Isozyme Variation within and among Accessions of Annual Phalaris Species in North American Germplasm Collections

Abstract

Accessions of annual Phalaris species in germplasm collections lack adequate genetic characterization for utilization. The objective of this study was to assess the level of isozyme variability of five annual Phalaris species, including 49 annual canarygrass (P. canariensis L.; 2n = 2x = 12), 24 P. brachystachys Link. (2n = 2x = 12), 48 P. minor Retz. (2n = 4x = 28), 19 P. paradoxa L. (2n = 2x = 14), and P. angusta Nees ex Tris (2n = 2x = 14) accessions from North American germplasm collections. Eight enzymes were used to detect polymorphism within and among accessions by scoring the presence or absence of 62 bands. Polymorphism was detected in 6 of 19 bands in P. canariensis, 12 of 22 bands in P. brachystachys, 34 of 40 bands in P. minor, 19 of 29 bands in P. paradoxa, and 6 of 21 bands in P. angusta. Polymorphism was detected in 23 accessions (47%) P. canariensis, 15 accessions (63%) of P. brachystachys, 35 accessions (73%) of P. minor, four accessions (19%) of P. paradoxa and three accessions of P. angusta (100%). Within‐accession polymorphic indices ranged from 0 to 0.03 in P. canariensis, 0 to 0.02 in P. brachystachys, 0 to 0.06 in P. minor, 0 to 0.04 in P. paradoxa, and 0.01 to 0.04 in P. angusta. Jaccard's similarity coefficients ranged from 0.83 to 1.0 in P. canariensis, 0.78 to 1.0 in P. brachystachys, 0.47 to 1.0 in P. minor, 0.44 to 1.0 in P. paradoxa, and 0.81 to 0.86 in P. angusta. Little isozyme variation existed either within or among accessions of the four diploid species. Phalaris minor, an autotetraploid, possessed greater variation among accessions rather than within accessions. In summary, limited variation was detected by means of isozymes in these five annual Phalaris species obtained from North American germplasm collections.