Fungi play major roles in ecosystem processes, but the determinants of fungal diversity and biogeographic patterns remain poorly understood. Using DNA metabarcoding data from hundreds of globally distributed soil samples, we demonstrate that fungal richness is decoupled from plant diversity. The plant-to-fungus richness ratio declines exponentially toward the poles. Climatic factors, followed by edaphic and spatial variables, constitute the best predictors of fungal richness and community composition at the global scale. Fungi show similar latitudinal diversity gradients to other organisms, with several notable exceptions. These findings advance our understanding of global fungal diversity patterns and permit integration of fungi into a general macroecological framework.

During surveys of dying vegetation in natural ecosystems and associated waterways in Australia many new taxa have been identified from Phytophthora ITS Clade 6. For representative isolates, the region spanning the internal transcribed spacer region of the ribosomal DNA, the nuclear gene encoding heat shock protein 90 and the mitochondrial cox1 gene were PCR amplified and sequenced. Based on phylogenetic analysis and morphological and physiological comparison, four species and one informally designated taxon have been described; Phytophthora gibbosa, P. gregata, P. litoralis, P. thermophila and P. taxon paludosa. Phytophthora gibbosa, P. gregata and P. taxon paludosa form a new cluster and share a common ancestor; they are homothallic and generally associated with dying vegetation in swampy or water-logged areas. Phytophthora thermophila and P. litoralis are sister species to each other and more distantly to P. gonapodyides. Both new species are common in waterways and cause scattered mortality within native vegetation. They are self-sterile and appear well adapted for survival in an aquatic environment and inundated soils, filling the niche occupied by P. gonapodyides and P. taxon salixsoil in the northern hemisphere. Currently the origin of these new taxa, their pathogenicity and their role in natural ecosystems are unknown. Following the precautionary principle, they should be regarded as a potential threat to native ecosystems and managed to minimise their further spread.

Accepted ArticleThis article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/gcb.13492 This article is protected by copyright. All rights reserved. Accepted ArticleThis article is protected by copyright. All rights reserved. AbstractGlobally, Phytophthora cinnamomi is listed as one of the 100 worst invasive alien species and active management is required to reduce impact and prevent spread in both horticulture and natural ecosystems. Conversely, there are regions thought to be suitable for the pathogen where no disease is observed. We developed a CLIMEX model for the global distribution of P. cinnamomi based on the pathogen's response to temperature and moisture and by incorporating extensive empirical evidence on the presence and absence of the pathogen. The CLIMEX model captured areas of climatic suitability where P. cinnamomi occurs that is congruent with all available records. The model was validated by the collection of soil samples from asymptomatic vegetation in areas projected to be suitable by the model for which there were few records. DNA was extracted and the presence or absence of P. cinnamomi determined by high throughput sequencing (HTS). While not detected using traditional isolation methods, HTS detected P. cinnamomi at higher elevations in eastern Australia and central Tasmania as projected by the CLIMEX model. Further support for the CLIMEX model was obtained by using the large dataset from southwest Australia where the proportion of positive records in an area is related to the Ecoclimatic Index value for the same area. We provide for the first time a comprehensive global map of the current P. cinnamomi distribution, an improved CLIMEX model of the distribution, and a projection to 2080 of the distribution with predicted climate change. This information provides the basis for more detailed regional scale modelling and supports risk assessment for governments to plan management of this important soil-borne plant pathogen.

The introduction and subsequent impact of Phytophthora cinnamomi within native vegetation is one of the major conservation issues for biodiversity in Australia. Recently, many new Phytophthora species have been described from Australia's native ecosystems; however, their distribution, origin, and potential impact remain unknown. Historical bias in Phytophthora detection has been towards sites showing symptoms of disease, and traditional isolation methods show variable effectiveness of detecting different Phytophthora species. However, we now have at our disposal new techniques based on the sampling of environmental DNA and metabarcoding through the use of highthroughput sequencing. Here, we report on the diversity and distribution of Phytophthora in Australia using metabarcoding of 640 soil samples and we compare the diversity detected using this technique with that available in curated databases. Phytophthora was detected in 65% of sites, and phylogenetic analysis revealed 68 distinct Phytophthora phylotypes. Of these, 21 were identified as potentially unique taxa and 25 were new detections in natural areas and/or new introductions to Australia. There are 66 Phytophthora taxa listed in Australian databases, 43 of which were also detected in this metabarcoding study. This study revealed high Phytophthora richness within native vegetation and the additional records provide a valuable baseline resource for future studies. Many of the Phytophthora species now uncovered in Australia's native ecosystems are newly described and until more is known we need to be cautious with regard to the spread and conservation management of these new species in Australia's unique ecosystems.

The invasive plant pathogen Phytophthora cinnamomi (Stramenopila, Oomycota) has been introduced into 15 of the 25 global biodiversity hotspots, threatening susceptible rare flora and degrading plant communities with severe consequences for fauna. We developed protocols to contain or eradicate P. cinnamomi from spot infestations in threatened ecosystems based on two assumptions: in the absence of living hosts, P. cinnamomi is a weakly competitive saprotroph; and in the ecosystems we treated, the transmission of the pathogen occurs mainly by root-toroot contact. At two P. cinnamomi-infested sites differing in climate and vegetation types, we applied increasingly robust treatments including vegetation (host) destruction, fungicides, fumigation and physical root barriers. P. cinnamomi was not recovered at three assessments of treated plots 6-9 months after treatments. Given the high rates of recovery of P. cinnamomi from untreated infested soil and the sampling frequency, the probability of failing to detect P. cinnamomi in treated soil was \0.0003. The methods described have application in containing large infestations, eradicating small infestations and protecting remnant populations of threatened species.