A genetic map of the lettuce downy mildew pathogen, Bremia lactucae, constructed from molecular markers and avirulence genes

Delphine Sicard, Erik Legg, Sarah Brown, Nirmal K. Babu, Oswaldo Ochoa, Padma Sudarshana, Richard W Michelmore

Research output: Contribution to journalArticle

17 Scopus citations


The genetic map of Bremia lactucae was expanded utilizing 97 F1 progeny derived from a cross between Finnish and Californian isolates (SF5 x C82P24). Genetic maps were constructed for each parent utilizing 7 avirulence genes, 83 RFLP markers, and 347 AFLP markers, and a consensus map was constructed from the complete data set. The framework map for SF5 contained 24 linkage groups distributed over 835cM; the map for C82P24 contained 21 linkage groups distributed over 606cM. The consensus map contained 12 linkage groups with markers from both parents and 24 parent-specific groups. Six avirulence genes mapped to different linkage groups; four were located at the ends of linkage groups. The closest linkages between molecular markers and avirulence genes were 3cM to Avr4 and 1cM to Avr7. Mating type seemed to be determined by a single locus, where the heterozygote determined the B2 type and the homozygous recessive genotype determined the B1 type.

Original languageEnglish (US)
Pages (from-to)16-30
Number of pages15
JournalFungal Genetics and Biology
Issue number1
StatePublished - Jun 2003



  • AFLP
  • Avirulence gene
  • Bremia lactucae
  • Downy mildew
  • Linkage map
  • Mating type
  • Oomycete
  • Plant pathogen
  • RFLP

ASJC Scopus subject areas

  • Genetics
  • Microbiology

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