Isozyme variation within and among accessions of annual Phalaris species in North American germplasm collections

Accessions of annual Phalaris species in germplasm collections lack adequat e 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 3 P. angusta Nees ex Tris (2n = 2x = 14) a ccessions from North American germplasm collections. Eight enzymes were use d to detect polymorphism within and among accessions by scoring the presenc e 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. Polymorph ism was detected in 23 accessions (47%) of P. canariensis, 15 accessions (6 3%) of P. bracystachys, 35 accessions (73%) of P. minor, four accessions (1 9%) of P. paradoxa and three accessions of P. angusta (100%). Within-access ion 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 i n P. minor, 0.44 to 1.0 in P. paradoxa, and 0.81 to 0.86 in P, angusta. Lit tle isozyme variation existed either within or among accessions of the four diploid species. Phalaris minor, an autotetraploid, possessed greater vari ation among accessions rather than within accessions. In summary, limited v ariation was detected by means of isozymes in these five annual Phalaris sp ecies obtained from North American germplasm collections.