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A Survey of Apomixis and Ploidy Levels among Poa L. (Poaceae) Using Flow Cytometry

Kelley, Alicia Michelle, Johnson, Paul G., Waldron, Blair L., Peel, Michael D.
Crop science 2009 v.49 no.4 pp. 1395
Poa, grasses, plant taxonomy, polyploidy, apomixis, chromosome number, frequency, flow cytometry, plant genetic resources, germplasm, germplasm conservation, sexual reproduction, plant reproduction, species differences
is a complex genus taxonomically and genetically. As a result, relatively little information exists for this economically important genus with regards to reproductive mode and variability in chromosome number. We examined apomixis frequency and ploidy levels in 83 accessions representing 33 species from the National Plant Germplasm System using flow cytometric techniques. In reproductive mode analysis, we analyzed at least three preparations of 50 seeds each from the accessions. In ploidy level analysis, at least three plants of each accession were analyzed. Sixty percent of the species had at least one apomictic or facultative apomictic accession; 40% were sexual. Thirty-three percent of the species had no sexual accessions. Autonomous apomixis was newly identified in and in addition to it being previously reported in were identified as obligate sexual, and as obligate apomictic. Two of four accessions exhibited facultative apomixis. Ploidy levels among sexually reproducing accessions ranged from 2 = 2 = 14 to 2 = 12 = 84, with most accessions between 2 = 3 = 21 to 2 = 8 = 56. Among apomictic accessions, ploidy levels ranged from 2 = 3 = 21 to 2 = 10 = 70, with most between 2 = 4 = 28 and 2 = 10 = 70. These results emphasize the wide variability in , both among and within species.