Taxonomic implications of SDS-PAGE analyses of seed proteins in North American taxa of Festuca subgenus Festuca (Poaceae)

Abstract

The banding patterns of seed storage proteins generated by sodium dodecylsulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of extracts of seed of North American native species of Festuca subgenus Festuca produced taxonomically useful characters. The results support (1) treating F. dasyclada Hackel ex. Beal as a Festuca and placing it in subgenus Festuca, (2) recognizing F. brachyphylla Schultes, F. idahoensis Elmer, and F. saximontana Rydb. as full species and (3) recognizing F. rubra ssp. densiuscula (Hackel) Piper and F. rubra ssp. richardsonii (Hooker) Hultén as subspecies. Limited evidence suggested that the seed protein profile of F. baffinensis differs from F. brachyphylla. Distinct height forms in adjacent plants of F. brachyphylla and F. idahoensis have almost identical seed protein banding profiles and on these criteria do not justify recognition as taxonomic entities. A Californian sample of F. saximontana var. purpusiana (St.-Yves) Frederiksen and Pavlick has a seed protein profile distinct from samples of F. saximontana var. saximontana, suggesting the variety name should be limited to endemic populations near the type locality in California and not applied to mere height forms in other areas. Variation in F. brachyphylla profiles may reflect (1) geographic isolation in populations and independent evolution of seed proteins, possibly as a result of founder effects, (2) isolating mechanisms such as differences in flowering time, or (3) introgression following hybridization with other taxa.