ARS | Publication request: Transfer of Flowering and Kousa Dogwood Simple Sequence Repeats (SSRs) to Selected Cornus (Cornaceae) Species

Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 13, 2010
Publication Date: May 1, 2010
Citation: Wadl, P., Wang, X., Moulton, J.K., Hokanson, S.C., Skinner, J.A., Rinehart, T.A., Reed, S.M., Pantalone, V., Trigiano, R. 2010. Transfer of Flowering and Kousa Dogwood Simple Sequence Repeats (SSRs) to Selected Cornus (Cornaceae) Species. Journal of the American Society for Horticultural Science. 135:279-288.

Interpretive Summary: In this study, we used primers developed from flowering and kousa dogwood to detect SSR loci in selected species of the Cornaceae. Specifically, we address the following questions: (1) Can the SSR primers developed for one species be used to amplify homologous loci of related species; (2) does the cross species transferability of SSR loci result from conservation of primer sites; and, (3) at what taxonomic level are these SSR primers potentially useful? We also present a phylogenetic tree of selected Cornus species based on SSR sequence data.

Technical Abstract: Cross species transferability of simple sequence repeats (SSRs) is common and allows SSRs isolated from one species to be applied to closely related species increasing the utility of previously isolated SSRs. Simple sequence repeats are popular PCR-based markers that are valued for their abundance, high levels of polymorphism, co-dominant mode of inheritance, and ease of genotyping. The development of SSRs is expensive and laborious and many laboratories lack the experience to isolate new SSR loci. The genus Cornus consists of 58 species that are ecologically and economically important. SSRs have previously been isolated from two closely related big-bracted species (C. florida and C. kousa). In this study, 36 SSRs were tested using 44 taxa from 18 Cornus species and hybrids for cross species transferability and genetic diversity was assessed for each locus using polymorphism information content (PIC). Cross species transferability of SSR loci was higher in more closely related species and PIC values ranged from 0 – 0.93. Evidence was found for conserved primer sites within Cornus as determined by the amplification of SSR loci in the taxa examined. PCR products from selected species were cloned and sequenced for three SSR loci (CF48, CF59, and CF124) and all individuals sequenced contained the appropriate SSR repeat. Phylogenetic relationships of 14 Cornus species were inferred using nucleotide sequences of SSR locus CF48. The most parsimonious tree resulting from this analysis was in concordance with phylogenies based on matK and ITS sequences. The SSR loci tested in this study will be useful in future breeding, population, and genetic studies within Cornus.