The morphology, behaviour and molecular phylogeny ofPhytophthorataxon Salixsoil and its redesignation asPhytophthora lacustrissp. nov. : Phytophthora lacustrissp. Nov.

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.

Summary: TOPALi v2 simplifies and automates the use of several methods for the evolutionary analysis of multiple sequence alignments. Jobs are submitted from a Java graphical user interface as TOPALi web services to either run remotely on high-performance computing clusters or locally (with multiple cores supported). Methods available include model selection and phylogenetic tree estimation using the Bayesian inference and maximum likelihood (ML) approaches, in addition to recombination detection methods. The optimal substitution model can be selected for protein or nucleic acid (standard, or protein-coding using a codon position model) data using accurate statistical criteria derived from ML co-estimation of the tree and the substitution model. Phylogenetic software available includes PhyML, RAxML and MrBayes. Availability: Freely downloadable from http://www.topali.org for Windows, Mac OS X, Linux and Solaris. Contact: iain.milne@scri.ac.uk

A molecular phylogenetic analysis of the genus Phytophthora was performed, 113 isolates from 48 Phytophthora species were included in this analysis. Phylogenetic analyses were performed on regions of mitochondrial (cytochrome c oxidase subunit 1; NADH dehydrogenase subunit 1) and nuclear gene sequences (translation elongation factor 1alpha; beta-tubulin) and comparisons made to test for incongruence between the mitochondrial and nuclear data sets. The genus Phytophthora was confirmed to be monophyletic. In addition, results confirm that the classical taxonomic grouping as described by [Waterhouse (1963)] does not reflect true phylogenetic relations. Phytophthora species were redistributed into 8 clades, providing a more accurate representation of phylogenetic relationships within the genus Phytophthora. The evolution and transition of morphological, pathogenic, and reproductive traits was inferred from the cladogram generated in this study. Mating system was inferred to be a homoplasious trait, with at least eight independent transitions from homothallism to heterothallism observed.