The inclusion of downy mildews in a multi-locus-dataset and its reanalysis reveals a high degree of paraphyly in Phytophthora
نویسندگان
چکیده
Pathogens belonging to the Oomycota, a group of heterokont, fungal-like organisms, are amongst the most notorious pathogens in agriculture. In particular, the obligate biotrophic downy mildews and the hemibiotrophic members of the genus Phytophthora are responsible for a huge variety of destructive diseases, including sudden oak death caused by P. ramorum, potato late blight caused by P. infestans, cucurbit downy mildew caused by Pseudoperonospora cubensis, and grape downy mildew caused by Plasmopara viticola. About 800 species of downy mildews and roughly 100 species of Phytophthora are currently accepted, and recent studies have revealed that these groups are closely related. However, the degree to which Phytophthora is paraphyletic and where exactly the downy mildews insert into this genus in relation to other clades could not be inferred with certainty to date. Here we present a molecular phylogeny encompassing all clades of Phytophthora as represented in a multi-locus dataset and two representatives of the monophyletic downy mildews from divergent genera. Our results demonstrate that Phytophthora is at least six times paraphyletic with respect to the downy mildews. The downy mildew representatives are consistently nested within clade 4 (contains Phytophthora palmivora), which is placed sister to clade 1 (contains Phytophthora infestans). This finding would either necessitate placing all downy mildews and Phytopthora species in a single genus, either under the oldest generic name Peronospora or by conservation the later name Phytophthora, or the description of at least six new genera within Phytophthora. The complications of both options are discussed, and it is concluded that the latter is preferable, as it warrants fewer name changes and is more practical.
منابع مشابه
Bridging the Gulf: Phytophthora and Downy Mildews Are Connected by Rare Grass Parasites
Downy mildews and root and foliar rots caused by Phytophthora are among the most destructive plant pathogens and therefore have attracted considerable attention during the past two decades. Although it has been realized that a close phylogenetic relationship exists, so far sharp distinction has been made between the obligate biotrophic downy mildews and the hemibiotrophic Phytophthora. In the s...
متن کاملMultiple origins of downy mildews and mito-nuclear discordance within the paraphyletic genus Phytophthora
Phylogenetic relationships between thirteen species of downy mildew and 103 species of Phytophthora (plant-pathogenic oomycetes) were investigated with two nuclear and four mitochondrial loci, using several likelihood-based approaches. Three Phytophthora taxa and all downy mildew taxa were excluded from the previously recognized subgeneric clades of Phytophthora, though all were strongly suppor...
متن کاملTwo new species of Peronosporaceae (downy mildews) from Iran
In survey of infected samples to downy mildew of broadbean, Chenopodium murale and Rumex chalpensis using Olympus microscope (BH2) and valid keys and recently published papers, two species were identified (Choi et al. 2009, Ershad 2009, Telle & Thines 2012).
متن کاملIdentification and Assessment of Fungal Diseases of Major Medicinal Plants
Medicinal plants are infected by fungal diseases. A four years survey indicated that, there are various fungal infections in roots and shoots of several medicinal plants that grown in Isfahan. Lavender (Lavandula angustifolia), rosemarry (Rosmarinus officinalis) and viper’s bugloss (Borago officinalis) plants were infected by Fusarium oxysporum and F. solani on roots, showing wilting and eventu...
متن کاملBaobabopsis, a new genus of graminicolous downy mildews from tropical Australia, with an updated key to the genera of downy mildews.
So far 19 genera of downy mildews have been described, of which seven are parasitic to grasses. Here, we introduce a new genus, Baobabopsis, to accommodate two distinctive downy mildews, B. donbarrettii sp. nov., collected on Perotis rara in northern Australia, and B. enneapogonis sp. nov., collected on Enneapogon spp. in western and central Australia. Baobabopsis donbarrettii produced both oos...
متن کامل