Pythium rhizo-oryzae sp. nov. Isolated from Paddy Fields: Taxonomy, ITS Region of rDNA, and Comparison with Related Species

Pins Gene Table v2.0: An Online Genome Database of 37 Pythium insidiosum Strains for Gene Content Exploration and Phylogenomic Analysis

Unlike most pathogenic oomycetes, Pythium insidiosum infects humans and animals instead of plants. P. insidiosum has three clinically relevant genotypes/clades that cause a severe disease called pythiosis. To develop strategies for infection control, it is necessary to understand the biology and pathogenesis of this pathogen. Investigating the evolutionary mechanisms behind the host-specific adaptation is vital, and comparative genomic analysis can help with this. To facilitate genomic analysis, an online bioinformatics tool called P. insidiosum (Pins) Gene Table v2.0 was developed. This tool includes genomic data from 37 genetically diverse P. insidiosum strains and four related species. The database contains 732,686 genes, grouped into 80,061 unique clusters and further divided into core and variable categories at genus, species, and genotype levels. A high-resolution phylogenomic relationship among P. insidiosum strains and other oomycetes was projected through hierarchical clustering and core gene analyses. 3156 P. insidiosum-specific genes were shared among all genotypes and may be responsible for causing disease in humans and animals. After comparing these species-specific genes to the MvirDB database, 112 had significant matches with 66 known virulence proteins, some of which might be involved in vascular occlusion, which is a pathological feature of pythiosis. The correlation of genotypes, geographic origins, and affected hosts of P. insidiosum suggests that clade-I strains are more specific to animals, while clade-II/III strains are more specific to humans. The clade-specific genes might link to host preference. In summary, Pins Gene Table v2.0 is a comprehensive genome database accessible to users with minimal bioinformatics experience for the analysis of P. insidiosum genomes.

Taxonomy, DNA barcoding and phylogeny of three new species of Pythium from Canada

Three new species of Pythium, namely, P. oopapillum, P. emineosum and P. camurandrum are presented in this paper based on morphological descriptions and molecular phylogenetic characterisation. These new species were isolated from various ecological regions in Canada. They have unique morphological features in the genus Pythium, and form distinct clades in maximum parsimony analyses, which are also supported by maximum likelihood phylogeny using general time reversible model (GTR), and Bayesian inference (BI) phylogeny using Markov Chain Monte Carlo (MCMC) analysis methods. A comparative study of the new species with closely related taxa, their clade positions, and morphological features are described in this paper.