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A phylogenetically diverse array of fungi live within healthy leaf tissue of dicotyledonous plants. Many studies have examined these endophytes within a single plant species and/or at small spatial scales, but landscape-scale variables that determine their community composition are not well understood, either across geographic space, across climatic conditions, or in the context of host plant phylogeny. Here, we evaluate the contributions of these variables to endophyte beta diversity using a survey of foliar endophytic fungi in native Hawaiian dicots sampled across the Hawaiian archipelago. We used Illumina technology to sequence fungal ITS1 amplicons to characterize foliar endophyte communities across five islands and 80 host plant genera. We found that communities of foliar endophytic fungi showed strong geographic structuring between distances of 7 and 36 km. Endophyte community structure was most strongly associated with host plant phylogeny and evapotranspiration, and was also significantly associated with NDVI, elevation and solar radiation. Additionally, our bipartite network analysis revealed that the five islands we sampled each harboured significantly specialized endophyte communities. These results demonstrate how the interaction of factors at large and small spatial and phylogenetic scales shapes fungal symbiont communities.

Marine fungal biodiversity remains vastly understudied, and even less is known of their biogeography and the processes responsible for driving these distributions in marine environments. We investigated the fungal communities associated with the seagrass Enhalus acoroides collected from Singapore and Peninsular Malaysia to test the hypothesis that fungal communities are homogeneous throughout the study area. Seagrass samples were separated into different structures (leaves, roots, and rhizomes), and a sediment sample was collected next to each plant. Amplicon sequencing of the fungal internal transcribed spacer 1 and subsequent analysis revealed significant differences in fungal communities collected from different locations and different structures. We show a significant pattern of distance decay, with samples collected close to each other having more similar fungal communities in comparison with those that are more distant, indicating dispersal limitations and/or differences in habitat type are contributing to the observed biogeographic patterns. These results add to our understanding of the seagrass ecosystem in an understudied region of the world that is also the global epicenter of seagrass diversity. This work has implications for seagrass management and conservation initiatives, and we recommend that fungal community composition be a consideration for any seagrass transplant or restoration programme., Examining marine fungi associated with the seagrass, Enhalus acoroides.

Marine environments abound with opportunities to discover new species of fungi even in relatively well-studied ecosystems such as coral reefs. Here, we investigated the fungal communities associated with the canopy forming macroalga Sargassum ilicifolium(Turner) C. Argardh (1820) in Singapore. We collected eight S. ilicifolium thalli from each of eight island locations and separated them into three structures—leaves, holdfast and vesicles. Amplicon sequencing of the fungal internal transcribed spacer 1 (ITS1) and subsequent analyses revealed weak but significant differences in fungal community composition from different structures. Fungal communities were also significantly different among sampling localities, even over relatively small spatial scales (≤ 12 km). Unsurprisingly, all structures from all localities were dominated by unclassified fungi. Our findings demonstrate the potential of marine environments to act as reservoirs of undocumented biodiversity that harbour many novel fungal taxa. These unclassified fungi highlight the need to look beyond terrestrial ecosystems in well-studied regions of the world, and to fully characterize fungal biodiversity in hotspots such as Southeast Asia for better understanding the roles they play in promoting and maintaining life on our planet.

The coral holobiont contains a diverse community of bacteria that have been widely acknowledged as a major contributor in the maintenance of host health and in promoting reef resilience under changing environments. However, little is known regarding the spatial distribution of these communities or the processes and mechanisms that are responsible for creating these patterns. Here we show that bacterial communities associated with the reef-building coral, Pocillopora acuta, from nine offshore islands in an urbanised coral reef ecosystem (Singapore) can diverge sharply and are significantly different among sampling locations. We suggest that small-scale environmental factors such as prevailing surface currents and wind direction, even over short distances (

Beneficial microbes such as plant mutualistic fungi, hold the promise of ameliorating challenges faced in native plant conservation such as disease management. As an alternative to costly chemical pest control, conservation efforts could potentially harness the benefits of plant mutualistic fungi to aid in defense and disease resistance, but there are few tests of this notion. We set out to test the efficacy of controlling a common foliar pathogen, the powdery mildew Neoerysiphe galeopsidis, by inoculating the endangered Hawaiian plant species Phyllostegia kaalaensis with potentially beneficial members of its wild-type mycobiome. We tested whether inoculating plants with above or belowground fungal mutualists, or both, led to increased disease resistance in the host. We found that while all treatments reduced average disease incidence, colonization by the foliar yeast Moesziomyces aphidis was the only treatment to do so significantly. These results provide an exciting new strategy for plant conservation practices.

A phylogenetically diverse array of fungi live within healthy leaf tissue of dicotyledonous plants. Many studies have examined these endophytes within a single plant species and/or at small spatial scales, but landscape-scale variables that determine their community composition are not well understood, either across geographic space, across climatic conditions, or in the context of host plant phylogeny. Here, we evaluate the contributions of these variables to endophyte beta diversity using a survey of foliar endophytic fungi in native Hawaiian dicots sampled across the Hawaiian archipelago. We used Illumina technology to sequence fungal ITS1 amplicons to characterize foliar endophyte communities across five islands and 80 host plant genera. We found that communities of foliar endophytic fungi showed strong geographic structuring between distances of seven and 36 km. Endophyte community structure was most strongly associated with host plant phylogeny and evapotranspiration, and was also significantly associated with NDVI, elevation, and solar radiation. Additionally, our bipartite network analysis revealed that the five islands we sampled each harbored significantly specialized endophyte communities. These results demonstrate how the interaction of factors at large and small spatial and phylogenetic scales shape fungal symbiont communities.

Microbes influence plant phenotypes but most known examples of this are from the study of below-ground microbes and plant disease modification. To examine the potential importance of phyllosphere microbes on non-disease related plant traits, we used sterile Arabidopsis clones to test the effects of foliar fungi on flowering phenology and reproductive allocation under conditions of varying water stress. We inoculated the sterile plants with fully-factorial combinations of four fungal isolates, then measured flowering time and reproductive allocation for each treatment group under normal and water-stressed conditions. All plants inoculated with foliar fungi had significantly later flowering and greater seed mass than the sterile control groups. The magnitude of this effect depended on the specific fungi present, but individual fungal effects diminished as inoculum richness increased. Above-ground microbes likely influence other plant traits as well and should be considered in any study measuring plant phenotypes.

Mesophotic coral ecosystems are an almost entirely unexplored and undocumented environment that likely contains vast reservoirs of undescribed biodiversity. Twenty-four macroalgae samples, representing four genera, were collected from a Hawaiian mesophotic reef at water depths between 65 and 86 m in the ‘Au‘au Channel, Maui, Hawai‘i. Algal tissues were surveyed for the presence and diversity of fungi by sequencing the ITS1 gene using Illumina technology. Fungi from these algae were then compared to previous fungal surveys conducted in Hawaiian terrestrial ecosystems. Twenty-seven percent of the OTUs present on the mesophotic coral ecosystem samples were shared between the marine and terrestrial environment. Subsequent analyses indicated that host species of algae significantly differentiate fungal community composition. This work demonstrates yet another understudied habitat with a moderate diversity of fungi that should be considered when estimating global fungal diversity.