Mycology

Systematics of genus Gnomoniopsis (Gnomoniaceae, Diaporthales)

by Donald Walker

Abstract:

Species of Gnomoniopsis are leaf- and stem-inhabiting
pyrenomycetes that infect plants... more Abstract:

Species of Gnomoniopsis are leaf- and stem-inhabiting
pyrenomycetes that infect plants in Fagaceae,
Onagraceae and Rosaceae. Morphology and
analyses of DNA sequences from three ribosomal
DNA and protein coding regions, namely b-tubulin,
translation elongation factor 1a (tef-1a) and the ITS
region including ITS1, 5.8S rDNA and ITS2, were
used to define species in Gnomoniopsis. Secondary
structural alignment of the ITS region across four
genera in Gnomoniaceae was used to increase the
potential number of homologous positions in the ITS
alignment. Ascospore isolates were grown from newly
collected specimens. Type specimens were compared
with these specimens to determine their identity. In
this paper a recent concept of Gnomoniopsis is
confirmed with phylogenetic resolution of additional
species. Four new combinations and one new species
are proposed. Nine species are described and
illustrated, and a key is provided to the 13 species
currently recognized in Gnomoniopsis.

Informativeness of dinucleotide repeat-based primers in fungal pathogen of rice Magnaporthe grisea.

by Sonia Chadha

Genetic diversity of Indian isolates of rice blast pathogen (Magnaporthe grisea) using molecular markers

by Sonia Chadha

Comparative assessment of REMAP and ISSR marker assays for genetic polymorphism studies in Magnaporthe grisea

by Sonia Chadha

Retrotransposon-microsatellite amplified polymorphism (REMAP) markers for genetic diversity assessment of the rice blast pathogen (Magnaporthe grisea).

by Sonia Chadha

Advection, diffusion and delivery over a network

by Luke Heaton

Many biological, geophysical and technological systems involve the transport of resource over a network. In this paper... more Many biological, geophysical and technological systems involve the transport of resource over a network. In this paper we present an efficient method for calculating the exact quantity of resource in each part of an arbitrary network, where the resource is lost or delivered out of the network at a given rate, while being sub ject to advection and diffusion. The key conceptual step is to partition the resource into material that does or does not reach a node over a given time step. As an example application we consider resource allocation within fungal networks, and analyze the spatial distribution of resource that emerges as such networks grow over time. Fungal growth involves the expansion of fluid filled vessels, and such growth necessarily involves the movement of fluid. We develop a model of delivery in growing fungal networks, and find good empirical agreement between our model and experimental data gathered using radio-labeled tracers. Our results lead us to suggest that in foraging fungi, growth-induced mass flow is sufficient to account for long distance transport, if the system is well insulated. We conclude that active transport mechanisms may only be required at the very end of the transport pathway, near the growing tips.

Mathematical modelling of fungal growth and function

by Luke Heaton

This contribution is based on the six presentations given at the Special Interest Group meeting on Mathematical... more 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 biomechanics 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.

Growth-induced mass flows in fungal networks

by Luke Heaton

Cord-forming fungi form extensive networks that continuously adapt to maintain an efficient transport system. As... more Cord-forming fungi form extensive networks that continuously adapt to maintain an efficient transport system. As osmotically driven water uptake is often distal from the tips, and aqueous fluids are incompressible, we propose that growth induces mass flows across the mycelium, whether or not there are intrahyphal concentration gradients. We imaged the temporal evolution of networks formed by Phanerochaete velutina, and at each stage calculated the unique set of currents that account for the observed changes in cord volume, while minimizing the work required to overcome viscous drag. Predicted speeds were in reasonable agreement with experimental data, and the pressure gradients needed to produce these flows are small. Furthermore, cords that were predicted to carry fast-moving or large currents were significantly more likely to increase in size than cords with slow-moving or small currents. The incompressibility of the fluids within fungi means there is a rapid global response to local fluid movements. Hence velocity of fluid flow is a local signal that conveys quasi-global information about the role of a cord within the mycelium. We suggest that fluid incompressibility and the coupling of growth and mass flow are critical physical features that enable the development of efficient, adaptive biological transport networks.

Diversity and distribution of terricolous lichens as indicator of habitat heterogeneity and grazing induced trampling in a temperate-alpine shrub and meadow

by Himanshu Rai

Himanshu Rai, D. K. Upreti and Rajan K. Gupta

Lichens are among the most sensitive biomonitors of ecosystem health and human induced disturbances. Terricolous... more Lichens are among the most sensitive biomonitors of ecosystem health and human induced disturbances. Terricolous lichens of Chopta–Tungnath (Garhwal, western Himalaya, India) were analysed for their ability to indicate habitat variability and disturbances induced by livestock grazing. Terricolous lichens were sampled from 12 sites, distributed across the three macrohabitats between 2,700 and 4,001 m, using 50 × 10 cm narrow frequency grids having five 10 × 10 cm sampling units. The terricolous lichen community of the area constituted, 20 species belonging to 10 genera, five families and four growth forms. Altitude and relative humidity were the major habitat factors found influencing the terricolous lichen community of the landscape. Fruticose and compound soil lichen growth forms were found indicative of habitat disturbance largely caused by grazing induced trampling. Terricolous lichen diversity of the area was delimited by grazing pressure at mid-altitudes (3,000–3,400 m) and by decreasing soil cover at higher altitudes (>3,400 m).

A new species complex including Claviceps fusiformis and Claviceps hirtella.

by Sylvie Pazoutova

Pažoutová S, Kolařík M, Odvody GN, Frederickson DE, Olšovská J, Man P, 2008. Fungal Diversity 31, 95-110.

Isolates of Claviceps species with lunate to fusiform macroconidia were collected from panicoid grasses in Texas and... more Isolates of Claviceps species with lunate to fusiform macroconidia were collected from panicoid grasses in Texas and Zimbabwe and described as new species based on anamorphs since no teleomorphs were available. Characterization was based upon morphology and partial sequences of rDNA and â-tubulin. The isolates grouped into two stronglysupported clades. The first clade contained ancestral C. hirtella and C. fusiformis from pearl millet (Pennisetum glaucum) in clade terminal position with Texas isolates from native cup grass (Eriochloa sericea) and pearl millet grouped between them. The second clade consisted of African isolates from Urochloa and Eragrostis. The isolates from Texas from pearl millet and buffel grass (Cenchrus ciliaris) and isolates from E. sericea were described as new species, Sphacelia texensis and Sphacelia eriochloae, respectively. Both species had morphology, DNA markers, and alkaloid production that was intermediate between those features exhibited in C. fusiformis and C. hirtella. The African isolates from Urochloa and Eragrostis were also described as a new species, Sphacelia lovelessii. In shaken cultures, C. hirtella readily produced a whole range of clavines with agroclavine and festuclavine predominating, but ergometrine was also detected. Claviceps fusiformis produced mainly agroclavine and elymoclavine, S. eriochloae produced mainly agroclavine, elymoclavin and festuclavine and the cultures of S. texensis contained small amounts of agroclavine and festuclavine. Only traces of clavines were found in cultures of S. lovelessii of the second clade. The alkaloid content of infected florets in the sphacelial (honeydew) developmental stage was also measured. Only C. fusiformis and S. eriochloae produced alkaloids in planta at this early stage.

Genetic variation of Phoma sorghina isolates from Southern Africa and Texas

by Sylvie Pazoutova

Folia Microbiol 54:217-229 (2009)

Genetic variability of Phoma sorghina, a ubiquitous facultative phytopathogen, was investigated on 41 isolates... more Genetic variability of Phoma sorghina, a ubiquitous facultative phytopathogen, was investigated on 41 isolates cultivated from surface-sterilized sorghum grains originating from South Africa and Texas; pearl millet isolates from Namibia were also included. Most of the isolates from Texas produced intense red pigments, especially on Czapek-Dox agar plates. Many African isolates formed conspicuous dark radial substrate hyphae with intercalated chlamydospores on oatmeal plates. Conidial dimensions and shape were very variable (mean lengths 4.5-5.7 microm). Haplotypes were defined based on 53 markers from banding patterns obtained with rep-PCR (primers: M13core, ERIC IR). The shared geographic origin was partially reflected in the clades of the haplotype phylogram. The values of G(ST) were intermediate; 16-37 % of the variation was found between the populations. Nm values of gene flow were 0.84-1.15. Average gene diversity H(E) was moderate (0.256). Sequences of ITS-rDNA were obtained from 21 isolates. Allele 1 was found in 9 isolates scattered throughout the clades, allele 2 occurred in 6 isolates (5 of them from the same clade), alleles 3 and 4 were shared by two isolates each and two isolates were unique. Alleles 1 and 2 were also found among highly related sequences from GenBank. All shared an 8-bp deletion near the 5' end of ITS2 that was not found in any other Phoma/Didymella species and which may be a typical marker for P. sorghina. Among related species, members of legume-associated Ascochyta/Didymella complex, Epicoccum spp., D. applanata and P. glomerata were found.

Host Specialization of Different Populations of Ergot Fungus (Claviceps purpurea)

by Sylvie Pazoutova

Czech J Genet Plant Breed 38:75-81 (2002)

In our previous study of Claviceps purpurea three populations were found: G1 on open localities, G2 from shady or wet... more In our previous study of Claviceps purpurea three populations were found: G1 on open localities, G2 from shady or wet habitats and G3 on Spartina stands of coastal salt marshes. The latter two are also chemoraces. In the Czech Republic, isolates of G1 and G2 were found. The ability of four isolates representing these populations to infect and develop sclerotia on different host species (Holcus lanatus, Helictotrichon pubescens, Phalaris arundinacea, Dactylis glomerata, Arrhenatherum elatius, Bromus inermis, Bromus erectus, Elytrigia repens, Avenella flexuosa, Lolium perenne, Poa nemoralis, Poa annua, and different cultivars of Poa pratensis) was studied along with their alkaloid production. P. pratensis and D. glomerata were infected by all the isolates and sclerotia were formed by isolates 207 (G1) and 434 (G2), and on two P. pratensis cultivars even by 481 (G3). Infection ability (formation of sphacelial stage and honeydew) was less host-restricted than formation of mature sclerotia. G2 and G3 strains infected A. flexuosa without sclerotia formation. L. perenne was infected only once by strain 207 (G1) without sclerotia formation. P. annua (natural host of G2), was infected by all isolates, but no sclerotia were formed even with G2 strains. From the two G2 isolates, strain 434 from Dactylis formed sclerotia on five host species, whereas isolate 475 originating from Phragmites stand formed only sphacelia. Composition of alkaloid mixture produced in sclerotia of the same strain from various hosts confirmed that host plant does not influence the type of alkaloids produced, only their ratio.

Heteropogon triticeus, a New Host of Claviceps sorghi in India

by Sylvie Pazoutova

J Phytopathol 150:196-199 (2002)

Claviceps sorghi occurred on Heteropogon triticeus in Gulbarga, Karnataka, India. Its external sphacelial morphology... more Claviceps sorghi occurred on Heteropogon triticeus in Gulbarga, Karnataka, India. Its external sphacelial morphology on this speciesiffered from that on sorghum in having long white sphacelial tips that protruded from spikelets or wound around awns. The tips were formed by parallel synnema-like hyphae and were covered by a phialide layer that produced elongated macroconidia (7–18 lm) and rounded to oval microconidia (3–5 lm). Unlike the macroconidia, the microconidia failed to germinate. Plated macroconidia underwent secondary sporulation. The white sclerotial stroma consisted of parallel hyphae with cylindrical cells that later became rounded due to accumulation of reserve metabolites. Some of these cells differentiated into a sclerotial rind that accumulated a terracotta coloured pigment. RAPD patterns and the rDNA nucleotide sequence confirmed the identity of the species.

Ergot fungus Claviceps cynodontis found on Bermuda grass (Cynodon dactylon) in the Americas.

by Sylvie Pazoutova

Can J Plant Pathol 27:541-546 (2005)

Claviceps cynodontis is a widespread parasite of Cynodon spp. (Bermuda grass) in the paleotropical and subtropical... more Claviceps cynodontis is a widespread parasite of Cynodon spp. (Bermuda grass) in the paleotropical and subtropical regions. The sphacelial stage of ergot on Cynodon dactylon in México and Texas was identified as that of Claviceps cynodontis by comparison of conidial morphology, rDNA sequence, and random amplified polymorphic DNA (RAPD) patterns with an African isolate of this species. Sequence of internal transcribed spacers ITS1-5.8S-ITS2 of Claviceps cynodontis clustered phylogenetically with those of Claviceps maximensis, Claviceps rhynchelytri, and Claviceps sp. SG (from Setaria geniculata). This is the first record of the identification of Claviceps cynodontis in the Americas.

Pleomorphic conidiation in Claviceps.

by Sylvie Pazoutova

Mycol Res 108:126-135 (2004)

Types of asexual sporulation in 17 Claviceps species and the closely related Corallocytostroma ornithocopreoides were... more Types of asexual sporulation in 17 Claviceps species and the closely related Corallocytostroma ornithocopreoides were revised in relation to the phylogeny of clavicipitaceous fungi. We observed: (1) enteroblastic conidiation from branched phialidic conidiophores typical of the genus (anamorph Sphacelia) in all species including Corallocytostroma; (2) widespread and often sequential formation of terminal holoblastic secondary conidia on tapering hyphae arising from sphacelial macroconidia; and (3) in addition to sphacelial conidiation, sympodial holoblastic conidiation of the Ephelis-type in cultures of C. zizaniae and in both the culture and sphacelial tissue of C. citrina. Secondary conidiation was not found in C. purpurea, C. citrina and C. sorghicola. During sphacelial fructification, most species produced macroconidia and microconidia. Only macroconidia formed in planta underwent secondary conidiation whereas microconidia did not germinate at all. In C. phalaridis, the formation of holoblastic 2–3 celled appendaged conidia was observed, similar to that of Aciculosporium and Neoclaviceps. In dendrograms based on ITS1-5.8S rDNA-ITS2 sequences, genera and species with appendaged conidia grouped on a highly supported clade with ancestral Corallocytostroma. The clade was placed inside a group of tropical species of Claviceps, without any relationship to Balansiae.

Genetic diversity of Claviceps africana on sorghum and Hyparrhenia.

by Sylvie Pazoutova

Plant Pathol 54:749-763 (2005)

Random amplified polymorphic DNA (RAPD) markers were used to survey genetic variability among 140 isolates of... more Random amplified polymorphic DNA (RAPD) markers were used to survey genetic variability among 140 isolates of Claviceps africana collected from Southern Africa, India, Thailand, Australia, and the Americas  in 1992-2002. Amplified fragment length polymorphisms (AFLP) were determined for a subset of the isolates. Both markers gave similar results in phenetic analysis of genetic distances between haplotypes of different geographical origin. In the Americas, a single RAPD haplotype was found throughout the various countries. The Eastern lineage consisted of two close haplotypes (one from India, the other from Thailand and Australia). Among five specialized isolates of C. africana from the alternate hosts, Hyparrhenia spp., three haplotypes were found. Eleven private alleles distinguished the Hyparrhenia population from that on sorghum. rDNA sequences of sorghum and Hyparrhenia isolates differed in three positions. The African sorghum population of C. africana consisted of 10 mostly closely related haplotypes. Low genotypic diversity (HE =0.0337) and the fact that most of the variation originated from between populations (GST = 0.866) suggested founder effects following recent invasion. In Southern Africa, no significant differentiation was found among six populations. Therefore, the data were pooled and tested for prevalence of clonal or sexual reproduction. The presence of the over-represented, widespread RAPD haplotype A, gametic disequilibrium (37% loci, detected by exact tests), Index of Association (IA) significantly higher than zero, and the high proportion of compatible loci (in the clone-corrected and total datasets found to be 94 and 99%, respectively) support the hypothesis about clonality as the predominant means of reproduction.

Claviceps nigricans and Claviceps grohii: Their Alkaloids and Phylogenetic Placement

by Sylvie Pazoutova

J Nat Prod 71:1085-1188 (2008)

Claviceps purpurea, C. grohii, C. zizaniae, C. cyperi, and C. nigricans are closely related ergot fungi and form a... more Claviceps purpurea, C. grohii, C. zizaniae, C. cyperi, and C. nigricans are closely related ergot fungi and form a monophyletic clade inside the genus Claviceps. Analysis of alkaloid content in C. nigricans sclerotia using UPLC detected ergocristine (1), ergosine (2), ?-ergocryptine (3), and ergocristam (4). Alkaloids 1, 3, and 4 were found in the sclerotia of C. grohii. The content of 4 in the mixture of alkaloids from C. nigricans and C. grohii (over 8% and over 20%, respectively) was unusually high. Submerged shaken cultures of C. nigricans produced no alkaloids, whereas C. grohii culture formed small amounts (15 mg L-1) of extracellular clavines and 1. In the previously used HPLC method the ergocristam degradation product could have been obscured by the ergosine peak. Therefore sclerotia of a C. purpurea habitat-specific population G2 with the dominant production of 1 and 2 have been reanalyzed, but no 4 was detected. The phylogeny of the C. purpurea-related species group is discussed with regard to alkaloid-specific nonribosomal peptide synthetase duplication leading to the production of two main ergopeptines instead of a single product.

Symbiotic relationship between Cerrena unicolor and the horntail Tremex fuscicornis recorded in the Czech Republic

by Sylvie Pazoutova

Czech Mycol 59:83-90 (2007)

From a specimen of Acer saccharinus collected in a Prague park, 38 females of Tremex fuscicornis (Hymenoptera,... more From a specimen of Acer saccharinus collected in a Prague park, 38 females of Tremex fuscicornis (Hymenoptera, Siricidae) were reared and sixteen isolates of a symbiotic basidiomycete were isolated from their mycangia. All isolates shared morphology and RAPD patterns. The fungus was identified using rDNA (regions ITS1, 5.8S, ITS2, and D1D2 part of the 28S rDNA) as Cerrena unicolor (Basidiomycota: Polyporales). The identification is discussed with respect to related horntail taxa and former identification attempts

New Claviceps species from warm-season grasses

by Sylvie Pazoutova

Pažoutová S, Odvody GN, Frederickson DE, Chudíčková M, Olšovská J, Kolařík M. (2011) New Claviceps species from warm-season grasses. Fungal Diversity, in press

Eight undescribed species of Claviceps were recognized from the combinations of molecular and morphological... more Eight undescribed species of Claviceps were recognized from the combinations of molecular and morphological characters. The teleomorph was observed only for Claviceps setariicola. Phylogenetic affinities of the new species inside the genus were revealed by a 5.8S-ITS-28S nrDNA analysis. Claviceps chloridicola, C. tenuispora, C. setariicola and C. setariiphila are related to C. maximensis; C. truncatispora is a sister species to C. pusilla. Claviceps clavispora and C. langdonii cluster with species colonizing maize and sorghum. The position of C. loudetiae is unclear. Comparisons with herbarium specimens showed C. setariicola as a well-established species on Setaria spp. in the southern USA. C. tenuispora was recorded on Cenchrus and Pennisetum in Brazil, USA, and Zimbabwe. C. setariiphila was found on S. geniculata in Brazil. C. chloridicola, C. loudetiae and C. truncatispora occurred in African savannas on Chloris, Loudetia, and Hyparrhenia spp., respectively. C. clavispora was found on Paspalum sp. and Urochloa sp. in Mexico and C. langdonii colonized Dichanthium spp. in the southern USA and probably in Mexico. The occurrence of C. pusilla on pearl millet in the USA (Texas) is reported and the record of C. sulcata on Urochloa brizantha in Brazil is confirmed by nrDNA sequence comparison with an African herbarium specimen. No alkaloids were detected in sclerotia and/or sphacelia of the new species.

Diversity of xylariaceous symbionts in Xiphydria woodwasps: role of vector and a host tree

by Sylvie Pazoutova

Fungal Ecol 3:392-401, 2011

Siricid woodwasps live in obligatory nutritional symbiosis with fungi. Screening of symbionts from mycetangia of... more Siricid woodwasps live in obligatory nutritional symbiosis with fungi. Screening of symbionts from mycetangia of emerging Xiphydria females (X. longicollis, X. prolongata, X. camelus, X. picta) from 28 locations and four tree genera yielded 1389 isolates. Each female carried pure culture of a single fungus. In X. longicollis (Quercus), Daldinia childiae was either the only fungus or a highly dominant one in the samples from moderately dry oak-hornbeam forests. Females from the alluvial sites harboured D. childiae and D. decipiens (approx. 1:1). X. camelus and X. picta (Alnus) share the dominant symbiont D. decipiens whereas X. camelus from Betula carries D. decipiens and D. petriniae (approx. 1:1). In X. prolongata, D. childiae was the dominant species followed by an undescribed Daldinia sp. (0-20% of isolates); D. decipiens was rare and in three females Hypoxylon macrocarpum was found. No symbiont occurred in a significant number among endophytes from the host trees.