PLANT GENETIC RESOURCES Identification of Western Wheatgrass Cultivars and Accessions by DNA Fingerprinting and Geographic Provenance

ecotypic variation (Asay and Jensen, 1996). Although forage quality rapidly declines as plants mature, it is Western wheatgrass [Pascopryum smithii (Rydb.) Löve ( Agrohighly palatable to all classes of livestock during the pyon smithii Rydb)] is an allogamous North American range grass early growing season and naturally cured leaves provide cultivated for seed production, hay, low-maintenance turf, and soil good winter forage. Western wheatgrass rapidly regenstabilization. The USDA maintains western wheatgrass cultivars, synthetic multiple-origin germplasms, and source-identified single-origin erates from rhizomes following wildfire and other disaccessions in the National Plant Germplasm System. The objective turbances (USDA Forest Service, 2001), and forms a of this study was to test similarity of amplified fragment length polydurable sod that is frequently used to stabilize disturbed morphism (AFLP) genotypes among individual plants classified by soils. This species is naturally abundant on heavy alkaaccession and geographic provenance, and compare rates of DNA line soils characteristic of intermittent swale bottoms, variation between single-origin and multiple-origin germplasm. Indishallow lake beds, or areas subjected to periodic floodvidual plants from 36 of 39 source-identified single-origin germplasm ing (Rogler, 1973). It is also well suited to reclamation sources group strictly by accession, on the basis of the average proporof saline sites (Beetle, 1955; Halvorson and Lang, 1989; tion of shared DNA fragments between individual genotypes. ConScheetz et al., 1981). versely, individual plant genotypes from three of the four synthetic Western wheatgrass is an allooctoploid (2n 8x multiple-origin accessions did not cluster by accession and displayed higher rates of DNA variation than did single-origin accessions. Al56) species comprised of the SSHHNNXX genome comthough different accessions of the same cultivar generally group tobination (Dewey, 1975). On the basis of cytological evigether, off-types were detected in six of the nine cultivar accessions. dence as well as ecological, morphological, and reproPairwise comparisons of interpopulation genetic distances (φst) among ductive characteristics in related allotetraploid (2n 39 single-origin accessions were correlated with geographical distances 4x 28) species and their hybrids, this species arose among the original collecting sites (r 0.66). Genotypes representing through hybridization between NNXX Leymus tritithese accessions form three natural groups on the basis of φst that coides (Buckl.) Pilger and SSHH Elymus lanceolatus correspond to three geographic regions of the USA: northern Great (Sribn. J. G. Sm.) Gould, or closely related perennial Plains, northern Rocky Mountains, and southern Rocky Mountains. Triticeae species with similar genome combinations Therefore, georaphically significant sources of DNA variation were (Dewey, 1975). Although most western wheatgrass plants detected and maintained within and among these ex situ germplasm sources. These results document genetic identity and diversity in the are highly self incompatible, some individual clones may USDA western wheatgrass germplasm collection and support the be self fertile (Jensen et al., 1990). Therefore, genetic premise that geographic provenance contributes to germplasm inheterogeneity should be maintained within and among tegrity. individual plants. Like its putative ancestral species, western wheatgrass is strongly rhizomatous and individual plants may form large recognizable clones in nature. W wheatgrass is an ecologically dominant, The USDA has made substantial efforts and commitnative perennial range grass in the northern Great ments to acquire, preserve, evaluate, document, and Plains (Hart et al., 1996). Cultivars of western wheatdistribute plant germplasm, primarily through the Nagrass are also planted for pasture, hay, and soil stabilizational Plant Germplasm System (NPGS). Although tion in this region (Asay and Jensen, 1996). However, much of this effort has been devoted to cultivated field the distribution of western wheatgrass further extends crops, a substantial number of nondomesticated species throughout much of temperate North America (Hitchincluding natural and cultivated forages are also maincock, 1951; Cronquist et al., 1977), including dry sagetained. Currently, NPGS preserves 48 western wheatbrush (Artemisia spp.) deserts and foothills of western grass accessions including cultivars and other potentially mountain regions, where it also displays considerable useful germplasm sources. Most of these NPGS accessions are described as single-origin accessions originally derived from well-defined localities. However, multipleS.R. Larson and K.B. Jensen, USDA-ARS, Forage and Range Reorigin cultivars and germplasm sources (Alderson and search Laboratory, Utah State University, Logan, UT 84322-6300; Sharp, 1994; Barker et al., 1995; Smoliak and Johnston, A.J. Palazzo, USDOD-ACE, Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover, NH 03755-1290. This work was 1984) have been derived from several broad-based westsupported by joint contributions of the USDA-ARS and United States Army Corps of Engineers (US ACE) BT25-EC-B09 project. Trade Abbreviations: AFLP, amplified fragment length polymorphism; names are included for the benefit of the reader, and imply no endorseAMOVA, analysis of molecular variance; FRRL, Forage and Range ment or preferential treatment of the products listed. Received 5 Dec. Research Laboratory; GRIN, Germplasm Resources Information 2001. *Corresponding author ([email protected]) Network; NPGS, National Plant Germplasm System; PMC, Plant Material Center; WRPIS, Western Region Plant Introduction Station. Published in Crop Sci. 43:394–401 (2003).