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United States Department of Agriculture

Agricultural Research Service

Research Project: Develop Improved Plant Genetic Resources to Enhance Pasture and Rangeland Productivity in the Semiarid Regions of the Western U.S.

Location: Forage and Range Research

Title: Biosystematics and evolutions of perennial Triticeae species revealed by genomic analyses

Authors
item Wang, Richard
item Lu, Baorong -

Submitted to: Journal of Systematics and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 25, 2014
Publication Date: March 27, 2014
Citation: Wang, R., Lu, B. 2014. Biosystematics and evolutions of perennial Triticeae species revealed by genomic analyses. Journal of Systematics and Evolution. doi:10.1111/jse.12084.

Interpretive Summary: To present an invited lecture at the opening of 7th International Triticeae Symposium held June 9-13, 2013, in Chengdu, China, literature published after 1984 were reviewed to address: (1) genome relationships among monogenomic diploid species, (2) progenitors of the unknown Y genome in Elymus polyploids, X in Thinopyrum intermedium, and Xm in Leymus, and (3) genome constitutions of some perennial Triticeae species that were unknown or misidentified.

Technical Abstract: Literature published after 1984 were reviewed to address: (1) genome relationships among monogenomic diploid species, (2) progenitors of the unknown Y genome in Elymus polyploids, X in Thinopyrum intermedium, and Xm in Leymus, and (3) genome constitutions of some perennial Triticeae species that were unknown or misidentified. A majority of publications substantiated the closeness of genomes Eb and Ee in Thinopyrum bessarabicum and Th. (Lophopyrum) elongatum, respectively, supporting the use of a common basic genome symbol. The E genome is then close to St of Pseudoroegneria and ABD of Triticum/Aegilops complex, providing an explanation for the relative ease of transferring genes from E to ABD. Although the exact proof is still lacking, W, P, and especially Xp are possible origins for Y of polyploid Elymus. The absence of E genome and the allopolyploidy nature of tetraploid Leymus species have been unequivocally confirmed by both cytogenetic and molecular studies. However, the donor of Xm of Leymus was only speculated to be related to P of Agropyron and F of Eremopyrum. The important forage grass, intermediate wheatgrass (Th intermedium) has been extensively studied. The presence of St (as the previously designated X) in Th. intermedium is now unequivocal. Its two more closely related genomes, E1 and E2, have been shown to be older versions of E genome rather than the present-day Eb and Ee. The speciation of Th. intermedium was similar to that on Triticum aestivum in that its Js = Es (like B) had the greatest difference from the present-day J (=Eb) by having repetitive sequences of V genome, whereas its St (like D) had the least difference from present-day St. Species having unknown or misidentified genome constitution have been correctly designated, including ESt, StP, StPY, StWY, EStP, HW, StYHW, and NsXm. Some of these species have been transferred to and renamed in appropriate genera.

Last Modified: 8/21/2014
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