Species Relationships in the Genus Agrostis Based on Flow Cytometry and MITE-Display Molecular Markers
2011
Amundsen, Keenan | Warnke, Scott
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, 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 dodecaploid (2n = 12x = 84). In the present study, the DNA content of 305 Agrostis accessions was measured by flow cytometry and used to predict ploidy. Ploidy assignment was difficult because the DNA content measures did not delineate the accessions into clear genome size groupings. Genetic diversity among 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 (1309) were used in Structure 2.3.3 and unweighted pair-grouped method 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.
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