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ARS Home » Northeast Area » Washington, D.C. » National Arboretum » Floral and Nursery Plants Research » Research » Publications at this Location » Publication #259044
Title: Species relationships in the genus Agrostis based on flow cytometry and MITE-display molecular markers

Author
item Amundsen, Keenan
item Warnke, Scott

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2012
Publication Date: 3/25/2012
Citation: Amundsen, K.L., Warnke, S.E. 2012. Species relationships in the genus Agrostis based on flow cytometry and MITE-display molecular markers. Crop Science. 51:1224-1231.

Interpretive Summary: It is estimated that there are between 150 and 200 bentgrasses (Agrostis species), and hybridization between some of these species is a proven method for improving cultivated bentgrasses. The pool of publicly available Agrostis germplasm, available through the National Plant Germplasm System (NPGS), represents 17% of the total number of Agrostis species. The total amount of genetic diversity of this germplasm should be assessed to determine if there are novel sources of stress resistance. Agrostis species have a base haploid chromosome number of seven and can range in ploidy from diploid (2n=2x=14) to decaploid (2n=10x=70). In the present study, the DNA content of 305 Agrostis accessions was measured and used to predict the ploidy level of each accession. Ploidy assignment was difficult because flow cytometry DNA content measures did not delineate the accessions into clear genome size groupings. The genetic diversity of a subset of those Agrostis accessions (75), along with related Polypogon and Apera species, was studied. Genetic markers were used to determine the amount of genetic diversity within this group of plants and resolve species relationships. Eight distinct clusters of accessions were observed, including two distinct groups of diploid germplasm. Little genetic variation was evident among the cultivated bentgrasses, suggesting the early formation of a genetic bottleneck among cultivated germplasm.

Technical Abstract: It is estimated that there are between 150 and 200 species of Agrostis, and interspecific hybridization is a proven method for improving cultivated Agrostis species. The pool of publicly available Agrostis germplasm, available through the National Plant Germplasm System (NPGS), represents 17% of the total number of Agrostis species. The total amount of genetic diversity of this germplasm should be assessed to determine if there are novel sources of stress resistance. Agrostis species have a base haploid chromosome number of seven and can range in ploidy from diploid (2n=2x=14) to decaploid (2n=10x=70). In the present study, the DNA content of 305 Agrostis accessions was measured by flow cytometry and used to predict the ploidy level of each accession. Ploidy assignment was difficult because flow cytometry DNA content measures did not delineate the accessions into clear genome size groupings. The genetic diversity of a subset of those Agrostis accessions (75), along with four Polypogon and two Apera accessions, was also studied. Genetic markers anchored to miniature inverted-repeat transposable elements (1,309) were used in Structure 2.3.3 and UPGMA (unweighted pair-grouped method analysis) cluster analyses. Eight distinct clusters of accessions were observed, including two distinct groups of diploid germplasm. Little genetic variation was evident among the cultivated A. stolonifera accessions based on the Structure analysis, suggesting the early formation of a genetic bottleneck among cultivated germplasm.