Phylogenetic relationships of Phytophthora species based on ribosomal ITS I DNA sequence analysis with emphasis on Waterhouse groups V and VI

Phylogenetic relationships among Phytophthora species were investigated by sequence analysis of the internal transcribed spacer region I of the ribosomal DNA repeat unit. The extensive collection of isolates included taxa from all six morphological groups recognized by Waterhouse (1963) including molecular groups previously identified using isozymes and mtDNA restriction fragment length polymorphisms. Similar to previous studies, the inferred relationships indicated that molecular groups of P. cryptogea}drechslerilike and P. megasperma-like taxa are polyphyletic. Morphological groups V and VI, which are dierentiated by the presence of amphigynous or paragynous antheridia, are not monophyletic: species of the two groups are interspersed in the tree. Species with papillate and semi-papillate sporangia (groups I‐IV) clustered together and this cluster was distinct from those of species with nonpapillate sporangia. There was no congruence between the mode of antheridial attachment, sporangial caducity, or homo- or heterothallic habit and the molecular grouping of the species. Our study provides evidence that the antheridial position together with homo- or heterothallic habit does not reflect phylogenetic relationships within Phytophthora. Consequently, confirming studies done previously (Cooke & Duncan 1997), this study provides evidence that the morphological characters used in Phytophthora taxonomy are of limited value for deducing phylogenetic relationships, because they exhibit convergent evolution.

[1]  O. K. Ribeiro.  A source book of the genus Phytophthora , 1979 .

[2]  E. Hansen,et al.  Cultural characters, protein patterns and unusual mating behaviour of Phytophthora gonapodyides isolates from Britain and North America , 1993 .

[3]  H. Judelson.  Genetic and physical variability at the mating type locus of the oomycete, Phytophthora infestans. , 1996, Genetics.

[4]  M. Sogin,et al.  Sequence Analysis of the Small Subunit Ribosomal Rnas of Three Zoosporic Fungi and Implications for Fungal Evolution , 1990 .

[5]  D. Maclean,et al.  Evolutionary relationships among Phytophthora species deduced from rDNA sequence analysis (vol 100, pg 437, 1996) , 1996 .

[6]  P. Oudemans,et al.  Mitochondrial and nuclear DNA diversity within six species ofPhytophthora , 1990 .

[7]  C. Hickman.  Key to the Species of Phytophthora de Bary, Grace M. Waterhouse, in: Mycological Papers no. 92. Commonwealth Mycological Institute, Kew (1963), 23, sd, . 6 , 1964 .

[8]  J. Thompson,et al.  CLUSTAL W: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice. , 1994, Nucleic acids research.

[9]  H. Förster,et al.  Taxonomic structure of Phytophthora cryptogea and P. drechsleri based on isozyme and mitochondrial DNA analyses. , 1991 .

[10]  T. White.  Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics , 1990 .

[11]  G. Hall,et al.  Revised tabular key to the species of Phytophthora. , 1990 .

[12]  P. Oudemans,et al.  Isozyme comparison within and among worldwide sources of three morphologically distinct species of Phytophthora , 1991 .

[13]  R. Pratt.  Morphology, pathogenicity and host range of Phytophthora megasperma, P. erythroseptica and P. parasitica from arrowleaf clover. , 1981 .

[14]  J. W. Taylor,et al.  Phylogeny of five fungus-like protoctistan Phytophthora species, inferred from the internal transcribed spacers of ribosomal DNA. , 1992, Molecular biology and evolution.

[15]  D. Maclean,et al.  Evolutionary relationships among Phytophthora species deduced from rDNA sequence analysis , 1996 .

[16]  M. Nei,et al.  The neighbor-joining method , 1987 .

[17]  J. Manners,et al.  An Assessment of Genetic Relationships between Members of the Phytophthora megasperma Complex and Phytophthora vignae using Molecular Markers , 1993 .

[18]  E. Hansen,et al.  Identity of a Phytophthora species attacking raspberry in Europe and North America. , 1993 .

[19]  J. Duncan,et al.  Phylogenetic analysis of Phytophthora species based on ITS1 and ITS2 sequences of the ribosomal RNA gene repeat , 1997 .

[20]  M. Coffey,et al.  An integrated study of morphological and isozyme patterns found within a worldwide collection of Phytophthora citrophthora and a redescription of the species , 1994 .

[21]  D. Erwin,et al.  Formae speciales differentiation of Phytophthora megasperma isolates from soybean and alfalfa. , 1980 .

[22]  P. H. Tsao,et al.  Phytophthora: Its Biology, Taxonomy, Ecology, and Pathology , 1988 .

[23]  W. Ko,et al.  Effect of culture media on antheridial configuration in Phytophthora boehmeriae , 1998 .

[24]  P. Oudemans,et al.  Evidence for distinct isozyme subgroups within Phytophthora citricola and close relationships with P. capsici and P. citrophthora. , 1994 .

[25]  G. Hardy,et al.  The role of paragynous and amphigynous antheridia in sexual reproduction of Phytophthora cinnamomi , 1997 .

[26]  H. Förster,et al.  Molecular taxonomy of Phytophthora megasperma based on mitochondrial and nuclear DNA polymorphisms , 1993 .

[27]  C. Brasier.  Evolutionary Biology of Phytophthora , 1992 .

[28]  E. Hansen,et al.  Species of the Phytophthora Megasperma Complex , 1991 .

[29]  J. Felsenstein.  CONFIDENCE LIMITS ON PHYLOGENIES: AN APPROACH USING THE BOOTSTRAP , 1985, Evolution; international journal of organic evolution.

[30]  F. A. Bisby,et al.  Taxonomic Analysis in Biology , 1985 .

[31]  D. S. Shaw,et al.  The taxonomic structure of Phytophthora megasperma: evidence for emerging biological species groups. , 1986 .

[32]  H. Förster,et al.  Molecular characterization of Phytophthora isolates with non-papillate sporangia causing root rot of raspberry using mtDNA restriction fragment length polymorphisms , 1992 .

[33]  Thomas J. White,et al.  PCR protocols: a guide to methods and applications. , 1990 .

[34]  G. M. Waterhouse.  The genus Phytophthora de Bary. Diagnoses (or descriptions) and figures from the original papers. Ed. 2. , 1970 .

[35]  T. Jung,et al.  Molecular evidence supports Phytophthora quercina as a distinct species , 1999 .

[36]  P. Oudemans,et al.  A revised systematics of twelve papillate Phytophthora species based on isozyme analysis , 1991 .

[37]  E. Hansen,et al.  Single-spore isolate variation: the effect on varietal designation in Phytophthora megasperma , 1982 .

[38]  G. M. Waterhouse.  The genus Phytophthora. Diagnoses (or descriptions) and figures from the original papers. , 1956 .

[39]  M. Coffey,et al.  Evidence for the existence of two subpopulations in Phytophthora capsici and a redescription of the species , 1995 .