Article

How far and how fast can mushroom spores fly? Physical limits on ballistospore size and discharge distance in the Basidiomycota

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Active discharge of basidiospores in most species of Basidiomycota is powered by the rapid movement of a droplet of fluid, called Buller's drop, over the spore surface. This paper is concerned with the operation of the launch mechanism in species with the largest and smallest ballistospores. Aleurodiscus gigasporus (Russulales) produces the largest basidiospores on record. The maximum dimensions of the spores, 34 × 28 µm, correspond to a volume of 14 pL and to an estimated mass of 17 ng. The smallest recorded basidiospores are produced by Hyphodontia latitans (Hymenochaetales). Minimum spore dimensions in this species, 3.5 × 0.5 µm, correspond to a volume of 0.5 fL and mass of 0.6 pg. Neither species has been studied using high-speed video microscopy, but this technique was used to examine ballistospore discharge in species with spores of similar sizes (slightly smaller than A. gigasporus and slightly larger than those of H. latitans). Extrapolation of velocity measurements from these fungi provided estimates of discharge distances ranging from a maximum of almost 2 mm in A. gigasporus to a minimum of 4 µm in H. latitans. These are, respectively, the longest and shortest predicted discharge distances for ballistospores. Limitations to the distances traveled by basidiospores are discussed in relation to the mechanics of the discharge process and the types of fruit-bodies from which the spores are released.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Spore morphology is further modified in many species by elaborate surface ornamentation and appendages. Spore size ranges from the 3 μm-long basidiospores of certain bracket fungi, to the "giant" spores of lichenized Ascomycota that measure up to 300 × 100 μm (Ingold 1971;Fischer et al. 2010). Corresponding estimates of spore mass, based on density measurements between 1.0 × 10 3 and 1.3 × 10 3 kg m -3 (Gregory 1973), range from 1 pg to 2 μg. ...
... Recently, spore discharge processes in fungi have been studied using ultra-high-speed video cameras (Pringle et al. 2005;Yafetto et al. 2008;Stolze-Rybczynski et al. 2009;Noblin et al. 2009;Fischer et al. 2010). Image capture at camera speeds ranging from 50,000 to one million frames per second has allowed the first direct observations of the motion of discharged spores. ...
... Gymnosporangium juniperi-virginianae (Basidiomycota, Pucciniomycetes) is a pathogenic rust fungus that causes cedar-apple rust. Active discharge of basidiospores in both species of Basidiomycota is powered by the rapid movement of a droplet of fluid, called Buller's drop, over the spore surface (Fischer et al. 2010). The basidiospores of A. tabescens are discharged for a distance of <0.1 mm from the surfaces of its gills; the spores of G. juniperi-virginianae are discharged >1.0 mm from the surface of orange gelatinous horns that emerge from galls that it forms on various juniper species. ...
Article
Viscous drag causes the rapid deceleration of fungal spores after high-speed launches and limits discharge distance. Stokes' law posits a linear relationship between drag force and velocity. It provides an excellent fit to experimental measurements of the terminal velocity of free-falling spores and other instances of low Reynolds number motion (Re<1). More complex, non-linear drag models have been devised for movements characterized by higher Re, but their effectiveness for modeling the launch of fast-moving fungal spores has not been tested. In this paper, we use data on spore discharge processes obtained from ultra-high-speed video recordings to evaluate the effects of air viscosity predicted by Stokes' law and a commonly used non-linear drag model. We find that discharge distances predicted from launch speeds by Stokes' model provide a much better match to measured distances than estimates from the more complex drag model. Stokes' model works better over a wide range projectile sizes, launch speeds, and discharge distances, from microscopic mushroom ballistospores discharged at <1 m s(-1) over a distance of <0.1mm (Re<1.0), to macroscopic sporangia of Pilobolus that are launched at >10 m s(-1) and travel as far as 2.5m (Re>100).
... Webster et al. provided photographic evidence of Buller's drop forming at the hilar appendix just before discharge and proposed a two-phase mechanism for spore ejection: the first phase involving Buller's drop enveloping the spore surface, acquiring momentum; the second involving the sharing of momentum and movement of the center of mass of the spore-drop complex due to the rapid wetting [5]. Subsequent works modeled the conversion of surface energy into kinetic energy with different degrees of complexity and monitored this process with progressively faster cameras [8,9,10,11,12]. Pringle et al. [8] propose that coalescence occurs between Buller's drop and a second drop present on the side of a spore (adaxial drop), while Noblin et al. [9] describe the process through four-stages and estimate that about half of the total surface energy is dissipated overall. Liu et al recently moved beyond energy balance including simulations of the fluid dynamics within Buller's drop during coalescence as well as experiments with bio-mimetic drops [12]. ...
... While spore size and gill distance may be under genetic control [15], Buller's drop forms extracellularly [16]. Whether and how fungi control Buller's drop size remains unknown, although data reporting characteristic sizes of Buller's drop for different species suggest individual species do control size [10,17,8,11]. ...
... Here we recapitulate the theory that relates the ejection velocity and flight time with the horizontal distance traveled by the spore at the moment of the ejection before falling between two gills [7,8,9,10,11,12]. We combine the expressions for ejection speed and flight time, to highlight their dependence on the sizes and densities of the spore and of Buller's drop. ...
Preprint
Full-text available
Basidiomycete fungi eject spores using a surface tension catapult; a fluid drop forms at the base of each spore and after reaching a critical size, coalesces with the spore and launches it from the gill surface. Although basidiomycetes function within ecosystems as both devastating pathogens and mutualists critical to plant growth, an incomplete understanding of ballistospory hinders predictions of spore dispersal and impedes disease forecasting and conservation strategies. Building on a nascent understanding of the physics underpinning the surface tension catapult, we first use the principle of energy conservation to identify ejection velocities resulting from a range of Buller's drop and spore sizes. We next model a spore's trajectory away from a basidium and identify a specific relationship among intergill distances and Buller's drop and spore radii enabling the maximum number of spores to be packaged within a minimum amount of gill tissue. We collect data of spore and gill morphology in wild mushrooms and we find that real species lie in a region where, in order to pack the maximum number of spores with minimum amount of biomass, the volume of Buller's drop should scale as the volume of the spore, and its linear size should be about half of spore size. Previously published data of Buller's drop and spore size confirm this finding. Our results suggest that the radius of Buller's drop is tightly regulated to enable maximum packing of spores.
... So far, the reasons behind such correlations remain speculative due to the incomplete understanding of the mechanistic links between spore traits and fungal life history processes. The use of high-speed video has recently enabled very interesting insights into the role of spore morphology in the ballistospore discharge mechanism used by many basidiomycete fungi (Stolze-Rybczynski et al., 2009;Fischer et al., 2010a). Furthermore, Roper et al. (2008) found evidence for aerodynamically optimized spore shape in an ascomycete fungus with explosive spore discharge. ...
... The diameter range of basidiospores varies between 1 μm and 30 μm, which makes them deposit by means of inertial mechanisms. Fungal spores exhibit a variety of shapes, structures, and colors (Ingold, 1971;Hjortstam et al., 1988;Niemelä, 2005;Knudsen & Vesterholt, 2008;Fischer et al., 2010a); and they are a useful source of highly monodisperse nonstandard model particles for the study of general aerosol physical processes. For instance, Griffiths & Vaughan (1986) used the spores of the ascomycete fungus Arthrinium to test different methods for calculating the drag force experienced by oblate ellipsoid particles. ...
... The spore size of our study species varied ca. from 1 to 10 μm, thus covering the range from the smallest to intermediate-sized basidiospores (Fischer et al., 2010a). With the exception of the common puffball Lycoperdon perlatum, all of our study species use the ballistospore discharge mechanism to propel spores into the air (Money, 1998;Pringle et al., 2005). ...
Article
One of the most common classes of bio-aerosols is fungal spores. While there is considerable species-specific variation in the morphological traits of fungal spores, their effect on spore dispersal is not well understood. Due to their super micron size, fungal spores deposit via inertial mechanisms. In this study, we combine experimental, theoretical, and statistical approaches to investigate the effects of spore morphology, airflow conditions, and surface structure on dry deposition of spores of forest-dwelling basidiomycete fungi. Firstly, we measured the spore aerodynamic diameter (D-a) of 66 species and spore equivalent diameter (D-e) of 37 species. D-e combined with spore wall thickness was the best predictor of D-a. We also derived a parameterization to calculate the spore density (rho(spore)); it ranged between 0.51 and 3.92 g/cm(3) (mean 1.57 g/cm(3)). Assuming that spores are prolate-ellipsoids and using calculated values of D-e instead of the measured ones would under estimate rho(spore). Secondly, we measured the inertial deposition of spores for 21 species in an experimental setup where spores were carried by turbulent airflow through a vertical pipe containing an obstacle (spruce twigs or a metal mesh). The deposition velocity on spruce twigs was 0.4-21 mm/s depending on the airflow velocity, spore size, and twig density. Evaluations of a three-layer deposition model suggested that the roughness length (F) of the twigs was 10-93 mu m and it depended on the friction velocity. The deposition velocity of spores on the metal mesh was 24-53 times higher than that on the twigs. Spore shape did not have an unambiguous effect on D-a or deposition on the mesh. Our study will facilitate the development of mechanistic dispersal models that incorporate the effect of species-specific spore traits as well as a physically realistic description of deposition to environmental surfaces.
... The relative humidity inside the sample chamber was controlled by maintaining a constant temperature and altering the vapor pressure (Hiranuma et al. 2008). This provides conditions of supersaturation inside the specimen chamber according to the Clausius-Clapyron equation [14]: 15 Á 100% RH = relative humidity P = pressure in torr P S = saturated vapor pressure at 273.15°C = 4.58 torr L V = latent heat of vaporization of water = 2.26 x 10 6 J kg -1 R V = Gas constant for water vapor = 461.5 J/(kg K) T C = temperature in°C For the analysis of hygroscopic behavior, each spore deposit of each species was subjected to 2-4 repetitions of identical changes relative humidity. ...
... Several factors dictate the maximum size of Buller's drop and the adaxial drop during spore discharge. Buller's drop is constrained by spore size and geometry, hydrophobicity of spore surface, and the growth of the adaxial drop with which it fuses [5,15]. In the ESEM experiments, droplets were observed growing from the hilar appendix, and from the adaxial surface, but not from both parts of the same spore surface simultaneously. ...
... In the ESEM experiments, droplets were observed growing from the hilar appendix, and from the adaxial surface, but not from both parts of the same spore surface simultaneously. The maximum size of droplets growing from the hilar appendix of spores is comparable to those predicted from spore dimensions [5,15] and associated with normal spore discharge (Fig 3). Droplets growing from the adaxial surface of spores became much larger, with the diameter of droplets often exceeding the diameter of the spore (Fig 6). ...
Article
Full-text available
Millions of tons of fungal spores are dispersed in the atmosphere every year. These living cells, along with plant spores and pollen grains, may act as nuclei for condensation of water in clouds. Basidiospores released by mushrooms form a significant proportion of these aerosols, particularly above tropical forests. Mushroom spores are discharged from gills by the rapid displacement of a droplet of fluid on the cell surface. This droplet is formed by the condensation of water on the spore surface stimulated by the secretion of mannitol and other hygroscopic sugars. This fluid is carried with the spore during discharge, but evaporates once the spore is airborne. Using environmental electron microscopy, we have demonstrated that droplets reform on spores in humid air. The kinetics of this process suggest that basidiospores are especially effective as nuclei for the formation of large water drops in clouds. Through this mechanism, mushroom spores may promote rainfall in ecosystems that support large populations of ectomycorrhizal and saprotrophic basidiomycetes. Our research heightens interest in the global significance of the fungi and raises additional concerns about the sustainability of forests that depend on heavy precipitation.
... Elastic Energy Storage in Sterigma-Fracture Release Mechanism: Momentum Catapult. In Basidiomycota, a phylum of fungi including many edible mushrooms, most spores are actively dispersed by a momentum catapult: a shooting mechanism characterized by the coalescence of two water droplets (the so-called Buller's drop and adaxial drop [32]) on the spore surface that generate the energy needed to discharge the spore(s) by momentum transfer [19,[33][34][35][36][37]. The sporogenous cell of the concerning species typically consists of cup-shaped reproductive units called basidiospores or ballistospores (mass without the droplets 8.4Á10 −7 milligram [mg] and with droplets 1.5Á10 −6 mg in Itersonilia perplexans [35]), connected to a stalk (sterigma) by the hilum (Fig 2A). ...
... (4) The hilum breaks under the tension created by the momentum transfer and the braking of the drop at the spore's tip [38], releasing the spore ( Fig 2D). The variation in the size of the spores and Buller's drops produces a range of launch accelerations from 3,302 to 25,484g [35,[38][39][40], launch velocities from 0.1 to 1.8 m/s [34,38,40], and launch distances from a few thousand of a millimeter [mm] in the smallest spores to a few millimeters in the larger spores [32,34,35,38,40]. Given their small size and mass, spores operate in a low Reynolds number (i.e. a dimensionless quantity that quantifies the relative effect of inertial and viscous drag forces) regime, where friction drag is relatively high. ...
... (4) The hilum breaks under the tension created by the momentum transfer and the braking of the drop at the spore's tip [38], releasing the spore ( Fig 2D). The variation in the size of the spores and Buller's drops produces a range of launch accelerations from 3,302 to 25,484g [35,[38][39][40], launch velocities from 0.1 to 1.8 m/s [34,38,40], and launch distances from a few thousand of a millimeter [mm] in the smallest spores to a few millimeters in the larger spores [32,34,35,38,40]. Given their small size and mass, spores operate in a low Reynolds number (i.e. a dimensionless quantity that quantifies the relative effect of inertial and viscous drag forces) regime, where friction drag is relatively high. ...
Article
Full-text available
Background In nature, shooting mechanisms are used for a variety of purposes, including prey capture, defense, and reproduction. This review offers insight into the working principles of shooting mechanisms in fungi, plants, and animals in the light of the specific functional demands that these mechanisms fulfill. Methods We systematically searched the literature using Scopus and Web of Knowledge to retrieve articles about solid projectiles that either are produced in the body of the organism or belong to the body and undergo a ballistic phase. The shooting mechanisms were categorized based on the energy management prior to and during shooting. Results Shooting mechanisms were identified with projectile masses ranging from 1·10−9 mg in spores of the fungal phyla Ascomycota and Zygomycota to approximately 10,300 mg for the ballistic tongue of the toad Bufo alvarius. The energy for shooting is generated through osmosis in fungi, plants, and animals or muscle contraction in animals. Osmosis can be induced by water condensation on the system (in fungi), or water absorption in the system (reaching critical pressures up to 15.4 atmospheres; observed in fungi, plants, and animals), or water evaporation from the system (reaching up to −197 atmospheres; observed in plants and fungi). The generated energy is stored as elastic (potential) energy in cell walls in fungi and plants and in elastic structures in animals, with two exceptions: (1) in the momentum catapult of Basidiomycota the energy is stored in a stalk (hilum) by compression of the spore and droplets and (2) in Sphagnum energy is mainly stored in compressed air. Finally, the stored energy is transformed into kinetic energy of the projectile using a catapult mechanism delivering up to 4,137 J/kg in the osmotic shooting mechanism in cnidarians and 1,269 J/kg in the muscle-powered appendage strike of the mantis shrimp Odontodactylus scyllarus. The launch accelerations range from 6.6g in the frog Rana pipiens to 5,413,000g in cnidarians, the launch velocities from 0.1 m/s in the fungal phylum Basidiomycota to 237 m/s in the mulberry Morus alba, and the launch distances from a few thousands of a millimeter in Basidiomycota to 60 m in the rainforest tree Tetraberlinia moreliana. The mass-specific power outputs range from 0.28 W/kg in the water evaporation mechanism in Basidiomycota to 1.97·10⁹ W/kg in cnidarians using water absorption as energy source. Discussion and conclusions The magnitude of accelerations involved in shooting is generally scale-dependent with the smaller the systems, discharging the microscale projectiles, generating the highest accelerations. The mass-specific power output is also scale dependent, with smaller mechanisms being able to release the energy for shooting faster than larger mechanisms, whereas the mass-specific work delivered by the shooting mechanism is mostly independent of the scale of the shooting mechanism. Higher mass-specific work-values are observed in osmosis-powered shooting mechanisms (≤ 4,137 J/kg) when compared to muscle-powered mechanisms (≤ 1,269 J/kg). The achieved launch parameters acceleration, velocity, and distance, as well as the associated delivered power output and work, thus depend on the working principle and scale of the shooting mechanism.
... Elastic Energy Storage in Sterigma-Fracture Release Mechanism: Momentum Catapult. In Basidiomycota, a phylum of fungi including many edible mushrooms, most spores are actively dispersed by a momentum catapult: a shooting mechanism characterized by the coalescence of two water droplets (the so-called Buller's drop and adaxial drop [32]) on the spore surface that generate the energy needed to discharge the spore(s) by momentum transfer [19,[33][34][35][36][37]. The sporogenous cell of the concerning species typically consists of cup-shaped reproductive units called basidiospores or ballistospores (mass without the droplets 8.4Á10 −7 milligram [mg] and with droplets 1.5Á10 −6 mg in Itersonilia perplexans [35]), connected to a stalk (sterigma) by the hilum (Fig 2A). ...
... (4) The hilum breaks under the tension created by the momentum transfer and the braking of the drop at the spore's tip [38], releasing the spore ( Fig 2D). The variation in the size of the spores and Buller's drops produces a range of launch accelerations from 3,302 to 25,484g [35,[38][39][40], launch velocities from 0.1 to 1.8 m/s [34,38,40], and launch distances from a few thousand of a millimeter [mm] in the smallest spores to a few millimeters in the larger spores [32,34,35,38,40]. Given their small size and mass, spores operate in a low Reynolds number (i.e. a dimensionless quantity that quantifies the relative effect of inertial and viscous drag forces) regime, where friction drag is relatively high. ...
... (4) The hilum breaks under the tension created by the momentum transfer and the braking of the drop at the spore's tip [38], releasing the spore ( Fig 2D). The variation in the size of the spores and Buller's drops produces a range of launch accelerations from 3,302 to 25,484g [35,[38][39][40], launch velocities from 0.1 to 1.8 m/s [34,38,40], and launch distances from a few thousand of a millimeter [mm] in the smallest spores to a few millimeters in the larger spores [32,34,35,38,40]. Given their small size and mass, spores operate in a low Reynolds number (i.e. a dimensionless quantity that quantifies the relative effect of inertial and viscous drag forces) regime, where friction drag is relatively high. ...
Article
Full-text available
p>Background In nature, shooting mechanisms are used for a variety of purposes, including prey capture, defense, and reproduction. This review offers insight into the working principles of shooting mechanisms in fungi, plants, and animals in the light of the specific functional demands that these mechanisms fulfill. Methods We systematically searched the literature using Scopus and Web of Knowledge to retrieve articles about solid projectiles that either are produced in the body of the organism or belong to the body and undergo a ballistic phase. The shooting mechanisms were categorized based on the energy management prior to and during shooting. Results Shooting mechanisms were identified with projectile masses ranging from 1.10<sup>-9</sup> mg in spores of the fungal phyla Ascomycota and Zygomycota to approximately 10,300 mg for the ballistic tongue of the toad Bufo alvarius. The energy for shooting is generated through osmosis in fungi, plants, and animals or muscle contraction in animals. Osmosis can be induced by water condensation on the system (in fungi), or water absorption in the system (reaching critical pressures up to 15.4 atmospheres; observed in fungi, plants, and animals), or water evaporation from the system (reaching up to -197 atmospheres; observed in plants and fungi). The generated energy is stored as elastic (potential) energy in cell walls in fungi and plants and in elastic structures in animals, with two exceptions: (1) in the momentum catapult of Basidiomycota the energy is stored in a stalk (hilum) by compression of the spore and droplets and (2) in Sphagnum energy is mainly stored in compressed air. Finally, the stored energy is transformed into kinetic energy of the projectile using a catapult mechanism delivering up to 4,137 J/kg in the osmotic shooting mechanism in cnidarians and 1,269 J/kg in the muscle-powered appendage strike of the mantis shrimp Odontodactylus scyllarus. The launch accelerations range from 6.6g in the frog Rana pipiens to 5,413,000g in cnidarians, the launch velocities from 0.1 m/s in the fungal phylum Basidiomycota to 237 m/ s in the mulberry Morus alba, and the launch distances from a few thousands of a millimeter in Basidiomycota to 60 m in the rainforest tree Tetraberlinia moreliana. The mass-specific power outputs range from 0.28 W/kg in the water evaporation mechanism in Basidiomycota to 1.97.10<sup>9</sup> W/kg in cnidarians using water absorption as energy source. Discussion and conclusions The magnitude of accelerations involved in shooting is generally scale-dependent with the smaller the systems, discharging the microscale projectiles, generating the highest accelerations. The mass-specific power output is also scale dependent, with smaller mechanisms being able to release the energy for shooting faster than larger mechanisms, whereas the mass-specific work delivered by the shooting mechanism is mostly independent of the scale of the shooting mechanism. Higher mass-specific work-values are observed in osmosis-powered shooting mechanisms ( ≤ 4,137 J/kg) when compared to muscle-powered mechanisms (≤ 1,269 J/kg). The achieved launch parameters acceleration, velocity, and distance, as well as the associated delivered power output and work, thus depend on the working principle and scale of the shooting mechanism.</p
... (Note that some ballistospores are launched directly into the open air, e.g. in yeasts and rusts, with typically larger spores. In those cases, an orthogonal launching direction maximizes the probability of escaping the viscous boundary layer formed around the hymenium [5,9].) How do physical processes shape the orthogonal direction taken by a launching spore, the directionality consistently reported since 1909 [1]? ...
... A typical mature spore is shaped like a prolate ellipsoid, distorted asymmetrically with a flatter adaxial face and a more curved abaxial face along its long axis [2]. The long radius (semi-major axis) of a spore ranges approximately from 1.5 to 15mm [2,9], while the radius of the full-grown Buller's drop ranges approximately from 0.3 to 10 mm [9]. The Buller's and adaxial drops are formed by the condensation of ambient water vapour, a process facilitated by hygroscopic substances secreted from the spore, e.g. ...
... A typical mature spore is shaped like a prolate ellipsoid, distorted asymmetrically with a flatter adaxial face and a more curved abaxial face along its long axis [2]. The long radius (semi-major axis) of a spore ranges approximately from 1.5 to 15mm [2,9], while the radius of the full-grown Buller's drop ranges approximately from 0.3 to 10 mm [9]. The Buller's and adaxial drops are formed by the condensation of ambient water vapour, a process facilitated by hygroscopic substances secreted from the spore, e.g. ...
Article
Thousands of fungal species use surface energy to power the launch of their ballistospores. The surface energy is released when a spherical Buller's drop at the spore's hilar appendix merges with a flattened drop on the adaxial side of the spore. The launching mechanism is primarily understood in terms of energetic models, and crucial features such as launching directionality are unexplained. Integrating experiments and simulations, we advance a mechanistic model based on the capillary-inertial coalescence between the Buller's drop and the adaxial drop, a pair that is asymmetric in size, shape and relative position. The asymmetric coalescence is surprisingly effective and robust, producing a launching momentum governed by the Buller's drop and a launching direction along the adaxial plane of the spore. These key functions of momentum generation and directional control are elucidated by numerical simulations, demonstrated on spore-mimicking particles, and corroborated by published ballistospore kinematics. Our work places the morphological and kinematic diversity of ballistospores into a general mechanical framework, and points to a generic catapulting mechanism of colloidal particles with implications for both biology and engineering. © 2017 The Author(s) Published by the Royal Society. All rights reserved.
... For spore size, we chose three categories (up to 10 µm, 10-100 µm, and greater than 100 µm) based upon the natural breaks in spore size occurring between higher taxonomic ranks. Motile spores and basidiospores were not placed in size groups, but formed separate groups due to their special modes of dispersal in the former, and the unique size constraints in the latter which are dictated by size limitations and fruiting body structure (Galente et al. 2011;Fischer et al. 2010;Stolze-Rybczynsk et al. 2009). Pigmentation is also characteristic of some types of spores, thus melanization status was included when known. ...
... These organ-specific taxa represent a small subset of the fungal microbiome, yet they provide some clues as to the mechanisms of assembly of the microbiome. For many fungi, the spores are the agents of dispersal, having evolved to optimally distribute propagules to target areas where they can thrive (Calhim et al, 2018;Deacon 1980;Evans et al. 2016;Fischer et al. 2010;Pringle et al. 2015;Pringle et al. 2016). Thus, we further examined these taxa in terms of characteristics that affect fungal propagule distribution: spore size and shape, pigmentation, and means of dispersal. ...
Article
Microbiomes from maize and soybean were characterized in a long-term three-crop rotation research site, under four different land management strategies, to begin unraveling the effects of common farming practices on microbial communities. The fungal and bacterial communities of leaves, stems, and roots in host species were characterized across the growing season using amplicon sequencing and compared with the results of a similar study on wheat. Communities differed across hosts, and among plant growth stages and organs, and these effects were most pronounced in the bacterial communities of the wheat and maize phyllosphere. Roots consistently showed the highest number of bacterial OTUs compared to above-ground organs, whereas the alpha diversity of fungi was similar between above- and below-ground organs. Network analyses identified putatively influential members of the microbial communities of the three host plant species. The fungal taxa specific to roots, stems, or leaves were examined to determine if the specificity reflected their life histories based on previous studies. The analysis suggests that fungal spore traits are drivers of organ specificity in the fungal community. Identification of influential taxa in the microbial community and understanding how community structure of specific crop organs is formed, will provide a critical resource for manipulations of microbial communities. The ability to predict how organ specific communities are influenced by spore traits will enhance our ability to introduce them sustainably.
... The motion forces result from the hygroscopic Buller's drop which grows within seconds by condensation at the hydrophobic hilar spore appendix and its rapid fusion with an also hygroscopic liquid film which arises in a dent on the adaxial side of the spore (McLaughlin et al. 1985;Webster and Davey 1985;Webster et al. 1989;Ingold 1992;Money 1998;Pringle et al. 2005). The spores are propelled into the free air space between lamellate hymenia or of a pore, fall out of the caps by gravity (Ingold 1957(Ingold , 1992Pringle et al. 2005;Money and Fischer 2009;Noblin et al. 2009;Fischer et al. 2010a), and might then be transported by air streams further to new substrates (Galante et al. 2011;Horton et al. 2013;Halbwachs and Bässler 2015;Dressaire et al. 2015Dressaire et al. , 2016. ...
... Overall charges of spores correlate little with spore sizes and actual spore charges are also independent on spore emission rates from mushrooms (Saar and Salm 2014). This is also reflected in our results on different species as shown in Fig. 3. Spore sizes have in contrast been shown to influence sizes of Buller's drops, the spore velocity upon ejection from the sterigmata, the length of the move vertically through a mushroom airspace before being braked (Stolze-Rybczynski et al. 2009;Fischer et al. 2010a), and the distance of spore deposition from the source (Norros et al. 2014), parameters which appear all be not of primary relevance to the electrostatic attraction and attachment of the spores to plastic lids reported here. ...
Article
Full-text available
The basidiospores of most Agaricomycetes are ballistospores. They are propelled off from their basidia at maturity when Buller’s drop develops at high humidity at the hilar spore appendix and fuses with a liquid film formed on the adaxial side of the spore. Spores are catapulted into the free air space between hymenia and fall then out of the mushroom’s cap by gravity. Here we show for 66 different species that ballistospores from mushrooms can be attracted against gravity to electrostatic charged plastic surfaces. Charges on basidiospores can influence this effect. We used this feature to selectively collect basidiospores in sterile plastic Petri-dish lids from mushrooms which were positioned upside-down onto wet paper tissues for spore release into the air. Bulks of 104 to >107 spores were obtained overnight in the plastic lids above the reversed fruiting bodies, between 104 and 106 spores already after 2–4 h incubation. In plating tests on agar medium, we rarely observed in the harvested spore solutions contaminations by other fungi (mostly none to up to in 10% of samples in different test series) and infrequently by bacteria (in between 0 and 22% of samples of test series) which could mostly be suppressed by bactericides. We thus show that it is possible to obtain clean basidiospore samples from wild mushrooms. The technique of spore collection through electrostatic attraction in plastic lids is applicable to fresh lamellate and poroid fruiting bodies from the wild, to short-lived deliquescent mushrooms, to older and dehydrating fleshy fruiting bodies, even to animal-infested mushrooms and also to dry specimens of long-lasting tough species such as Schizophyllum commune.
... Therefore, we grouped our OTU list based on propagule qualities; size (length on longest side), cell motility, presence of yeast forms, melanization, and means of dispersal. For spore size, we chose three categories (up to 10 µm, 10-100 µm, and greater than 100 µm) based upon the natural breaks in spore size occurring between large taxonomic groups Motile spores and basidiospores were not placed in size-based groups, but formed separate groups due to their special modes of dispersal in the former, and the unique size continuum in the latter which is dictated by size limitations not identified in other fungal taxa (Fischer et al. 2010). Spore pigmentation is also characteristic of some types of spores, melanization was included when known. ...
... However, they provide some clues as to the assembly of the microbiome, likely driven by delivery of propagules. For most fungi, the spores are the agents of dispersal, having evolved to optimally distribute propagules to desirable areas (Fischer et al. 2010;Pringle et al. 2016). Therefore, we hypothesized that a major determining factor for organ specificity is the dispersal mechanism of each of these taxa. ...
Preprint
Microbiomes from maize and soybean were characterized in a long-term crop rotation research site, under four different land management strategies, to begin unraveling the effects of common farming practices on microbial communities. The fungal and bacterial communities of leaves, stems, and roots in all crops were characterized across the growing season using amplicon sequencing. The wheat rotation has been previously characterized and included here for comparison. Communities differed across plant growth stages and organs, and these effects were most pronounced in the bacterial communities of wheat and maize above-ground organs. Roots consistently had the highest number of unique bacterial OTUs compared to above-ground organs, whereas the alpha diversity of fungi was similar above- and below-ground. Network analyses identified putatively influential members of the microbial communities of the three crops. The fungal OTUs specific to roots, stems or leaves were examined to determine if the specificity reflected their life histories based on previous studies. The analysis suggests that fungal dispersal mechanisms are drivers in organ specificity of the fungal community. Understanding the microbial community structure across the organs of crop plants and identifying influential taxa will provide a critical resource for researchers in future manipulations of naturally occurring microbial communities to reduce plant diseases and to increase crop yields. The ability to predict how these microbes will be dispersed to the target organ will enhance our ability to introduce them sustainably.
... For movements characterized by higher Re, more complex models have been devised to determine drag but none have been evaluated for modelling the launch of fast moving fungal spores. In Fischer et al. (2010) the first empirical test of Stokes’ Law and a commonly used complex drag model (Clift et al. 2005, White 1974, Vogel 2005) was presented with launch speed data obtained from ultra-high-speed video recordings and experimental measurements of discharge distances (Pringle et al. 2005, Yafetto et al. 2008, Stolze-Rybczynski et al. 2008; Fischer et al. 2010b). They found that discharge distances predicted from launch speeds by the simpler Stokes’ model provide a much better match to measured distances than the more complex drag model. ...
Article
Full-text available
This contribution is based on the six presentations given at the Special Interest Group meeting on Mathematical modelling of fungal growth and function held during IMC9. The topics covered aspects of fungal growth ranging across several orders of magnitude of spatial and temporal scales from the bio-mechanics of spore ejection, vesicle trafficking and hyphal tip growth to the form and function of mycelial networks. Each contribution demonstrated an interdisciplinary approach to questions at specific scales. Collectively, they represented a significant advance in the multi-scale understanding of fungal biology.
... In particular, foliar endophytes of woody plants have been described as a highly diverse group of fungi that are transmitted horizontally via spores or herbivorous vectors, restricted to above-ground tissues, and form localised infections ( Rodriguez et al. 2009;Chaverri and Gazis 2011). The successful establishment of these endophytes, as well as of many other fungi, might be affected by a patchy distribution of small-scale habitat characteristics (Unterseher and Tal 2006), and by dispersal limitation (Fischer et al. 2010). It is conceivable that this may induce potentially complex spatial and temporal patterns in the composition of the endophytic community. ...
Article
Full-text available
Leaf-inhabiting endophytic fungi of Fraxinus ex-celsior growing in a floodplain forest were isolated during 2008 to investigate vertical community structure, species richness and seasonal variation. The analysis of 848 fungal endophytes from 213 leaves resulted in 50 different species. In the understorey, infection density and species richness were higher than in the crowns of mature trees throughout the whole vegetation period. Within tree crowns, sun-exposed leaves of the top canopy exhibited the lowest infection rates. Most species were rare or absent in spring and in the light crowns and frequent in autumn and the understorey. However, some species, especially the two most frequent, Alternaria infectoria and A. alternata, devi-ated from these patterns. Young leaves were nearly free of endophytes. Apparently, the subsequent infection and estab-lishment of fungi strongly depend on microclimatic param-eters and leaf characters, which create highly variable spatial and temporal colonisation patterns within an individual tree.
... For instance, do fungi that infect trees through wounds in the canopy produce spores predominately under high turbulence, when most spores are expected to deposit high in the canopy? Many wooddecay fungi are characterized by very small spores (down to 1 lm; Parmasto and Parmasto 1992, Fischer et al. 2010). One evolutionary factor behind this could be that small spore size is beneficial in species occurring in forests where the deposition to the canopy makes dispersal especially size sensitive. ...
Article
In species that disperse by airborne propagules an inverse relationship is often assumed between propagule size and dispersal distance. However, for microscopic spores the evidence for the relationship remains ambiguous. Lagrangian stochastic dispersion models that have been successful in predicting seed dispersal appear to predict similar dispersal for all spore sizes up to -40 microm diameter. However, these models have assumed that spore size affects only the downwards drift of particles due to gravitation and have largely omitted the highly size-sensitive deposition process to surfaces such as forest canopy. On the other hand, they have assumed that spores are certain to deposit when the air parcel carrying them touches the ground. Here, we supplement a Lagrangian stochastic dispersion model with a mechanistic deposition model parameterized by empirical deposition data for 1-10 microm spores. The inclusion of realistic deposition improved the ability of the model to predict empirical data on the dispersal of a wood-decay fungus (aerodynamic spore size 3.8 microm). Our model predicts that the dispersal of 1-10 microm spores is in fact highly sensitive to spore size, with 97-98% of 1 microm spores but only 12-58% of 10-microm spores dispersing beyond 2 km in the simulated range of wind and canopy conditions. Further, excluding the assumption of certain deposition at the ground greatly increased the expected dispersal distances throughout the studied spore size range. Our results suggest that by evolutionary adjustment of spore size, release height and timing of release, fungi and other organisms with microscopic spores can change the expected distribution of dispersal locations markedly. The complex interplay of wind and canopy conditions in determining deposition resulted in some counterintuitive predictions, such as that spores disperse furthest under intermediate wind, providing intriguing hypotheses to be tested empirically in future studies.
... Spores can be ejected substantial distances depending on the fungal species: 2–300 mm in the case of ascospores and 0.04–1.26 mm in the case of basidiospores (Jones and Harrison, 2004; Fischer et al., 2010). ...
Chapter
Bioaerosols have consequences for human, animal and plant health, for biogeochemical and atmospheric processes and for the conservation and maintenance of buildings and monuments. Renewed interest in the microbial component of bioaerosols is leading to the exploration of their long distance transport, particle-climate interactions, the atmosphere as a habitat, and the impact of aerial dissemination on evolutionary history of organisms and its consequence for disease epidemiology. This chapter focuses on the methodology used to study the origins and transport of microorganisms in the atmosphere and their interactions with the physical and chemical properties of the atmosphere and on the dynamics of the processes revealed. Particular attention is given to the concept of microbial flux. Measuring microbial flux under field conditions is a major challenge in aerobiology and is essential for identifying sources and their real impact on aerosol load. A second major challenge is the assessment of long distance transport of microorganisms under conditions where there are multiple sources or when specific sources are unknown. Changes in land use provide an opportunity and a need to specifically evaluate how this will alter the abundance and fate of microorganisms in the atmosphere.
... Spores disperse from mushrooms in two phases [7]: a powered phase, in which an initial impulse delivered to the spore by a surface tension catapult carries it clear of the gill or pore surface, followed by a passive phase in which the spore drops below the pileus and is carried away by whatever winds are present in the surrounding environment. The powered phase requires feats of engineering both in the mechanism of ejection [8][9][10] and in the spacing and orientation of the gills or pores [11,12]. However, spore size is the only attribute whose influence on the passive phase of dispersal has been studied [13]. ...
Article
Thousands of fungal species rely on mushroom spores to spread across landscapes. It has long been thought that spores depend on favorable airflows for dispersal -- that active control of spore dispersal by the parent fungus is limited to an impulse delivered to the spores to carry them clear of the gill surface. Here we show that evaporative cooling of the air surrounding the mushroom pileus creates convective airflows capable of carrying spores at speeds of centimeters per second. Convective cells can transport spores from gaps that may be only a centimeter high, and lift spores ten centimeters or more into the air. The work reveals how mushrooms tolerate and even benefit from crowding, and provides a new explanation for their high water needs.
... Spores disperse from basidiomycete mushrooms in two phases (7): a powered phase, in which an initial impulse delivered to the spore by a surface tension catapult carries it clear of the gill or pore surface, followed by a passive phase in which the spore drops below the pileus and is carried away by whatever winds are present in the surrounding environment. The powered phase requires feats of engineering both in the mechanism of ejection (8)(9)(10) and in the spacing and orientation of the gills or pores (11,12). However, spore size is the only attribute whose influence on the passive phase of dispersal has been studied (13). ...
Article
Thousands of basidiomycete fungal species rely on mushroom spores to spread across landscapes. It has long been thought that spores depend on favorable winds for dispersal-that active control of spore dispersal by the parent fungus is limited to an impulse delivered to the spores to carry them clear of the gill surface. Here we show that evaporative cooling of the air surrounding the pileus creates convective airflows capable of carrying spores at speeds of centimeters per second. Convective cells can transport spores from gaps that may be only 1 cm high and lift spores 10 cm or more into the air. This work reveals how mushrooms tolerate and even benefit from crowding and explains their high water needs.
... Moreover, one of the most notable characteristics of S. pararoseus is the process of ballistospores discharge. Ballistospores discharge is a unique type of spore produced by phylum Basidiomycetes fungi, however, does not occur in other fungal phyla [34]. As shown in Fig. 3, the S. pararoseus NGR was patched on agar medium to form colonies, and the ballistospores are vertically shot into the lid of the plate to form a "mirror" with their colonies. ...
Article
Full-text available
Background: Sporobolomyces pararoseus is regarded as an oleaginous red yeast, which synthesizes numerous valuable compounds with wide industrial usages. This species hold biotechnological interests in biodiesel, food and cosmetics industries. Moreover, the ballistospores-shooting promotes the colonizing of S. pararoseus in most terrestrial and marine ecosystems. However, very little is known about the basic genomic features of S. pararoseus. To assess the biotechnological potential and ballistospores-shooting mechanism of S. pararoseus on genome-scale, the whole genome sequencing was performed by next-generation sequencing technology. Results: Here, we used Illumina Hiseq platform to firstly assemble S. pararoseus genome into 20.9 Mb containing 54 scaffolds and 5963 predicted genes with a N50 length of 2,038,020 bp and GC content of 47.59%. Genome completeness (BUSCO alignment: 95.4%) and RNA-seq analysis (expressed genes: 98.68%) indicated the high-quality features of the current genome. Through the annotation information of the genome, we screened many key genes involved in carotenoids, lipids, carbohydrate metabolism and signal transduction pathways. A phylogenetic assessment suggested that the evolutionary trajectory of the order Sporidiobolales species was evolved from genus Sporobolomyces to Rhodotorula through the mediator Rhodosporidiobolus. Compared to the lacking ballistospores Rhodotorula toruloides and Saccharomyces cerevisiae, we found genes enriched for spore germination and sugar metabolism. These genes might be responsible for the ballistospores-shooting in S. pararoseus NGR. Conclusion: These results greatly advance our understanding of S. pararoseus NGR in biotechnological potential and ballistospores-shooting, which help further research of genetic manipulation, metabolic engineering as well as its evolutionary direction.
... Mechanistic knowledge of spore ejection ("liberation") processes can elucidate the key environmental criteria-and the timing-for spore release 3 . Epidemiological models can then be used to infer disease transmission leading to predictions regarding the distance of spore travel 4 , likely timing of subsequent infection 3 , and development of disease foci across fields or even continents 5 . Once spores of plant-associated fungi are liberated, they are dispersed via water, soil, vectors, or air (depending on their location in the plant), and the dispersal mode strongly influences the subsequent dispersal gradient 6 . ...
Article
Full-text available
Fungi have evolved an array of spore discharge and dispersal processes. Here, we developed a theoretical model that explains the ejection mechanics of aeciospore liberation in the stem rust pathogen Puccinia graminis. Aeciospores are released from cluster cups formed on its Berberis host, spreading early-season inoculum into neighboring small-grain crops. Our model illustrates that during dew or rainfall, changes in aeciospore turgidity exerts substantial force on neighboring aeciospores in cluster cups whilst gaps between spores become perfused with water. This perfusion coats aeciospores with a lubrication film that facilitates expulsion, with single aeciospores reaching speeds of 0.053 to 0.754 m·s⁻¹. We also used aeciospore source strength estimates to simulate the aeciospore dispersal gradient and incorporated this into a publicly available web interface. This aids farmers and legislators to assess current local risk of dispersal and facilitates development of sophisticated epidemiological models to potentially curtail stem rust epidemics originating on Berberis.
... Small, i.e. thinner-walled, spores would have fewer chances to survive gut passage. At the same time, larger spores are of advantage regarding a more effective ballistic liberation (Fischer et al. 2010). Note that thick-walled and melanised spores have conspicuous germ pores that allow for quick germination (Garnica et al. 2007). ...
Article
The spores of most coprophilous mushrooms require passage through a mammalian gut. Guts and faeces constitute a chemically and microbially aggressive environment. Hence, the spores need to be armed, e.g. by melanisation and thick walls, possibly leading to large spores due to volume constraints. Conversely, litter is a less stressful substrate that may become colonised by mushrooms with less fortified spores. Compared with litter, dung pats are spatially constrained, which limits mycelial growth. Small mycelia can only produce small fruit bodies. Moreover, on quickly perishing faeces, fruiting takes place under fierce competition by microbes and dung-dwelling invertebrates. Therefore, coprophilous mushrooms are forced to mature fast, implying small fruit bodies as well. Competition in spatially less constrained litter substrates can be pronounced but should not lead to quick nutrient depletion as in dung, hence would allow for mushroom assemblages with on average larger fruit bodies. To find evidence for our assumptions, we compiled a database of fruit body and spore sizes of mushroom genera which contain coprophilous species, comprising 633 (including ca. 20% coprophilous) species across 18 genera worldwide. The data set was subjected to a phylogenetically informed statistical analysis. Our hypotheses were confirmed though the selective pressure of the faecal environment appears to be more forceful on spores considering the fact that the mean spore size differences are more pronounced than differences in mean fruit body size. It would be worthwhile to further elucidate this phenomenon and the coprophilous trait syndrome in general with molecular methods.
... & Taipale, which are reported in boreal and Arctic environments of Europe; these were confirmed using molecular comparisons with environmental sequences from North American Caboň et al. 2019). Thus, large intercontinental distributions appear to be a pattern for Arctic and alpine ectomycorrhizal genera, which contrasts with data for temperate habitats that suggest that most ectomycorrhizal fungal species have small geographic distributions (Bazzicalupo et al. 2019) and that spore dispersal from basidiocarps appears limited (Fischer et al. 2010). Historical changes in glaciation, extensive host ranges ; , and possible long-distance dispersal could help explain these distributions (Geml et al. 2012;Timling et al. 2014). ...
Article
Full-text available
Russula (Russulales) is an important ectomycorrhizal fungal genus in Arctic and alpine regions where it occurs with Salix, Betula, Dryas, and Polygonum, yet a complex phylogenetic analysis of the genus in these habitats is lacking. This research compared collections of Russula from the Rocky Mountain alpine (Colorado, Montana, Wyoming) with reference specimens from Arctic and alpine habitats, mostly in Europe, using an in-depth morphological study and a phylogenetic analysis of the nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS barcode) and the second largest subunit of the RNA polymerase II gene (rpb2). One hundred thirty-nine Russula collections were sequenced, including type material. Ten species are reported from alpine or treeline habitats in the Rocky Mountains. This is the first formal report of R. cf. altaica, R. saliceticola, and R. subrubens from the Rocky Mountains and of R. purpureofusca in North America. Russula laevis is reported for the first time under this name with a voucher, and not as an environmental sample. Previous reports of R. nana and R. laccata are molecularly confirmed. Two species are reported from subalpine habitats at treeline: R. montana with conifers and R. cf. altaica with Betula. In this study, R. laccata, R. subrubens, and R. laevis were collected in alpine habitats but have been reported below treeline in Europe; these species may also be present at lower elevations in North America. Most species have an intercontinental distribution and have been reported in other alpine or Arctic habitats. Two unidentified and potentially new species were only found in North America and are discussed. A key to the alpine Russulas of North America is provided.
... Another possibility is that such fungal spores were discharged preferentially during precipitation. Indeed, agaricomycetes comprise a group of fungi that actively discharge spores primarily under humid conditions [5], including Stereum, Trametes, and Schizophyllum [54][55][56]. Peroneutypa has a closely related sordariomycete genus Eutypella [57] whose ascospores are discharged only when rainfall occurs [58]. Our observation suggests two non-mutually exclusive hypotheses: (1) spores serve as nuclei in clouds, and/or (2) spores are released selectively during precipitation. ...
Article
Full-text available
Fungi release spores into the global atmosphere. The emitted spores are deposited to the surface of the Earth by sedimentation (dry deposition) and precipitation (wet deposition), and therefore contribute to the global cycling of substances. However, knowledge is scarce regarding the diversities of fungi deposited from the atmosphere. Here, an automatic dry and wet deposition sampler and high-throughput sequencing plus quantitative PCR were used to observe taxonomic diversities and flux densities of atmospheric fungal deposition. Taxon-specific fungal deposition velocities and aerodynamic diameters (da) were determined using a collocated cascade impactor for volumetric, particle-size-resolved air sampling. Large multicellular spore-producing dothideomycetes (da ≥ 10.0 μm) were predominant in dry deposition, with a mean velocity of 0.80 cm s-1 for all fungal taxa combined. Higher taxonomic richness was observed in fungal assemblages in wet deposition than in dry deposition, suggesting the presence of fungal taxa that are deposited only in wet form. In wet deposition, agaricomycetes, including mushroom-forming fungi, and sordariomycetes, including plant pathogenic species, were enriched, indicating that such fungal spores serve as nuclei in clouds, and/or are discharged preferentially during precipitation. Moreover, this study confirmed that fungal assemblage memberships and structures were significantly different between dry and wet deposition (P-test, p < 0.001). Overall, these findings suggest taxon-specific involvement of fungi in precipitation, and provide important insights into potential links between environmental changes that can disturb regional microbial communities (e.g., deforestation) and changes in precipitation patterns that might be mediated by changes in microbial communities in the atmosphere.
... Presumably the natural shaking of leaves by wind injects some organisms into the air. Other organisms, such as ferns, 24,25 mosses 26,27 and fungi [28][29][30] (see also review by Sakes et al. 31 ) actively eject their spores into the air. Another example is described by Dressaire et al.: 32 cooling of air by evaporation from mushrooms causes air to come down from above and form a horizontal flow outward from the fungus. ...
Article
Many microorganisms are alive while suspended in the atmosphere, and some seem to be metabolically active during their time there. One of the most important factors threatening their life and activity is solar ultraviolet (UV) radiation. Quantitative understanding of the spatial and temporal survival patterns in the atmosphere, and of the ultimate deposition of microbes to the surface, is limited by a number factors some of which are discussed here. These include consideration of appropriate spectral sensitivity functions for biological damage (e.g. inactivation), and the estimation of UV radiation impingent on a microorganism suspended in the atmosphere. We show that for several bacteria (E. coli, S. typhimurium, and P. acnes) the inactivation rates correlate well with irradiances weighted by the DNA damage spectrum in the UV-B spectral range, but when these organisms show significant UV-A (or visible) sensitivities, the correlations become clearly non-linear. The existence of these correlations enables the use of a single spectrum (here DNA damage) as a proxy for sensitivity spectra of other biological effects, but with some caution when the correlations are strongly non-linear. The radiative quantity relevant to the UV exposure of a suspended particle is the fluence rate at an altitude above ground, while down-welling irradiance at ground-level is the quantity most commonly measured or estimated in satellite-derived climatologies. Using a radiative transfer model that computes both quantities, we developed a simple parameterization to exploit the much larger irradiance data bases to estimate fluence rates, and present the first fluence-rate based climatology of DNA-damaging UV radiation in the atmosphere.
... Cząstki aerozolu biologicznego obejmują stałe frakcje zawieszone w powietrzu i pochodzące od organizmów żywych, w tym drobnoustroje i nienaruszone lub rozdrobnione fragmenty komórkowe lub tkankowe zawierające materiał biologiczny, taki jak resztki roślin, czy złuszczony naskórek zwierzęcy. W skład organizmów lub struktur żywych występujących w postaci bioaerozolu wchodzą zarówno formy wegetatywne, jak i przetrwalne, między innymi bakterie [20][21][22][23][24][25], grzyby [26][27][28][29][30][31][32][33][34][35][36], porosty i protisty (w tym glony) [24,[37][38][39][40][41][42][43], pyłki roślin [43][44][45][46][47], archeowce [48][49][50][51], zarodniki, przetrwalniki i nasiona [29,30] oraz wirusy [4,[52][53][54][55]. Stałe fragmenty materiału biologicznego lub wydzieliny organizmów reprezentowane są natomiast przez rozdrobnione szczątki roślinne i zwierzęce (detrytus), fragmenty drobnoustrojów i odchodów, brochosomy, złuszczający się naskórek, włosy i sierść, a także metabolity organizmów, między innymi toksyny czy glukany [3,40,42,[56][57][58][59][60][61][62][63][64][65][66][67][68][69]. ...
Article
There are very few studies related to the characterization of biological components, especially fungal ones, present in the particulate matter (PM) of atmospheric aerosols in Brazil. The biogenic components of PM can have a direct relationship with respiratory diseases outbreaks and can also be linked to climate processes. Studies indicate that fungal spores constitute one of the major biological components present in the atmosphere and can be responsible for a significant amount of particulate mass concentration. This work aims to (i) identify the main fungal types in the atmosphere of São Paulo; (ii) estimate the fungal type concentrations and variations in the atmosphere; (iii) investigate the fungal spore seasonality; and (iv)estimate their diurnal behavior. In order to achieve that, a "Burkard 7-day Recording" air sampler operating at 10 L/min was used to collect spore samples on a 24/7 basis, from September 2013 to September 2014, at the main campus of the University of São Paulo, an area mostly impacted by vehicular emission and characterized by the presence of green areas. Fungal types were grouped considering their morphological similarity (i.e., cell number, coloration, shape and size) and predetermined taxonomic group (phylum, family and genus). After this initial classification, fungal types were grouped in three main groups, Ascomycota and Basidiomycota, which included only the teleomorph form of the fungi, and Deuteromycota, which includes the anamorph form of both phyla. Fungal types were characterized using an optical microscope, and 45 major fungal types were found, with Basidiomycota being the main phylum. The average concentration was 5736 (±2459) spores/m³ per day, with the highest concentration at 23780 spores/m³ in autumn at night and the lowest concentration at 567 spores/m³ in autumn in the morning. Higher concentrations of Ascospores (AS) and Basidiospores (BS) occurred in summer and spring, whereas Mitospores presented the highest concentration in winter and autumn. In addition, spore concentrations presented different profiles according to hourly variation, with the highest concentration of Total spores occurring at dawn. However, the concentration of Mitospores was higher during the afternoon, probably due to spore releasing mechanisms or to their transport. Ascomycota and Deuteromycota presented an antagonistic behavior in most situations.
Article
A polyethylene based packaging material containing nano-Ag, nano-TiO2, nano-SiO2, and attapulgite has been prepared. The effect of nanocomposite packaging material (Nano-PM) on the senescence of Flammulina velutipes during 15 days of postharvest storage at 4 °C and a relative humidity of 90% were analyzed. The results showed that compared with normal packaging material (Normal-PM) and no packaging (No-PM), Nano-PM improved the appearance quality, reduced weight loss and cap opening. The degree of maturity and increase in molecular weight of F. velutipes polysaccharides (FVP) were delayed. The content loss of proteoglycan protein was less and degree of oxidation was lower. The storage with Nano-PM reduced the fibrosis of texture, cellulase activity, the accumulation of hydrogen peroxide (H2O2) and superoxide radical (O2⁻) by 18.9%, 48.3%, 26.6% and 27.8%, respectively (P < .05). The Nano-PM effectively delayed the postharvest senescence of F. velutipes, hence prolonged its shelf life and increased its preservation quality.
Article
Basidiomycete fungi eject basidiospores using a surface tension catapult. A fluid drop forms at the base of each spore and, after reaching a critical size, coalesces with the spore and launches it from the gill surface. It has long been hypothesized that basidiomycete fungi pack the maximum number of spores into a minimal investment of biomass. Building on a nascent understanding of the physics underpinning the surface tension catapult, we modeled a spore’s trajectory away from a basidium and demonstrated that to achieve maximum packing the size of the fluid drop, the size of the spore, and the distance between gills must be finely coordinated. To compare the model with data, we measured spore and gill morphologies from wild mushrooms and compared measurements with the model. The empirical data suggest that in order to pack the maximum number of spores into the least amount of biomass, the size of Buller’s drop should be smaller but comparable to the spore size. Previously published data of Buller’s drop and spore sizes support our hypothesis and also suggest a linear scaling between spore radius and Buller’s drop radius. Morphological features of the surface tension catapult appear tightly regulated to enable maximum packing of spores. If mushrooms are maximally packed and Buller’s drop radii scale linearly with spore radii, we predict that intergill distance should be proportional to spore radius to the power 3/2.
Article
Full-text available
Field mycologists have a deep understanding of the morphological traits of basidiospores with regard to taxonomical classification. But often the increasing evidence that these traits have a biological meaning is overlooked. In this review we have therefore compiled morphological and ecological facts about basidiospores of agaricoid fungi and their functional implications for fungal communities as part of ecosystems. Readers are introduced to the subject, first of all by drawing attention to the dazzling array of basidiospores, which is followed by an account of their physical and chemical qualities, such as size, quantity, structure and their molecular composition. Continuing, spore generation, dispersal and establishment are described and discussed. Finally, possible implications for the major ecological lifestyles are analysed, and major gaps in the knowledge about the ecological functions of basidiospores are highlighted.
Article
Aquatic hyphomycetes strongly contribute to organic matter dynamics in streams but their abilities to colonize leaf litter buried in streambed sediments remain unexplored. Here, we conducted field and laboratory experiments (slow-filtration columns and stream-simulating microcosms) to test the following hypotheses: (a) that the hyporheic habitat acting as a physical sieve for spores filters out unsuccessful strategists from a potential species pool, (b) that decreased pore size in sediments reduces species dispersal efficiency in the interstitial water, and (c) that the physicochemical conditions prevailing in the hyporheic habitat will influence fungal community structure. Our field study showed that spore abundance and species diversity were consistently reduced in the interstitial water compared with surface water within three differing streams. Significant differences occurred among aquatic hyphomycetes, with dispersal efficiency of filiform-spore species being much higher than those with compact or branched/tetraradiate spores. This pattern was remarkably consistent with laboratory experiments that tested the influence of sediment pore size on spore dispersal in microcosms. Furthermore, leaves inoculated in a stream and incubated in slow filtration columns exhibited a fungal assemblage dominated by only two species while five species were co-dominant on leaves from the stream-simulating microcosms. Results of this study highlight that the hyporheic zone exerts two types of selection pressure on the aquatic hyphomycete community, a physiological stress and a physical screening of the benthic spore pool, both leading to drastic changes in the structure of fungal community.
Article
Plant pathogens are responsible for the annual yield loss of crops worldwide and pose a significant threat to global food security. A necessary prelude to many plant disease epidemics is the short-range dispersal of spores, which may generate several disease foci within a field. New information is needed on the mechanisms of plant pathogen spread within and among susceptible plants. Here, we show that self-propelled jumping dew droplets, working synergistically with low wind flow, can propel spores of a fungal plant pathogen (wheat leaf rust) beyond the quiescent boundary layer and disperse them onto neighboring leaves downwind. An array of horizontal water-sensitive papers was used to mimic healthy wheat leaves and showed that up to 25 spores/h may be deposited on a single leaf downwind of the infected leaf during a single dew cycle. These findings reveal that a single dew cycle can disperse copious numbers of fungal spores to other wheat plants, even in the absence of rain splash or strong gusts of wind.
Article
In the northwestern Himalayan mountains of India, the hypogeous sequestrate fungus Trappeindia himalayensis is harvested from forests dominated by the ectomycorrhizal tree Cedrus deodara (Himalayan cedar). This truffle has basidiospores that are ornamented with raised reticulation. The original description of Trappeindia himalayensis suggested that the gleba of this species is similar to young specimens of Scleroderma (Boletales), whereas its basidiospores are ornamented with raised reticulation, suggesting a morphological affinity to Leucogaster (Russulales) or Strobilomyces (Boletales). Given this systematic ambiguity, we have generated DNA sequence data from type material and other herbarium specimens and present the first molecular phylogenetic analysis of this unusual Cedrus-associated truffle. Despite the irregular ornamented basidiospore morphology, T. himalayensis is resolved within the genus Rhizopogon (Suillineae, Boletales) and represents a unique lineage that has not been previously detected. All known Rhizopogon species possess an ectomycorrhizal trophic mode, and because of its placement in this lineage, it is likely that Trappeindia himalayensis is an ectomycorrhizal partner of Cedrus deodara. This study highlights the importance of generating sequence data from herbarium specimens in order to identify fungal biodiversity and clarify the systematic relationships of poorly documented fungi.
Thesis
The aim of this thesis is to develop experiments to understand the physics of motility in two microbial systems, living in the realm of low Reynolds number, i.e. when viscous forces dominate over inertial forces. The first part of the thesis discusses the growth of bacterial biofilms over a solid surface. Bacterial biofilms are communities of cells closely packed together inside a polymeric matrix. From the physical viewpoint, these colonies behave as gels and the polymeric matrix creates osmotic fluxes that enable biofilms to grow and move on a surface as a community. Here I develop an experiment to explore biofilm collective motility in contact with external gradients of osmotic pressure. To produce stable osmotic gradients in agar gels, I develop a custom-made setup through millifluidics. Biofilms respond to the external gradient by developing an asymmetric shape, consistent with the expectations. The second part of the thesis discusses the spore discharge mechanism in the fungal phylum Basidiomycetes. In these species, a drop coalesces with the spore, which results in spore discharge at enormous accelerations. This surface tension catapult reaches its maximum efficiency when the size of the drop is comparable to that of the spore. I study morphologies of several gilled mushrooms, where spores are packaged at the surface of complex shaped gills. I find that for those species, drop size must be precisely controlled. This poses the question of how mushrooms may regulate a process that occurs extracellularly, despite fluctuating physical conditions.
Article
Full-text available
Most basidiomycete fungi actively eject their spores. The process begins with the condensation of a water droplet at the base of the spore. The fusion of the droplet onto the spore creates a momentum that propels the spore forward. The use of surface tension for spore ejection offers a new paradigm to perform work at small length scales. However, this mechanism of force generation remains poorly understood. To elucidate how fungal spores make effective use of surface tension, we performed a detailed mechanical analysis of the three stages of spore ejection: the transfer of energy from the drop to the spore, the work of fracture required to release the spore from its supporting structure and the kinetic energy of the spore after ejection. High-speed video imaging of spore ejection in Auricularia auricula and Sporobolomyces yeasts revealed that drop coalescence takes place over a short distance ( approximately 5 microm) and energy transfer is completed in less than 4 mus. Based on these observations, we developed an explicit relation for the conversion of surface energy into kinetic energy during the coalescence process. The relation was validated with a simple artificial system and shown to predict the initial spore velocity accurately (predicted velocity: 1.2 m s(-1); observed velocity: 0.8 m s(-1) for A. auricula). Using calibrated microcantilevers, we also demonstrate that the work required to detach the spore from the supporting sterigma represents only a small fraction of the total energy available for spore ejection. Finally, our observations of this unique discharge mechanism reveal a surprising similarity with the mechanics of jumping in animals.
Article
Full-text available
Spore discharge in the majority of the 30,000 described species of Basidiomycota is powered by the rapid motion of a fluid droplet, called Buller's drop, over the spore surface. In basidiomycete yeasts, and phytopathogenic rusts and smuts, spores are discharged directly into the airflow around the fungal colony. Maximum discharge distances of 1-2 mm have been reported for these fungi. In mushroom-forming species, however, spores are propelled over much shorter ranges. In gilled mushrooms, for example, discharge distances of <0.1 mm ensure that spores do not collide with opposing gill surfaces. The way in which the range of the mechanism is controlled has not been studied previously. In this study, we report high-speed video analysis of spore discharge in selected basidiomycetes ranging from yeasts to wood-decay fungi with poroid fruiting bodies. Analysis of these video data and mathematical modeling show that discharge distance is determined by both spore size and the size of the Buller's drop. Furthermore, because the size of Buller's drop is controlled by spore shape, these experiments suggest that seemingly minor changes in spore morphology exert major effects upon discharge distance. This biomechanical analysis of spore discharge mechanisms in mushroom-forming fungi and their relatives is the first of its kind and provides a novel view of the incredible variety of spore morphology that has been catalogued by traditional taxonomists for more than 200 years. Rather than representing non-selected variations in micromorphology, the new experiments show that changes in spore architecture have adaptive significance because they control the distance that the spores are shot through air. For this reason, evolutionary modifications to fruiting body architecture, including changes in gill separation and tube diameter in mushrooms, must be tightly linked to alterations in spore morphology.
Article
Full-text available
A variety of spore discharge processes have evolved among the fungi. Those with the longest ranges are powered by hydrostatic pressure and include "squirt guns" that are most common in the Ascomycota and Zygomycota. In these fungi, fluid-filled stalks that support single spores or spore-filled sporangia, or cells called asci that contain multiple spores, are pressurized by osmosis. Because spores are discharged at such high speeds, most of the information on launch processes from previous studies has been inferred from mathematical models and is subject to a number of errors. In this study, we have used ultra-high-speed video cameras running at maximum frame rates of 250,000 fps to analyze the entire launch process in four species of fungi that grow on the dung of herbivores. For the first time we have direct measurements of launch speeds and empirical estimates of acceleration in these fungi. Launch speeds ranged from 2 to 25 m s(-1) and corresponding accelerations of 20,000 to 180,000 g propelled spores over distances of up to 2.5 meters. In addition, quantitative spectroscopic methods were used to identify the organic and inorganic osmolytes responsible for generating the turgor pressures that drive spore discharge. The new video data allowed us to test different models for the effect of viscous drag and identify errors in the previous approaches to modeling spore motion. The spectroscopic data show that high speed spore discharge mechanisms in fungi are powered by the same levels of turgor pressure that are characteristic of fungal hyphae and do not require any special mechanisms of osmolyte accumulation.
Article
Full-text available
Ballistospore discharge is a feature of 30000 species of mushrooms, basidiomycete yeasts and pathogenic rusts and smuts. The biomechanics of discharge may involve an abrupt change in the center of mass associated with the coalescence of Buller's drop and the spore. However this process occurs so rapidly that the launch of the ballistospore has never been visualized. Here we report ultra high-speed video recordings of the earliest events of spore dispersal using the yeast Itersonilia perplexans and the distantly related jelly fungus Auricularia auricula. Images taken at camera speeds of up to 100,000 frames/ s demonstrate that ballistospore discharge does involve the coalescence of Buller's drop and the spore. Recordings of I. perplexans demonstrate that although coalescence may result from the directed collapse of Buller's drop onto the spore, it also may involve the movement of the spore toward the drop. The release of surface tension at coalescence provides the energy and directional momentum to propel the drop and spore away from the fungus. Analyses show that ballistospores launch into the air at initial accelerations in excess of 10,000 g. There is no known analog of this micromechanical process in animals, plants or bacteria, but the recent development of a surface tension motor may mimic the fungal biology described here.
Article
Aleurodiscus gigasporus sp. nov. is characterized by ornamented, broadly ellipsoid basidiospores 29-34(-39) × 22-28(-30) μm, abundant acanthophyses, rare monilioid gloeocystidia 6 μm diam, and hyphae with clamp connections. It has been collected on Keteleeria davidiana. Aleurodiscus subglobosporus sp. nov. is characterized by subglobose, ornamented basidiospores 19-20(-23) × 15-19(-21) μm, abundant acanthophyses, infrequent gloeocystidia about 100 × 12 μm, and hyphae with clamp connections. It has been collected on Abies veichii.
Article
Ballistospores of basidiomycete fungiform at the tips of spear-shaped projections called sterigmata that extend from basidia. At maturity, a spherical drop of fluid appears at the base of each spore, and a few seconds later the spore is propelled into the surrounding air. The development of the fluid drop was first reported in 1889, but a century of innovative research was necessary to solve the mechanistic link between the drop and spore discharge. Through an extraordinary series of experiments the composition of the drop has now been established, its development is explained, and an effective solution to the relationship between drop appearance and spore discharge has been proposed. Drop formation is initiated when a femtomole quantity of mannitol and hexoses is excreted from a specific site at the base of the spore, forming a hygroscopic nucleus upon which water condenses from the surrounding air. Discharge of the spore occurs when the drop fuses with a film of liquid that curves over the adjacent spore surface. This rapid coalescence results in a decrease in surface free energy within the liquid and displaces the center of mass of the spore. The change in weight distribution exerts a force that is opposed by the pressurized sterigma, and the spore is shot away from the basidium into the surrounding air. The mechanism is described as a surface-tension catapult. During discharge, ballistospores are subjected to an acceleration of 25 000 g, which is about ten thousand times the acceleration experienced by astronauts during the launch of the Space Shuttle! Even more impressive is the fact that while the Shuttle consumes 50% of its weight in fuel in the first 2 min of flight, ballistospore discharge is fueled by the mannitol and hexoses that cause water to condense on the spore surface, and these solutes represent only 1% of the mass of the spore.
Article
The mechanism of ballistospore self-propulsion by basidiomycetes involves the hygroscopic adsorption of water vapour by a drop of liquid (Buller's drop) on the hilar appendix of the spore until it makes contact with another expanding drop, the adaxial drop on the face of the spore above it. Aliquots of liquid from Buller's drop have been collected from Itersonilia perplexans using micropipettes. Analysis of the droplets by microfluorescence assays indicated the presence of mannitol and hexoses. Using the same technique, washings from basidiospore deposits of I. perplexans, containing the evaporated remnants of Buller's drops and the adaxial drops carried away by the spores on discharge, were further shown to contain mannitol and hexoses. Glc analyses of washings from spore deposits of a range of basidiomycetes also indicated the presence of mannitol and hexoses. Calculations based on the estimated concentrations of mannitol and hexoses in Buller's drop from Itersonilia show that the concentration of solutes is sufficient to bring about the condensation of water vapour from a saturated atmosphere and thus to cause the growth of Buller's drop at rates previously measured. When brought close to, but not in contact with, the surface of an agar plate, crystals of pure mannitol rapidly deliquesced. Mannitol and hexoses contribute significantly to the hygroscopic nature of Buller's drop in basidiomycetes.
Article
Ballistospore discharge in Itersonilia perplexans is described. Evidence is presented that a drop of liquid, and not a gas bubble, develops at the hilar appendix immediately before discharge. Spores detached on a micromanipulator needle produce liquid drops. The trajectories of several spores have been plotted. The horizontal and vertical distances of discharge have been measured, and the terminal velocity of sedimentation. From these values, the initial discharge velocity has been estimated at 5.5 m s−1. Evidence is presented that discharged spores carry a negative electrical charge. Two possible mechanisms for spore projection are discussed, a rapid transference of the centre of mass of the spore associated with wetting, and a change in the electrical charge on the spore surface at wetting, followed by electrostatic repulsion.
Article
A revised classification of Oudemansiella is presented, incorporating both Oudemansiella s.str. and Xerula within a single genus. The following taxa are proposed: Oudemansiella sect. Dactylosporina (Clemencon) stat.nov., Oudemansiella americana (Dorfelt) comb.nov., O. japonica (Dorfelt) comb.nov., and var. ahmadii (Dorfelt) comb.nov., var. colensoi (Dorfelt) comb.nov., O. pudens (Pers.) comb.nov. and var. fusca (Lucand ex Quel.) comb. nov., O. radicata var. africana (Dorfelt) comb.nov., var. alba (Dorfelt) comb.nov., var. australis (Dorfelt) comb. nov., var. furfuracea (Peck) comb. nov., var. hygrophoroides (Singer & Clemencon) comb. nov., var. rubescens (Melik-Chacatrajan) comb.nov., var. superbiens (Berk.) comb, nov., O. raphanipes (Berk.) comb.nov. Keys are provided to subgenera, species and varieties. Species of both Megacollybia and Mycenella are excluded from the genus. A detailed account of basidiospore structure within the genus, which provides evidence in support of the proposed classification, is presented. The tegumental layers of the spore wall comprise a thick coriotunica, incorporating variable development of a corium and an epitunica, and a myxosporium, which is often differentiated into a podostratum, mucostratum and a fragmenting sporothecium. Epitunica ornamentation is confirmed in the section Albotomentosi.
Article
Smooth patch is a pathological bark lesion. The disease causes the outer and corky regions of the bark to flake off. Although saprophytic, it indirectly affects the health of a tree through the reduced bark thickness and the consequent decreased protection against desiccation, wood-destroying fungi and mechanical injury.
Article
Basidiospores oiCoprinus cinereus were examined before and during spore discharge using light microscopy, and SEM of frozen-hydrated and other preparations. The process of droplet development at the hilar appendix was divided into three stages: pre-droplet, early and late enlargement. The fully expanded droplet was preserved only in frozen-hydrated specimens. Two-step droplet enlargement was also observed with TEM in Boletus rubinellus, and the droplet at the early enlargement stage was enclosed by a trilaminate membrane. The droplet was not observed in Auricularia species, but basidiospore preservation for SEM was optimum in Auricularia auricula with frozen-hydrated preparations. The hilar appendix of Auricularia fuscosuccinea as studied by TEM was simple compared with those of the Homobasidiomycetes. The implications of the data for evolution of the ballistosporic basidiospore and the discharge mechanism are considered.
Article
Evidence is presented in support of the hypothesis that the expansion of Buller's drop on basidiospores is by condensation of water vapour around hygroscopic material extruded from the hilar appendix. Earlier work had shown that detached ballistospores of Itersonilia could still develop Buller's drop which could attain 60% of the volume of the spore, but with no measurable decrease in spore size. Using time-lapse photomicrography it was shown that in 8 basidiomycetes including Uredinales, Homo- and Heterobasidiomycetes, drop expansion was not associated with reduction in basidiospore dimensions. The rate of drop expansion in a near-saturated atmosphere over water-agar was similar in 5 basidiomycetes. In Auricularia auricula-judae the rate of drop expansion could be controlled by lowering the water activity of the agar by the addition of 1–3% mannitol. When liquid which condensed around basidiospores of Agaricus bisporus on a cooled microscope slide was evaporated, a hygroscopic residue remained. In a theoretical treatment of the expansion of a drop by condensation from a saturated atmosphere around hygroscopic material it is shown that the expansion of a drop to a radius of 4 μm in 10–14 s could be achieved by a lowering of the water vapour pressure at the surface of the drop equivalent to a relative saturation deficit of about 1·5 × 10−3. This suggests that a low solute concentration of the order of 0·08 m in the drop would be sufficient. It is also shown that the shape of the drop expansion curves is consistent with the physical principles involved.
Chapter
Movement is one of the defining characteristics of living organisms. Contrary to common perceptions, fungi show a remarkable range of motion. Motion inside fungal cells, including mass flow of cytoplasm, was first observed by Antonie van Leewenhoek and influenced the eighteenth-century view of fungi as an eccentric branch of the animal kingdom (Ainsworth 1976). This flow of cytoplasm accompanies the extension of hyphae, and there are a number of similarities between this growth process and amoeboid locomotion (Heath and Steinberg 1999). Faster movements include invertebrate capture by constricting rings and microscopic harpoons (Müller 1958; Beakes and Glocking 1998) and a series of spectacular mechanisms that launch fungal spores into air (Ingold 1971). Spore discharge and dispersal are related and it is important to distinguish between them. Discharge refers to the mechanical process that separates the spore, or sporangium, from its parent mycelium; dispersal follows discharge. Both processes are vital to the activities of phytopathogens. This chapter emphasizes spore discharge in pathogens, but mechanisms among saprobes are also discussed to provide an overview of the diversity of launch processes among the fungi.
Article
Gilled mushrooms are produced by multiple orders within the Agaricomycetes. Some species form a single array of unbranched radial gills beneath their caps, many others produce multiple files of lamellulae between the primary gills, and branched gills are also common. In this largely theoretical study we modeled the effects of different gill arrangements on the total surface area for spore production. Relative to spore production over a flat surface, gills achieve a maximum 20-fold increase in surface area. The branching of gills produces the same increase in surface area as the formation of free-standing lamellulae (short gills). The addition of lamellulae between every second gill would offer a slightly greater increase in surface area in comparison to the addition of lamellulae between every pair of opposing gills, but this morphology does not appear in nature. Analysis of photographs of mushrooms demonstrates an excellent match between natural gill arrangements and configurations predicted by our model.
Article
Studies on the discharge of ballistospores by Sporobolomyces holsaticus have shown that the ejection mechanism resides exclusively in the spore. They support Olive's contention that the spore is propelled by the sudden rupture of a gas-filled vesicle which is formed between the inner and outer layers of the wall at the hilar end of the spore. Evidence based on microscopic observations, micromanipulation, and electron microscopy is presented. In addition to gas, liquid is also released during spore discharge. An explanation of the discharge mechanism is presented which accommodates earlier and conflicting views.
Article
Since wind speed drops to zero at a surface, forced ejection should facilitate spore dispersal. But for tiny spores, with low mass relative to surface area, high ejection speed yields only a short range trajectory, so pernicious is their drag. Thus, achieving high speeds requires prodigious accelerations. In the ascomycete Gibberella zeae, we determined the launch speed and kinetic energy of ascospores shot from perithecia, and the source and magnitude of the pressure driving the launch. We asked whether the pressure inside the ascus suffices to account for launch speed and energy. Launch speed was 34.5 ms-1, requiring a pressure of 1.54 MPa and an acceleration of 870,000 g--the highest acceleration reported in a biological system. This analysis allows us to discount the major sugar component of the epiplasmic fluid, mannitol, as having a key role in driving discharge, and supports the role of potassium ion flux in the mechanism.
Article
The ascomycetous fungi produce prodigious amounts of spores through both asexual and sexual reproduction. Their sexual spores (ascospores) develop within tubular sacs called asci that act as small water cannons and expel the spores into the air. Dispersal of spores by forcible discharge is important for dissemination of many fungal plant diseases and for the dispersal of many saprophytic fungi. The mechanism has long been thought to be driven by turgor pressure within the extending ascus; however, relatively little genetic and physiological work has been carried out on the mechanism. Recent studies have measured the pressures within the ascus and quantified the components of the ascus epiplasmic fluid that contribute to the osmotic potential. Few species have been examined in detail, but the results indicate diversity in ascus function that reflects ascus size, fruiting body type, and the niche of the particular species.
Introduction to Fungi Ballistospore discharge in Itersonilia perplexans
  • J Webster
  • Weber
Webster J, Weber RWS, 2007. Introduction to Fungi. Cambridge University Press, Cambridge. Webster J, Davey RA, Duller GA, Ingold CT, 1984. Ballistospore discharge in Itersonilia perplexans. Transactions of the British Mycological Society 82: 13e29.
Ultrastructure and evolution of ballistosporic basidiospores. Botanical Journal of the Linnean Society 91: 253e271. Money NP, 1998. More g's than the Space Shuttle: the mechanism of ballistospore discharge Biomechanics of spore discharge in phytopathogens The Mycota
  • Ingold
  • Ct
Ingold CT, 2001b. Range in size and form of basidiospores and ascospores. Mycologist 15: 165e166. McLaughlin DJ, Beckett A, Yoon KS, 1985. Ultrastructure and evolution of ballistosporic basidiospores. Botanical Journal of the Linnean Society 91: 253e271. Money NP, 1998. More g's than the Space Shuttle: the mechanism of ballistospore discharge. Mycologia 90: 547e558. Money NP, Fischer MWF, 2009. Biomechanics of spore discharge in phytopathogens. In: Deising H (ed), The Mycota, Volume 5, Plant Relationships, 2nd edn. Springer Verlag, New York, pp. 115e133. Mü ller D, 1954. Die Abschleuderung der Sporen von Sporobolomy-ces-Spiegelhefe-gefilmt. Friesia 5: 65e74.
Fungal cannons: explosive spore discharge in the Ascomycota Mushroom spores e the analysis of Buller's drop On the mechanism of ballistospore discharge
  • F Trail
  • Turner
  • Jcr
  • Webster
Trail F, 2007. Fungal cannons: explosive spore discharge in the Ascomycota. FEMS Microbiology Letters 276: 12e18. Turner JCR, Webster J, 1995. Mushroom spores e the analysis of Buller's drop. Chemical Engineering Science 50: 2359e2360. Van Neil CB, Garner GE, Cohen AL, 1972. On the mechanism of ballistospore discharge. Archiv fü r Mikrobiologie 84: 129e140.
Ballistospore discharge
  • Webster
Webster J, Chen C-Y, 1990. Ballistospore discharge. Transactions of the Mycological Society of Japan 31: 301e315.
Comparative Morphology and Taxonomy of the Fungi Mycetozoa and Bacteria (English translation)
  • A De Bary
De Bary, A. Comparative Morphology and Taxonomy of the Fungi Mycetozoa and Bacteria (English translation). Oxford: Clarendon Press; 1887.
  • Ahr Buller
Buller, AHR. Researches on Fungi. Vol. vol. 1. London: Longmans, Green & Company; 1909.
  • R L Gilbertson
  • L Ryvarden
Gilbertson, RL.; Ryvarden, L. North American Polypores. Vol. vol. 1. Oslo, Norway: Fungiflora A/S; 1986.
  • J Webster
  • C-Y Chen
  • Ballistospore Discharge
Webster J, Chen C-Y. Ballistospore discharge. Transactions of the Mycological Society of Japan 1990;31:301-315.
Biomechanics of spore discharge in phytopathogens
  • N P Money
  • Mwf Fischer
Money, NP.; Fischer, MWF. Biomechanics of spore discharge in phytopathogens. In: Deising, H., editor. The Mycota, Volume 5, Plant Relationships. 2nd edition. New York: Springer Verlag; 2009. p. 115-133.
Vapor as the source of water in Buller’s drop
  • Webster