Parasitic Fungi Research Articles

Host genotype and infection status interact to shape microbiomes in Daphnia magna.

Host–bacterial communities (microbiomes) are influenced by a wide range of factors including host genotype and parasite exposure. However, few studies disentangle temporal and host-genotype-specific variation in microbiome response to infection across several host tissues. We experimentally exposed the freshwater crustacean Daphnia magna to its fungal parasite Metschnikowia bicuspidata and characterized changes in host–bacterial communities associated with the parasite's development within the host. We used 16S rRNA gene sequencing to assess bacterial communities of the host (a) 24 h (‘initial parasite exposure’) and (b) 10 days (‘successful infection’) after exposure to a standard dose of M. bicuspidata spores, in host guts, body tissue (excluding guts) and whole individuals. We also investigated whether bacterial community responses to parasite exposure varied by host genotype.Parasite exposure did not immediately alter host gut bacterial communities, but drove host-genotype-specific changes in the bacterial community composition of whole individuals. We validated that these changes were not driven by shifts in bacterial communities of the culturing medium, due to the addition of the parasite spore solution. Successful infection (i.e. the proliferation of M. bicuspidata spores in the host body) reduced alpha diversity and shifted abundance of dominant bacterial orders in the gut. Moreover, it induced a host-genotype-specific changes in body bacterial community composition. Overall, bacterial community responses to parasite exposure and subsequent infection are complex: they occur in a host-genotype-dependent manner, differentially at distinct timepoints after parasite exposure, and in specific host tissue.

Cordyceps Polysaccharides: A Review of Their Immunomodulatory Effects.

Cordyceps primarily consists of ascomycetes, a parasitic fungus that infects insects and arthropods. Recently, Cordyceps has been shown to manifest a diverse range of pharmacological activities, rendering it applicable for the treatment and mitigation of various diseases, such as diabetes, acute liver injury, and colitis. Many active constituents have been identified from Cordyceps sinensis, including cordycepin, adenosine, sterols, and polysaccharides. Polysaccharides constitute a primary active component of Cordyceps, exhibiting immunomodulatory effects. We searched the Web of Science database with the keywords of cordyceps, polysaccharide, and immune modulation; collected related studies from 2004 to 2024; and eliminated articles with low influence and workload. A review of the research advancements regarding the immunomodulatory effects of Cordyceps polysaccharides was conducted with the aim of furnishing valuable reference information. Research indicates that polysaccharides exhibiting immunomodulatory activity are predominantly sourced from Cordyceps sinensis and Cordyceps militaris. Immunological experimental results demonstrate that Cordyceps polysaccharides can augment the activities of macrophages, lymphocytes, and dendritic cells while fostering the expression of immune-active substances such as cytokines and chemokines. Furthermore, animal experiments have substantiated the immunomodulatory effects of Cordyceps polysaccharides. These effects encompass ameliorating immune suppression induced by drugs or radiation, enhancing immune organ indices, elevating the expression of immunoreactive substances, and mitigating immune evasion prompted by tumors. In conclusion, Cordyceps polysaccharides exhibit significant immunomodulatory activity and merit further investigation.

Chytrid fungi infecting Arctic microphytobenthic communities under varying salinity conditions

This study aimed to investigate the presence and diversity of fungal parasites in Arctic coastal microphytobenthic communities. These communities represent a key component in the functioning of Arctic trophic food webs. Fungal parasites, particularly Chytridiomycota (chytrids), play significant roles by controlling microalgal bloom events, impacting genetic diversity, modifying microbial interactions, and accelerating nutrient and energy transfer to higher trophic levels. In the context of rapid Arctic warming and increased glacier meltwater, which significantly affects these communities, we used high-throughput sequencing to explore fungal community composition. Our results show that chytrids dominate fungal communities in Arctic benthic habitats and that the overall fungal diversity is primarily influenced by the salinity gradient. Chytrid representation is positively correlated with the presence of potential benthic diatom (Surirella, Nitzschia, Navicula) and green algae (Ulvophyceae) hosts, while microscopic observations provide further evidence for the presence of active chytrid infections.

Exposure to fungal infection decreases eye size in the zooplankton, Daphnia

Abstract Immune responses can be energetically expensive and subject to trade-offs. Prior work on the freshwater zooplankton, Ceriodaphnia cornuta, demonstrated an association between eye size and infection, leading to questions about whether investment in eyes trades off against investment in immunity. We used the crustacean host, Daphnia dentifera, and its fungal parasite, Metschnikowia bicuspidata, to investigate the relationships between eye size, parasite resistance and infection. In the field, we found a negative correlation between size-corrected eye area (SCEA) and Metschnikowia infection, suggesting that either SCEA decreases infection (thereby indicating resistance) or that infection decreases SCEA. Controlled laboratory experiments reinforced the latter result: exposure to the fungal parasite decreased a host’s SCEA, regardless of the parasite dose or host genotype. We also uncovered significant plasticity in this trait—both host age and resource level increased SCEA. Identifying causality in physiological correlations is challenging. Our results suggest that negative associations between parasitism and energetically-expensive traits can arise through plasticity.

Fungal Parasite Transmission in a Planktonic Ecosystem Under Light and Nutrient Constraints.

The two main components of the planktonic ecosystem are phytoplankton and zooplankton. Fungal parasites can infect zooplankton and spread between them. In this paper, we construct a dynamic model to describe the spread of fungal parasites among zooplankton. Basic reproduction number for fungal parasite transmission among zooplankton are rigorously derived. The dynamics of this system are analyzed including dissipativity and equilibria. We further explore the effects of ecological factors on population dynamics and the relationship between fungal parasite transmission and phytoplankton blooms. Interestingly, our theoretical and numerical results indicate that a low-light or oligotrophic aquatic environment is helpful in mitigating the transmission of fungal parasites. We also show that fungal parasites on zooplankton can increase phytoplankton biomass and induce blooms.

Unveiling the Diversity and Ecological Roles of Macrofungi in Ayer Hitam Forest Reserve, Selangor, Malaysia

The biodiversity of macrofungi in remaining lowland dipterocarp forest in highly urbanization pressures is infrequently studied, even though their significant impact on the ecosystem of forested and non-forested habitats. Therefore, this research endeavours to unravel the diversity of macrofungi from different substrates in the Ayer Hitam Forest Reserve located in Selangor, Malaysia. Through a combination of field surveys, the study seeks to contribute valuable insights into the complex relationships between macrofungi and the surrounding habitats where macrofungal community structure was mainly influenced by substrate richness and microclimates. Sporocarps of macrofungi were collected from selected sites using opportunistic sampling methods. A total of 333 sporocarps were obtained and identified based on morphological and molecular analysis. Basidiomycota prevailed in the Ayer Hitam Forest Reserve where 27 species belonging to 14 families were successfully identified. Saprophytic fungi (22 species, 81.5%) dominated the areas, and a small number of mycorrhizal (1 species, 3.7%) and parasitic (4 species, 14.8%) fungi were found. Based on species diversity, order Polyporales is the highest occurrence species in the sampling areas with a Shannon-Weiner Index value of 2.103 and Simpson Index value of 0.954, Evenness Index value of 0.601, making it the most abundant order containing Microporus species, The findings are expected to enhance our knowledge of the biodiversity of macrofungi from different substrates in Ayer Hitam Forest Reserve, which can lead to conservation efforts and promote the ecological significance of macrofungi in tropical forest ecosystems.

Diversity of microbial, biocontrol agents and nematode abundance on a susceptible Prunus rootstock under a Meloidogyne root gradient infection.

Root-knot nematodes (RKNs) of the genus Meloidogyne are one of the most damaging genera to cultivated woody plants with a worldwide distribution. The knowledge of the soil and rhizosphere microbiota of almonds infested with Meloidogyne could help to establish new sustainable and efficient management strategies. However, the soil microbiota interaction in deciduous woody plants infected with RKNs is scarcely studied. This research was carried out in six commercial almond groves located in southern Spain and infested with different levels of Meloidogyne spp. within each grove. Several parameters were measured: nematode assemblages, levels and biocontrol agents in Meloidogyne's eggs, levels of specific biocontrol agents in rhizoplane and soil, levels of bacteria and fungi in rhizoplane and soil, fungal and bacterial communities by high-throughput sequencing of internal transcribed spacer (ITS), and 16S rRNA gene in soil and rhizosphere of the susceptible almond hybrid rootstock GF-677 infested with Meloidogyne spp. The studied almond groves showed soil degradation by nematode assemblies and fungi:bacterial ratio. Fungal parasites of Meloidogyne eggs were found in 56.25% of the samples. However, the percentage of parasitized eggs by fungi ranged from 1% to 8%. Three fungal species were isolated from Meloidogyne eggs, specifically Pochonia chlamydosporia, Purpureocillium lilacinum, and Trichoderma asperellum. The diversity and composition of the microbial communities were more affected by the sample type (soil vs rhizosphere) and by the geographical location of the samples than by the Meloidogyne density, which could be explained by the vigorous hybrid rootstock GF-677 and a possible dilution effect. However, the saprotrophic function in the functional guilds of the fungal ASV was increased in the highly infected roots vs the low infected roots. These results indicate that the presence of biocontrol agents in almond fields and the development of new management strategies could increase their populations to control partially RKN infection levels.

Mechanisms Underlying Ophiocordyceps Infection and Behavioral Manipulation of Ants: Unique or Ubiquitous?

Parasite manipulation of host behavior, as an effective strategy to establish transmission, has evolved multiple times across taxa, including fungi. Major strides have been made to propose molecular mechanisms that underlie manipulative parasite-host interactions including the manipulation of carpenter ant behavior by Ophiocordyceps. This research suggests that the secretion of parasite proteins and light-driven biological rhythms are likely involved in the infection and manipulation biology of Ophiocordyceps and other manipulating parasites. Here, we discuss research on Ophiocordyceps considering findings from other (fungal) parasites that either are relatively closely related (e.g., other insect- and plant-infecting Hypocreales) or also manipulate insect behavior (e.g., Entomophthorales). As such, this review aims to put forward this question: Are the mechanisms behind Ophiocordyceps manipulation and infection unique, or did they convergently evolve? From this discussion, we pose functional hypotheses about the infection biology of Ophiocordyceps that will need to be addressed in future studies.

Marine plankton community and net primary production responding to island-trapped waves in a stratified oligotrophic ecosystem

The oligotrophic Adriatic Sea is characterized during a typical summer by low productivity caused by strong water column stratification, which inhibits vertical mixing and nutrient supply to the euphotic zone. These conditions can be disrupted by transient physical forcing, which enhances nutrient fluxes and creates localized hotspots of relatively high net primary production. In this study, plankton abundance and diversity were investigated in relation to the physical forcing and nutrient concentrations in an area affected by island-trapped waves (ITWs) near Lastovo Island (Adriatic Sea). The episodic ITW events resulted in enhanced uplift and vertical excursion of the thermocline, marked by anomalously higher nutrient concentrations and a corresponding increase in net primary production in the thermocline layer. Physicochemical properties explained 11.7 % (p = 0.002) of the variability in micro- and nanophytoplankton and 88.9 % (p = 0.001) in the picoplankton community. A significant response to the ITW phenomenon in the plankton community composition (p = 0.001) was observed for bacterioplankton. Among the identified amplicon sequence variances, primary producers were scarce and mainly represented cyanobacteria (Synechococcus strain CC9902), stramenopiles (Pelagomonas), and chlorophytes (Ostreococcus). The remaining amplicon sequence variances were assigned to the classes Copepoda, parasitic fungi (Meyerozyma spp.), mixotrophic dinoflagellates (family Peridiniales, mostly the genus Blastodinium), and parasitic Ciliophora (Scuticociliata). Bacterial ecological functions corresponded to chemoheterotrophic, degradation, and fermentation processes, whereas samples collected after the most intense ITW episode also showed abundant bacteria linked to microplastic degradation and parasitosis. These results highlight the ecological role of localized physical phenomena in enhancing nearshore primary productivity and fine shifts in plankton taxa in oligotrophic systems.

Detection of wood-decay by Ganoderma adspersum in elm trees – A pilot study using a trained dog

The use of biodetection dogs is increasing but systematic approaches to their certification and validation are lacking. In this pilot study, the ANSI/ASB standard 088 (2020) was used to assess the performance of a dog trained to detect wood-decay caused by the parasitic fungus Ganoderma adspersum in elm trees. Controlled tests were followed up with a field study where the dog examined elms in two cities. The health of the elms indicated by the dog and a number of trees that were not indicated were followed up by sonic tomography and visual inspection. The pilot showed that the dogs performance during the controlled testing was similar to the performance during the field study: an overall sensitivity of 91% during the controlled tests and a positive predictive value (PPV) of 81% during the field study. Where the dog was able to assess 30–60 trees in an hour, sonic tomography takes at least an hour per tree. Combining a biodetection dog trained to detect G. adspersum into routine tree inspections can help to identify the pathogen earlier than tree inspectors can and focus resources efficiently.

The influence of soil salinization, induced by the backwater effect of the Yellow River, on microbial community dynamics and ecosystem functioning in arid regions

Irrigation practices and groundwater levels are critical factors contributing to soil salinization in arid and semi-arid regions. However, the impact of soil salinization resulting from Yellow River water irrigation and recharge on microbial communities and their functions in the Huinong District has not been thoroughly documented. In this study, high-throughput sequencing technology was employed to analyze the diversity, composition, and structure of bacterial and fungal communities across a gradient of salinized soils. The results indicated that the alpha diversity of bacterial communities was significantly higher in slightly saline soils compared to highly saline soils. Soil salinization notably influenced the composition of both bacterial and fungal communities. Highly salinized soils were enriched with bacterial taxa such as Halomonas, Salinimicrobium, Pseudomonas, Solibacillus, and Kocuria, as well as fungal taxa including Emericellopsis, Alternaria, and Podospora. In these highly saline soils, bacterial taxa associated with iron respiration, sulfur respiration, and hydrocarbon degradation were more prevalent, whereas fungal taxa linked to functions such as soil animal pathogens, arbuscular mycorrhizal symbiosis, endophytes, dung saprotrophy, leaf saprotrophy, soil saprotrophy, fungal parasitism, and plant pathogenicity were less abundant. Random forest analysis identified nine bacterial and eighteen fungal taxa as potential biomarkers for salinity discrimination in saline soils. Symbiotic network analysis further revealed that soil salinization pressure reduced the overall complexity and stability of bacterial and fungal communities. Additionally, bacterial community assembly showed a tendency shift from stochastic to deterministic processes in response to increasing salinity, while fungal community assembly remained dominated by deterministic processes. provide robust evidence that soil salinity is a major inhibitor of soil biogeochemical processes in the Huinong District and plays a critical role in shaping bacterial and fungal communities, their symbiotic networks, and their assembly processes.

Disentangling how the opportunistic parasitic fungus Armillaria affects the flammability of coarse deadwood in exotic pine plantations

Parasitic wood fungi are important to forest carbon cycles globally. However, whether or how they affect the flammability of coarse deadwood is poorly understood. Given the predicted climate-driven increase in wildfires and associated carbon emissions into the atmosphere, potentially amplifying climate warming, filling this knowledge gap should have high priority. We thereto investigated coastal plantations of the exotic black pine, Pinus nigra J.F. Arnold, in the Netherlands, which are widely suffering from Armillaria infection. We hypothesized that branches from forest stands with a visible Armillaria infection will burn differently compared with branches from stands without a visible Armillaria infection, due to Armillaria infection having an additional effect on the branch traits. We tested this hypothesis by burning coarse Pinus nigra branches across a range of densities from infected and uninfected forest patches under standardized conditions in a fire lab and by measuring Armillaria biomass (via ddPCR), deadwood traits and key flammability parameters. Armillaria infection did enhance the flammability of Pinus nigra branches (e.g. more ignitable, longer flame duration and higher percentage mass loss). This higher flammability originated from both direct Armillaria influences, e.g. via changing wood structure (before and/or after wood death), and indirect influences, e.g. by facilitating nitrogen fixation in wood, thereby increasing wood decomposability and consequently reducing wood density. Our findings also have important implications for understanding the role of pathogens in fire regimes more broadly.

Six Species of Phyllachora with Three New Taxa on Grass from Sichuan Province, China.

Phyllachora (Phyllachoraceae, Phyllachorales) species are parasitic fungi with a wide global distribution, causing tar spots on plants. In this study, we describe three newly discovered species: Phyllachora chongzhouensis, Phyllachora neidongensis, and Phyllachora huiliensis from Poaceae in China. These species were characterized using morphological traits and multi-locus phylogeny based on the internal transcribed spacer region (ITS) with the intervening 5.8S rRNA gene, the large subunit of the rRNA gene (LSU), and the 18S ribosomal RNA gene (SSU). Three known species of P. chloridis, P. graminis, and P. miscanthi have also been redescribed, because, in reviewing the original references of P. chloridis, P. graminis, and P. miscanthi, these were found to be relatively old and in Chinese or abbreviated. In addition, the illustrations were simple. In molecular identification, the ITS sequence is short, while the ITS, LSU, and SSU are incomplete. Therefore, this study provides new important references for the redescription of three known species and provides further evidence for the identification of new taxa.

Wheat Leaf Rust Fungus Effector Protein Pt1641 Is Avirulent to TcLr1.

Wheat leaf rust fungus is an obligate parasitic fungus that can absorb nutrients from its host plant through haustoria and secrete effector proteins into host cells. The effector proteins are crucial factors for pathogenesis as well as targets for host disease resistance protein recognition. Exploring the role of effector proteins in the pathogenic process of Puccinia triticina Eriks. (Pt) is of great significance for unraveling its pathogenic mechanisms. We previously found that a cysteine-rich effector protein, Pt1641, is highly expressed during the interaction between wheat and Pt, but its specific role in pathogenesis remains unclear. Therefore, this study employed techniques such as heterologous expression, qRT-PCR analysis, and host-induced gene silencing (HIGS) to investigate the role of Pt1641 in the pathogenic process of Pt. The results indicate that Pt1641 is an effector protein with a secretory function and can inhibit BAX-induced programmed cell death in Nicotiana benthamiana. qRT-PCR analyses showed that expression levels of Pt1641 were different during the interaction between the high-virulence strain THTT and low-virulence strains FGD and Thatcher, respectively. The highest expression level in the low-virulence strain FGD was four times that of the high-virulence strain THTT. The overexpression of Pt1641 in wheat near-isogenic line TcLr1 induced callose deposition and H2O2 production on TcLr1. After silencing Pt1641 in the Pt low-virulence strain FGD on wheat near-isogenic line TcLr1, the pathogenic phenotype of Pt physiological race FGD on TcLr1 changed from ";" to "3", indicating that Pt1641 plays a non-toxic function in the pathogenicity of FGD to TcLr1. This study helps to reveal the pathogenic mechanism of wheat leaf rust and provides important guidance for the mining and application of Pt avirulent genes.

Engineered fungus containing a caterpillar gene kills insects rapidly by disrupting their ecto- and endo-microbiomes

Similar to the physiological importance of gut microbiomes, recent works have shown that insect ectomicrobiotas can mediate defensive colonization resistance against fungal parasites that infect via cuticle penetration. Here we show that engineering the entomopathogenic fungus Metarhizium robertsii with a potent antibacterial moricin gene from silkworms substantially enhances the ability of the fungus to kill mosquitos, locusts, and two Drosophila species. Further use of Drosophila melanogaster as an infection model, quantitative microbiome analysis reveals that engineered strains designed to suppress insect cuticular bacteria additionally disrupt gut microbiomes. An overgrowth of harmful bacteria such as the opportunistic pathogens of Providencia species is detected that can accelerate insect death. In support, quantitative analysis of antimicrobial genes in fly fat bodies and guts indicates that topical fungal infections result in the compromise of intestinal immune responses. In addition to providing an innovative strategy for improving the potency of mycoinsecticides, our data solidify the importance of both the ecto- and endo-microbiomes in maintaining insect wellbeing.

HISTORY OF MYCOLOGICAL RESEARCH AT ODESA (NOVOROSSIA) UNIVERSITY (1865–1890)

Introduction. The development of mycological research in the south of Ukraine in the mid-nineteenth century was caused by a number of factors: the emergence of mycology as a scientific field, the growth of the population, for which the medical aspects of studying fungi causing dangerous diseases of humans and animals were relevant; active development of agriculture, which was significantly damaged by fungal diseases of cultivated plants. With the opening of Novorossiysk University, its biologists began to pay attention to these problems. There are only fragmentary facts about their research in the literature, scattered in different sources, so we also considered it necessary to present the materials we found from their personal biographies. The aim of our work was to study the history of mycological research at Odesa (Novorossiysk) University in the third quarter of the nineteenth century. Research methods. We studied the minutes of the meetings of the Academic Council of the Imperial Novorossiysk University (INU), the Novorossiysk Society of Naturalists (NNS), the Society of Agriculture of Southern Russia (SSAR), and the Odesa Branch of the Imperial Russian Society of Horticulture (OVIRTS); we studied the scientific publications of these institutions and societies; and we clarified the biographical data of little-known scientists from the documents of various institutions. In order to create a single holistic picture of the development of mycological research in the second half of the nineteenth century, the chronology of the accumulation of new knowledge in this field was studied. Main results. At the initial stage of mycological research at Odesa University (in the second half of the nineteenth century) in the south of Ukraine, the attention of scientists (M. K. Sredynskyi, I. F. Koshchuk, V. F. Khmelevskyi) was focused on the study of mycological diversity in the region. They studied (I. F. Koshchug, V. F. Khmelevskyi, I. M. Krasylshchyk) diseases of agricultural plants caused by parasitic fungi and methods of controlling them, the biology of individual pathogens of these diseases (L. S. Tsenkovskyi, Y. Y. Valts, L. A. Rishavi). For the first time in the south of Ukraine, fungi-parasites of harmful insects (bread beetle and beet weevil) were studied and the method of their reproduction and use in biological control of these insects was introduced (I. I. Mechnikov, I. M. Krasylshyk, V. I. Shmankevych, O. O. Yanovych, O. I. Pohibko and E. L. Rekalo).

Climate Changes and its Effect on Yartsagunbu Collectors in the Himalayan Region of North-Western Nepal

This paper explores the effects of climate change on the distribution of Yartsagunbu based on local people’s experiences. Yartsagunbu (Ophiocordyceps Sinensis) is a high-valued fungus that is understood as a stamina enhancer and endoparasitic complex of the parasitic fungus. It is found in the alpine and subalpine grasslands of the Himalayas and the Tibetan Plateau, at 3,000–5,200 meters above sea level. Yartsagunbu has been a significant livelihood resource and generates significant income for the collectors in rural Dolpa, Mugu, Jumla, Bajhang, and Manang of Nepal. This paper has explored climate change and its effects on the Yartsagunbu collectionin the Dolpa district. This brings out the Tarali people’s local experiences and perceptions of climate change and its effect on Yartsagunbu. Data and information for the study were collected from multiple fieldworks during the period 2019, 2020, and 2021. Furthermore, it is supported by personal experience of Yartsagunbu harvesting from the years 2001 to 2005. Present and past trends of Yartsagunbu harvesting experience and perception are collected by interviews with Yartsagunbu collectors, traders, and senior citizens. The finding of the study reveals that climate change is affecting the Yartsaguubu abundance and livelihood of Yartsagunbu collectors.

An independent Taiwanese lineage of powdery mildew on the endemic host species Koelreuteria henryi

BackgroundPowdery mildews (Erysiphaceae, Ascomycota) are common plant disease agents and also cause stress for forest and fruit trees worldwide as well as in Taiwan. The powdery mildew Erysiphe bulbouncinula on Koelreuteria host trees was considered an endemic species in China. While in China the host was K. paniculata and only the teleomorph stage found, the anamorph and the teleomorph were both recorded for the host in Taiwan, K. henryi. We aimed to clarify the relationship of the powdery mildews recorded under E. bulbouncinula with an apparently disjunct distribution.ResultsSpecimens of powdery mildew on K. henryi from Taiwan were characterized based on the anamorph morphology and DNA sequences. They revealed a new record of Sawadaea koelreuteriae for this host species and Taiwan and a new species of Erysiphe, E. formosana, sister to E. bulbouncinula from China.ConclusionsIn Erysiphe on Koelreuteria hosts, speciation of plant parasitic fungi seems to be correlated with disjunct host and geographic distribution possibly shaped by extinction of potential host species which are known only as fossils. Two of the three extant East Asian species of Koelreuteria are now known as hosts of specific Erysiphe species. We may predict a further not yet discovered Erysiphe species on the third East Asian species, K. bipinnata, in South and Southwest China. In the speciation in Sawadaea, the extinction events in Koelreuteria can be excluded from being involved.

Structure and Function of Fungal Community in Channel Sediments of Different Sections of Jialing River

This study aimed to explore the effects of different disturbances on the fungal communities in the sediments of the Jialing River in order to provide scientific basis for the protection of the river ecosystem. The fungal community in the sediments of the main stream of the Jialing River was taken as the research object, and high-throughput sequencing and bioinformatics techniques were used to analyze the differences in the composition and function of fungal communities in river sediment of different types of disturbance （project disturbance, tributary disturbance, sand mining disturbance, and reclamation disturbance） and non-disturbance sections. The results showed that： ① The reclamation and project disturbances significantly inhibited the diversity and richness of fungal communities （P<0.05）. The tributary disturbance increased the richness of fungal communities, whereas the impact of sand mining disturbance on sediment fungal communities was not significant. ② The diversity and composition of fungal communities tended to be similar at the different sampling sites in the section with low input of exogenous substances （non-disturbance and sand mining disturbance）, whereas there were obvious differences in the diversity of fungal communities at the different sampling sites of high input of external substances （tributary disturbance, project disturbance, and reclamation disturbance） sections. ③ Ascomycota, Rozellomycota, and Basidiomycota were the main dominant fungal phyla in the sediments of the Jialing River. The relative abundance of Rozellomycota was the highest in the sand mining interference section, and the relative abundance of Basidiomycota was the highest in the tributary interference section. Project disturbance significantly increased the relative abundance of saprotrophs, animal pathogens, plant pathogens, and dung saprotrophs, whereas other disturbances inhibited the relative abundance of fungal parasitic fungi, plant pathogens, and plant saprophytes. In conclusion, human disturbance has caused changes in fungal diversity, community structure, and function in the sediment of the Jialing River, and xenobiotic input was a key factor contributing to this phenomenon. The results can provide a reference for predicting and evaluating the ecological quality of river sediments.

Isocitrate lyase promotes Puccinia striiformis f. sp. tritici susceptibility in wheat (Triticum aestivum) by suppressing accumulation of glyoxylate cycle intermediates.

Plant fungal parasites manipulate host metabolism to support their own survival. Among the many central metabolic pathways altered during infection, the glyoxylate cycle is frequently upregulated in both fungi and their host plants. Here, we examined the response of the glyoxylate cycle in bread wheat (Triticum aestivum) to infection by the obligate biotrophic fungal pathogen Puccinia striiformis f. sp. tritici (Pst). Gene expression analysis revealed that wheat genes encoding the two unique enzymes of the glyoxylate cycle, isocitrate lyase (TaICL) and malate synthase, diverged in their expression between susceptible and resistant Pst interactions. Focusing on TaICL, we determined that the TaICL B homoeolog is specifically upregulated during early stages of a successful Pst infection. Furthermore, disruption of the B homoeolog alone was sufficient to significantly perturb Pst disease progression. Indeed, Pst infection of the TaICL-B disruption mutant (TaICL-BY400*) was inhibited early during initial penetration, with the TaICL-BY400* line also accumulating high levels of malic acid, citric acid, and aconitic acid. Exogenous application of malic acid or aconitic acid also suppressed Pst infection, with trans-aconitic acid treatment having the most pronounced effect by decreasing fungal biomass 15-fold. Thus, enhanced TaICL-B expression during Pst infection may lower accumulation of malic acid and aconitic acid to promote Pst proliferation. As exogenous application of aconitic acid and malic acid has previously been shown to inhibit other critical pests and pathogens, we propose TaICL as a potential target for disruption in resistance breeding that could have wide-reaching protective benefits for wheat and beyond.