Ultrastructural alterations in Fusarium sambucinum and Heterobasidion annosum treated with aluminum chloride and sodium metabisulfite

Aluminum chloride (AlCl(3)) and sodium metabisulfite (Na(2)S(2)O(5)) have received increasing attention as antifungal agents for the control of plant diseases. In an effort to understand their toxic action on fungi, ultrastructural changes and membrane damage in Fusarium sambucinum (Ascomycota) and Heterobasidion annosum (Basidiomycota) in response to salt exposure was investigated using transmission electron microscopy. Conidial membrane damage was quantified using SYTOX Green stain, which only enters altered membranes. The results showed that mortality of the conidia was generally closely associated with SYTOX stain absorption in F. sambucinum treated with Na(2)S(2)O(5) and in H. annosum treated with AlCl(3) or Na(2)S(2)O(5), suggesting that these salts cause membrane alterations. For both fungi, ultrastructural alterations in conidia treated with AlCl(3) and Na(2)S(2)O(5) included membrane retraction, undulation, and invagination. At higher concentrations or exposure periods to the salts, loss of membrane integrity, cytoplasmic leakage, and cell rupture were observed. Ultrastructural alterations and increased SYTOX stain absorption in salt-treated conidia appear consistent with a mode of action where AlCl(3) and Na(2)S(2)O(5) alter membrane integrity and permeability.

Morphological-anatomical characterization and identification of Tomentella ectomycorrhizas

Over the last two decades, much information has been gathered on the ectomycorrhizal fungus community composition of plant associations of boreal, temperate, and tropical regions. Worldwide, Tomentella ectomycorrhizas (ECM) are often common and dominant in the mycorrhizosphere of coniferous and deciduous forests. They are present under different environmental conditions and associate with diverse plant hosts. Tomentella sporocarps, however, are rarely found aboveground, so Tomentella species are often missing from fungus community studies based on fruit-body presence. Tomentella is a resupinate genus of Thelephoraceae (Basidiomycota) forming black-brown, brown, yellow, or ochre ECM on the roots of gymnosperm and angiosperm trees, distinguished by typical morphological-anatomical characteristics (clamped hyphae, angular mantle, surface network, special rhizomorphs and cystidia). In this paper, we review the taxonomic position and morphological-anatomical characteristics of Tomentella ECM. A short summary of the microscopic features used for distinguishing tomentelloids during morphotyping and identification is presented in order to support molecular and ecological studies of ectomycorrhizal fungus communities.

[Cellular features of immune reaction of common wheat with Lr19 gene to brown rust fungus infection]

The effect of resistant gene Lr19 on the development of brown rust fungus Puccinia triticina in the immune line of Thatcher variety was similar to that of nonhost species. The development of the fungus was inhibited in the plant tissue at the early stages. The fungus cells demonstrated structural disorganization of the nuclei and mitochondria before host cell invasion. The plant cell membranes and chloroplasts were changed; large chromatin aggregates appeared in their nuclei. Hypersensitive reaction developed after inhibition of the fungus.

A phylogenetic hypothesis of Ustilaginomycotina based on multiple gene analyses and morphological data

The subphylum Ustilaginomycotina comprises about 1500 species of basidiomycetous plant parasites. They are usually dimorphic, producing a saprobic haploid yeast phase and a parasitic dikaryotic hyphal phase. With only a few exceptions they occur on angiosperms and are found mainly on members of the Poaceae and Cyperaceae. Molecular methods recently have shown that anamorphic species such as members of Malassezia or Tilletiopsis should be included in this group. Here we present the most recent consensus as to the phylogeny of this group and discuss its relevant characteristics. Our morphological, ultrastructural and molecular phylogenetic data point to the existence of three lines of Ustilaginomycotina: Entorrhizomycetes, Ustilaginomycetes and Exobasidiomycetes. Entorrhizomycetes is represented by Entorrhizales, a small group of unusual teliosporic root parasites on Juncaceae and Cyperaceae. Ustilaginomycetes, to which the majority of Ustilaginomycotina belong, is a teliosporic and gastroid group characterized by the presence of enlarged interaction zones. Ustilaginomycetes is dichotomous, consisting of predominantly holobasidiate Urocystales and predominantly phragmobasidiate Ustilaginales. Exobasidiomycetes forms local interaction zones. This group is predominantly holobasidiate and consists of teliosporic Doassansiales, Entylomatales, Georgefischeriales and Tilletiales, nonteliosporic Ceraceosorales, Exobasidiales and Microstromatales, as well as the anamorphic Malasseziales. Entorrhizomycetes, Exobasidiomycetes and Ceraceosorales are proposed as new taxa, and the description of Ustilaginomycetes is emended.

Isolation and characterization of some mycelia inhabiting Tuber ascomata

Tuber spp. are ectomycorrhizal ascomycetes that produce subterranean ascomata known as truffles. Truffles can be regarded as complex microhabitats hosting bacteria and yeasts. In this paper we show that guest filamentous fungi are also associated to truffle ascomata, regardless of the Tuber spp., and report the morpho-molecular characterization of seven truffle-hosted mycelia isolated from healthy and intact Tuber ascomata. Some of these isolates were shown to be related to the fungal endophytes of plants. Interestingly, the truffle-hosted mycelia grew stuck to the hyphal wall of their partner when co-cultivated with the Tuber borchii mycelium, but not when co-cultivated with the test species Agaricus macrosporus. The present data suggest that guest filamentous fungi can be added to the list of truffle-interacting microorganisms.

Metabolism of fatty acid in yeast: addition of reducing agents to the reaction medium influences β-oxidation activities, γ-decalactone production, and cell ultrastructure inSporidiobolus ruineniicultivated on ricinoleic acid methyl ester

The sensitivity of Sporidiobolus ruinenii yeast to the use of reducing agents, reflected in changes in the oxidoreduction potential at pH 7 (Eh7) environment, ricinoleic acid methyl ester catabolism, γ-decalactone synthesis, cofactor level, β-oxidation activity, and ultrastructure of the cell, was studied. Three environmental conditions (corresponding to oxidative, neutral, and reducing conditions) were fixed with the use of air or air and reducing agents (hydrogen and dithiothreitol). Lowering Eh7to neutral conditions (Eh7 = +30 mV and +2.5 mV) favoured the production of lactone more than the more oxidative condition (Eh7 = +350 mV). In contrast, when a reducing condition was used (Eh7= –130 mV), the production of γ-decalactone was very low. These results were linked to changes in the cofactor ratio during lactone production, to the β-oxidation activity involved in decanolide synthesis, and to ultrastructural modification of the cell.

Molecular and morphological discrimination of stipitate hydnoids in the genera Hydnellum and Phellodon

Hydnellum and Phellodon species, generally considered ectomycorrhizal partners of a range of woody angiosperms and gymnosperms particularly within Fagaceae and Pinaceae, appear to be declining in continental Europe. They are listed as priority species in the UK Biodiversity Action Plan, but their UK conservation status remains uncertain. Interpretation of species distribution data is hampered by a lack of consensus regarding some key discriminatory morphological characters and difficulties with their interpretation. DNA sequencing of the ITS1 region of the ribosomal gene cluster discriminated between the known British species of Phellodon but revealed more terminal clusters than currently recognised taxa. Although the main focus within Hydnellum was on the very similar species pair H. concrescens and H. scrobiculatum, a few samples of H. caeruleum, H. ferrugineum, H. peckii, and H. spongiosipes were included in the study for reference. DNA sequencing of material identified on spore-based criteria as H. concrescens yielded two main groups, but samples received as H. scrobiculatum were generally more variable. Of these, two were reassigned and the remaining group, with very similar spores (although shorter than in published descriptions of H. scrobiculatum), had highly variable sequence data. The results and conservation importance of these fungi highlight the need for a taxonomic reassessment of P. melaleucus, P. niger, H. concrescens, and H. scrobiculatum collections from Britain and continental Europe using a combined molecular and morphological approach. Specific PCR primers were constructed to discriminate fruit bodies, mycelium, and mycorrhizal roots of P. niger and P. confluens from each other and from other stipitate hydnoids.

Involvement of reactive oxygen species during early stages of ectomycorrhiza establishment between Castanea sativa and Pisolithus tinctorius

Evidence for the participation of reactive oxygen species (ROS) and antioxidant systems in ectomycorrhizal (ECM) establishment is lacking. In this paper, we evaluated ROS production and the activities of superoxide dismutase (SOD) and catalase (CAT) during the early contact of the ECM fungus Pisolithus tinctorius with the roots of Castanea sativa (chestnut tree). Roots were placed in contact with P. tinctorius mycelia, and ROS production was evaluated by determining the levels of H(2)O(2) and O(2) (.-) during the early stages of fungal contact. Three peaks of H(2)O(2) production were detected, the first two coinciding with O(2) (.-) bursts. The first H(2)O(2) production peak coincided with an increase in SOD activity, whereas CAT activity seemed to be implicated in H(2)O(2) scavenging. P. tinctorius growth was evaluated in the presence of P. tinctorius-elicited C. sativa crude extracts prepared during the early stages of fungal contact. Differential hyphal growth that matched the H(2)O(2) production profile with a delay was detected. The result suggests that during the early stages of ECM establishment, H(2)O(2) results from an inhibition of ROS-scavenging enzymes and plays a role in signalling during symbiotic establishment.

Heterokaryon formation in Thanatephorus cucumeris anastomosis group 2-2 IV

Thirty single basidiospore isolates (SBIs) obtained from four field isolates of the basidiomycete fungus Thanatephorus cucumeris AG 2-2 IV were examined for heterokaryon formation. SBIs of three of four field isolates (Rh509, 92155 and R94) did not produce a tuft of mycelium in the hyphal interaction zone between paired isolates on 2% charcoal agar. Field isolates Rh509, 92155 and R94 indicated no death of interacting mycelium with their progenies on glass slide and microscopic examination. AFLP (amplified fragment length polymorphism) phenotypes of parent and their SBIs were identical. Field isolates Rh509, 92155 and R94 and their SBIs were homothallic. SBIs obtained from field isolate SA-1 were grouped into two mating types (SBI-M1 and SBI-M2), and a tuft of mycelium was formed between paired SBIs-M1 and -M2. SBIs of field isolate SA-1 indicated that no death and death of interacting mycelium were randomly observed. AFLP phenotypes among SBIs of isolate SA-1 were not identical and were also different from their parent isolate. AFLP phenotypes of tuft mycelia produced between heterothallic SBI-M1 and -M2 were heterokaryotic. The mating system of field isolate SA-1 and its SBIs was heterothallic. Both SBIs-M1 and -M2 further produced tuft mycelium with homothallic field isolates and their SBIs. AFLP banding patterns suggested that tuft mycelium was heterokaryotic produced from between heterothallic and homothallic isolates. Results from these experiments clarified that both homothallic and heterothallic isolates exist in population of T. cucumeris AG 2-2 IV, and that genetic exchange can occur between homothallic and heterothallic isolates.

Paxillus involutus mycorrhiza attenuate NaCl-stress responses in the salt-sensitive hybrid poplar Populusxcanescens

In order to characterise the effect of ectomycorrhiza on Na+-responses of the salt-sensitive poplar hybrid Populus x canescens, growth and stress responses of Paxillus involutus (strain MAJ) were tested in liquid cultures in the presence of 20 to 500 mM NaCl, and the effects of mycorrhization on mineral nutrient accumulation and oxidative stress were characterised in mycorrhizal and non-mycorrhizal poplar seedlings exposed to 150 mM NaCl. Paxillus involutus was salt tolerant, showing biomass increases in media containing up to 500 mM NaCl after 4 weeks growth. Mycorrhizal mantle formation on poplar roots was not affected by 150 mM NaCl. Whole plant performance was positively affected by the fungus because total biomass was greater and leaves accumulated less Na+ than non-mycorrhizal plants. Energy dispersive X-ray microanalysis using transmission electron microscopy analysis of the influence of mycorrhization on the subcellular localisation of Na+ and Cl- in roots showed that the hyphal mantle did not diminish salt accumulation in root cell walls, indicating that mycorrhization did not provide a physical barrier against excess salinity. In the absence of salt stress, mycorrhizal poplar roots contained higher Na+ and Cl- concentrations than non-mycorrhizal poplar roots. Paxillus involutus hyphae produced H2O2 in the mantle but not in the Hartig net or in pure culture. Salt exposure resulted in H2O2 formation in cortical cells of both non-mycorrhizal and mycorrhizal poplar and stimulated peroxidase but not superoxide dismutase activities. This shows that mature ectomycorrhiza was unable to suppress salt-induced oxidative stress. Element analyses suggest that improved performance of mycorrhizal poplar under salt stress may result from diminished xylem loading of Na+ and increased supply with K+.

Phylogenetic relationships of Auriculoscypha based on ultrastructural and molecular studies

The phylogeny of Auriculoscypha anacardiicola, an associate of scale insects in India, is investigated using subcellular characters and MP and Bayesian analyses of combined nuLSU-rDNA, nuSSU-rDNA and 5.8S rDNA sequence data. It has simple septa with a pulley-wheel-shaped pore plug, which is diagnostic of phytoparasitic members of the Pucciniomycetes, and hyphal wall break on branching, a phenomenon unique to some simple septate heterobasidiomycetes. The septal ultrastructure of A. anacardiicola is similar to that of the genus Septobasidium. The close relationship to Septobasidium is also confirmed by rDNA sequence analyses. The polyphyletic nature of the order Platygloeales, noted in earlier studies, is evident from the present molecular analysis as well. The placement of Auriculoscypha in the Platygloeales can no longer be justified and both ultrastructural and molecular evidence strongly support the placement of Auriculoscypha in the Septobasidiales.

Identification of bacteria isolated from diseased Neungee mushroom,Sarcodon aspratus

As the first step in an investigation of the problem with quality deterioration seen in the Neungee mushroom (Sarcodon aspratus) due to bacterial overgrowth during its storage, an attempt to isolate bacterial strains was made using infected gills of Sarcodon aspratus. Five bacterial strains were isolated; one phototrophic cyanobacterial species and four heterotrophic Gram negative rods. The four heterotrophic bacterial isolates (strains P, S, R, and MK1) were subjected to identification based on biochemical characteristics using the Biolog system, cellular fatty acid analysis using the MIDI system, cytology by scanning microscopy, and 16s rDNA sequence analysis. A slow grower, the P strain (ca. 0.7 microm x 1.5 microm), which forms pink colonies on Tryptic Soy agar (TSA) and glucose minimal salt medium containing thiamine (MT medium), belongs to genus Methylobacterium, and is likely M. radiotolerans. The methanol-utilizing capacity of the P strain was confirmed by growth on methanol-supplemented medium as a sole carbon source. Both the S and R strains (ca. 0.5 microm x 0.8 microm) produced smooth and slightly rough white colonies, respectively, on TSA, MT, and potato dextrose (PD) agar are members of the Burkholderia cepacia complex. Although both strains showed some differences from each other in colony morphology, nitrogen fixation capacity, and denitrification, they were considered to be Burkholderia stabilis because their 16s rDNA sequences showed 99.93% similarity with those of B. stabilis LMG 14294T (NCBI AF 148554). The MK1 strain, a rod-shaped bacterium with a tapered end (ca. 0.6 microm x 1.8 microm), produces a copious mucoid substance on MT and PD agar, but not on TSA. Despite extensive identification studies, the M strain is not currently identifiable, which suggests that it is a novel bacterium.

Molecular phylogeny of Hyphoderma and the reinstatement of Peniophorella

Hyphoderma is a large genus of corticioid homobasidiomycetes. In earlier homobasidiomycete-wide molecular phylogenetic studies the genus has appeared as polyphyletic. This paper describes the results from phylogenetic analyses of 22 species of Hyphoderma using nuclear 5.8 S and 28 S rDNA. Species with echinocysts and stephanocysts form a distinct clade well separated from Hyphoderma s. str. For this group the old genus name Peniophorella is available with P. pubera as the type species. Nineteen new combinations in Peniophorella are made and a key to the species is given. The clade representing Hyphoderma in its restricted sense receives only indicative support and a further subdivision of the genus may become necessary. H. capitatum, H. orphanellum, and H. sibiricum belong neither to Peniophorella nor to Hyphoderma s. str. Hypochnicium is a sister group to Hyphoderma. The phylogenetic analyses support the segregation of Hypochnicium analogum and H. vellereum as Gloeohypochnicium analogum and Granulobasidium vellereum, respectively, and the inclusion of H. detriticum in Hyphodontia. Hyphodermopsis and Bulbillomyces are best regarded as synonyms of Hypochnicium.

X-ray absorption spectroscopy (XAS) of toxic metal mineral transformations by fungi

Fungi can be highly efficient biogeochemical agents and accumulators of soluble and particulate forms of metals. This work aims to understand some of the physico-chemical mechanisms involved in toxic metal transformations focusing on the speciation of metals accumulated by fungi and mycorrhizal associations. The amorphous state or poor crystallinity of metal complexes within biomass and relatively low metal concentrations make the determination of metal speciation in biological systems a challenging problem but this can be overcome by using synchrotron-based element-specific X-ray absorption spectroscopy (XAS) techniques. In this research, we have exposed fungi and ectomycorrhizas to a variety of copper-, zinc- and lead-containing minerals. X-ray absorption spectroscopy studies revealed that oxygen ligands (phosphate, carboxylate) played a major role in toxic metal coordination within the fungal and ectomycorrhizal biomass during the accumulation of mobilized toxic metals. Coordination of toxic metals within biomass depended on the fungal species, initial mineral composition, the nitrogen source, and the physiological state/age of the fungal mycelium.

Molecular study of the genus Astraeus

The aim of the present work was to determine phylogenetic relationships among Astraeus species and to support macroscopic and microscopic characters of Astraeus with analysis of the ITS rDNA region. Collections of Astraeus basidiomes were made from different geographical areas in Thailand and compared with existing collections made worldwide. The marriage of observations on morphological features, including basidiospore ornamentation and molecular data demonstrated the presence of several Astraeus species. Sequences for 41 Astraeus collections were compared and the phylogenetic analyses grouped Thai Astraeus collections into two distinct groups. One contained A. odoratus and an Asian species described herein as A. asiaticus. There are at least two additional species: A. pteridis, and one so far un-named from North America. Our results show that molecular data can be used in combination with traditional morphological characteristics to resolve taxonomic uncertainties in the genus Astraeus.

Pileus differentiation and pileus-specific protein expression in Flammulina velutipes

Fruiting bodies of Flammulina velutipes formed under complete darkness had a poorly developed pileus on top (pinhead fruiting body), and lacked a hymenium. Upon light stimulation, the pileus immediately began to develop on the apical region of the pinhead fruiting body. Swelling of the apical region caused by cell division was observed 2 days after light treatment; at day 4, the junction fracture between the pileus and stipe, and formation of the hymenium primordia were observed; at 6 days, gills were observed. We identified a cell wall-associated protein (PSH) that was specifically induced in the pileus, but not in the stipe, following light treatment of the pinhead fruiting body. Cloning and sequence analysis of the gene encoding PSH (psh) revealed a motif in the C-terminal region of the predicted amino acid sequence that was similar to hydrophobin. The level of transcription of psh was low in the stipe, but it was expressed at a high level in the pileus of the normal fruiting body. Transcription was also low in pinhead fruiting bodies, but increased after light treatment. These results indicate that psh is specifically expressed during pileus differentiation induced by light stimulation.

[Ultrastructural basis of biotrophic relationships between brown rust fungus and common wheat]

The ultrastructural research of relationships between common wheat and brown rust fungus Puccinia triticina demonstrated that the biotrophy was based on the induction of plant cytoplasmic aggregate organization, nuclear migration to haustorium and stimulation of mesophyll cell metabolism. Resistant reactions in the form of hypersensitivity and depositions on plant cell walls were suppressed up to fungal sporogenesis. Cytoplasmic reorganization and nuclear taxis to haustorium were not registered in the epidermal and vascular bundle sheath cells.

Cantharellus pleurotoides, a new and unusual basidiomycete from Guyana

Cantharellus pleurotoides sp. nov. (Cantharellaceae, Cantharellales, Basidiomycota) is described from the Pakaraima Mountains of Guyana, occurring in rainforests dominated by ectomycorrhizal Dicymbe spp. (Caesalpiniaceae). This fungus is singular among Cantharellus species described worldwide in possessing a pleurotoid basidioma. Macromorphological, micromorphological, and habitat data are provided for the new species.

The cytoskeleton in the unique cell reproduction by conidiogenesis of the long-neck yeast Fellomyces (Sterigmatomyces) fuzhouensis

The morphology of conidiogenesis and associated changes in microtubules, actin distribution and ultrastructure were studied in the basidiomycetous yeast Fellomyces fuzhouensis by phase-contrast, fluorescence, and electron microscopy. The interphase cell showed a central nucleus with randomly distributed bundles of microtubules and actin, and actin patches in the cortex. The conidiogenous mother cell developed a slender projection, or stalk, that contained cytoplasmic microtubules and actin cables stretched parallel to the longitudinal axis and actin patches accumulated in the tip. The conidium was produced on this stalk. It contained dispersed cytoplasmic microtubules, actin cables, and patches concentrated in the cortex. Before mitosis, the nucleus migrated through the stalk into the conidium and cytoplasmic microtubules were replaced by a spindle. Mitosis started in the conidium, and one daughter nucleus then returned to the mother via an eccentrically elongated spindle. The cytoplasmic microtubules reappeared after mitosis. A strong fluorescence indicating accumulated actin appeared at the base of the conidium, where the cytoplasm cleaved eccentrically. Actin patches then moved from the stalk together with the retracting cytoplasm to the mother and conidium. No septum was detected in the long neck by electron microscopy, only a small amount of fine "wall material" between the conidium and mother cell. Both cells developed a new wall layer, separating them from the empty neck. The mature conidium disconnected from the empty neck at the end-break, which remained on the mother as a tubular outgrowth. Asexual reproduction by conidiogenesis in the long-neck yeast F. fuzhouensis has unique features distinguishing it from known asexual forms of reproduction in the budding and fission yeasts. Fellomyces fuzhouensis develops a unique long and narrow neck during conidiogenesis, through which the nucleus must migrate into the conidium for eccentric mitosis. This is followed by eccentric cytokinesis. We found neither an actin cytokinetic ring nor a septum in the long neck, from which cytoplasm retracted back to mother cell after cytokinesis. Both the conidium and mother were separated from the empty neck by the development of a new lateral wall (initiated as a wall plug). The cytoskeleton is clearly involved in all these processes.

The number of nuclei in basidiospores of 63 species of ectomycorrhizal Homobasidiomycetes

The production of even a limited number of heterokaryotic spores would be advantageous for establishing new individuals after long distance dispersal. While Suillus and Laccaria species are known to produce binucleate, heterokaryotic spores, this condition is poorly studied for most ectomycorrhizal fungi. To begin addressing this matter the number of nuclei in basidiospores was recorded from 142 sporocarps in 63 species and 20 genera of ectomycorrhizal (EM) fungi. The mean proportion of binucleate basidiospores produced by sporocarps within a species ranged from 0.00 to 1.00, with most genera within a family showing similar patterns. Basidiospores from fungi in Amanita, Cortinariaceae and Laccaria were primarily binucleate but were likely still homokaryotic. Basidiospores from fungi in Boletaceae, Cantharellus, Rhizopogonaceae, Russulaceae, Thelephorales and Tricholoma were primarily uninucleate, but binucleate basidiospores were observed in many genera and in high levels in Boletus. Further research is needed to relate basidiospore nuclear number to reproductive potential in ectomycorrhizal species.

Notes on a plant parasite fungus in Portugal: Gymnosporangium cornutum

A rust fungus identified as Gymnosporangium cornutum was found on Sorbus aucuparia in Serra da Estrela (Manteigas), and the disease was severe at that location. Despite the abundance and worldwide occurrence of the genus Gymnosporangium, studies in Portugal are still limited.

Crinipellis brasiliensis, a new species based on morphological and molecular data

Crinipellis perniciosa infects a diversity of hosts causing severe damage to T. cacao production in many Brazilian growing regions. We compared isolates of Crinipellis from different geographic origins and hosts in Brazil by structural analysis using light (LM) and scanning electronic microscopy (SEM), as well as RFLP and sequence data based on the nuclear rDNA ITS region. Statistical analyses of morphometric data of basidia and basidiospores revealed a distinct group of isolates of Crinipellis obtained from Heteropterys acutifolia when compared to representatives from Theobroma cacao, Solanum lycocarpum and Heteropterys nervosa. A similar distinction also was observed based on sequence data of the ITS region such that combined results allowed for the segregation of a new species within the genus Crinipellis.

The vacuole system is a significant intracellular pathway for longitudinal solute transport in basidiomycete fungi

Mycelial fungi have a growth form which is unique among multicellular organisms. The data presented here suggest that they have developed a unique solution to internal solute translocation involving a complex, extended vacuole. In all filamentous fungi examined, this extended vacuole forms an interconnected network, dynamically linked by tubules, which has been hypothesized to act as an internal distribution system. We have tested this hypothesis directly by quantifying solute movement within the organelle by photobleaching a fluorescent vacuolar marker. Predictive simulation models were then used to determine the transport characteristics over extended length scales. This modeling showed that the vacuolar organelle forms a functionally important, bidirectional diffusive transport pathway over distances of millimeters to centimeters. Flux through the pathway is regulated by the dynamic tubular connections involving homotypic fusion and fission. There is also a strongly predicted interaction among vacuolar organization, predicted diffusion transport distances, and the architecture of the branching colony margin.

Morphology of the rust fungus Puccinia boroniae revisited

Puccinia boroniae Henns. is a rust fungus endemic to Australia, infecting various Boronia spp. This study describes and illustrates, using light and scanning electron microscopy, the telial stage, teliospore germination and basidiospore production of specimens collected from commercial Boronia plantations in Western Australia. Unusual formation of a single basidiospore per germinating teliospore, and the pycnial stage, observed on Boronia megastigma leaves, are reported for the first time for P. boroniae.

Description of the Life-cycle of the Pearl Millet Rust Fungus–Puccinia substriata var. penicillariae with a Proposal of Reducing var. indica to a Synonym

Pearl millet (Pennisetum glaucum) is a major staple food crop in the drier parts of the old world, like Africa and India. Recently, its cultivation became more widespread in no-tillage crop farming systems in central Brazil, but it is also being used for cultivation during the dry season in other areas in Brazil. An emerging problem for the wider adoption of this crop in Brazil is the damage caused by the rust Puccinia substriata. This fungal disease is among the worst limitations for this crop worldwide. The rust occurring in Brazil was initially identified as the P. substriata var. penicillariae, but little information on the taxonomy and life-cycle of this rust is available in Brazil. The life-cycle of this rust variety remains somewhat obscure and the connection between the telial stage on pearl millet and the aecial stage on Solanaceae has never been experimentally demonstrated. Natural infection and inoculations under controlled conditions allowed for a complete description of all stages of this rust and the elucidation of its life-cycle, confirming that Solanum aethiopicum and Solanum melongena are aecial hosts. This coincidence for the alternate host and the limited and ambiguous morphological basis for the distinction of the varieties penicillariae and indica support the view that they are synonyms. Var. indica should be regarded as a late synonym of var. penicillariae.