Ten simple rules for leading a successful undergraduate-intensive research lab.

Participating in mentored research is an enormous benefit to undergraduate students. These immersive experiences can dramatically improve retention and completion rates, especially for students from traditionally underserved populations in STEM disciplines. Scientists typically do not receive any formal training in management or group dynamics before taking on the role of a lab head. Thus, peer forums and shared wisdom are crucial for developing the vision and skills involved with mentorship and leading a successful research lab. Faculty at any institution can help improve student outcomes and the success of their labs by thoughtfully including undergraduates in their research programs. Moreover, faculty at primarily undergraduate institutions have special challenges that are not often acknowledged or addressed in public discussions about best practices for running a lab. Here, we present 10 simple rules for fostering a successful undergraduate research lab. While much of the advice herein is applicable to mentoring undergraduates in any setting, it is especially tailored to the special circumstances found at primarily undergraduate institutions.

Wallace's line structures seagrass microbiota and is a potential barrier to the dispersal of marine bacteria.

BACKGROUND: The processes that shape microbial biogeography are not well understood, and concepts that apply to macroorganisms, like dispersal barriers, may not affect microorganisms in the same predictable ways. To better understand how known macro-scale biogeographic processes can be applied at micro-scales, we examined seagrass associated microbiota on either side of Wallace's line to determine the influence of this cryptic dispersal boundary on the community structure of microorganisms. Communities were examined from twelve locations throughout Indonesia on either side of this theoretical line. RESULTS: We found significant differences in microbial community structure on either side of this boundary (R2 = 0.09; P = 0.001), and identified seven microbial genera as differentially abundant on either side of the line, six of these were more abundant in the West, with the other more strongly associated with the East. Genera found to be differentially abundant had significantly smaller minimum cell dimensions (GLM: t923 = 59.50, P < 0.001) than the overall community. CONCLUSION: Despite the assumed excellent dispersal ability of microbes, we were able to detect significant differences in community structure on either side of this cryptic biogeographic boundary. Samples from the two closest islands on opposite sides of the line, Bali and Komodo, were more different from each other than either was to its most distant island on the same side. We suggest that limited dispersal across this barrier coupled with habitat differences are primarily responsible for the patterns observed. The cryptic processes that drive macroorganism community divergence across this region may also play a role in the bigeographic patterns of microbiota.

Connecting the multiple dimensions of global soil fungal diversity.

How the multiple facets of soil fungal diversity vary worldwide remains virtually unknown, hindering the management of this essential species-rich group. By sequencing high-resolution DNA markers in over 4000 topsoil samples from natural and human-altered ecosystems across all continents, we illustrate the distributions and drivers of different levels of taxonomic and phylogenetic diversity of fungi and their ecological groups. We show the impact of precipitation and temperature interactions on local fungal species richness (alpha diversity) across different climates. Our findings reveal how temperature drives fungal compositional turnover (beta diversity) and phylogenetic diversity, linking them with regional species richness (gamma diversity). We integrate fungi into the principles of global biodiversity distribution and present detailed maps for biodiversity conservation and modeling of global ecological processes.

The core mangrove microbiome reveals shared taxa potentially involved in nutrient cycling and promoting host survival.

BACKGROUND: Microbes have fundamental roles underpinning the functioning of our planet, they are involved in global carbon and nutrient cycling, and support the existence of multicellular life. The mangrove ecosystem is nutrient limited and if not for microbial cycling of nutrients, life in this harsh environment would likely not exist. The mangroves of Southeast Asia are the oldest and most biodiverse on the planet, and serve vital roles helping to prevent shoreline erosion, act as nursery grounds for many marine species and sequester carbon. Despite these recognised benefits and the importance of microbes in these ecosystems, studies examining the mangrove microbiome in Southeast Asia are scarce.cxs RESULTS: Here we examine the microbiome of Avicenia alba and Sonneratia alba and identify a core microbiome of 81 taxa. A further eight taxa (Pleurocapsa, Tunicatimonas, Halomonas, Marinomonas, Rubrivirga, Altererythrobacte, Lewinella, and Erythrobacter) were found to be significantly enriched in mangrove tree compartments suggesting key roles in this microbiome. The majority of those identified are involved in nutrient cycling or have roles in the production of compounds that promote host survival. CONCLUSION: The identification of a core microbiome furthers our understanding of mangrove microbial biodiversity, particularly in Southeast Asia where studies such as this are rare. The identification of significantly different microbial communities between sampling sites suggests environmental filtering is occurring, with hosts selecting for a microbial consortia most suitable for survival in their immediate environment. As climate change advances, many of these microbial communities are predicted to change, however, without knowing what is currently there, it is impossible to determine the magnitude of any deviations. This work provides an important baseline against which change in microbial community can be measured.

Inclusion of database outgroups reduces false positives in fungal metabarcoding taxonomic assignments.

Metabarcoding studies of fungal communities rely on curated databases for assigning taxonomy. Any host or other nonfungal environmental sequences that are amplified during polymerase chain reaction (PCR) are inherently assigned taxonomy by these same databases, possibly leading to ambiguous nonfungal amplicons being assigned to fungal taxa. Here, we investigated the effects of including nonfungal outgroups in a fungal taxonomic database to aid in detecting and removing these nontarget amplicons. We processed 15 publicly available fungal metabarcode data sets and discovered that roughly 40% of the reads from these studies were not fungal, although they were assigned as Fungus sp. when using a database without nonfungal outgroups. We discuss implications for metabarcoding studies and recommend assigning taxonomy using a database with outgroups to better detect these nonfungal amplicons.

Global patterns in endemicity and vulnerability of soil fungi.

Fungi are highly diverse organisms, which provide multiple ecosystem services. However, compared with charismatic animals and plants, the distribution patterns and conservation needs of fungi have been little explored. Here, we examined endemicity patterns, global change vulnerability and conservation priority areas for functional groups of soil fungi based on six global surveys using a high-resolution, long-read metabarcoding approach. We found that the endemicity of all fungi and most functional groups peaks in tropical habitats, including Amazonia, Yucatan, West-Central Africa, Sri Lanka, and New Caledonia, with a negligible island effect compared with plants and animals. We also found that fungi are predominantly vulnerable to drought, heat and land-cover change, particularly in dry tropical regions with high human population density. Fungal conservation areas of highest priority include herbaceous wetlands, tropical forests, and woodlands. We stress that more attention should be focused on the conservation of fungi, especially root symbiotic arbuscular mycorrhizal and ectomycorrhizal fungi in tropical regions as well as unicellular early-diverging groups and macrofungi in general. Given the low overlap between the endemicity of fungi and macroorganisms, but high conservation needs in both groups, detailed analyses on distribution and conservation requirements are warranted for other microorganisms and soil organisms.

Hawaiian Fungal Amplicon Sequence Variants Reveal Otherwise Hidden Biogeography.

To study biogeography and other ecological patterns of microorganisms, including fungi, scientists have been using operational taxonomic units (OTUs) as representations of species or species hypotheses. However, when defined by 97% sequence similarity cutoff at an accepted barcode locus such as 16S in bacteria or ITS in fungi, these OTUs can obscure biogeographic patterns, mask taxonomic diversity, and hinder meta-analyses. Amplicon sequence variants (ASVs) have been proposed to alleviate all of these issues and have been shown to do so in bacteria. Analyzing ASVs is just emerging as a common practice among fungal studies, and it is unclear whether the benefits found in bacterial studies of using such an approach carryover to fungi. Here, we conducted a meta-analysis of Hawaiian fungi by analyzing ITS1 amplicon sequencing data as ASVs and exploring ecological patterns. These surveys spanned three island groups and five ecosystems combined into the first comprehensive Hawaiian Mycobiome ASV Database. Our results show that ASVs can be used to combine fungal ITS surveys, increase reproducibility, and maintain the broad ecological patterns observed with OTUs, including diversity orderings. Additionally, the ASVs that comprise some of the most common OTUs in our database reveals some island specialists, indicating that traditional OTU clustering can obscure important biogeographic patterns. We recommend that future fungal studies, especially those aimed at assessing biogeography, analyze ASVs rather than OTUs. We conclude that similar to bacterial studies, ASVs improve reproducibility and data sharing for fungal studies.

Biogeographic structure of fungal communities in seagrass Halophilia ovalis across the Malay Peninsula.

Distributed across both the tropical Atlantic and Pacific oceans, the seagrass Halophilia ovalis stabilizes coastal sediment, thereby preventing shoreline erosion and is also an important food source for megaherbivores such as dugongs. However, seagrass meadows globally are under severe duress due to both climate change and anthropogenic activities. We characterized the mycobiome of Halophilia ovalis at seven sites in the Malay Peninsula using ITS1 rDNA amplicon sequences and investigated differences in fungal community structure. We found that geographic location was a significant factor shaping fungal communities and that marine sediment harboured significantly higher diversity when compared to H. ovalis leaves, roots and rhizomes. Taken together, it is likely that locality rather than specific plant structure determines fungal community structure in H. ovalis. Because the plant mycobiome is known to exert a strong effect on plant health, to maximize the success of future seagrass transplantation and restoration work we propose that these efforts consider the importance of seagrass mycobiomes at all stages.

Host age is not a consistent predictor of microbial diversity in the coral Porites lutea.

Corals harbour diverse microbial communities that can change in composition as the host grows in age and size. Larger and older colonies have been shown to host a higher diversity of microbial taxa and this has been suggested to be a consequence of their more numerous, complex and varied micro-niches available. However, the effects of host age on community structure and diversity of microbial associates remain equivocal in the few studies performed to date. To test this relationship more robustly, we use established techniques to accurately determine coral host age by quantifying annual skeletal banding patterns, and utilise high-throughput sequencing to comprehensively characterise the microbiome of the common reef-building coral, Porites lutea. Our results indicate no clear link between coral age and microbial diversity or richness. Different sites display distinct age-dependent diversity patterns, with more anthropogenically impacted reefs appearing to show a winnowing of microbial diversity with host age, possibly a consequence of corals adapting to degraded environments. Less impacted sites do not show a signature of winnowing, and we observe increases in microbial richness and diversity as the host ages. Furthermore, we demonstrate that corals of a similar age from the same reef can show very different microbial richness and diversity.

Fungal communities living within leaves of native Hawaiian dicots are structured by landscape-scale variables as well as by host plants.

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.

Fungal aerobiota are not affected by time nor environment over a 13-y time series at the Mauna Loa Observatory.

Fungi are ubiquitous and often abundant components of virtually all ecosystems on Earth, serving a diversity of functions. While there is clear evidence that fungal-mediated processes can influence environmental conditions, and in turn select for specific fungi, it is less clear how fungi respond to environmental fluxes over relatively long time frames. Here we set out to examine changes in airborne fungi collected over the course of 13 y, which is the longest sampling time to date. Air filter samples were collected from the Mauna Loa Observatory (MLO) on Hawaii Island, and analyzed using Illumina amplicon sequencing. As a study site, MLO is unique because of its geographic isolation and high elevation, making it an ideal place to capture global trends in climate and aerobiota. We found that the fungal aerobiota sampled at MLO had high species turnover, but compositional similarity did not decrease as a function of time between samples. We attribute these patterns to neutral processes such as idiosyncratic dispersal timing and trajectories. Furthermore, the composition of fungi at any given point was not significantly influenced by any local or global environmental variables we examined. This, and our additional finding of a core set of persistent fungi during our entire sampling period, indicates some degree of stability among fungi in the face of natural environmental fluctuations and human-associated global change. We conclude that the movement of fungi through the atmosphere is a relatively stochastic process.

Seagrass-associated fungal communities show distance decay of similarity that has implications for seagrass management and restoration.

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.

Foliar microbiome transplants confer disease resistance in a critically-endangered plant.

There has been very little effort to incorporate foliar microbiomes into plant conservation efforts even though foliar endophytes are critically important to the fitness and function of hosts. Many critically endangered plants that have been extirpated from the wild are dependent on regular fungicidal applications in greenhouses that cannot be maintained for remote out-planted populations, which quickly perish. These fungicides negatively impact potentially beneficial fungal symbionts, which may reduce plant defenses to pathogens once fungicide treatments are stopped. Using the host/parasite system of Phyllostegia kaalaensis and Neoerysiphe galeopsidis, we conducted experiments to test total foliar microbiome transplants from healthy wild relatives onto fungicide-dependent endangered plants in an attempt to mitigate disease and reduce dependency on fungicides. Plants were treated with total microbiome transplants or cultured subsets of this community and monitored for disease severity. High-throughput DNA screening of fungal ITS1 rDNA was used to track the leaf-associated fungal communities and evaluate the effectiveness of transplantation methods. Individuals receiving traditionally isolated fungal treatments showed no improvement, but those receiving applications of a simple leaf slurry containing an uncultured fungal community showed significant disease reduction, to which we partially attribute an increase in the mycoparasitic Pseudozyma aphidis. These results were replicated in two independent experimental rounds. Treated plants have since been moved to a native habitat and, as of this writing, remain disease-free. Our results demonstrate the effectiveness of a simple low-tech method for transferring beneficial microbes from healthy wild plants to greenhouse-raised plants with reduced symbiotic microbiota. This technique was effective at reducing disease, and in conferring increased survival to an out-planted population of critically endangered plants. It was not effective in a closely related plant. Plant conservation efforts should strive to include foliar microbes as part of comprehensive management plans.

Uncovering unseen fungal diversity from plant DNA banks.

Throughout the world DNA banks are used as storage repositories for genetic diversity of organisms ranging from plants to insects to mammals. Designed to preserve the genetic information for organisms of interest, these banks also indirectly preserve organisms' associated microbiomes, including fungi associated with plant tissues. Studies of fungal biodiversity lag far behind those of macroorganisms, such as plants, and estimates of global fungal richness are still widely debated. Utilizing previously collected specimens to study patterns of fungal diversity could significantly increase our understanding of overall patterns of biodiversity from snapshots in time. Here, we investigated the fungi inhabiting the phylloplane among species of the endemic Hawaiian plant genus, Clermontia (Campanulaceae). Utilizing next generation DNA amplicon sequencing, we uncovered approximately 1,780 fungal operational taxonomic units from just 20 DNA bank samples collected throughout the main Hawaiian Islands. Using these historical samples, we tested the macroecological pattern of decreasing community similarity with decreasing geographic proximity. We found a significant distance decay pattern among Clermontia associated fungal communities. This study provides the first insights into elucidating patterns of microbial diversity through the use of DNA bank repository samples.

Fungi associated with mesophotic macroalgae from the 'Au'au Channel, west Maui are differentiated by host and overlap terrestrial communities.

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.

Ecological distribution of protosteloid amoebae in New Zealand.

During the period of March 2004 to December 2007, samples of aerial litter (dead but still attached plant parts) and ground litter (dead plant material on the ground) were collected from 81 study sites representing a wide range of latitudes (34°S to 50°S) and a variety of different types of habitats throughout New Zealand (including Stewart Island and the Auckland Islands). The objective was to survey the assemblages of protosteloid amoebae present in this region of the world. Twenty-nine described species of protosteloid amoebae were recorded by making morphological identifications of protosteloid amoebae fruiting bodies on cultured substrates. Of the species observed, Protostelium mycophaga was by far the most abundant and was found in more than half of all samples. Most species were found in fewer than 10% of the samples collected. Seven abundant or common species were found to display significantly increased likelihood for detection in aerial litter or ground litter microhabitats. There was some evidence of a general correlation between environmental factors - annual precipitation, elevation, and distance from the equator (latitude) - and the abundance and richness of protosteloid amoebae. An increase in each of these three factors correlated with a decrease in both abundance and richness. This study provides a thorough survey of the protosteloid amoebae present in New Zealand and adds to a growing body of evidence which suggests several correlations between their broad distributional patterns and environmental factors.

Pil1, an eisosome organizer, plays an important role in the recruitment of synaptojanins and amphiphysins to facilitate receptor-mediated endocytosis in yeast.

The eisosome protein Pil1 is known to be implicated in the endocytosis of Ste3, but the precise biological function of it during endocytosis is poorly understood. Here, we present data to reveal Pil1's role in receptor-mediated endocytosis. Using live cell imaging, we show that endocytic patches carrying Abp1 and Las17 persisted much longer in PIL1-deficient cells. The loss of Pil1 also greatly affected both the scission efficiency and the frequency of formation of endocytic sites carrying Rvs161- and Rvs167-GFP. Furthermore, the mistargeting of the synaptojanins, Sjl1 and Sjl2, to the cytoplasm in pil1Δ cells suggests that Pil1 is required for the proper recruitment of the synaptojanins to endocytic sites. A severe motility defect of Abp1-GFP during its internalization in a codeletant of PIL1 and SJL2 indicates a functional interplay between them in endocytosis. Together, these results establish that Pil1 is involved in the recruitment of endocytic proteins to optimize endocytosis.