Location: Forage and Range ResearchTitle: Roegneria alashanica Keng: a species with the StStStYStY genome constitution
Submitted to: Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2017
Publication Date: 3/17/2017
Citation: Wang, R., Jensen, K.B. 2017. Roegneria alashanica Keng: a species with the StStStYStY genome constitution. Genome. 60(6):546-551.
Interpretive Summary: The taxonomy and nomenclature of the tribe Triticeae, which contains many important North American and Asian cool-season forage grasses, has been and continues to be in a state of uncertainty. This problem is especially great for the genus Elymus, which is comprised of taxonomic allopolyploids with many genome combinations. This problem makes breeding forage grasses of the Elymus species difficult if their genetic make-ups are unknown. The genome constitution of species Roegneria alashanica has been in question but was resolved herein with a molecular marker analysis that specifically identified the Y genome. It was demonstrated that R. alashanica does not contain the Y genome but has two different versions of the St genome. It was therefore reclassified as a tetraploid species in the genus Pseudoroegneria, to which bluebunch wheatgrass belongs. Correct classification of a species can benefit all biological researchers in planning their experiments. For example, plant breeders knowing correct species designations can more effectively design hybridization combinations to transfer desirable yield and quality traits from one species to the target crop. This, in turn, improves breeding efficiency.
Technical Abstract: The genome constitution of tetraploid Roegneria alashanica Keng has been in question for a long time. Most scientific studies have suggested that R. alashanica had two versions of the St genome. Thus, the genome constitution of R. alashanica was assumed to be St1St2 similar to that of Pseudoroegneria elytrigioides (C. Yen et J.L. Yang) B.R. Lu. A study, however, concluded that R. alashanica had the StY genome formula, which is expected for tetraploid Roegneria species. For the present study, R. alashanica, Elymus longearistatus (Bioss.) Tzvelev (StY-genomes), Pseudoroegneria strigosa (M. Bieb.) A. Love (St), P. libanoctica (Hackel) D.R. Dewey (St), and P. spicata (Pursh) A. Love (St) were screened for the Y-genome specific marker, B14(F+R)269. All E. longearistatus plants expressed intense bands specific to the Y genome. However, only 6 out of 10 R. alashanica plants exhibited relatively faint bands for the B14(F+R)269 STS marker. Previously, the genome in Pseudoroegneria species exhibiting such faint Y-genome specific marker was designated as StY. Based on these results, R. alashanica lacks the Y genome found in E. longearistatus but likely possess two closely related versions of the St genome, St and StY. Due to its genome constitution, R. alashanica should be classified in the genus Pseudoroenera and given the new name, Pseudoproegneria alashanica (Keng) R. R.-C. Wang and K. B. Jensen.