Plant Identity Research Articles

The Metabolome of Associations between Xylem-Feeding Insects and their Bacterial Symbionts.

Metabolomics has increasingly led to important insights in chemical ecology by identifying environmentally relevant small molecules that mediate inter-organismal interactions. Nevertheless, the application of metabolomics to investigate interactions between phytophagous insects and their microbial symbionts remains underutilized. Here, we investigated the metabolomes of the bacteriomes (organs bearing symbiotic bacteria) isolated from natural populations of five species of xylem-feeding insects. We identified three patterns. First, the metabolomes varied among the five species, likely influenced by insect phylogeny, food plant and taxonomic identity of the symbionts. Second, the ratio of glutamine: glutamate in the bacteriomes was 0.7-3.6 to 1, indicative of nitrogen-sufficient metabolism and raising the possibility that the insect sustains nitrogen-enriched status of the bacteriomes despite the nitrogen scarcity of the xylem diet. Finally, bacteriomes from insect species bearing genetically-similar symbionts displayed limited variation in their metabolomes, suggesting that the metabolic pattern of the bacteriome metabolic pools is correlated with the genetic repertoire of the symbionts. Altogether, these metabolomic patterns yield specific hypotheses of underlying processes that are testable by wider sampling of natural populations and experimental study.

Identifying plant DNA in the faeces of a generalist insect pest to inform trap cropping strategy

Monocropping elevates many insects to the status of economic pests. In these agroecosystems, non-crop habitats are sometimes deployed as trap crops to reduce pest damage. This environmentally friendly alternative to pesticides can be particularly fitting when dealing with native invaders that may be afforded legal protection or enjoy public sympathy as is the case for the ground wētā Hemiandrus sp. ‘promontorius’ (Orthoptera) in New Zealand. However, this approach requires knowledge of the insects’ diet to select the most appropriate plant species for trap cropping. Here, ingested plant DNA in the faeces of wētā was analysed to help develop strategies for mitigating its damage in New Zealand vineyards. DNA was extracted from faeces of wētā collected from six different vineyards over four seasons. Using a DNA metabarcoding approach, we amplified the rbcL gene region and sequenced the amplicons on an Illumina MiSeq platform. The identity of plants in the diet of this insect was determined by comparing the sequences generated with those available in the GenBank database and cross-checking the results with a database of plants known to be present in New Zealand. A total of 47 plant families and 79 genera were detected. Of the genera identified, Vitis, Poa, Festuca, Anthoxanthum, Anagallis, Camelina, Epilobium, Menyanthes, Pedicularis, Urtica, Garrya, Pinus and Tilia were the major ones (i.e. they were present in more than 50% of the faecal samples). The composition of the above plant taxa in faecal materials was significantly different between collection sites or dates, except for Menyanthes. The occurrence of the latter was significantly different between collection sites. These results indicate that effectively mitigating wētā damage to vines requires the use of a diverse mix of plant species for trap cropping as wētā seem to be highly generalist in their feeding behaviour even when plant diversity is relatively low.

Foraging strategies are maintained despite workforce reduction: A multidisciplinary survey on the pollen collected by a social pollinator.

The way pollinators gather resources may play a key role for buffering their population declines. Social pollinators like bumblebees could adjust their foraging after significant workforce reductions to keep provisions to the colony optimal, especially in terms of pollen diversity and quantity. To test what effects a workforce reduction causes on the foraging for pollen, commercially-acquired colonies of the bumblebee Bombus terrestris were allowed to forage in the field and they were experimentally manipulated by removing half the number of workers. For each bumblebee, the pollen pellets were taxonomically identified with DNA metabarcoding of the ITS2 region followed by a statistical filtering based on ROC curves to filter out underrepresented OTUs. Video cameras and network analyses were employed to investigate changes in foraging strategies and behaviour. After filtering out the false-positives, HTS metabarcoding yielded a high plant diversity in the pollen pellets; for plant identity and pollen quantity traits no differences emerged between samples from treated and from control colonies, suggesting that plant choice was influenced mainly by external factors such as the plant phenology. The colonies responded to the removal of 50% of their workers by increasing the foraging activity of the remaining workers, while only negligible changes were found in diet breadth and indices describing the structure of the pollen transport network. Therefore, a consistency in the bumblebees’ feeding strategies emerges in the short term despite the lowered workforce.

Plant growth rate and nitrogen uptake shape rhizosphere bacterial community composition and activity in an agricultural field.

Plant-microbial interactions in the rhizosphere are an essential link in soil nitrogen (N) cycling and plant N supply. Plant phenotype and genotype interact with the soil environment to determine rhizosphere community structure and activity. However, the relative contributions of plant identity, phenology and soil resource availability in shaping rhizosphere effects are not well understood. Four summer annuals and a collection of maize hybrids were grown in a common garden experiment conducted at two levels of organic nutrient availability. Plant biomass, N accumulation, rhizosphere bacterial community composition, and rhizosphere potential extracellular enzyme activity were assessed at vegetative, flowering and grain-filling stages of maize. Plant N uptake was strongly coupled with protease activity in the rhizosphere. Temporal trends in rhizosphere community composition varied between plant species. Changes in rhizosphere community composition could be explained by variation in plant growth dynamics. These findings indicate that species-level variation in plant growth dynamics and resource acquisition drive variation in rhizosphere bacterial community composition and activity linked to plant N uptake.

Multiple trade-offs regulate the effects of woody plant removal on biodiversity and ecosystem functions in global rangelands.

Woody plant encroachment is a major land management issue. Woody removal often aims to restore the original grassy ecosystem, but few studies have assessed the role of woody removal on ecosystem functions and biodiversity at global scales. We collected data from 140 global studies and evaluated how different woody plant removal methods affected biodiversity (plant and animal diversity) and ecosystem functions (plant production, hydrological function, soil carbon) across global rangelands. Our results indicate that the impact of removal is strongly context dependent, varying with the specific response variable, removal method, and traits of the target species. Over all treatments, woody plant removal increased grass biomass and total groundstorey diversity. Physical and chemical removal methods increased grass biomass and total groundstorey biomass (i.e., non-woody plants, including grass biomass), but burning reduced animal diversity. The impact of different treatment methods declined with time since removal, particularly for total groundstorey biomass. Removing pyramid-shaped woody plants increased total groundstorey biomass and hydrological function but reduced total groundstorey diversity. Environmental context (e.g., aridity and soil texture) indirectly controlled the effect of removal on biomass and biodiversity by influencing plant traits such as plant shape, allelopathic, or roots types. Our study demonstrates that a one-size-fits-all approach to woody plant removal is not appropriate, and that consideration of woody plant identity, removal method, and environmental context is critical for optimizing removal outcomes. Applying this knowledge is fundamental for maintaining diverse and functional rangeland ecosystems as we move toward a drier and more variable climate.

Plant-plant competition influences temporal dynamism of soil microbial enzyme activity

Root-derived compounds can change rates of soil organic matter decomposition (rhizosphere priming effects) through microbial production of extracellular enzymes. Such soil priming can be affected by plant identity and soil nutrient status. However, the effect of plant-plant competition on the temporal dynamics of soil organic matter turnover processes is not well understood. This study used zymography to detect the spatial and temporal pattern of cellulase and leucine aminopeptidase activity, two enzyme classes involved in soil organic matter turnover. The effect of plant-plant competition on enzyme activity was examined using barley (Hordeum vulgare) plants grown in i) isolation, ii) intra- and iii) inter-cultivar competition. The enzyme activities of leucine aminopeptidase and cellulase were measured from portions of the root system at 18, 25 and 33 days after planting, both along the root axis and in the root associated area with detectable enzyme activity. The activities of cellulase and leucine aminopeptidase were both strongly associated with plant roots, and increased over time. An increase in the area of cellulase activity around roots was delayed when plants were in competition compared to in isolation. A similar response was found for leucine aminopeptidase activity, but only when in intra-cultivar competition, and not when in inter-cultivar competition. Therefore, plant-plant competition had a differential effect on enzyme classes, which was potentially mediated through root exudate composition. This study demonstrates the influence of plant-plant competition on soil microbial activity and provides a potential mechanism by which temporal dynamism in plant resource capture can be mediated.

Influences of plant interspecific competition and arbuscular mycorrhizal fungi on nitrogen form preference of an invasive plant

Invasive plant species are often able to alter soils in a way that benefits their own fitness over that of native species. While interspecific competitions may drive species to acquire different forms of nitrogen (N) to avoid intensive competition, plant-mycorrhizal interactions can also influence plant nutrient acquisition. Yet, it is unclear whether a variation in N acquisition by an invasive species is driven by interspecific resource partitioning due to competition with native species or by its symbiosis with arbuscular mycorrhizal (AM) fungi. We conducted a pot experiment to examine the effects of competition and fungicide on the uptake of different N forms by Flaveria bidentis, an invasive plant having symbiotic relationships with AM fungi, and two coexisting native species, mycotrophic Bidens maximowicziana and non-mycotrophic Amaranthus retroflexus (referred to by genus hereafter), by growing them either in two-species mixtures or in monocultures. We found that the growth of Flaveria was suppressed by its association with AM fungi regardless of the presence of competing native species, but the degree of suppression was related to the native species with which Flaveria competed. When growing in monocultures, all three species showed a strong preference for NO3−-N over NH4+-N and glycine-N regardless of mycorrhizal status. However, under competition conditions, Flaveria increased 15N recovery in any form of N available (in particular NH4+-15N), depending on neighboring plant identity and AM fungi association, whereas Amaranthus specially tended to decrease NH4+-15N uptake when competing with Flaveria, suggesting a niche complementarity in the utilization of N between two species. Our findings suggested that AM fungi may have the potential to limit the invasion of Flaveria, in the short term, and that interspecific competition plays an important role in partitioning soil N acquisition between plant species.

Plant identity control on soil food web structure and C transfers under perennial bioenergy plantations

Conversion from arable cropping systems to perennial bioenergy crops is increasing across Europe to meet market energy demands, but our understanding of how this land use change is affecting below-ground diversity and C allocation remains limited. Here, we assessed the impact of conversion from arable cropland to Miscanthus and Short Rotation Coppice (SRC) willow in UK bioenergy commercial plantations on earthworm community structure and abundance. At this same location we then conducted an in-situ 13CO2 pulse-chase labelling experiment in the two bioenergy plantations to trace the fate of recently photosynthetically assimilated carbon into roots, bulk soil, soil microbial (PLFA) and earthworm communities. Results showed that land conversion from annual arable crops to both Miscanthus and SRC willow perennial bioenergy crops led to severe reductions of soil earthworm abundance and biomass. SRC willow had higher microbial biomass relative to Miscanthus, whereas Miscanthus provided a better habitat for a more functionally diverse earthworm community. Transfer of labile C compounds to soil pools was faster under Miscanthus supporting activity of bacterial grazers in the soil food chain, whereas a fungal-driven detrital decomposition processes dominated under SRC willow plantations. Taken together, these findings indicate that plant identity in land conversions have a strong influence not only on the abundance and structure of soil communities but also on which basal resources (root exudates, dead organic matter or microbial derived compounds) are preferentially consumed, and ultimately on the rates of mobilisation of these different C pools.

Plant invader alters soil food web via changes to fungal resources.

While aboveground impacts of invasive plants are well documented, their influence on soil food webs remains less understood. Previous research has revealed that bottom-up forces are widespread in soil food webs of woodlands. Thus, an invasive plant that negatively impacts the base of the food web will likely decrease primary consumers as well as their predators. We examined how a North American plant invader, garlic mustard (Alliaria petiolata), affects arthropod primary (springtails and oribatid mites) and secondary (predaceous mites) consumers of the soil food web via changes to fungal resources. We measured the abundances of plants, soil fungi, fungivores, and predators in garlic mustard-invaded and uninvaded 1-m2 plots in five Midwestern USA woodlands. We then conducted a mesocosm (0.25-m2 plots) experiment to tease apart the direct and indirect effects of garlic mustard by manipulating plant identity (garlic mustard vs. native plant), soil history (invaded vs. uninvaded), and fungicide application (fungicide vs. no fungicide). Our first study revealed that plots without garlic mustard had 2.8 and 1.4 × more fungi and fungivores, respectively. Predator densities did not differ. Fungal composition and structural equation modeling (SEM) revealed the garlic mustard effects on fungivores were correlated with fungal declines. The mesocosm experiment confirmed that the impacts were indirect, as fungicide plots harbored similar fungivore densities, whereas fungivore densities differed according to plant identity and soil history in the fungicide-free plots. Our results reveal that by altering soil fungal abundance, an invasive plant can indirectly affect primary consumers in soil food webs, but this indirect effect does not influence predators.

Plant Identity Shaped Rhizospheric Microbial Communities More Strongly Than Bacterial Bioaugmentation in Petroleum Hydrocarbon-Polluted Sediments.

Manipulating the plant-root microbiota has the potential to reduce plant stress and promote their growth and production in harsh conditions. Community composition and activity of plant-roots microbiota can be either beneficial or deleterious to plant health. Shifting this equilibrium could then strongly affect plant productivity in anthropized areas. In this study, we tested whether repeated bioaugmentation with Proteobacteria influenced plant productivity and the microbial communities associated with the rhizosphere of four plant species growing in sediments contaminated with petroleum hydrocarbons (PHCs). A mesocosm experiment was performed in randomized block design with two factors: (1) presence or absence of four plants species collected from a sedimentation basin of a former petrochemical plant, and (2) bioaugmentation or not with a bacterial consortium composed of ten isolates of Proteobacteria. Plants were grown in a greenhouse over 4 months. MiSeq amplicon sequencing, targeting the bacterial 16S rRNA gene and the fungal ITS, was used to assess microbial community structures of sediments from planted or unplanted microcosms. Our results showed that while bioaugmentation caused a significant shift in microbial communities, presence of plant and their species identity had a stronger influence on the structure of the microbiome in PHCs contaminated sediments. The outcome of this study provides knowledge on the diversity and behavior of rhizosphere microbes associated with indigenous plants following repeated bioaugmentation, underlining the importance of plant selection in order to facilitate their efficient management, in order to accelerate processes of land reclamation.

OsLUGL is involved in the regulating auxin level and OsARFs expression in rice (Oryza sativa L.)

Specification of floral organ identity is critical for floral morphology and inflorescence architecture. Floral organ identity in plants is controlled by floral homeotic A/B/C/D/E-class genes. Although multiple genes regulate floral organogenesis, our understanding of the regulatory network remains fragmentary. Here, we characterized a rice floral organ gene KAIKOUXIAO (KKX), mutation of which produces an uncharacteristic open hull, abnormal seed and semi-sterility. KKX encodes a putative LEUNIG-like (LUGL) transcriptional regulator OsLUGL. OsLUGL is preferentially expressed in young panicles and its protein can interact with OsSEU, which functions were reported as an adaptor for LEUNIG. OsLUGL-OsSEU functions together as a transcriptional co-regulatory complex to control organ identity. SEP3 (such as OsMADS8) and AP1 (such as OsMADS18) serve as the DNA-binding partner of OsLUGL-OsSEU complex. Further studies indicated that OsMADS8 and OsMADS18 could bind to the promoter of OsGH3-8. The altered expression of OsGH3-8 might cause the increased auxin level and the decreased expression of OsARFs. Overall, our results demonstrate a possible pathway whereby OsLUGL-OsSEU-OsAP1-OsSEP3 complex as a transcriptional co-regulator by targeting the promoter of OsGH3-8, then affecting auxin level, OsARFs expression and thereby influencing floral development. These findings provide a valuable insight into the molecular functions of OsLUGL in rice floral development.

Effects of Earthworms and Agricultural Plant Species on the Soil Nematode Community in a Microcosm Experiment

Both earthworms and plants may affect the soil nematode community. However, the effects of earthworms and plant species interactions on soil nematode community are poorly understood. We explored how an epigeic earthworm Eisenia fetida affects the soil nematode community in systems with three representative plants (wheat, cotton and cabbage) which were grown in pots with or without added earthworms under greenhouse conditions. Earthworm presence decreased the abundance of total nematode and all four nematode trophic groups, except for the fungivore and predator/omnivore nematodes in wheat systems, but increased the genus richness of nematode in all treatments. Due to plant identity and different root exudates, plants had significant effects on soil nematode abundance. Compared with the no plant and without earthworm treatment, wheat and cabbage had the higher stimulation of the abundance of total nematode, bacterivores and fungivores, and cotton had the higher stimulation of the abundance of fungivores and predators-omnivores; whereas earthworm presence mostly weakened the stimulation effects of plant species on soil nematode abundance which indicated earthworms had the enhanced effects in the presence of plants. The interaction affected soil nematode abundance (total nematodes, bacterivore, fungivore and omnivore-predators) and community diversity indices (diversity index H′, evenness index J′, community maturity index ∑MI, Simpson dominance index λ and nematode channel ratio NCR). Principal component analysis showed that plant species affected soil nematode community composition. Redundancy analysis indicated plant species and biomass accounted for 41.60% and 34.13% of the variation in soil nematode community structure, respectively; while earthworms explained only 6.13%. Overall, current study suggest that earthworm could inhibit nematode abundance; whereas, plants have exerted greater influences on nematode community structure than earthworm presence due to their species-specific effects on different trophic groups of nematodes.

Influence of introduced arbuscular mycorrhizal fungi and phosphorus sources on plant traits, soil properties, and rhizosphere microbial communities in organic legume-flax rotation

We identify P management strategies combining arbuscular mycorrhizal fungal (AMF) inoculation with rock phosphate or composted manure for intensive organic grain-production systems. We measured the response of plants traits and soil properties to the factorial combination of three rates of organic-approved P sources applied in rotation phase-1 of legume–flax cropping systems, and of granular AMF inoculant applied in the first, second, or both rotation phases, or not applied. Treatment combinations effects on the rhizosphere communities of AMF, fungi, and bacteria were tested by amplicon sequencing, in two pedoclimates. Inoculation had limited effects in both environments. Composted manure decreased lentil yield, but increased lentil N and P concentrations and soil P fertility on the Chernozem, while increasing pea productivity on the Luvisol. Composted manure applied in rotation phase-1 had a residual effect on flax productivity, N and P concentrations, and soil P fertility in both environments. Rock phosphate reduced soil P fertility and flax productivity on the Gray Luvisol. The β diversity of the rhizosphere communities was unaffected by treatments, while the α diversity of bacteria and AMF was altered by AMF inoculation and fertilization only in the Gray Luvisol. Correlations between microbial species and plant traits or soil properties were inconsistent, reflecting the complex relationships among microbial community, plant identity, and environmental conditions. Here, composted manure was more influential than AMF inoculation and rock phosphate. Given the influence of environmental conditions, small field trials are recommended before wide-scale adoption of their use.

Leaf inputs from invasive and native plants drive differential mosquito abundances

Ecological impacts of invasive alien species can be unpredictable and simultaneously span multiple habitat types and taxonomic groups. Invasive alien plants can have particularly severe impacts, and plant inputs into aquatic environments can profoundly alter community composition of invertebrates, such as mosquitoes. Here, we examine larval mosquito colonisation of aquatic containers treated with leaves from four different terrestrial plants: the invasive tickberry Lantana camara, invasive guava Psidium guajava, native sycamore fig Ficus sycomorus and native silver cluster-leaf Terminalia sericea. Larval mosquito abundances differed significantly accordingly to leaf treatment, whilst no mosquitoes colonised leaf-free controls. Leaf litter from the invasive L. camara, invasive P. guajava and native F. sycomorus drove significant increases in mosquito abundances relative to native T. sericea. We demonstrate the importance of plant identity for larval mosquito proliferations in aquatic habitats, with changes in plant community composition following terrestrial plant invasions potentially resulting in increased mosquito abundances. In turn, this may have implications for the vectoring of mosquito-borne disease.

Bacterial communities differ between plant species and soil type, and differentially influence seedling establishment on serpentine soils

Root-associated microbial communities influence plant phenotype, growth and local abundance, yet the factors that structure these microbial communities are still poorly understood. California landscapes contain serpentine soils, which are nutrient-poor and high in heavy metals, and distinct from neighboring soils making them ideal for studying the factors that structure root microbiomes and their functions. Here, we surveyed the rhizoplane of serpentine-indifferent plants, which grow on and off serpentine soil, to determine the relative influence of plant identity and soil chemistry on rhizoplane microbial community structure using 16S rRNA metabarcoding. Additionally, we experimentally examined if serpentine vs. non-serpentine microorganisms differentially affected plant growth in serpentine soil. Rhizoplane bacterial communities differed among plant species, soil types, and the interaction between them in both the field and experimental soils. In the experiment, soil microbial community source influenced seedling survival, but plant growth phenotypes were largely invariant to microbial community with a few exceptions. Rhizosplane bacterial species composition differed between plant species and soil types, and Amplicon Sequence Variants (ASVs) from the phyla Acidobacteria and Proteobacteria (Genus: Microvirga) were characteristic of serpentine soils. While soil microbial community composition influenced seedling survival in the current study, further study is required to disentangle the role of microbial associations and plant tolerance to serpentine.

Projecting consequences of global warming for the functional diversity of fleshy‐fruited plants and frugivorous birds along a tropical elevational gradient

AbstractAimSpecies in ecological communities are linked by biotic interactions. It is therefore important to simultaneously study the impacts of global warming on interdependent taxa from different trophic levels. Here, we quantify current and potential future associations of functional diversity (based on multiple traits) and functional identity (based on individual traits) between interacting taxa using projection models under climate change.LocationA tropical elevational gradient (500–3,500 m a.s.l.) in the Manú biosphere reserve, south‐east Peru.MethodsWe investigated different scenarios of how species' elevational ranges might change under climate change based on projected future increases in mean annual temperature and current associations of species' elevational ranges with temperature. We computed the functional diversity and identity of current and potential future plant and bird communities based on morphological traits that have been shown to be important for plant–frugivore interactions. Finally, we tested for changes in the associations between projected functional diversity and identity of future plant and bird communities.ResultsProjected functional diversity of plants and birds decreased under range contraction and range shift scenarios at low elevations. At mid‐ and high elevations, functional diversity of both species groups increased most strongly under range expansion. Correspondence between plant and bird functional diversity was weakest under range contraction, while it remained strong under range expansion and shift. Similarly, the correspondence of projected plant and bird functional identity was weakest under a range contraction scenario.Main conclusionsOur findings suggest that a scenario in which species are dispersal‐limited and sensitive to increasing temperatures is likely to cause a functional mismatch between plant and bird communities along this tropical elevational gradient. This implies that certain functional types of plants could miss avian seed dispersers in the future. Our approach of studying functional diversity of interacting taxa could be more widely applied to identify potential future mismatches between trophic levels.

Interspecific variation in crop and weed responses to arbuscular mycorrhizal fungal community highlights opportunities for weed biocontrol

New, non-chemical weed suppression methods are needed to support multi-tactic integrated weed management (IWM) programs that reduce reliance on herbicides. One such approach is to manage arbuscular mycorrhizal (AM) fungal communities to enhance their weed biocontrol. Successful implementation will require a better understanding of AM fungi-crop-weed relationships under field conditions, especially in the face of soil disturbances imposed by agricultural practices. We examined root AM fungal communities of four weed species and one model crop species (i.e., corn) in a field experiment with contrasting tillage and cover cropping treatments in Illinois, USA. Our objectives were to quantify the impact of AM fungi on the growth of corn and weed species, to assess influences of plant species, tillage, and cover cropping on AM fungal community structure, and to characterize the co-occurrence patterns of AM fungal taxa in weed and corn roots. Our results showed that effects of AM fungal taxa on corn and weed growth varied widely depending on plant species, and several AM fungal taxa had species-specific negative effects on weeds but not on corn. In addition, plant identity was the primary factor affecting root AM fungal community structure and co-occurrence patterns, whereas effects of tillage and cover cropping were relatively limited. We propose that AM fungal taxa that have selectively suppressive effects on weeds but not on corn are candidates for developing new strategies for weed biocontrol as part of IWM. Future approaches to weed management based on direct inoculation with AM fungal taxa or manipulation of AM fungal communities through specific management practices, are promising opportunities to increase the density of weed-suppressive AM fungal taxa in agroecosystems, and our methods provide important insights for AM fungal taxa selection.

Altitudinal gradients fail to predict fungal symbiont responses to warming.

Climate change is shifting altitudinal species ranges, with potential to disrupt species interactions. Altitudinal gradient studies and warming experiments can both increase understanding of climate effects on species interactions, but few studies have used both together to improve predictions. We examined whether plant-fungal symbioses responded similarly to altitude and 23yr of experimental warming. Root- and leaf-associated fungi, which can mediate plants' climate sensitivity, responded divergently to elevation vs. warming. Fungal colonization, diversity, and composition varied with altitude, but climate variables were generally weak predictors; other factors such as host plant identity, plant community composition, or edaphic variables likely drive fungal altitudinal distributions. Manipulated warming altered fungal colonization, but not composition or diversity. Leaf symbionts were more sensitive to climate and experimental warming than root symbionts. Altitudinal patterns and responses to warming differed among host plant species and fungal groups, indicating that predicting climate effects on symbioses will require tracking both host and symbiont identities. Combining experimental and observational methods can yield valuable insight into how climate change may alter plant-symbiont interactions, but our results indicate that altitude does not always serve as an adequate proxy for warming effects on fungal symbionts of plants.

Phyllosphere epiphytic and endophytic fungal community and network structures differ in a tropical mangrove ecosystem

BackgroundRevealing the relationship between plants and fungi is very important in understanding biodiversity maintenance, community stability, and ecosystem functioning. However, differences in the community and network structures of phyllosphere epiphytic and endophytic fungi are currently poorly documented. In this study, we examined epiphytic and endophytic fungal communities associated with the leaves of six mangrove species using Illumina MiSeq sequencing of internal transcribed spacer 2 (ITS2) sequences.ResultsA total of 635 operational taxonomic units (OTUs) of endophytic and epiphytic fungi were obtained at a 97% sequence similarity level; they were dominated by Dothideomycetes and Tremellomycetes. Plant identity had a significant effect on the OTU richness of endophytic fungi, but not on epiphytic fungi. The community composition of epiphytic and endophytic fungi was significantly different, and plant identity had a greater effect on endophytic fungi than on epiphytic fungi. Network analysis showed that both epiphytic and endophytic network structures were characterized by significantly highly specialized and modular but lowly connected and anti-nested properties. Furthermore, the endophytic network had higher levels of specialization and modularity but lower connectance and stronger anti-nestedness than the epiphytic network.ConclusionsThis study reveals that the phyllosphere epiphytic and endophytic fungal communities differ, and plant identity has a greater effect on the endophytic fungi than on epiphytic fungi. These findings demonstrate the role of host plant identity in driving phyllosphere epiphytic and endophytic community structure.

Role of Grazing Intensity on Shaping Arbuscular Mycorrhizal Fungi Communities in Patagonian Semiarid Steppes

Arbuscular mycorrhizal fungi (AMF) are vital for maintaining ecosystem structure and functioning and can be affected by complex interactions between plants and herbivores. Information found in the literature about how ungulate grazing affects AMF is in general contradictory but might be caused by differences in grazing intensities (GIs) among studies. Hence we studied how different GIs affect the composition, diversity, and abundance of AMF communities in a semiarid steppe of Patagonia. We predicted that 1) total AMF spore abundance (TSA) and diversity would decrease only under intense-grazing levels and 2) AMF species spore abundance would depend on their life-history strategies and on the GI. To test our predictions, we compared AMF communities among nongrazed (NG), moderately grazed (MG, 0.1–0.3 sheep ha1), and intensely grazed sites (IG, > 0.3 sheep ha1). GI was the most important factor driving changes in TSA and diversity, regardless of host plant identity. TSA, diversity, and evenness significantly decreased in IG sites but were not affected by MG. AMF species spore abundance varied depending on their life-history strategies and GI. Families with high growth rates like Glomeraceae and probably Pacisporaceae showed the highest spore abundance in all sites but decreased under IG. Species with higher carbon demands like Gigasporaceae showed low spore abundance and frequency in NG and MG sites and were absent in IG sites. In contrast, species with low growth rates, but efficient carbon usage, like Acaulosporaceae, showed low spore abundance in all sites but increased in IG sites compared with NG or MG sites. We conclude that intensification of grazing reduces AMF diversity and abundance, with the likely loss of AMF benefits for plants, such as improved nutrient and water uptake and soil aggregation. Therefore, sustainable grazing systems should be designed to improve or restore AMF communities, particularly in degraded rangelands, like the Patagonian steppes.