Cross-Species Amplification of SSRs in the Genus Vaccinium P.S. Boches, N.V. Bassil and K. Hummer USDA-ARS, NCGR 33447 Peoria Rd. Corvallis, OR 97333 USA J. Rowland USDA-ARS, Fruit Laboratory Bldg. 010A Rm. 238 Beltsville, MD 20705 USA Keywords: blueberry, genetics, DNA, microsatellites, EST Abstract Primers were designed to amplify 36 simple sequence repeat (SSR) sequences identified in an Expressed Sequence Tag (EST) library derived from Vaccinium coryinbosum. They were tested for amplification in other species of the genus Vacciniun,. Two representatives each from the species V. ovatum, V. arboreum, V. elliottii, V. ten ellum, V. darrowii, V. bracteatum, V. oldhamii (one representative only), V. macrocarpon, V. viüs-idea, V. parv 4folium, V. crass ?[ olium and diploid corymbosuni were tested. Sixteen SSRs were amplified in all genotypes tested. Analysis of variance indicated significant differences between species in the number of loci that were amplified. EST-SSR Loci developed in tetraploid V. corymbosum were most easily transferable to other members of section () Cyanococcus and least easily transferable to sections Oxycoccos, Herpothamnus, Myrtilius, and Batodendron in descending order. Several loci amplified exclusively in sections Cyanoccus, Batodendron, Bracteatum and Ciiata, possibly indicating a genetic link between Vaccinium in the southeastern United States and those present in Asia. INTRODUCTION This study was part of an ongoing effort at the Agricultural Research Service (ARS) of the United States Department of Agriculture's (USDA) National Clonal Germplasm Repository (NCGR) in Corvallis, OR., to develop robust and polymorphic SSR markers for use throughout the genus Vaccinium. SSRs derived from ESTs are ideal for marker development in a genus because they are more easily transportable between related species than SSRs derived from genomic libraries (Kantety et al., 2002, Scott et al., 2000). The degree to which EST-SSRs cross-amplify between related species varies across plant genera. SSRs were reported to be more easily transportable between species in the Vitaceae than in the Prunaceae family (Decroocq et al., 2003). Such variation in cross-species amplification between the two families was proposed to result from a more recent species divergence in the Vitaceae. Currently, relationships among sections within the genus Vaccintum (Vander Kloet. 1988; Kron et al., 2002) remain unresolved. Vaccinium is distributed across all continents except Australia and Antarctica and exhibits a high level of morphological diversity. In North America,the genus is represented by nine sections that are not generally interfertile. Some of these sections have circumpolar or disjunct distributions in Asia and South America as well. Vaccinium species in section Cyanococcus have been used to breed improved blueberry cultivars. In this study, we examine the extent to which EST-SSRs markers derived from V. corymbosum are conserved in representatives of other members of Cyanococcus and in nine other sections. MATERIALS AND METHODS Plant Material and DNA Extraction Genotypes were selected to represent most of the Vaccinium sections present in the USDA National Clonal Germplasm Repository, as well as species closely related to V corymbosum. Diploid species were chosen whenever possible. Information about these genotypes is presented in Table 1. Newly expanded leaves collected from field grown Proc vH1 IS on Vacciniuni Culture 119 Eds: L. Lopes do Fonseca et al, Acta Hort 715, ISI-IS 2006