Restriction endonuclease profiles of mitochondrial DNA and the origin of the b genome of bread wheat, Triticum aestivum

Abstract

In an attempt to identify the donor of the B genome in the emmer (AABB) and dinkel (AABBDD) wheats (Triticum turgidum and T. aestivum, respectively), the restriction endonuclease profiles of two regions around the mitochondrial cytochrome oxidase subunit I gene were compared with those of five putative diploid ancestors belonging to the Sitopsis section of the Aegilops genus: Ae. longissima, Ae. speltoides, Ae. bicornis, Ae. sharonensis and Ae. searsii. The mitochondria of the diploid donors of genome A (T. monococcum, section Monococca) and genome D (Ae. squarrosa, section Vertebrata) were also tested. The results indicate that none of these diploid species is likely to have either donated the B genome or to be closely related to the donor. The restriction fragment patterns of T. turgidum and T. aestivum were identical, supporting the hypothesis that T. turgidum is the immediate maternal relative of T. aestivum. The restriction endonuclease profiles of T. monococcum var. boeoticum and T. m. var. urartu were also identical supporting their conspecific systematic assignment. No real taxonomic distinction exists between Triticum and Aegilops. With the possible exception of Ae. longissima, the mitochondria of the Sitopsis section constitute a natural clade. Ae. speltoides shows high levels of mitochondrial polymorphism between accessions. © 1989, The Genetical Society of Great Britain.