sequencing of wheat.