title: Polymorphic SSR markers for Plasmopara obducens (Peronosporaceae), the newly emergent downy mildew pathogen of Impatiens (Balsaminaceae).
abstract: OBJECTIVE
  Simple sequence repeat (SSR) markers were developed for Plasmopara obducens, the causal agent of the newly emergent downy mildew disease of Impatiens walleriana.
  
  
  RESULTS
  A 202-Mb draft genome assembly was generated from P. obducens using Illumina technology and mined to identify 13,483 SSR motifs. Primers were synthesized for 62 marker candidates, of which 37 generated reliable PCR products. Testing of the 37 markers using 96 P. obducens samples showed 96% of the markers were polymorphic, with 2-6 alleles observed. Observed and expected heterozygosity ranged from 0.000-0.892 and 0.023-0.746, respectively. Just 17 markers were sufficient to identify all multilocus genotypes.
  
  
  CONCLUSIONS
  These are the first SSR markers available for this pathogen, and one of the first molecular resources. These markers will be useful in assessing variation in pathogen populations and determining the factors contributing to the emergence of destructive impatiens downy mildew disease.
authors.affiliation: USDA-ARS, Systematic Mycology and Microbiology Laboratory, Beltsville, Maryland 20705 USA ; Rutgers University, Department of Plant Biology and Pathology, New Brunswick, New Jersey 08901 USA.
authors.forename: Catalina
authors.initials: C
authors.lastname: Salgado-Salazar
authors.affiliation: USDA-ARS, Systematic Mycology and Microbiology Laboratory, Beltsville, Maryland 20705 USA ; Rutgers University, Department of Plant Biology and Pathology, New Brunswick, New Jersey 08901 USA.
authors.forename: Yazmín
authors.initials: Y
authors.lastname: Rivera
authors.affiliation: USDA-ARS, Systematic Mycology and Microbiology Laboratory, Beltsville, Maryland 20705 USA ; Oak Ridge Institute for Science and Education, ARS Research Participation Program, Oak Ridge, Tennessee 37831 USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Veltri
authors.affiliation: USDA-ARS, Systematic Mycology and Microbiology Laboratory, Beltsville, Maryland 20705 USA.
authors.forename: Jo Anne
authors.initials: JA
authors.lastname: Crouch
keywords: Plasmopara obducens; de novo assembly; high-throughput marker identification; ornamental impatiens; population genetics; simple sequence repeats