01965nas a2200205 4500008004100000022001400041245009800055210006900153260001200222300001200234490000700246520128100253100001701534700001201551700001801563700001601581700001501597700001601612856013101628 2005 eng d a1437-478100aGenetic diversity of European populations of the oak fine-root pathogen Phytophthora quercina0 aGenetic diversity of European populations of the oak fineroot pa c02/2005 a57 - 700 v353 a

The recently discovered oak-specific fine root plant pathogen Phytophthora quercina is a significant factor in the current phase of European oak decline but its origins and ecology are poorly understood. A genome-wide analysis of 260 amplified fragment length polymorphism (AFLP) markers was used to examine the genetic diversity of 72 isolates from five oak species at 28 sites in Germany (particularly Bavaria), Italy, France, Hungary and the UK. Within-site diversity was examined at 16 sites. The limited genetic diversity (within and between sites) and lack of genetic substructuring according to geographic origin or host species suggest the rapid spread of a relatively recently introduced species. Two subgroups were distinguished and these may reflect an initial introduction of isolates of two different genetic backgrounds. The relatively low genetic diversity is probably because of the predominantly inbreeding (homothallic) nature of P. quercina. However, evidence of limited intra-site diversity, temporal variation and the lack of clonality within the European population suggest that some diversity is being maintained by occasional outcrossing and turnover of a reservoir of long-lived soil-borne oospore (sexually derived) inoculum.

1 aCooke, D E L1 aJung, T1 aWilliams, N A1 aSchubert, R1 aOƟwald, W1 aDuncan, J M uhttps://forestphytophthoras.org/references/genetic-diversity-european-populations-oak-fine-root-pathogen-phytophthora-quercina01905nas a2200253 4500008004100000022001400041245006400055210006200119300001000181490000700191520118100198653001401379653003301393653000801426653001701434653001201451653000901463100001701472700001401489700001601503700001401519700001701533856010101550 2000 eng d a1087-184500aA molecular phylogeny of Phytophthora and related Oomycetes0 amolecular phylogeny of Phytophthora and related Oomycetes a17-320 v303 a

Phylogenetic relationships among 50 Phytophthora species and between Phytophthora and other oomycetes were examined on the basis of the ITS sequences of genomic rDNA. Phytophthora grouped with Pythium, Peronospora, and Halophytophthora, distant from genera in the Saprolegniales. Albugo was intermediate between these two groups. Unlike Pythium, Phytophthora was essentially monophyletic, all but three species forming a cluster of eight clades. Two clades contained only species with nonpapillate sporangia. The other six clades included either papillate and semipapillate, or semipapillate and nonpapillate types, transcending traditional morphological groupings, which are evidently not natural assemblages. Peronospora was related to P. megakarya and P. palmivora and appears to be derived from a Phytophthora that has both lost the ability to produce zoospores and become an obligate biotroph. Three other Phytophthoras located some distance from the main Phytophthora-Peronospora cluster probably represent one or more additional genera.

10aevolution10ainternal transcribed spacers10aITS10aPeronospora.10aPythium10arDNA1 aCooke, D E L1 aDrenth, A1 aDuncan, J M1 aWagels, G1 aBrasier, C M uhttp://www.sciencedirect.com/science/article/B6WFV-45FC03G-1G/2/1cb8ec25d08dae3a16f56e74cd92e99e