- Email: [email protected]
Mycological Research News
mycological research 112 (2008) 611–612
journal homepage: www.elsevier.com/locate/mycres
Mycological Research News1 In this issue Protection of old-growth forest fungi in the Pacific Northwest [Review] (pp. 613–638). Molecular phylogeny of Neoerysiphe (pp. 639–649). Community structure of Phialocephala fortinii in European tree nurseries (pp. 650–662). Clonal lineages in Australian Puccinia graminis f. sp. avenae (pp. 663–673). Ecology of polypores in Micaronesian flooded forests (pp. 674–680). Ectomycorrhizal mycelial species in apatite-amended bags in a spruce forest (pp. 681–688). Oomycete communities in declining Phragmites australis stands (pp. 689–696). Habitat colonization models in eumyxetozoans (pp. 697–707). Downregulation of arginosuccinate lyase in Agaricus bisporus (pp. 708–716). Sensitivity of fungi to lithium chloride in culture media (pp. 717–724). Isoforms of malic enzyme in Mortierella alpina (pp. 725–730). A rugulosin-producing endophyte in Picea glauca seedlings (pp. 731–736). Cloning and characteristics of BcatrA in Botryotinia fuckeliana (pp. 737–746). Oxidative stress responses in Paracoccidioides brasiliensis (pp. 747–756).
Multidrug resistance in fungi Resistance to a range of drugs has become an important issue for the successful treatment of opportunistic infections by Candida species of people with compromised immunity, especially those with AIDS. In order to understand the basis of multidrug resistance, Thakur et al. (2008) studied the phenomenon in C. glabrata, in which a Pdrlp orthologue that regulates drug efflux pumps and controls is known. Transcription signalling mechanisms have a role in regulating detoxification enzymes in mammals, but had not previously been demonstrated in non-vertebrates. They showed that the Pdrlp orthologues of C. glabrata and Saccharomyces cerevisiae bound xenobiotics to activate genes encoding efflux pumps in a similar manner to the vertebrate receptor PXR. This fresh understanding of the regulatory pathway in fungi exposes new targets for therapeutic treatment of multidrug resistant fungal infecions. Thakur JK, Arthanari H, Yang F, Pan S-J, Fan X, Breger J, Freuh DP, Gulshan K, Li DK, Mylonakis E, Struhl K, Moye-Rowley WS, Cormack BP, Wagner G, Na¨a¨r AM, 2008. A nuclear receptor-like pathway regulating multidrug reistence in fungi. Nature 452: 604–609.
Have carnivorous fungi been found in Cretaceous amber? In a recent note in Science, Schmidt et al. (2007) report what they interpret as fossil evidence of a nematode-trapping fungus in a specimen of Cretaceous amber (ca 100 Myr old) from France. This paper has had great impact in the popular online press. The authors show photographs of a yeast-like fungus reminiscent of Debaryomyces hansenii (fig. 1 C–D and S1 B), one-celled rings that they consider sticky nematode-trapping devices (fig. 1 A-B, S1 A and S1 D), and nematodes found nearby (fig. S1 C-D). None of the photographs shows a ring attached to a sporulating hypha, nor was any trapped nematode documented (those shown are too slender to have been captured by the purported ‘‘traps’’). In a drawing (fig. 1E) the authors present a reconstructed life-cycle showing a trapped nematode in a ring, rings attached to a hypha, formation of a ring before closure, and a blastosporic yeast. We have tried to obtain the slides deposited in Paris on loan without any success, and our reaction here therefore relies on the photographs published by Schmidt et al. Fungi that trap nematodes with adhesive or constricting rings are members of the Orbiliomycetes, one of the oldest classes of phylum Ascomycota, and oldest in subphylum Pezizomycotina. Their segregation must have occurred much earlier than in Cretaceous times (Spatafora et al. 2007). Taylor & Berbee (2007) give a conservative estimate for the radiation of the Pezizomycotina of 215–400 Myr before present. Finding orbiliaceous structures in Cretaceous amber would be exciting but not at all surprising. Ascomycetous yeasts of the Saccharomycotina diverged prior to the Orbiliomycetes (Spatafora et al. 2007). A connection between a ‘‘trapping fungus’’ and a yeast is unlikely, and we consider that the published picture is probably an artefact of the two organisms being closely associated in space (perhaps only as a result of being captured in resin). The more organic connection between short conidiogenous cells and a main hypha shown in their fig. 1C illustrates a structure presently unknown in the Orbiliomycetes and would preclude the identification of these hyphae as belonging to the Orbiliaceae. Non-constricting ring traps are only known from the genus Dactylellina (Scholler et al. 1999). The rings are three-celled, with three septa, not one as shown by Schmidt et al. (2007),
1 Mycological Research News is compiled by the Senior Editor, David L. Hawksworth, Departamento de Biologı´a Vegetal II, Facultad de Farmacia, Universidad Complutense de Madrid, Plaza Ramo´n y Cajal, Ciudad Universitaria, ES-28040 Madrid, Spain (e-mail: d.hawks [email protected]), to whom items for inclusion should be sent. Unsigned items are by the Senior Editor.
612
and are stalked. A nematode that enters a loop would be stopped if its body diameter exceeds the loop diameter. Nematodes are unable to move backwards, so they continue to try to move forward and get jammed. Their struggle breaks the ring from the stalk and the nematode glides away with the ring around its body. The attached ring germinates to form an infection peg that penetrates the nematode, and forms an infection bulb, followed by digestion of the body contents. The ring thus not only serves as a trapping device but also as a diaspore. Schmidt et al. write that the rings are ‘‘probably detached easily from the supporting hyphae and are found dissociated from the mycelium.’’ In Dactylellina, rings are detached only after intense struggling of captured nematodes, and detached rings are only found attached to nematodes, not lying on the substrate where they would no longer be in the position to catch passing prey. The attachment of detritus to the rings as shown by Schmidt et al. (2007, fig. S1 A) most probably is due to unspecific binding. The rings even of adhesive traps are not sticky all over and do not collect detritus. An adhesive non-constricting ring trap cannot function, because the nematode would get caught on the ring before entering it. Regrettably, fossil records of fungi are scanty and, with a few notable exceptions (e.g. Hibbett et al. 1997), the morphology preserved in these fossils is suggestive but inconclusive for identification. With all due respect for the importance of fossil documents, we are not prepared to accept the unlikely combination of ring-shaped traps and yeast-like growth as compatible with nematode capturing, which in the photographs of Schmidt et al. (2007) is not convincingly proven. Evidently, the structure of the prey and the predacious organs must be commensurate if they are to function. In view of the relatively few well-identifiable fossil fungal records showing an amazing constancy of features through millions of years (Dotzler et al. 2006), we warn against postulating combinations of unusual features in a single hypothetic fossilized organism with functions that are not sufficiently proven. In nature quite different organisms are always densely entangled, thus mimicking a variation that more careful and informed analysis resolves as a mixture.
We acknowledge the constructive suggestions from Birgit Nordbring-Hertz, Hans-Bo¨rje Jansson, David S Hibbett, Annemarthe Rubner, and Walter Sudhaus. George Barron independently forwarded a similar view towards National Geographic News (UK) and Scientific American Magazine. In a reaction to our draft, Schmidt et al. contributed arguments that served only to re-inforce our interpretation and sharpen our statements. Dotzler N, Krings M, Taylor TN, Agerer R, 2006. Germination shields in Scutellospora (Glomeromycota: Diversisporales, Gigasporaceae) from the 400 million-year-old Rhynie Chert. Mycological Progress 5: 178–184. Hibbett DS, Grimaldi D, Donoghue M, 1997. Fossil mushrooms from Miocene and Cretaceous ambers and the evolution of homobasidiomycetes. American Journal of Botany 84: 981–991. Schmidt AR, Do¨rfelt H, Perrichot V, 2007. Carnivorous fungi from Cretaceous amber. Science 318: 1743 and supporting online material. Scholler M, Hagedorn G, Rubner A, 1999. A reevaluation of predatory orbiliaceous fungi. II. A new generic concept. Sydowia 51: 89–113.
D. L. Hawksworth
Spatafora JW, 32 others, 2007 [‘‘2006’’]. A five-gene phylogeny of Pezizomycotina. Mycologia 98: 1018–1028. Taylor JW, Berbee ML, 2007 [‘‘2006’’]. Dating divergences in the Fungal Tree of Life: review and new analyses. Mycologia 98: 838–849.
R. Greg Thorn Department of Biology, University of Western Ontario, 1151 Richmond Street North London, Ontario N6A 5B7, Canada E-mail address: [email protected] Markus Scholler Staatliches Museum fu¨r Naturkunde, Erbprinzenstr. 13, D-76133 Karlsruhe, Germany Walter Gams Molenweg 15, 3743 CK Baarn, The Netherlands
A ‘fungal loop’ in the nitrogen cycle of aridland ecosystems In a review of pulse dynamics and microbial processes in aridland ecosystems Collins et al. (2008) incorporated findings from pulse-reserve models. These models postulate that episodic precipitation events stimulate biological activity and generate biomass. They find that fungi play a critical and underappreciated role in carbon and nitrogen dynamics in aridland soils which affect decomposition, nitrification and other transformations, nutrient storage, and translocation of these compounds between plants and biotic soil crusts. The nitrogen ‘fungal loop’ they describe, integrates spatial structure and pulse dynamics and further extends the pulsereserve paradigm to include the key microbial processes in aridland ecosystems. High temperatures and low precipitation favour fungi over bacteria in these ecosystems, and, consequently, the fungi drive the below-ground decomposition, forming a complex hyphal network (the ‘fungal loop’) which integrates biotic crusts on the surface with patches of vegetation. While this result may not be unexpected to fungal ecologists, it is gratifying to see this topic featured in a leading review of one of the main ecological journals. Figure 1 in Collins et al.’s review, which links the ‘fungal loop’ to environmental conditions that favour it, is especially lucid and may be expected to find use in lectures on the role of fungi in ecosystem processes. Collins SL, Sinsabaugh RL, Crenshaw C, Green L, Porras-Alfaro A, Stursova M, Zeglin LH, 2008. Pulse dynamics and microbial processes in aridland ecosystems. Journal of Ecology 96: 413–420.
New scientific name in this issue Oidium aloysiae sp. nov.
0953-7562/$ – see front matter doi:10.1016/j.mycres.2008.04.012
journal homepage: www.elsevier.com/locate/mycres
Mycological Research News1 In this issue Protection of old-growth forest fungi in the Pacific Northwest [Review] (pp. 613–638). Molecular phylogeny of Neoerysiphe (pp. 639–649). Community structure of Phialocephala fortinii in European tree nurseries (pp. 650–662). Clonal lineages in Australian Puccinia graminis f. sp. avenae (pp. 663–673). Ecology of polypores in Micaronesian flooded forests (pp. 674–680). Ectomycorrhizal mycelial species in apatite-amended bags in a spruce forest (pp. 681–688). Oomycete communities in declining Phragmites australis stands (pp. 689–696). Habitat colonization models in eumyxetozoans (pp. 697–707). Downregulation of arginosuccinate lyase in Agaricus bisporus (pp. 708–716). Sensitivity of fungi to lithium chloride in culture media (pp. 717–724). Isoforms of malic enzyme in Mortierella alpina (pp. 725–730). A rugulosin-producing endophyte in Picea glauca seedlings (pp. 731–736). Cloning and characteristics of BcatrA in Botryotinia fuckeliana (pp. 737–746). Oxidative stress responses in Paracoccidioides brasiliensis (pp. 747–756).
Multidrug resistance in fungi Resistance to a range of drugs has become an important issue for the successful treatment of opportunistic infections by Candida species of people with compromised immunity, especially those with AIDS. In order to understand the basis of multidrug resistance, Thakur et al. (2008) studied the phenomenon in C. glabrata, in which a Pdrlp orthologue that regulates drug efflux pumps and controls is known. Transcription signalling mechanisms have a role in regulating detoxification enzymes in mammals, but had not previously been demonstrated in non-vertebrates. They showed that the Pdrlp orthologues of C. glabrata and Saccharomyces cerevisiae bound xenobiotics to activate genes encoding efflux pumps in a similar manner to the vertebrate receptor PXR. This fresh understanding of the regulatory pathway in fungi exposes new targets for therapeutic treatment of multidrug resistant fungal infecions. Thakur JK, Arthanari H, Yang F, Pan S-J, Fan X, Breger J, Freuh DP, Gulshan K, Li DK, Mylonakis E, Struhl K, Moye-Rowley WS, Cormack BP, Wagner G, Na¨a¨r AM, 2008. A nuclear receptor-like pathway regulating multidrug reistence in fungi. Nature 452: 604–609.
Have carnivorous fungi been found in Cretaceous amber? In a recent note in Science, Schmidt et al. (2007) report what they interpret as fossil evidence of a nematode-trapping fungus in a specimen of Cretaceous amber (ca 100 Myr old) from France. This paper has had great impact in the popular online press. The authors show photographs of a yeast-like fungus reminiscent of Debaryomyces hansenii (fig. 1 C–D and S1 B), one-celled rings that they consider sticky nematode-trapping devices (fig. 1 A-B, S1 A and S1 D), and nematodes found nearby (fig. S1 C-D). None of the photographs shows a ring attached to a sporulating hypha, nor was any trapped nematode documented (those shown are too slender to have been captured by the purported ‘‘traps’’). In a drawing (fig. 1E) the authors present a reconstructed life-cycle showing a trapped nematode in a ring, rings attached to a hypha, formation of a ring before closure, and a blastosporic yeast. We have tried to obtain the slides deposited in Paris on loan without any success, and our reaction here therefore relies on the photographs published by Schmidt et al. Fungi that trap nematodes with adhesive or constricting rings are members of the Orbiliomycetes, one of the oldest classes of phylum Ascomycota, and oldest in subphylum Pezizomycotina. Their segregation must have occurred much earlier than in Cretaceous times (Spatafora et al. 2007). Taylor & Berbee (2007) give a conservative estimate for the radiation of the Pezizomycotina of 215–400 Myr before present. Finding orbiliaceous structures in Cretaceous amber would be exciting but not at all surprising. Ascomycetous yeasts of the Saccharomycotina diverged prior to the Orbiliomycetes (Spatafora et al. 2007). A connection between a ‘‘trapping fungus’’ and a yeast is unlikely, and we consider that the published picture is probably an artefact of the two organisms being closely associated in space (perhaps only as a result of being captured in resin). The more organic connection between short conidiogenous cells and a main hypha shown in their fig. 1C illustrates a structure presently unknown in the Orbiliomycetes and would preclude the identification of these hyphae as belonging to the Orbiliaceae. Non-constricting ring traps are only known from the genus Dactylellina (Scholler et al. 1999). The rings are three-celled, with three septa, not one as shown by Schmidt et al. (2007),
1 Mycological Research News is compiled by the Senior Editor, David L. Hawksworth, Departamento de Biologı´a Vegetal II, Facultad de Farmacia, Universidad Complutense de Madrid, Plaza Ramo´n y Cajal, Ciudad Universitaria, ES-28040 Madrid, Spain (e-mail: d.hawks [email protected]), to whom items for inclusion should be sent. Unsigned items are by the Senior Editor.
612
and are stalked. A nematode that enters a loop would be stopped if its body diameter exceeds the loop diameter. Nematodes are unable to move backwards, so they continue to try to move forward and get jammed. Their struggle breaks the ring from the stalk and the nematode glides away with the ring around its body. The attached ring germinates to form an infection peg that penetrates the nematode, and forms an infection bulb, followed by digestion of the body contents. The ring thus not only serves as a trapping device but also as a diaspore. Schmidt et al. write that the rings are ‘‘probably detached easily from the supporting hyphae and are found dissociated from the mycelium.’’ In Dactylellina, rings are detached only after intense struggling of captured nematodes, and detached rings are only found attached to nematodes, not lying on the substrate where they would no longer be in the position to catch passing prey. The attachment of detritus to the rings as shown by Schmidt et al. (2007, fig. S1 A) most probably is due to unspecific binding. The rings even of adhesive traps are not sticky all over and do not collect detritus. An adhesive non-constricting ring trap cannot function, because the nematode would get caught on the ring before entering it. Regrettably, fossil records of fungi are scanty and, with a few notable exceptions (e.g. Hibbett et al. 1997), the morphology preserved in these fossils is suggestive but inconclusive for identification. With all due respect for the importance of fossil documents, we are not prepared to accept the unlikely combination of ring-shaped traps and yeast-like growth as compatible with nematode capturing, which in the photographs of Schmidt et al. (2007) is not convincingly proven. Evidently, the structure of the prey and the predacious organs must be commensurate if they are to function. In view of the relatively few well-identifiable fossil fungal records showing an amazing constancy of features through millions of years (Dotzler et al. 2006), we warn against postulating combinations of unusual features in a single hypothetic fossilized organism with functions that are not sufficiently proven. In nature quite different organisms are always densely entangled, thus mimicking a variation that more careful and informed analysis resolves as a mixture.
We acknowledge the constructive suggestions from Birgit Nordbring-Hertz, Hans-Bo¨rje Jansson, David S Hibbett, Annemarthe Rubner, and Walter Sudhaus. George Barron independently forwarded a similar view towards National Geographic News (UK) and Scientific American Magazine. In a reaction to our draft, Schmidt et al. contributed arguments that served only to re-inforce our interpretation and sharpen our statements. Dotzler N, Krings M, Taylor TN, Agerer R, 2006. Germination shields in Scutellospora (Glomeromycota: Diversisporales, Gigasporaceae) from the 400 million-year-old Rhynie Chert. Mycological Progress 5: 178–184. Hibbett DS, Grimaldi D, Donoghue M, 1997. Fossil mushrooms from Miocene and Cretaceous ambers and the evolution of homobasidiomycetes. American Journal of Botany 84: 981–991. Schmidt AR, Do¨rfelt H, Perrichot V, 2007. Carnivorous fungi from Cretaceous amber. Science 318: 1743 and supporting online material. Scholler M, Hagedorn G, Rubner A, 1999. A reevaluation of predatory orbiliaceous fungi. II. A new generic concept. Sydowia 51: 89–113.
D. L. Hawksworth
Spatafora JW, 32 others, 2007 [‘‘2006’’]. A five-gene phylogeny of Pezizomycotina. Mycologia 98: 1018–1028. Taylor JW, Berbee ML, 2007 [‘‘2006’’]. Dating divergences in the Fungal Tree of Life: review and new analyses. Mycologia 98: 838–849.
R. Greg Thorn Department of Biology, University of Western Ontario, 1151 Richmond Street North London, Ontario N6A 5B7, Canada E-mail address: [email protected] Markus Scholler Staatliches Museum fu¨r Naturkunde, Erbprinzenstr. 13, D-76133 Karlsruhe, Germany Walter Gams Molenweg 15, 3743 CK Baarn, The Netherlands
A ‘fungal loop’ in the nitrogen cycle of aridland ecosystems In a review of pulse dynamics and microbial processes in aridland ecosystems Collins et al. (2008) incorporated findings from pulse-reserve models. These models postulate that episodic precipitation events stimulate biological activity and generate biomass. They find that fungi play a critical and underappreciated role in carbon and nitrogen dynamics in aridland soils which affect decomposition, nitrification and other transformations, nutrient storage, and translocation of these compounds between plants and biotic soil crusts. The nitrogen ‘fungal loop’ they describe, integrates spatial structure and pulse dynamics and further extends the pulsereserve paradigm to include the key microbial processes in aridland ecosystems. High temperatures and low precipitation favour fungi over bacteria in these ecosystems, and, consequently, the fungi drive the below-ground decomposition, forming a complex hyphal network (the ‘fungal loop’) which integrates biotic crusts on the surface with patches of vegetation. While this result may not be unexpected to fungal ecologists, it is gratifying to see this topic featured in a leading review of one of the main ecological journals. Figure 1 in Collins et al.’s review, which links the ‘fungal loop’ to environmental conditions that favour it, is especially lucid and may be expected to find use in lectures on the role of fungi in ecosystem processes. Collins SL, Sinsabaugh RL, Crenshaw C, Green L, Porras-Alfaro A, Stursova M, Zeglin LH, 2008. Pulse dynamics and microbial processes in aridland ecosystems. Journal of Ecology 96: 413–420.
New scientific name in this issue Oidium aloysiae sp. nov.
0953-7562/$ – see front matter doi:10.1016/j.mycres.2008.04.012