A comparison of Peronospora parasitica (Downy mildew) isolates from Arabidopsis thaliana and Brassica oleracea using amplified fragment length polymorphism and internal transcribed spacer 1 sequence analyses

Amplified fragment length polymorphism (AFLP) fingerprints and internal tra nscribed spacer 1 (ITS1) sequences from 27 Peronospora parasitica isolates (collected from Arabidopsis thaliana or Brassica oleracea), 5 Albugo candid a isolates (from the same hosts and from Capsella bursa-pastoris), and 1 Br emia lactucae isolate (from Lactuca sativa) were compared. The AFLP analysi s divided the isolates into five groups that correlated with taxonomic spec ies and, in most cases, with host origin. The only exception was a group co nsisting of A. candida isolates from both B. oleracea and C. bursa-pastoris . ITS1 sequence analysis divided the isolates into the same five groups, de monstrated the divergence between P. parasitica isolates from A. thaliana a nd B. oleracea, and, using previously published ITS1 sequences, clearly sho wed the relationship between A. candida isolates from different hosts. (C) 2000 Academic Press.