title: EST databases as a source for molecular markers: lessons from Helianthus.
abstract: Expressed sequence tag (EST) databases represent a potentially valuable resource for the development of molecular markers for use in evolutionary studies. Because EST-derived markers come from transcribed regions of the genome, they are likely to be conserved across a broader taxonomic range than are other sorts of markers. This paper describes a case study in which the publicly available cultivated sunflower (Helianthus annuus) EST database was used to develop simple sequence repeat (SSR) markers for use in the genetic analysis of a rare sunflower species, Helianthus verticillatus, as well as the more widespread Helianthus angustifolius. EST-derived SSRs were found to be more than 3 times as transferable across species as compared with anonymous SSRs (73% vs. 21%, respectively). Moreover, EST-SSRs whose primers were located within protein-coding sequence were more readily transferable than those derived from untranslated regions, and the former loci were no less variable than the latter. The utility of existing EST databases as a means for facilitating population genetic analyses in plants was further explored by cross-referencing publicly available EST resources against available lists of rare or invasive flowering plant taxa. This survey revealed that more than one-third of all plant-derived EST collections of sufficient size could conceivably serve as a source of EST-SSRs for the analysis of rare, endangered, or invasive plant species worldwide.
authors.affiliation: Department of Biological Sciences, Vanderbilt University, VU Station B 351634, Nashville, TN 37232, USA.
authors.forename: Catherine H
authors.initials: CH
authors.lastname: Pashley
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Ellis
authors.forename: David E
authors.initials: DE
authors.lastname: McCauley
authors.forename: John M
authors.initials: JM
authors.lastname: Burke
mesh_terms: D019659:Asteraceae / Q000235:genetics; D030561:Databases, Nucleic Acid / Q000706:statistics & numerical data*; D020224:Expressed Sequence Tags; D017343:Genes, Plant; D005819:Genetic Markers; D005838:Genotype; D006368:Helianthus / Q000235:genetics*; D018598:Minisatellite Repeats / Q000235:genetics; D013045:Species Specificity
chemical_list: D005819:Genetic Markers