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During a survey of Phytophthora diversity in Panama, fast-growing oomycete isolates were obtained from naturally fallen leaves of an unidentified tree species in a tropical cloud forest. Phylogenetic analyses of sequences from the nuclear ITS, LSU and ßtub loci and the mitochondrial cox1 and cox2 genes revealed that they belong to a new species of a new genus, officially described here as Synchrospora gen. nov., which resided as a basal genus within the Peronosporaceae. The type species S. medusiformis has unique morphological characteristics. The sporangiophores show determinate growth, multifurcating at the end, forming a stunted, candelabra-like apex from which multiple (8 to >100) long, curved pedicels are growing simultaneously in a medusa-like way. The caducous papillate sporangia mature and are shed synchronously. The breeding system is homothallic, hence more inbreeding than outcrossing, with smooth-walled oogonia, plerotic oospores and paragynous antheridia. Optimum and maximum temperatures for growth are 22.5 and 25–27.5 °C, consistent with its natural cloud forest habitat. It is concluded that S. medusiformis as adapted to a lifestyle as a canopy-dwelling leaf pathogen in tropical cloud forests. More oomycete explorations in the canopies of tropical rainforests and cloud forests are needed to elucidate the diversity, host associations and ecological roles of oomycetes and, in particular, S. medusiformis and possibly other Synchrospora taxa in this as yet under-explored habitat. [ABSTRACT FROM AUTHOR]

Slow growing oomycete isolates with morphological resemblance to Phytophthora were obtained from forest streams during routine monitoring for the EU quarantine forest pathogen Phytophthora ramorum in Ireland and Northern Ireland. Internal Transcribed Spacer (ITS) sequence analysis indicated that they belonged to two previously unknown species of Nothophytophthora, a recently erected sister genus of Phytophthora. Morphological and temperature-growth studies were carried out to characterise both new species. In addition, Bayesian and Maximum-Likelihood analyses of nuclear 5-loci and mitochondrial 3-loci datasets were performed to resolve the phylogenetic positions of the two new species. Both species were sterile, formed chlamydospores and partially caducous nonpapillate sporangia, and showed slower growth than any of the six known Nothophytophthora species. In all phylogenetic analyses both species formed distinct, strongly supported clades, closely related to N. chlamydospora and N. valdiviana from Chile. Based on their unique combination of morphological and physiological characters and their distinct phylogenetic positions the two new species are described as Nothophytophthora irlandica sp. nov. and N. lirii sp. nov. Their potential lifestyle and geographic origin are discussed. [ABSTRACT FROM AUTHOR]

The Valdivian rainforest, one of the global hotspots of biodiversity, is a temperate rainforest originating as a Tertiary relic from the supercontinent Gondwana. In November 2014, a survey of Phytophthora diversity was performed in 13 natural forest stands and 20 forest streams and rivers in two protected areas near Valdivia and in a temperate montane forest in the Concepción area. One planted stand each of the introduced tree species Castanea sativa and Fagus sylvatica were also included. Using baiting assays, eight described species and four previously unknown taxa of Phytophthora were isolated from 86% of the 50 rhizosphere soil samples from seven of the eight tree species sampled in 12 forest stands, and from 20 streams: P. chlamydospora, P. cinnamomi, P. kernoviae, P. lacustris, P. plurivora, P. pseudosyringae, P. ×cambivora, P. ×stagnum, P. valdiviana nom. prov. from Clade 2b, P. madida nom. prov. from Clade 8a, and P. chilensis nom. prov. and P. pseudokernoviae nom. prov. The latter two species are the closest relatives of P. kernoviae from Clade 10. Phytophthora pseudokernoviae nom. prov. was also isolated from necrotic leaves of Drimys winteri. From the Valdivia river, a swarm of three Clade 6 hybrids was recovered. Each hybrid isolate resulted from multiple reticulation events with P. thermophila as maternal and both P. amnicola and P. chlamydospora as paternal parents. In addition, three previously unknown and recently described Nothophytophthora species, N. caduca, N. chlamydospora and N. valdiviana, were isolated from several forest streams. Phytophthora cinnamomi, the most common and widespread species in soils of native forests, was associated with severe dieback of Valdivian rainforest trees, in particular D. winteri, Luma apiculata, Nothofagus dombeyi and the endangered Saxegothaea conspicua. A first pathogenicity test demonstrated high aggressiveness of P. cinnamomi to several native tree species, including N. dombeyi, Blepharocalyx cruckshanksii and Gevuina avellana. [ABSTRACT FROM AUTHOR]