Spore Dispersal Research Articles

Experimental transport of Trichomanes speciosum spores on Azorean woodpigeon feathers as a possible explanation for interisland dispersal

AbstractTrichomanes speciosum is a protected fern whose sporophyte generation is abundant on the island of Terceira (Azores archipelago, Portugal) but whose dispersal mechanism has never been directly documented. Based on its distribution, bird‐mediated epizoochory is a likely mechanism for spore dispersal, but there is no evidence to support this hypothesis. Laboratory experiments were performed to test the transportability of T. speciosum spores by the woodpigeon (Columba palumbus azorica), by observing the persistence of artificially added spores to feather samples that had been exposed to treatments of different wind speeds (2, 4, 6, and 8.25 m s−1) to simulate flight. The spores attached readily to the woodpigeon feathers, and 47% of the spores, on average, were lost after applying the maximum wind speed of the experiment. Spore loss was significantly related to wind speed but not to time of exposure. These findings suggest that if a fern spore adheres to the feathers of a woodpigeon, it has a probability of around 53% to remain there during flight and to eventually be dropped away from its origin. This study not only sheds new light on the possibility of T. speciosum spores being dispersed by woodpigeons, but also provides mechanistic evidence for spore retention on bird surfaces more generally.

Spore dispersal patterns of the ascomycete fungus Ramulariacollo-cygni and their influence on disease epidemics

Ramularia leaf spot is a major economic disease of barley caused by the dothidiomycete fungus Ramulariacollo-cygni. The fungus has a complex life cycle which includes extensive late season spore release events and a seed-borne phase. Predicting disease epidemics during the growing season remains a difficult challenge. To better understand the interaction between spore movement and disease epidemics, spore samplers were set up in Germany (two sites over 4 years), Poland (seven sites over 2 years) and the UK (two sites over 9 years), where the disease has been observed. Spore concentrations were determined using a real time PCR assay, and meteorological data were obtained from co-located automatic stations. Spore release events were seen to peak in June on mainland Europe and July in the UK. The pattern of spore release was broadly similar across countries with earlier peaks in mainland Europe. A relationship was observed in the UK between July spore levels and disease in following winter barley crops. Rainfall and temperature were proposed as significant drivers of spore release in these months. The major environmental parameter associated with spore release across the two UK sites was crop surface wetness, although some site-specific interactions were noted for rainfall and wind movement. Regression analysis of spore patterns and disease epidemics indicates a relationship between spore levels 75–105 days pre harvest and final disease levels in UK winter barley crops. This relationship was not observed in spring barley. The implications on risk forecasts are discussed.

Differential Effects of Desiccation on Hornworts with Contrasting Life Histories in Tropical Montane Forests: A Functional Trait—Based Perspective

Desiccation tolerance (DT) is the ability of an organism or structure to dry completely and subsequently survive in that air-dry state. Hornworts are excellent plant models to study desiccation effects as they have contrasting life histories which are likely associated with DT. We tested whether (1) epiphytic species had more efficient DT responses to drying and postrehydration than non-epiphytic species and whether (2) “green” spores were more sensitive than non-green spores to extreme drying. Hornwort species were collected from the Atlantic Forest of Rio de Janeiro, Brazil. We studied five species (gametophytes and spores: Dendroceros crispus, D. crispatus, Nothoceros vincentianus, Phaeoceros carolinianus; and only spores of Anthoceros lamellatus), using different relative humidity values, drying durations, and postrehydration conditions. All DT treatments affected the chlorophyll fluorescence (Fv/Fm) of gametophytes, with species-specific responses. D. crispatus and D. crispus (epiphytes) performed better than P. carolinianus and N. vincentianus, with fast recovery of Fv/Fm values postrehydration. The ability of non-green spores of P. carolinianus and A. lamellatus and green spores of D. crispus to support desiccation led us to reject our second hypothesis. The DT strategies of hornworts highlighted the trade-offs that are important in spore dispersal and plant establishment, such as fast colonization in Dendroceros spp. and potential spore soil banks in Phaeoceros and Anthoceros species.

Timing of fungicide application against Cercospora leaf spot disease based on aerial spore dispersal of Cercospora beticola in sugar beet

Cercospora leaf spot is an important foliar disease in sugar beet caused by Cercospora beticola. Tolerant cultivars are available, but application of fungicides is still mandatory for disease control. The timing of the fungicide application is crucial as it determines the outcome of disease epidemiology. A disease incidence (DI) of 5% is widely used as a threshold for fungicide application. Recently a method was developed that allows the quantification of aerial spore dispersal of C. beticola for measuring spore flight intensity. It was aimed in this study to prove if fungicide application based on spore flight might improve disease control compared to DI. In a field trial with artificial inoculation, a single fungicide application at the onset of spore flight slowed down disease development as indicated by reduced disease severity and aerial spore dispersal. However, it did not provide sufficient control in terms of sugar yield. Only a second fungicide application based on spore flight detection achieved an efficacy similar to two fungicide applications based on DI. In contrast, a single fungicide application based either on spore flight or DI was sufficient in two on-farm trials under natural infection with moderate disease pressure. This highlights the necessity of an early timed first fungicide application followed by a second application under high disease pressure induced by artificial inoculation. Although fungicide application based on spore flight achieved sufficient control success in on-farm trials, it seems not to improve disease control compared to the usage of DI as threshold.

Host density shapes the relative contribution of vector-based and aerial transmission of a pathogenic fungus.

Pathogen transmission mode is a key determinant of epidemiological outcomes. Theory shows that host density can influence the spread of pathogens differentially depending on their mode of transmission. Host density could therefore play an important role in determining the pathogen transmission mode. We tested theoretical expectations using floral arrays of the alpine carnation Dianthus pavonius in field experiments of spore dispersal of the anther-smut fungus, Microbotryum, by vector (pollinator)-based floral transmission and passive aerial transmission at a range of host densities. Pollinators deposited fewer spores per plant at high host density than at lower density (ranging from a 0.2-2 m spacing between plants), and vector-based spore deposition at higher densities declined more steeply with distance from diseased plant sources. In contrast, while aerial spore deposition declined with distance from the diseased source, the steepness of this decline was independent of host density. Our study indicates that the amount and distance of vector-based transmission are likely to be a nonmonotonic function of host density as a result of vector behavior, which is not readily encapsulated by fixed dispersal functions. We conclude that the spatial spread of pathogens by vectors is likely to be greater at lower and intermediate densities, whereas the spatial spread of aerially transmitted pathogens would be greater at high densities. These contrasting patterns could lead to differential importance of each transmission mode in terms of its contribution to subsequent infections across host densities.

The dingo (Canis familiaris) as a secondary disperser of mycorrhizal fungal spores

Context Many mycorrhizal fungi are vital to nutrient acquisition in plant communities, and some taxa are reliant on animal-mediated dispersal. The majority of animals that disperse spores are relatively small and have short-distance movement patterns, but carnivores – and especially apex predators – eat many of these small mycophagists and then move greater distances. No studies to date have assessed the ecosystem services carnivores provide through long-distance spore dispersal. Aims In this study, we aimed to investigate whether Australia’s free-ranging dogs (Canis familiaris), including dingoes, act as long-distance spore dispersers by predating smaller mycophagous animals and then secondarily dispersing the fungi consumed by these prey species. Methods To answer this question, we collected dingo scats along 40 km of transects in eastern Australia and analysed the scats to determine the presence of fungal spores and prey animals. Using telemetry and passage rate data, we then developed a movement model to predict the spore dispersal potential of dingoes. Key results We found 16 species of mammalian prey to be eaten by dingoes, and those dingo scats contained spores of 14 genera of mycorrhizal fungi. These fungi were more likely to appear in the scats of dingoes if primary mycophagist prey mammals had been consumed. Our model predicted dingo median spore dispersal distance to be 2050 m and maximum dispersal potential to be 10 700 m. Conclusions Our study indicates that dingoes are providing a previously overlooked ecosystem service through the long-distance dispersal of mycorrhizal fungi. Many of the fungi found in this study form hypogeous (underground) fruiting bodies that are unable to independently spread spores via wind. Because dingoes move over larger areas than their prey, they are especially important to these ecosystem functions. Implications Our novel approach to studying an overlooked aspect of predator ecology is applicable in most terrestrial ecosystems. Similar modelling approaches could also be employed to understand the dispersal potential of both primary and secondary spore dispersers globally. Because this study highlights an unrecognised ecosystem service provided by dingoes, we hope that it will stimulate research to develop a more comprehensive understanding of other apex predators’ ecosystem functions.

Tasmanian bandicoots as fungal dispersers: A comparison in mycophagy between the southern brown bandicoot (Isoodon obesulus) and the eastern barred bandicoot (Perameles gunnii)

Mycophagous mammals perform important ecosystem services through their dispersal of mycorrhizal fungi (particularly truffles). In order to better understand the role of Tasmanian bandicoots in these associations, we examined the stomach and scat contents of specimens of southern brown bandicoots (Isoodon obesulus) and eastern barred bandicoots (Perameles gunnii) preserved in the mammal collections of the Queen Victoria Museum and Art Gallery. Our study shows that fungi are consumed by both species and that these mammals likely play a key role in ecosystem function through their dispersal of mycorrhizal fungal spores.

Simplifying Barley Leaf Rust Research: An Easy and Reproducible Infection Protocol for Puccinia hordei on a Small Laboratory Scale.

Barley (Hordeum vulgare) is one of the most important agricultural crops in the world, but pathogen infections regularly limit its annual yield. A major threat is the infection with the biotrophic leaf rust fungus, Puccinia hordei. Rust fungi have a complex life cycle, and existing resistances can be easily overcome. To address this problem, it is crucial to develop barley varieties with improved and durable resistance mechanisms. An essential step towards this goal is a simple and reproducible infection protocol to evaluate potential resistance phenotypes in the lab. However, available protocols sometimes lack detailed procedure or equipment information, use spore application methods that are not suitable for uniform spore dispersion, or require special mineral oils or engineered fluids. In addition, they are often optimized for pathogen-dedicated greenhouses or phytochambers, which may not be available to every research institute. Here, we describe an easy and user-friendly procedure to infect barley with Puccinia hordei on a small laboratory scale. This procedure utilizes inexpensive and simple tools to evenly split and apply spores to barley leaves. The treated plants are incubated in affordable and small phytocabinets. Our protocol enables a quick and reproducible infection of barley with leaf rust, a method that can easily be transferred to other rust fungi, including stripe rust, or to other plant species. Key features Step-by-step infection protocol established for barley cv. Golden Promise, the gold standard genotype for genetic transformation Plant age-independent protocol Precise spore application by using inexpensive pipe cleaners for uniform symptom formation and increased reproducibility No specialized equipment needed Includes simple spore harvesting method Protocol is applicable to other biotrophic pathogens (stripe rust or powdery mildew) and other plants (e.g., wheat) Protocol is also applicable for a detached leaf assay Graphical overview.

Contrasting coffee leaf rust epidemics between forest coffee and semi-forest coffee agroforestry systems in SW-Ethiopia

Ethiopian Arabica coffee is produced in different agroforestry systems which differ in forest management intensity. In forest coffee systems (FC), coffee shrubs grow naturally in the understory of Afromontane forests with little human intervention, whereas in semi-forest coffee systems (SFC) thinning of the canopy and removal of the understory is applied. Coffee leaf rust (CLR) disease is a growing concern for coffee agroforestry, but to what extent infection pressure is affected by management intensity is poorly known. Here we assessed CLR infection through time across FC and SFC systems in SW-Ethiopia. CLR infection was significantly higher for SFC, with a gradual reduction of this difference during the beginning of dry season (November) through main rainy season of (July). Our findings also demonstrated that CLR infections were significantly lower in the FC system as compared to SFC system in both years 2015/16 and 2020/21. The higher CLR infection was partly explained by lower crown cover and higher human impact. We expect that reduced wind speed and droplet penetration under closed canopies and reduced human-facilitated spore dispersal are the dominating mechanisms behind lower CLR infection in FC systems, yet lower coffee density in FC may also play a role. Overall, our results indicate that although higher management intensity still generally results in higher total yields per hectare, proportionally larger losses due to CLR infection can be expected. Therefore, introducing more coffee genetic diversity, screening resistant coffee varieties and increasing canopy cover in the SFC will mitigate the CLR disease pressure and guarantee the sustainability of higher yields of the system in the future. Also, lower yields in the FC will be rewarded through providing price premiums so that farmers instantly get a higher price for their lower yield, guaranteeing livelihoods.

Dispersal and plant arrangement condition the timing and magnitude of coffee rust infection

One central issue in coffee-leaf rust (Hemileia vastatrix) epidemiology is to understand what determines the intensity and the timing of yearly infections in coffee plantations. However, most experimental and theoretical studies report infection as an average at the plot level, obscuring the role of potentially key factors like rust dispersal or the planting pattern. Here, we first review the rust epidemic patterns of different sites, which reveal large variability in the duration and magnitude of the different epidemiologic phases. We then present a spatially explicit and parametrised model, where the host population is subdivided into discrete patches linked through spore dispersal, modeled as simple diffusion. With this model, we study the role of the planting arrangement, the dispersal intensity and plant-level variables on the maximum average tree infection (MATI) and its timing. Our results suggest that the epidemic timeline can be divided into two phases: a time lag and a growth phase per se. The model shows that the combination of the dispersal magnitude and plant aggregation modifies the MATI and the time to MATI, mainly by preventing some plants from reaching their maximum peak during the epidemic. It also affects the epidemic curves, which can have a stepped, or a rather smooth pattern in plots with otherwise similar conditions. The initial rust infection modulates the time lag before the epidemic and the infected leaf-fall rate drastically changes the MATI. These findings highlight the importance of explicitly considering the spatial aspects of coffee agroecosystems when measuring and managing rust infection, and help us to further understand the spatio-temporal dynamics of ecological systems in general.

Inhibition of Phytopathogenic and Beneficial Fungi Applying Silver Nanoparticles In Vitro.

In the current research, our work measured the effect of silver nanoparticles (AgNP) synthesized from Larrea tridentata (Sessé and Moc. ex DC.) on the mycelial growth and morphological changes in mycelia from different phytopathogenic and beneficial fungi. The assessment was conducted in Petri dishes, with Potato-Dextrose-Agar (PDA) as the culture medium; the AgNP concentrations used were 0, 60, 90, and 120 ppm. Alternaria solani and Botrytis cinerea showed the maximum growth inhibition at 60 ppm (70.76% and 51.75%). Likewise, Macrophomina spp. required 120 ppm of AgNP to achieve 65.43%, while Fusarium oxisporum was less susceptible, reaching an inhibition of 39.04% at the same concentration. The effect of silver nanoparticles was inconspicuous in Pestalotia spp., Colletotrichum gloesporoides, Phytophthora cinnamomi, Beauveria bassiana, Metarhizium anisopliae, and Trichoderma viridae fungi. The changes observed in the morphology of the fungi treated with nanoparticles were loss of definition, turgidity, and constriction sites that cause aggregations of mycelium, dispersion of spores, and reduced mycelium growth. AgNP could be a sustainable alternative to managing diseases caused by Alternaria solani and Macrophomina spp.

Mycophagy of Attini Ants (Hymenoptera, Formicidae, Myrmicinae) with Agaricales Mushrooms (Basidiomycota, Agaricomycetes) at Riparian Zone in Southern Brazil

Attini ants (Hymenoptera, Formicidae, Myrmicinae) have great diversity in exploiting food resources. However, little is known about the mycophagy involving Agaricales fungi (Basidiomycota, Agaricomycetes). Moreover, these associations are of paramount importance in riparian zones, as the interaction among soil, fauna and flora is fundamental to the maintenance of these environments. Thus, the aim of this study was to describe cases of mycophagy between ants and fungi in order to understand how these associations occur in riparian zones. To this, collections were made between 2021-2022 in the valleys of the Rio Vacacaí, Rio dos Sinos and Rio Pardo in the state of Rio Grande do Sul, Brazil. The samples were analyzed for characters macro and microscopic and identified taxonomically. Mycophagy activities of six species of ants worker were cataloged, among them Acromyrmex niger, Acromyrmex versicolor, Tranopelta gilva, Tranopelta subterranea, Pheidole flavens and Mycetosoritis hartmanni, which included in their diet the mushrooms Agaricus rufoaurantiacus, Macrocybe titans, Agrocybe underwoodii, Dactylosporina steffenii, Lepiota micropholis and Neopaxillus echinospermus, respectively. The observed interactions demonstrate the dispersal of fungal spores through ant body structures, such as legs, antennae, thorax and abdomen; basidiomata as aliment source, such as pileus, lamellae and stipe; and generalized and specialized levels of predation on various fungi structures. Our results demonstrate unprecedented mycophagous relationships and show that Agaricales fungi can be considered a food source for Attini in riparian zones in Brazil south.

The Hydrophobin Gene Family Confers a Fitness Trade-off between Spore Dispersal and Host Colonization in Penicillium expansum.

Hydrophobins are small amphipathic surface proteins found exclusively in fungi. In filamentous ascomycetes, one conserved role of a subset of hydrophobins is their requirement for spore dispersal. Other contributions of these proteins to fungal biology are less clear and vary across genera. To determine the functions of hydrophobins in the biology and virulence of this fungus, we created seven single mutants and a septuple-deletion mutant (Δsep) of the entire putative P. expansum hydrophobin gene family. One spore hydrophobin, HfbA, shared 72.56% sequence identity to the Aspergillus fumigatus spore hydrophobin RodA and was required for efficient spore dispersion in P. expansum. The Δsep mutant was likewise reduced in spore dispersal, hypothesized to be due to the aberrant shape and clumping of the Δsep conidia and conidiophores. Additionally, the Δsep mutant presented several differences in physiological traits, including decreased survival in extreme cold temperatures and increased production of several toxic secondary metabolites. Most striking was the unexpected fitness advantage that the Δsep strain displayed in competitive passaging with the wild-type strain on host apple where the mutant significantly increased in percentage of the colonizing population. This work uncovers potential ecological trade-offs of hydrophobin presence in filamentous fungi. IMPORTANCE Hydrophobins are amphipathic secreted proteins uniquely found in filamentous fungi. These proteins self-assemble and constitute the outer most layer of fungal surfaces thus mediating multiple aspects of fungal interactions with their environments. Hydrophobins facilitate spore dispersal, yet a full understanding of the function and need for multiple hydrophobins in fungal species remains elusive. To address the role of this protein family in Penicillium expansum, the causative agent of blue mold disease in pome fruit, all seven putative hydrophobin genes were deleted and the mutant assessed for numerous physiological traits and virulence on fruit. Despite showing a decrease in spore dispersal, the septuple-deletion mutant was more fit than the wild type in competitive pathogenicity tests on apple. Our findings suggest this gene family illustrates a functional trade-off between dispersal and host colonization in P. expansum.

Towards quantifying microbial dispersal in the environment.

Towards quantifying microbial dispersal in the environment.

Irrigation can create new green bridges that promote rapid intercontinental spread of the wheat stem rust pathogen

Wheat stem rust epidemics caused by the obligate pathogenic fungus Puccinia graminis f.sp. tritici have historically driven severe yield losses on all wheat growing continents and, after many decades of control, stem rust is re-emerging as a disease of concern. In 1998, a highly virulent race able to overcome 90% of world wheat cultivars, Ug99, was identified in Uganda. Since initial detection, the pathogen has evolved many new variants and spread to many countries. The original variant spread from East Africa to the Middle East with three years between detection in Ethiopia and subsequent detection in Yemen. In 2014, another Ug99 variant (TTKTT), with one of the most complex virulence profiles, was detected in Kenya. This variant also spread from East Africa to the Middle East, but with only one year between detection in Ethiopia and subsequent detection in Iraq. Here we investigate potential airborne migration routes to account for the rapid spread of TTKTT in East Africa and beyond to the Middle East by using an integrated model combining the outputs from a meteorology-driven fungal spore dispersion model with epidemiological models to account for seasonal availability of susceptible crops and conditions for spore release and infectivity. We find viable pathways in the 2018/19 season that incorporate critical stepping-stone locations in Yemen or Saudi Arabia, but only in the presence of newly irrigated regions in Ethiopia. Our results indicate the potential and increasing importance of irrigated wheat areas in Ethiopia, Yemen and Saudi Arabia for inter-regional stem rust movements. Future movement of stem rust races out of East Africa is considered likely as irrigated areas expand. Targeted surveillance and the use of mitigation strategies including the use of durable resistant varieties in regions of irrigation are required to reduce the risks of enhanced dispersal of stem rust to other regions.

Wind-flow dynamics and spore-like particle dispersal over agroforestry systems: Impact of the tree density distribution

Agroforestry systems associating trees with crops are gaining a growing interest due to their environmental benefits in a context of climate change and biodiversity loss. Still, the impact of trees on the wind dynamics within agroforestry systems remains poorly understood despite the key role played by the wind in energy and mass exchanges, including disease and pest propagation. Here, we present the first detailed analysis of the wind dynamics over agroforestry systems, combining in situ measurements and instantaneous airflow simulations, with a numerical application on spore-like particle dispersion from an infection point source at crop top. Simulations reproduce remarkably well most characteristics of the turbulent wind flow within the agroforestry system. Simulations reveal the presence of two inflection points on the mean wind velocity profile, at crop and tree tops, both inducing the development of mixing-layer type eddies, controlling most of the turbulent exchanges within the agroforestry system. Relative to the local wind, the turbulence at the crop scale is more intense and intermittent in presence of trees. With increasing tree density, the turbulence at crop top becomes dominated by tree-scale motions developing at tree top. The presence of trees has a different impact on particle dispersion according to the particle size and the wind intensity. Trees accentuate the vertical and transversal dispersal of submicron spores while they enhance the short-range deposition of coarser spores on crops, the more as the wind is low, and thus limit the long-range dispersal of coarse spores. Finally, a simple parameterization of the mean wind velocity vertical profile is proposed for agroforestry systems, depending only on the foliage densities and heights of the tree and crop layers. This parameterization leads to an indication of the agroforestry system efficiency to limit spore propagation through an estimation of the Rouse number at crop top.

Populations of Puccinia striiformis f. sp. tritici in Winter Spore Production Regions Spread from Southwestern Oversummering Areas in China.

Stripe rust, caused by Puccinia striifomis f. sp. tritici (Pst), is one of the most destructive wheat diseases in China. Understanding the interregional dispersal of Pst inoculum is important for controlling the disease. In the present study, wheat stripe rust samples collected from the winter spore production and oversummering regions in November 2018 to March 2019 were studied through virulence testing and molecular characterization. From 296 isolates, 96 races were identified using a set of 19 Chinese wheat cultivars and 111 races were identified using 18 Yr single-gene lines as differentials. The isolates from Hubei province in the winter spore production area had the highest similarity in virulence with those from eastern Yunnan in the oversummering area. Molecular characterization using 13 simple-sequence repeat and 43 Kompetitive allele specific PCR-single nucleotide polymorphism markers supported the conclusion that the Pst populations in the winter spore production regions were from Guizhou and eastern Yunnan, key oversummering areas in the southwest. Furthermore, an analysis of wind movement at the 700-hPa high altitude also supported the conclusion of spore dispersal from the southwestern oversummering region to the south-central winter spore production region. The results of this study provide an epidemiological basis for deploying various effective resistance genes in different regions to control stripe rust.

Mycorrhizal fungi and invertebrates: Impacts on Tuber melanosporum ascospore dispersal and lifecycle by isopod mycophagy

The icon ectomycorrhizal (EcM) species, Tuber melanosporum, requires mycophagy for ascospore dispersal. Isopods are often found within fruitbodies and to explore why, Oniscus asellus were presented with T. melanosporum as a food source. Fruitbodies were consumed at a rate of 4.0 mg per isopod, over 24 h. Most of the recovered faecal pellets contained ascospores after 12 h. Gut-transit inflicted little mechanical damage to ascospores, and the majority were still contained with an ascus 30 h post feeding. Further, ascospores were observed in faecal pellets 18 days after consumption. Combined, the results suggest a previously overlooked role for isopods in EcM spore dispersal. The impacts for EcM ecology and the role of isopods in Tuber spp. lifecycles, including mating type distribution, is discussed alongside the emerging threat of climate change and how such knowledge can inform management by custodians of relevant habitat types.

Spatial distribution of modern pollen and fungal spores and their ecological indication in Qinghai Lake on northeastern Tibetan Plateau, China

The Qinghai-Tibet Plateau (QTP) – also called the “third pole” – is an ideal area to study the long-term relationship between people and the environment due to its sensitivity to both climate change and anthropogenic activities. Qinghai Lake in the north-eastern QTP is considered a key site to explore this issue. Fossil pollen and fungal spores extracted from lake sediments are effective proxies of palaeoecological evolution and ancient anthropogenic activities, but rely on the modern studies of pollen and fungal spores for an accurate interpretation of the fossil record. In this study, 36 surface-sediment samples from Qinghai Lake were collected from different water depths for pollen and fungal spore analyses to explore the modern characteristics of assemblages and dispersion of pollen and fungal spores. Our results show that the modern pollen assemblages of Qinghai Lake are mainly dominated by Artemisia, Cyperaceae, Poaceae, and Chenopodiaceae, with similar pollen assemblages across the lake, while pollen concentrations show a significant enrichment towards the sedimentary centres of the lake. The modern pollen assemblages reflect the characteristics of the vegetation communities and land use in the basin well. The percentages of Artemisia and Chenopodiaceae pollen are significantly higher in the lake surface-sediment samples than those from topsoil samples of the basin, while percentages of Cyperaceae pollen are lower than those in the topsoil samples. Rivers are an important vector for transporting pollen of intrazonal vegetation, including Cyperaceae, Poaceae, and Hippophae, into Qinghai Lake. Additionally, Cerealia Poaceae pollen (>37 µm) is an effective indicator of farming activities in the Qinghai Lake basin. Fungal spores have higher heterogeneity in their percentages and concentrations from different sampling sites, with Glomus spp. and Delitschia spp. being more abundant near the lakeshore, while other fungal spores, including Sordaria spp., Sporormiella spp. Pleospora spp., Coniochaeta spp., Savoryella spp., and Urocystis sp., having higher percentages and concentrations towards the centre of the lake, with the particle size of the fungal spores being an important factor affecting their transportation and deposition in the lake. This study provides essential data on modern processes and a theoretical basis for accurately interpreting fossil pollen and fungal spore records from lake sediments on the QTP.

Diploid-dominant life cycles characterize the early evolution of Fungi

Most of the described species in kingdom Fungi are contained in two phyla, the Ascomycota and the Basidiomycota (subkingdom Dikarya). As a result, our understanding of the biology of the kingdom is heavily influenced by traits observed in Dikarya, such as aerial spore dispersal and life cycles dominated by mitosis of haploid nuclei. We now appreciate that Fungi comprises numerous phylum-level lineages in addition to those of Dikarya, but the phylogeny and genetic characteristics of most of these lineages are poorly understood due to limited genome sampling. Here, we addressed major evolutionary trends in the non-Dikarya fungi by phylogenomic analysis of 69 newly generated draft genome sequences of the zoosporic (flagellated) lineages of true fungi. Our phylogeny indicated five lineages of zoosporic fungi and placed Blastocladiomycota, which has an alternation of haploid and diploid generations, as branching closer to the Dikarya than to the Chytridiomyceta. Our estimates of heterozygosity based on genome sequence data indicate that the zoosporic lineages plus the Zoopagomycota are frequently characterized by diploid-dominant life cycles. We mapped additional traits, such as ancestral cell-cycle regulators, cell-membrane- and cell-wall-associated genes, and the use of the amino acid selenocysteine on the phylogeny and found that these ancestral traits that are shared with Metazoa have been subject to extensive parallel loss across zoosporic lineages. Together, our results indicate a gradual transition in the genetics and cell biology of fungi from their ancestor and caution against assuming that traits measured in Dikarya are typical of other fungal lineages.