Phyllosphere Fungal Communities Research Articles

Foraging ants affect community composition and diversity of phyllosphere fungi on a myrmecophilous plants, Mallotus japonicus.

Many microorganisms inhabit the aboveground parts of plants (i.e. the phyllosphere), which mainly comprise leaves. Understanding the structure of phyllosphere microbial communities and their drivers is important because they influence host plant fitness and ecosystem functions. Despite the high prevalence of ant-plant associations, few studies have used quantitative community data to investigate the effects of ants on phyllosphere microbial communities. In the present study, we investigated the effects of ants on the phyllosphere fungal communities of Mallotus japonicus using high-throughput sequencing. Mallotus japonicus is a myrmecophilous plants that bears extrafloral nectaries, attracting several ant species, but does not provide specific ant species with nest sites like myrmecophytes do. We experimentally excluded ants with sticky resins from the target plants and collected leaf discs to extract fungal DNA. The ribosomal DNA internal transcribed spacer 1 (ITS1) regions of the phyllosphere fungi were amplified and sequenced to obtain fungal community data. Our results showed that the exclusion of ants changed the phyllosphere fungal community composition; however, the effect of ants on OTU richness was not clear. These results indicate that ants can change the community of phyllosphere fungi, even if the plant is not a myrmecophyte.

Mutualistic and antagonistic phyllosphere fungi contribute to plant recruitment in natural communities

Abstract Phyllosphere fungal communities participate in multiple ecological functions (litter decomposition, disease‐causing, plant defence). However, there is a lack of knowledge on whether and how these functions contribute to plant community dynamics under natural conditions. One of the aspects of plant dynamics in which these fungi can most clearly affect is recruitment, since the success of newly germinated plants can be seriously compromised by pathogenic activity or the absence of mutualistic interactions. To determine the relationship between phyllosphere fungal communities and plant recruitment, we combined published information on the frequency of plant–plant recruitment interactions and phyllosphere fungal communities in 38 woody species from two mixed forests in southern Spain. Our results indicate that phyllosphere pathogens and saprotrophs have a negative effect on canopy–recruit interactions, while epiphytic fungi have a positive effect. Additionally, the presence of canopy species hosting high richness of epiphytes or counting with a high diversity of saprotrophic fungi favours the formation of an abundant sapling bank. Synthesis. Our results suggest that phyllosphere fungi play a relevant role in the assembly of the sapling bank in forest communities, thus, potentially influencing plant community dynamics. Beyond the well‐known negative effect of pathogenic fungi on recruitment, our results show the mutualistic effect of fungal epiphytes and a dual role of saprotrophs as antagonistic, decreasing recruitment of certain species, or mutualistic, enhancing recruitment in the sapling bank.

Nitrogen fertilization modulates rice phyllosphere functional genes and pathogens through fungal communities

The phyllosphere is a vital yet often neglected habitat hosting diverse microorganisms with various functions. However, studies regarding how the composition and functions of the phyllosphere microbiome respond to agricultural practices, like nitrogen fertilization, are limited. This study investigated the effects of long-term nitrogen fertilization with different levels (CK, N90, N210, N330) on the functional genes and pathogens of the rice phyllosphere microbiome. Results showed that the relative abundance of many microbial functional genes in the rice phyllosphere was significantly affected by nitrogen fertilization, especially those involved in C fixation and denitrification genes. Different nitrogen fertilization levels have greater effects on fungal communities than bacteria communities in the rice phyllosphere, and network analysis and structural equation models further elucidate that fungal communities not only changed bacterial-fungal inter-kingdom interactions in the phyllosphere but also contributed to the variation of biogeochemical cycle potential. Besides, the moderate nitrogen fertilization level (N210) was associated with an enrichment of beneficial microbes in the phyllosphere, while also resulting in the lowest abundance of pathogenic fungi (1.14 %). In contrast, the highest abundance of pathogenic fungi (1.64 %) was observed in the highest nitrogen fertilization level (N330). This enrichment of pathogen due to high nitrogen level was also regulated by the fungal communities, as revealed through SEM analysis. Together, we demonstrated that the phyllosphere fungal communities were more sensitive to the nitrogen fertilization levels and played a crucial role in influencing phyllosphere functional profiles including element cycling potential and pathogen abundance. This study expands our knowledge regarding the role of phyllosphere fungal communities in modulating the element cycling and plant health in sustainable agriculture.

Insights on the fungal communities associated with needle reddening of the endangered Abies nebrodensis

AbstractAbies nebrodensis is a species of fir endemic to Sicily, represented by only 30 trees in the natural population and is currently classified as critically endangered by IUCN. In such context, monitoring its health status is essential for the proper management and preservation of this species. Phytosanitary surveys of trees of the natural population of A. nebrodensis and on potted plants raised in the local forest nursery were carried out, and the phyllosphere fungal community was investigated. The health condition of trees in the natural population were fairly good, with needle reddening and blight as the most frequently observed symptoms on the foliage, while in the nursery similar disorders were registered on about the 1.3% of potted plants. Results on fungal isolations highlighted the presence of species belonging to Valsa, Cytospora (which includes anamorphs of Valsa) and Rhizosphaera genera as the most represented on both reddened and green needles; these results suggest that these fungi likely live as endophytes, resuming their growth when needles are affected by environmental stressors such as wind, hail, mechanical wounds and do not represent a biotic constraint for A. nebrodensis. The disorders observed appear mostly as a consequence of the harsh site in which the relic species lives. Together with the fungal community observed on symptomatic and healthy needles, they indicate that A. nebrodensis adapted and tolerates its altered habitat.

Host Identity Determines the Bacterial and Fungal Community and Network Structures in the Phyllosphere of Plant Species in a Temperate Steppe

Elucidating the plant−microbiome network is of importance in understanding species coexistence in natural ecosystems. The phyllosphere, which is the aerial parts of terrestrial plants, is inhabited by diverse microbes. However, few studies have focused on the phyllosphere microbiome and plant-microbiome network in temperate grasslands. In this study, we explored the diversity, community structure, and network architecture of phyllosphere bacteria and fungi in 19 plant species native to the temperate grassland in Inner Mongolia, China. We obtained 3,313 and 758 phyllosphere bacterial and fungal operational taxonomic units, respectively, and found that the bacterial community was dominated by Proteobacteria, Actinobacteriota, and Firmicutes, whereas the fungal community was dominated by Ascomycota and Basidiomycota. Plant identity exerted significant impacts on α-diversities of both bacterial and fungal communities. The composition of bacterial and fungal communities differed among plant species. Plant identity had a greater effect on fungal than bacterial communities. Both bacterial and fungal network structures were characterized by specialized, modular, lowly connected, and no nested properties. The plant−fungal network had a high level of specification, modularity, antinestedness, and connectance compared with the plant−bacterial network. Our results suggest more intimate relationships between plants and phyllosphere fungi than between plants and phyllosphere bacteria and also that the phyllosphere fungal community in the temperate grassland ecosystem is more resistant to environmental disturbance than the phyllosphere bacterial community. These findings may contribute to our understanding of the mechanisms by which species coexist and communities stabilize in grassland ecosystems.

Microbial biomarkers of tree water status for next-generation biomonitoring of forest ecosystems.

Next-generation biomonitoring proposes to combine machine-learning algorithms with environmental DNA data to automate the monitoring of the Earth's major ecosystems. In the present study, we searched for molecular biomarkers of tree water status to develop next-generation biomonitoring of forest ecosystems. Because phyllosphere microbial communities respond to both tree physiology and climate change, we investigated whether environmental DNA data from tree phyllosphere could be used as molecular biomarkers of tree water status in forest ecosystems. Using an amplicon sequencing approach, we analysed phyllosphere microbial communities of four tree species (Quercus ilex, Quercus robur, Pinus pinaster and Betula pendula) in a forest experiment composed of irrigated and non-irrigated plots. We used these microbial community data to train a machine-learning algorithm (Random Forest) to classify irrigated and non-irrigated trees. The Random Forest algorithm detected tree water status from phyllosphere microbial community composition with more than 90% accuracy for oak species, and more than 75% for pine and birch. Phyllosphere fungal communities were more informative than phyllosphere bacterial communities in all tree species. Seven fungal amplicon sequence variants were identified as candidates for the development of molecular biomarkers of water status in oak trees. Altogether, our results show that microbial community data from tree phyllosphere provides information on tree water status in forest ecosystems and could be included in next-generation biomonitoring programmes that would use in situ, real-time sequencing of environmental DNA to help monitor the health of European temperate forest ecosystems.

The Changes of Phyllosphere Fungal Communities among Three Different Populus spp.

As an ecological index for plants, the diversity and structure of phyllosphere microbial communities play a crucial role in maintaining ecosystem stability and balance; they can affect plant biogeography and ecosystem function by influencing host fitness and function. The phyllosphere microbial communities reflect the immigration, survival, and growth of microbial colonists, which are influenced by various environmental factors and leaves' physical and chemical properties. This study investigated the structure and diversity of phyllosphere fungal communities in three different Populus spp., namely-P. × euramaricana (BF3), P. nigra (N46), and P. alba × P. glandulosa (84K). Leaves' chemical properties were also analyzed to identify the dominant factors affecting the phyllosphere fungal communities. N46 exhibited the highest contents of total nitrogen (Nt), total phosphorus (Pt), soluble sugar, and starch. Additionally, there were significant variations in the abundance, diversity, and composition of phyllosphere fungal communities among the three species: N46 had the highest Chao1 index and observed_species, while 84K had the highest Pielou_e index and Simpson index. Ascomycota and Basidiomycota are the dominant fungal communities at the phylum level. Results from typical correlation analyses indicate that the chemical properties of leaves, especially total phosphorus (Pt), total nitrogen (Nt), and starch content, significantly impact the structure and diversity of the phyllosphere microbial community. However, it is worth noting that even under the same stand conditions, plants from different species have distinct leaf characteristics, proving that the identity of the host species is the critical factor affecting the structure of the phyllosphere fungal community.

Leaf traits and temperature shape the elevational patterns of phyllosphere microbiome

AbstractAimThe phyllosphere microbiome is central to plant health, distribution, and ecosystem function, yet, we lack a clear understanding of the drivers shaping their diversity in mountain ranges. Here, we examined how the endo‐ and epiphytic phyllosphere microbiomes of mountains simultaneously respond to climate and leaf functional traits.LocationTemperate forests of Changbai Mountain Natural Reserve, China.MethodsWe collected the leaves of dominant tree species along seven elevations from 800 to 1950. We investigated changes in species richness and Shannon diversity of endo‐ and epiphytic phyllosphere fungal and bacterial communities (using next‐generation sequencing of ITS2 and 16S) along an 1150 m elevational gradient. We also examined the direct and indirect effects of climate (mean annual temperature; MAT) and 13 leaf morphological and chemical traits on the microbiome of the phyllosphere.ResultsPhyllosphere microbiome declined monotonically with increasing elevation, contrasting with the hump‐shaped biodiversity patterns that are commonly reported. We observed a steeper decline in epiphytic bacterial diversity than in endophytic bacteria, whereas conversely endophytic fungi diversity declined more dramatically with increasing elevation than epiphytic fungi. Host plant traits – those involved in resource uptake and leaf surface temperature – predominantly shaped the elevational patterns of endophytic phyllosphere microbiome, whereas MAT mostly increased the richness and Shannon diversity of epiphytic organisms. We also observed weak, but significant indirect effects suggesting that host plant traits are important biotic drivers mediating climate effects on endophytic phyllosphere microbiome. Also, no covariation between bacteria and fungi was observed (neither for endophytic nor for epiphytic organisms), supporting neutral associations between bacterial and fungal communities, irrespective of the elevation.Main ConclusionsBoth direct and mediating effects of plant traits should be considered to better understand the drivers shaping the richness and Shannon diversity of endo‐ and epiphytic phyllosphere microbiomes, and more generally the plant–microbe associations. Our study also offers a trait‐based attempt to disentangle the effects of biotic and abiotic filters in shaping endo‐ and epiphytic phyllosphere microbiome along an elevational gradient.

Effects of maize resistance and leaf chemical substances on the structure of phyllosphere fungal communities.

It is well known that plant genotype can regulate phyllosphere fungi at the species level. However, little is known about how plant varieties shape the fungal communities in the phyllosphere. In this study, four types of maize varieties with various levels of resistances to Exserohilum turcicum were subjected to high-throughput sequencing to reveal the properties that influences the composition of phyllosphere fungal communities. The dominant fungi genera for all four maize varieties were Alternaria at different relative abundances, followed by Nigrospora. Hierarchical clustering analysis, non-metric multidimensional scaling and similarity analysis confirmed that the fungal communities in the phyllosphere of the four varieties were significantly different and clustered into the respective maize variety they inhabited. The findings from Redundancy Analysis (RDA) indicated that both maize resistance and leaf chemical constituents, including nitrogen, phosphorus, tannins, and flavonoids, were the major drivers in determining the composition of phyllosphere fungal communities. Among these factors, maize resistance was found to be the most influential, followed by phosphorus. The co-occurrence network of the fungal communities in the phyllosphere of highly resistant variety had higher complexity, integrity and stability compared to others maize varieties. In a conclusion, maize variety resistance and leaf chemical constituents play a major role in shaping the phyllosphere fungal community. The work proposes a link between the assembled fungal communities within the phyllosphere with maize variety that is resistant to pathogenic fungi infection.

Boxwood phyllosphere fungal and bacterial communities and their differential responses to film-forming anti-desiccants

BackgroundAnti-desiccant is a class of agrochemicals widely used to protect plants from water stresses, rapid temperature variations, heat and sunburn, frost and freeze damages, transplant shock, and pathogen and pest attack. Although anti-desiccants are generally considered non-toxic to organisms, it is unclear whether they may impact the phyllosphere microbial communities. In this study, three film-forming anti-desiccant products, TransFilm, Vapor Gard, and Wilt-Pruf were applied to the canopy of two boxwood cultivars ‘Vardar Valley’ and ‘Justin Brouwers’ on April 13 and August 26, 2021. Shoot samples were collected from boxwood plants treated with each of the three products, as well as nontreated control on June 16, August 26 (before the second treatment), and October 18. Microbial and plant genomic DNA was isolated together and 16S rRNA gene and the extended internal transcribed spacer regions were amplified with PCR and sequenced on a Nanopore MinION platform for bacterial and fungal identification.ResultsBacterial communities were more diverse than fungal communities. At the phylum level, the boxwood phyllosphere was dominated by Proteobacteria and Ascomycota; at the genus level, Methylobacterium and Shiraia were the most abundant bacteria and fungi, respectively. Among the three film-forming anti-desiccants, Vapor Gard and Wilt-Pruf had more impact than TransFilm on the microbial communities. Specifically, broader impacts were observed on fungal than bacterial community composition and structure, with most affected fungi being suppressed while bacteria promoted.ConclusionThis study addressed several major knowledge gaps regarding boxwood phyllosphere microbiota and the impact of anti-desiccants on plant microbiome. We identified diverse microbial communities of boxwood, a major evergreen woody crop and an iconic landscape plant. We also found differential effects of three film-forming anti-desiccants on the composition and structure of bacterial and fungal communities. These findings advanced our understanding of the associated microbiome of this landmark plant, enabling growers to fully utilize the potentials of microbiome and three anti-desiccants in improving boxwood health and productivity.

Urban greenspace types influence the microbial community assembly and antibiotic resistome more in the phyllosphere than in the soil

Urban greenspace (UGS) is recognized to confer significant societal benefits, but few studies explored the microbial communities and antibiotic resistance genes (ARGs) from different urban greenspace types. Here, we collected leaf and soil samples from forest, greenbelt, and parkland to analyze microbial community assembly and ARG profile. For phyllosphere fungal community, the α-diversity was higher in forest, compared to those in greenbelt and parkland. Moreover, urban greenspace types altered the community assembly. Stochastic processes had a greater effect on phyllosphere fungal community in greenbelt and parkland, while in forest they were dominated by deterministic processes. In contrast, no significant differences in bacterial community diversity, community assembly were observed between the samples collected from different urban greenspace types. A total of 153 ARGs and mobile genetic elements (MGEs) were detected in phyllosphere and soil with resistance to the majority classes of antibiotics commonly applied to humans and animals. Structural equation model further revealed that a direct association between greenspace type and ARGs in the phyllosphere even after considering the effects of all other factors simultaneously. Our findings provide new insights into the microbial communities and antibiotic resistome of urban greenspaces and the potential risk linked with human health.

Community assembly and network structure of epiphytic and endophytic phyllosphere fungi in a subtropical mangrove ecosystem.

Microorganisms can influence plant growth and health, ecosystem functioning, and stability. Community and network structures of mangrove phyllosphere fungi have rarely been studied although mangroves have very important ecological and economical values. Here, we used high throughput sequencing of the internal transcribed spacer 2 (ITS2) to assess epiphytic and endophytic phyllosphere fungal communities of six true mangrove species and five mangrove associates. Totally, we obtained 1,391 fungal operational taxonomic units (OTUs), including 596 specific epiphytic fungi, 600 specific endophytic fungi, and 195 shared fungi. The richness and community composition differed significantly for epiphytes and endophytes. Phylogeny of the host plant had a significant constraint on epiphytes but not endophytes. Network analyses showed that plant-epiphyte and plant-endophyte networks exhibited strong specialization and modularity but low connectance and anti-nestedness. Compared to plant-endophyte network, plant-epiphyte network showed stronger specialization, modularity, and robustness but lower connectance and anti-nestedness. These differences in community and network structures of epiphytes and endophytes may be caused by spatial niche partitioning, indicating their underlying ecological and environmental drivers are inconsistent. We highlight the important role of plant phylogeny in the assembly of epiphytic but not endophytic fungal communities in mangrove ecosystems.

Metabolite-Mediated Responses of Phyllosphere Microbiota to Rust Infection in Two Malus Species.

Plants recruit beneficial microbes to enhance their ability to fight pathogens. However, the current understanding of microbial recruitment is largely limited to belowground systems (root exudates and the rhizosphere). It remains unclear whether the changes in leaf metabolites induced by infectious pathogens can actively recruit beneficial microbes to mitigate the growth of foliar pathogens. In this study, we integrated microbiome and metabolomic analyses to systematically explore the dynamics of phyllosphere fungal and bacterial communities and key leaf metabolites in two crabapple species (Malus sp. "Flame" and Malus sp. "Kelsey") at six stages following infection with Gymnosporangium yamadae. Our results showed that the phyllosphere microbiome changed during lesion expansion, as highlighted by a reduction in bacterial alpha-diversity and an increase in fungal alpha-diversity; a decreasing and then an increasing complexity of the microbial co-occurrence network was observed in Kelsey and a decreasing complexity occurred in Flame. In addition, nucleotide sugars, diarylheptanoids, and carboxylic acids with aromatic rings were more abundant in early stages of collection, which positively regulated the abundance of bacterial orders Pseudomonadales (in Kelsey), Acidimicrobiales, Bacillales, and Flavobacteriales (in Flame). In addition, metabolites such as flavonoids, lignin precursors, terpenoids, coumarins, and quaternary ammonium salts enriched with the expansion of lesions had a positive regulatory effect on fungal families Rhynchogastremataceae and Golubeviaceae (in Flame) and the bacterial order Actinomycetales (in Kelsey). Our findings highlight that plants may also influence phyllosphere microorganisms by adjusting leaf metabolites in response to biotic stress. IMPORTANCE Our findings demonstrate the response patterns of bacterial and fungal communities in the Malus phyllosphere to rust fungus G. yamadae infection, and they also reveal how the phyllosphere microbiome changes with the expansion of lesions. We identified several metabolites whose relative abundance varied significantly with lesion expansion. Using a framework for assessing the role of leaf metabolites in shaping the phyllosphere microbiome of the two Malus species, we identified several specific metabolites that have profoundly selective effects on the microbial community. In conclusion, our study provides new evidence of the ecological niche of the phyllosphere in supporting the "cry for help" strategy for plants.

Different patterns and drivers of fungal communities between phyllosphere and rhizosphere in alpine grasslands

Abstract Epiphytic fungi are vital in enhancing their host plant performance and can also cause plant diseases. Generally, phyllosphere fungal community are majorly driven by climate, while rhizosphere fungal community are determined by soil properties and spatial distance. However, the differences in the relative effects of environmental factors on fungal community compositions and network structures remain far from clear between phyllosphere and rhizosphere. In this study, we conducted a large‐scale field survey along a 1400 km transect in the Tibetan Plateau and explored the composition and structure of phyllosphere and rhizosphere fungal communities from two dominant grass species (Leontopodium nanum and Stipa purpurea). L. nanum is widely distributed in relatively wet areas of alpine grasslands but S. purpurea prefers relatively dry areas. The geographical distributions of these two species overlap in the middle of the transect First, we found that precipitation was more important than temperature to affect fungal alpha diversity. High precipitation significantly promoted fungal alpha diversity in both phyllosphere and rhizosphere. Second, climate and spatial variables explained more variations in fungal community in the phyllosphere than rhizosphere. Specifically, greater precipitation promoted the relative abundances of pathotrophic fungi in the phyllosphere and rhizosphere, whereas lower precipitation only stimulated the relative abundances of symbiotrophic fungi in the rhizosphere. Third, precipitation had different impacts on phyllosphere and rhizosphere fungal networks between host species. Drought caused lower node number of fungal networks in the phyllosphere and rhizosphere of L. nanum. However, for S. purpurea, drought led to more complex and positive fungal networks in the phyllosphere and rhizosphere. Overall, these results indicated that precipitation caused different fungal community compositions along the transect between phyllosphere and rhizosphere, but consistently shaped their fungal networks. This study is among the first to provide compelling evidence on the large‐scale spatial variations and controlling factors for epiphytic fungal community in alpine grasslands. These new findings help to understand the role of epiphytic fungal community in affecting the functions of alpine grasses to cope with extreme environments. Read the free Plain Language Summary for this article on the Journal blog.

Elevated O3 concentrations alter the compartment-specific microbial communities inhabiting rust-infected poplars.

Elevated ozone (O3 ) can affect the susceptivity of plants to rust pathogens. However, the collective role of microbiomes involved in such interaction remains largely elusive. We exposed two cultivated poplar clones exhibiting differential O3 sensitivities, to non-filtered ambient air (NF), NF + 40 ppb or NF + 60 ppb O3 -enriched air in field open-top chambers and then inoculated Melampsora larici-populina urediniospores to study their response to rust infection and to investigate how microbiomes inhabiting four compartments (phyllosphere, rhizosphere, root endosphere, bulk soil) are involved in this response. We found that hosts with higher O3 sensitivity had significantly lower rust severity than hosts with lower sensitivity. Furthermore, the effect of increased O3 on the diversity and composition of microbial communities was highly dependent on poplar compartments, with the microbial network complexity patterns being completely opposite between the two clones. Notably, microbial source analysis estimated that phyllosphere fungal communities predominately derived from root endosphere and vice versa, suggesting a potential transmission mechanism between plant above- and below-ground systems. These promising results suggest that further investigations are needed to better understand the interactions of abiotic and biotic stresses on plant performance and the role of the microbiome in driving these changes.

Biotic filters driving the differentiation of decomposer, epiphytic and pathogenic phyllosphere fungi across plant species

The phyllosphere is a wide and complex ecosystem that provides a key support for microbial diversity. Fungal communities inhabiting the leaf are functionally variable and play important roles on plant performance. Factors conditioning the arrival and colonization of fungal communities will determine the phyllosphere fungal composition. Plant identity, leaf functional traits and host plant phylogeny have been shown to be regulators of the microbial colonization of the leaves, and can be considered as biotic filters determining the assembly of phyllosphere fungal communities. By high‐throughput sequencing we analysed the phyllosphere fungal communities from 38 Mediterranean woody plant species in two forests of south‐eastern Iberian Peninsula. We analysed the effect of plant species and site on fungal community composition. We also tested the effect of leaf functional traits and plant phylogeny on plant species differences in their fungal communities, and on the structure of the plant–fungus interaction network. Plant species account for a larger proportion than site in the variability of the composition of phyllosphere fungal communities. Leaf traits and host phylogeny influence the arrival and colonization of phyllosphere fungal communities across plant species. Plants with pubescent leaves and phylogenetically closer harbour more similar communities of decomposers, pathogens and epiphytes. Leaf habit (i.e. evergreen versus deciduous) also influences the community composition of decomposer and epiphytic fungi. Leaf carbon, leaf water content and leaf mass per area affect differentially each functional guild. Plant–fungus interaction networks present a modular structure in which plants belonging to the same module share more fungal species and are phylogenetically closer. We provide evidence that even though phyllosphere fungal communities are complex ecosystems, fungi with contrasting relationships with the plant (decomposers, epiphytes and pathogens) respond similarly to a common subset of leaf traits that impose physical limitations to the assembly of phyllosphere fungal communities.

Giant pandas' staple food bamboo phyllosphere fungal community and its influencing factors.

Giant pandas have developed a series of foraging strategies to adapt to their special bamboo diets. Although bamboo is an important food resource for giant pandas in Liziping National Nature Reserve (Liziping NR), China, there are relatively few studies on their phyllosphere fungal community and its influencing factors. Herein, we used ITS1 amplification and metagenomic sequencing to analyze the phyllosphere fungi diversity and functions (KEGG, CAZyme, and antibiotic resistance gene) and explore the influencing factors for the three giant pandas foraging bamboo species (Arundinaria spanostachya, AS; Yushania lineolate, YL; and Fargesia ferax, FF) over different seasons (spring vs. autumn) in Liziping NR, China. We found that Ascomycota and Basidiomycota were the most dominant phyla in the bamboo phyllosphere. The alpha diversity (e.g., the Sobs index and Shannon index) was relatively higher in autumn samples than in spring samples, and the community structure differed significantly between the three bamboo species in spring and autumn. Some biotic and abiotic variables (e.g., the elevation and mean base diameter of bamboo) significantly influenced the abundance, diversity, and community structure of the bamboo phyllosphere fungal community. Moreover, the functional analysis showed the differences in the glycoside hydrolase community and antibiotic resistance gene (ARG) profile between spring and autumn samples. Co–occurrence network modeling suggested that AS phyllosphere fungal communities in autumn employed a much more complex network than that in spring, and the abundance of multidrug, tetracycline, and glycopeptide resistance genes was high and closely correlated with other ARGs. These results indicate that fungal community’s abundance, diversity, and community structure are mainly affected by the season, host species, and elevation. The season and host species are major factors affecting the biological functions (KEGG and CAZyme), ARGs, and interactions between sympatric bacterial and fungal communities in bamboo phyllosphere. This integrated study can provide a reference basis for the seasonal management of bamboo resources foraged by wild giant pandas, and predict the risk of antibiotic resistance in bamboo phyllosphere fungal flora in Liziping NR (Xiaoxiangling mountains), China.

Drought Tolerance Traits in Neotropical Trees Correlate with the Composition of Phyllosphere Fungal Communities

Plant-associated microorganisms have been shown to aid plants in coping with drought. However, the underlying mechanisms are poorly understood and there is uncertainty regarding which microbial taxa and functions are mostly involved. We explored these issues in Neotropical rainforests and identified foliar microorganisms that may play a role in drought tolerance of trees. Our objectives were to (i) test the relationship between drought tolerance traits in Neotropical trees and the diversity and composition of their foliar fungal and bacterial communities and (ii) identify leaf microbial taxa positively or negatively associated with drought tolerance traits. Our results showed that the composition of leaf fungal communities but not bacterial communities was related to drought tolerance. We identified 27 fungal amplicon sequence variants whose relative abundance covaried with drought tolerance traits. Most variants were assigned to fungal clades often described as plant pathogens and increased in abundance with drought susceptibility. This greater relative abundance of leaf pathogens in the most drought-susceptible trees might increase their vulnerability to climate change. Moreover, we identified the Strelitziana and Ochroconis fungal genera as potential candidates for future culture-dependent studies aimed at understanding and improving drought tolerance in Neotropical forests. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Effect of ozonated water, mancozeb, and thiophanate-methyl on the phyllosphere microbial diversity of strawberry.

Phyllosphere microorganisms are closely linked to plant health. This study investigated the effect of ozonated water, mancozeb, and thiophanate-methyl on phyllosphere microorganisms in strawberry plants of the “Hongyan” variety. Sequencing analysis of the phyllosphere bacterial and fungal communities was performed using 16S rRNA gene fragment and ITS1 region high-throughput sequencing after spraying ozonated water, mancozeb, thiophanate-methyl, and clear water. Proteobacteria, Actinobacteria, and Firmicutes were the dominant bacterial phyla in strawberry. The relative abundance of Proteobacteria (82.71%) was higher in the ozonated water treatment group than in the other treatment groups, while the relative abundance of Actinobacteria (9.38%) was lower than in the other treatment groups. The strawberry phyllosphere fungal communities were mainly found in the phyla Basidiomycota and Ascomycota. The relative abundance of Basidiomycota was highest in the ozonated water treatment group (81.13%), followed by the mancozeb treatment group (76.01%), while the CK group only had an abundance of 43.38%. The relative abundance of Ascomycota was lowest in the ozonated water treatment group (17.98%), 23.12% in the mancozeb treatment group, 43.39% in the thiophanate-methyl treatment group, and 55.47% in the CK group. Pseudomonas, Halomonas, and Nesterenkonia were the dominant bacterial genera on strawberry surfaces, while Moesziomyces, Aspergillus, and Dirkmeia were the dominant fungal genera. Ozonated water was able to significantly increase the richness of bacteria and fungi and decrease fungal diversity. However, bacterial diversity was not significantly altered. Ozonated water effectively reduced the relative abundance of harmful fungi, such as Aspergillus, and Penicillium, and enriched beneficial bacteria, such as Pseudomonas and Actinomycetospora, more effectively than mancozeb and thiophanate-methyl. The results of the study show that ozonated water has potential as a biocide and may be able to replace traditional agents in the future to reduce environmental pollution.

Community structure of phyllosphere fungi associated with dominant tree species in a broad-leaved Korean pine forest of Changbai Mountain, Northeast China

Forest is the main component of terrestrial ecosystems that harbors about 40% of the existing species on the earth. As a vital component of biodiversity, phyllosphere microbes in the canopy play a critical and unique role in maintaining plant health, improving host resistance, and influencing global biogeochemical cycle. However, the studies on the community structure of phyllosphere fungi in natural forests are scarce as compared to that on rhizosphere microbes. Consequently, we know litter about how phyllosphere fungi associates with leaf traits. In this study, we analyzed fungal community composition of canopy leaves of six dominant tree species (i.e., Pinus koraiensis, Tilia amurensis, Quercus mongolica, Acer mono, Fraxinus mandshurica, and Ulmus japonica), in a broad-leaved Korean pine forest of Changbai Mountain Nature Reserve in Jilin Province, using high-throughput sequencing. We compared the differences of phyllosphere fungal community structure and functional groups of different dominant tree species. Moreover, 14 key leaf functional traits of their host trees were measured to investigate the relationships between fungal community composition and leaf functional traits. We found that the dominant phyla and class of phyllosphere fungi were Ascomycota and Basidiomycota, and Dothideomycetes and Taphrinomycetes, respectively. Results of LEfSe analysis indicated that all the tree species except Ulmus japonica had significant biomarkers, such as the Eurotiomycetes of Pinus koraiensis and the Ascomycetes of Quercus mongolica. The main functional groups of phyllosphere fungi were pathotroph. The results of redundancy and envfit analysis showed that functional traits related to plant nutrient acquisition as well as resistance to diseases and pests were the main factors influencing the community structure of phyllosphere fungi.