Climate and seasonality drive the richness and composition of tropical fungal endophytes at a landscape scale

Understanding how species-rich communities persist is a foundational question in ecology. In tropical forests, tree diversity is structured by edaphic factors, climate, and biotic interactions, with seasonality playing an essential role at landscape scales: wetter and less seasonal forests typically harbor higher tree diversity than more seasonal forests. We posited that the abiotic factors shaping tree diversity extend to hyperdiverse symbionts in leaves—fungal endophytes—that influence plant health, function, and resilience to stress. Through surveys in forests across Panama that considered climate, seasonality, and covarying biotic factors, we demonstrate that endophyte richness varies negatively with temperature seasonality. Endophyte community structure and taxonomic composition reflect both temperature seasonality and climate (mean annual temperature and precipitation). Overall our findings highlight the vital role of climate-related factors in shaping the hyperdiversity of these important and little-known symbionts of the trees that, in turn, form the foundations of tropical forest biodiversity

Diversity, taxonomic composition, and functional aspects of fungal communities in living, senesced, and fallen leaves at five sites across North America

Background. Fungal endophytes inhabit symptomless, living tissues of all major plant lineages to form one of earth's most prevalent groups of symbionts. Many reproduce from senesced and/or decomposing leaves and can produce extracellular leaf degrading enzymes, blurring the line between symbiotrophy and saprotrophy. To better understand the endophyte saprotroph continuum we compared fungal communities and functional traits of focal strains isolated from living leaves to those isolated from leaves after senescence and decomposition, with a focus on foliage of woody plants in five biogeographic provinces ranging from tundra to subtropical scrub forest. Methods. We cultured fungi from the interior of surface-sterilized leaves that were living at the time. of sampling (i.e., dophytes), leaves that were dead and were retained in plant canopies (dead leaf fungi,eDn LF), and fallen. leaves (leaf litter.fungi,LLF) from 3-4 species of woody plants in each of five sites in. North America. Our sampling encompassed 18 plant species. representing. two families of Pinophyta.and five families of Angiospermae. Diversity and composition of fungal communities within and among leaf life stages, hosts, and sites were compared using ITS-partial L SU rDNA data. We evaluated substrate use and enzyme activity by a subset of fungi isolated'onlyfrom living tissues vs. fungi isolated only from non-living leaves. Results Across the diverse biomes and plant taxa surveyed here, culturable fungi living leays were isolated less frequently and were less diverse than those isolated from non-living leaves. Fungal communities in living leaves also differed detectably in composition from communities in dead leaves and leaf litter within focal sites and host taxa, regardless of differential weighting of rare and abundant fungi. All focal isolates grew on cellulose, lignin, and pectin as sole carbon sources, but none displayed igninolytic or pectinolytic activity in vitro. Cellulolytic activity differed among fungal classes. Within Dothideomycetes, activity differed significantly between fungi from living vs. non-living leaves, but such differences were not observed in Sordariomycetes. Discussion. Although some fungi with endophytic life stages clearly persist for periods of time in leaves after senescence and incorporation into leaf litter, our sampling across diverse biomes and host lineages detected consistent differences between fungal assemblages in living vs. non-living leaves, reflecting incursion by fungi from the leaf exterior after leaf death and as leaves begin to decompose. However, fungi found only in living leaves do not differ consistently in cellulolytic activity from those fungi detected thus far only in dead leaves. Future analyses should consider Basidiornycota in addition to the Ascomycota fungi evaluated here, and should explore more dimensions of functional traits and persistence to further define the endophytism-to-saprotrophy continuum.National Science Foundation [DEB0640996, DEB072825]; National Science Foundation (NSF); Mycological Society of AmericaThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Soilborne fungi have host affinity and host-specific effects on seed germination and survival in a lowland tropical forest

The Janzen-Connell (JC) hypothesis provides a conceptual framework for explaining the maintenance of tree diversity in tropical forests. Its central tenet-that recruits experience high mortality near conspecifics and at high densities-assumes a degree of host specialization in interactions between plants and natural enemies. Studies confirming JC effects have focused primarily on spatial distributions of seedlings and saplings, leaving major knowledge gaps regarding the fate of seeds in soil and the specificity of the soilborne fungi that are their most important antagonists. Here we use a common garden experiment in a lowland tropical forest in Panama to show that communities of seed-infecting fungi are structured predominantly by plant species, with only minor influences of factors such as local soil type, forest characteristics, or time in soil (1-12 months). Inoculation experiments confirmed that fungi affected seed viability and germination in a host-specific manner and that effects on seed viability preceded seedling emergence. Seeds are critical components of reproduction for tropical trees, and the factors influencing their persistence, survival, and germination shape the populations of seedlings and saplings on which current perspectives regarding forest dynamics are based. Together these findings bring seed dynamics to light in the context of the JC hypothesis, implicating them directly in the processes that have emerged as critical for diversity maintenance in species-rich tropical forests.NSF [DEB-1120205, DEB-1119758]; College of Agriculture and Life Sciences at The University of Arizona; Simons Foundation [429440]No copyright information listed.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Age-related variation in the oral microbiome of urban Cooper’s hawks (Accipiter cooperii)

Abstract Background Bird species worldwide are affected by trichomoniasis caused by the protist Trichomonas gallinae. In avivorous raptors such as Cooper’s hawks (Accipiter cooperii), nestlings are more susceptible than fledglings and adults. Previous research suggested a link between oral pH and susceptibility: the oral pH of fledgling and adult hawks is more than seven times more acidic than that of nestlings. We speculated that this age-specific difference in pH would correspond to age-specific differences in the oral microbiota of Cooper’s hawks. We examined the oral microbiomes of 31 healthy, wild Cooper’s hawks in Tucson, Arizona (USA). Individuals represented three age classes (nestlings, fledglings, and adults). We designed our study with multiple controls, replicated sampling, mock communities, and stringent quality-controls to address challenges that can limit the inferential quality of microbiome data sets. Results Richness of bacterial communities in oral cavities of Cooper’s hawks differed as a function of age but not as a function of sex, sampling date, or sampling location. Bacterial communities in oral cavities of nestlings differed from those of fledglings and adults, whereas communities in fledglings and adults did not differ from each other. Communities were similar in males and females and did not differ over the sampling season. Prevalence of acid-producing bacteria in fledgling and adults vs. nestlings is consistent with previous reports of age-specific variation in oral pH, but further research is needed to establish a causal link to pH levels or susceptibility to disease. Analyses of mock communities demonstrated high repeatability and showed that operon number and read abundance were highly correlated. Conclusions The oral microbiota of wild Cooper’s hawks differs between nestlings and older birds. Variation in the oral microbiome is consistent with differences in oral pH between nestlings and older individuals. Overall our study provides a first perspective on bacterial communities associated with oral cavities of a wild raptor

Methodological Approaches Frame Insights into Endophyte Richness and Community Composition

Isolating microbes is vital to study microbiomes, but insights into microbial diversity and ecology can be constrained by recalcitrant or unculturable strains. Culture-free methods (e.g., next-generation sequencing, NGS) have become popular in part because they detect greater richness than culturing alone. Both approaches are used widely to characterize microfungi within healthy leaves (foliar endophytes), but methodological differences among studies can constrain large-scale insights into endophyte ecology. We examined endophytes in a temperate plant community to quantify how certain methodological factors, such as the choice of cultivation media for culturing and storage period after leaf collection, affect inferences regarding endophyte communities; how such effects vary among plant taxa; and how complementary culturing and NGS can be when subsets of the same plant tissue are used for each. We found that endophyte richness and composition from culturing were consistent across five media types. Insights from culturing and NGS were largely robust to differences in storage period (1, 5, and 10 days). Although endophyte richness, composition, and taxonomic diversity identified via culturing vs. NGS differed markedly, both methods revealed host-structured communities. Studies differing only in cultivation media or storage period thus can be compared to estimate endophyte richness, composition, and turnover at scales larger than those of individual studies alone. Our data show that it is likely more important to sample more host species, rather than sampling fewer species more intensively, to quantify endophyte diversity in given locations, with the richest insights into endophyte ecology emerging when culturing and NGS are paired. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.12 month embargo; published 07 January 2021This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Anteaglonialides A–F and Palmarumycins CE₁–CE₃ from <i>Anteaglonium</i> sp. FL0768, a Fungal Endophyte of the Spikemoss <i>Selaginella arenicola</i>

Anteaglonialides A–F (<b>1</b>–<b>6</b>), bearing a spiro­[6-(tetrahydro-7-furanyl)­cyclohexane-1,2′-naphtho­[1,8-<i>de</i>]­[1,3]-dioxin]-10-one skeleton, three new spirobisnaphthalenes, palmarumycins CE₁–CE₃ (<b>7</b>–<b>9</b>), nine known palmarumycin analogues, palmarumycins CP₅ (<b>10</b>), CP_4a (<b>11</b>), CP₃ (<b>12</b>), CP₁₇ (<b>13</b>), CP₂ (<b>14</b>), and CP₁ (<b>15</b>), CJ-12,371 (<b>16</b>), 4-<i>O</i>-methyl CJ-12,371 (<b>17</b>), and CP₄ (<b>18</b>), together with a possible artifact, 4a(5)-anhydropalmarumycin CE₂ (<b>8a</b>), and four known metabolites, <i>O</i>-methylherbarin (<b>19</b>), herbarin (<b>20</b>), herbaridine B (<b>21</b>), and hyalopyrone (<b>22</b>), were encountered in a cytotoxic extract of a potato dextrose agar culture of <i>Anteaglonium</i> sp. FL0768, an endophytic fungus of the sand spikemoss, <i>Selaginella arenicola.</i> The planar structures and relative configurations of the new metabolites <b>1</b>–<b>9</b> were elucidated by analysis of extensive spectroscopic data, and the absolute configuration of <b>1</b> was determined by the modified Mosher’s ester method. Application of the modified Mosher’s ester method combined with the NOESY data resulted in revision of the absolute configuration previously proposed for <b>10</b>. Co-occurrence of <b>1</b>–<b>6</b> and <b>7</b>–<b>18</b> in this fungus led to the proposal that the anteagloniolides may be biogenetically derived from palmarumycins. Among the metabolites encountered, anteaglonialide F (<b>6</b>) and known palmarumycins CP₃ (<b>12</b>) and CP₁ (<b>15</b>) exhibited strong cytotoxic activity against the human Ewing’s sarcoma cell line CHP-100, with IC₅₀ values of 1.4, 0.5, and 1.6 μM, respectively

Cytotoxic and Noncytotoxic Metabolites from <i>Teratosphaeria</i> sp. FL2137, a Fungus Associated with <i>Pinus clausa</i>

A new naphthoquinone, teratosphaerone A (<b>1</b>), four new naphthalenones, namely, teratosphaerone B (<b>2</b>), structurally related to <b>1</b>, iso-balticol B (<b>3</b>), iso-balticol B-4,9-acetonide (<b>4</b>), and (+)-balticol C (<b>5</b>), a new furanonaphthalenone, (3a<i>S</i>,9<i>R</i>,9a<i>S</i>)-1­(9a),3­(3a),9-hexahydromono­sporascone (<b>6</b>), and the known metabolite monosporascone (<b>7</b>) were isolated from <i>Teratosphaeria</i> sp. FL2137, a fungal strain inhabiting the internal tissue of recently dead but undecomposed foliage of <i>Pinus clausa</i>. The structures of <b>1</b>–<b>6</b> were elucidated on the basis of their spectroscopic data including 2D NMR, and absolute configurations of <b>2</b>, <b>3</b>, and <b>6</b> were determined by the modified Mosher’s ester method. When evaluated in a panel of five tumor cell lines, metabolites <b>1</b> and <b>7</b> isolated from a cytotoxic fraction of the extract exhibited moderate selectivity for metastatic breast adenocarcinoma cell line MDA-MB-231. Of these, <b>1</b> showed cytotoxicity to this cell line with an IC₅₀ of 1.2 ± 0.1 μM

Delitschiapyrone A, a Pyrone–Naphthalenone Adduct Bearing a New Pentacyclic Ring System from the Leaf-Associated Fungus <i>Delitschia</i> sp. FL1581

Delitschiapyrone A (<b>1</b>), an α-pyrone–naphthalenone adduct with an unprecedented pentacyclic ring system, was isolated from a solid culture of the leaf-associated fungus <i>Delitschia</i> sp. FL1581. The structure of <b>1</b> was elucidated by spectroscopic analysis and X-ray crystallography, and its absolute configuration was defined by experimental and calculated ECD. Biosynthetically, the unique 6/6/5/7/6 pentacyclic core of <b>1</b> may be formed by an intermolecular Diels–Alder-type addition of the precursors derived from (1′<i>R</i>)-2′,3′-dihydropyrenocine C (<b>2</b>) and 6-ethyl-2,7-dimethoxyjuglone (<b>3</b>) found to co-occur with <b>1</b> in this fungus