Hyperparasitism of Aphanocladium album on Aecidiospores and Teliospores of Puccinia graminis f. sp. tritici

Aphanocladium album invaded rapidly 100% of aecidiospores of Puccinia graminis f. sp. tritici resulting in total collapse of the cells. Only 2% of teliospores were invaded. A. album penetrated through the germ pores. The precocious formation of teliospores which occurs immediately following uredial infection may be regarded as defence mechanism of the rust against its hyperparasite.     

MORPHOLOGY AND CYTOLOGY OF TILLETIA CARIES AND T. CONTROVERSA IN AXENIC CULTURE

On a wheat-based medium, the pathogenic phase of the common and dwarf bunt fungi grew slowly at 15–18 C and continued to produce massive quantities of teliospores in all subcultures for over 2 years. At warmer temperatures or on a chemically defined medium, the teliosporogenic colonies reverted to haploid mononucleate colonies. The hyphae of the teliosporogenic colonies were stained with a modified Giemsa technique and found to be thick, contorted, highly branched and short celled with usually one or two nuclei per cell. In contrast, the haploid mononucleate hyphae were thinner, straighter, and longer and never contained more than one nucleus per cell. The vegetative hyphae of T. caries and T. controversa were indistinguishable. Teliospores, formed at the terminal end of binucleate hyphae, were initially binucleate but became mononucleate before the mature cell wall formed.     

A Comparison of Polypeptides from Teliospores of Tilletia controversa (Kuhn) and Tilletia tritici (Bjerk) Wint.

Teliospores from 12 races of Tilletia tritici (Bjerk.) Wint. and twelve isolates of Tilletia controversa (Kuhn) were sampled from field-inoculated wheat (Triticum aestivum L.) differential cultivars. Proteins were extracted from the teliospores and analysed by one dimensional electrophoresis. An abundant 116 kD polypeptide detected in extracts from teliospores of all isolates of T. controversa was not detected in T. tritici teliospore extracts. Spores which were mechanically disrupted yielded greater quantities of the protein compared to intact teliospores, and this suggested the polypeptide was derived from within the teliospore. The presence of the polypeptide was correlated with dwarf bunt-causing Tilletia- Isolates of dwarf bunt-causing Tilletia that were intermediate between T. tritici and T. controversa in either morphology or germination characteristics contained the polypeptide while a common bunt-causing race of T. tritici (T18) with intermediate characteristics lacked the protein. The 116 kD polypeptide present in all T. controversa isolates may provide a stable biochemical marker for identification of these teliospores in wheat shipments.     

Die Parasitierung des Bohnenrostes Uromyces appendiculatus var. appendiculatus durch den Hyperparasiten Verticillium lecanii: Untersuchungen zur Wirt-Erkennung, Penetration und Abbau der Rostpilzsporen

Hyperparasitism of Uromyces appendiculatus var. appendiculatus by Verticillium lecanii Host Recognition, Penetration and Degradation of Spores Culture filtrates of the hyperparasite Verticillium lecanii contain numerous lytic enzymes. When specific substrates were added to the filtrate, degradation of chitin is increased by a factor of 2,25 and degradation of starch is increased by a factor of 1,5. The degradation of uredo- and teliospores of Uromyces appendiculatus var. appendiculatus is documented cytologically. Appressoria-like structures initiated direct penetration of the spore walls. Additional routes of penetration through the germpores of both sporetypes and the pedicles of the teliospores were observed. Degradation of the spore cytoplasm is described. Sugars on the surface of uredo- and teliospores and on hyphae of the hyperparasite were characterized using the gold-marked lectins Con A and WGA. Their role in the host-parasite recognition process is discussed.     

Chaconia hennenii, a new holomorph species for Uredo maclurae and Uredo celtidis (Uredinales)

Chaconia hennenii is proposed as a new holomorph species for Uredo maclurae (= Physopella maclurae) on Maclura tinctoria (Moraceae) after the discovery of teliospores. Uredo celtidis described on Celtis (Ulmaceae) is synonymous with U. maclurae and belongs to the same holomorph species, as revealed by morphologically indistinguishable urediniospores and newly discovered teliospores. The host genus of U. celtidis is not Celtis, but most probably Maclura, too. Chaconia hennenii is unique among known Chaconia species by the apical wall thickening of the teliospores.     

Studies in Heterobasidiomycetes, Part 31*). On the Anther Smuts of Silene vuigaris (Moench) Garcke

Microbotryum silenes-inflatae (DC) G. Deml & Oberw. and Microbotryum violaceoirregulare (Brandenburger & Schwinn) G. Deml & Oberw., both parasitic in the anthers of Silene vulgaris (Moench) Garcke, are compared by their morphology, karyology, and some cultural characteristics. The infection of their hosts is similar in both species, but causes different sizes of the flowers and different color of the spore mass. The teliospore initials of that smuts are produced in dikaryotic sporogenous hyphae. During gelatinization of the hyphal coat, surface ornamentations on the teliospores are formed. Mature teliospores are monokaryotic, and presumably diploid, reticulate in Microbotryum silenes-inflatae and echinulate in M. violaceo-irregulare. Teliospores of both species germinate without a resting periode. Germination results in a commonly three-celled promycelium, which in M. silenes-inflatae separates from the producing teliospore, while in M. violaceo-irregulare it remains on the teliospore during basidiospore formation. The basidiospores are monokaryotic and propagate by budding. Monokaryotic strains were isolated and characterized by standard yeast identification tests and by some enzymatic activities on solid media. While no differences in the enzymatic activities can be found, the species differ in their utilization of carbon sources.     

Development of Seed Immunoblot Binding Assay for Detection of Karnal bunt (Tilletia indica) of Wheat

Polyclonal antisera were produced in albino white rabbits against intact teliospores of Karnal bunt (Tilletia indica). The Immunoprobe generated was used for the development of Immunoblot binding assay for detecting Karnal bunt (KB) infections in wheat seed samples. The antiserum reacted strongly with intact teliospores of T. indica, Pantnagar isolate in agglutination reaction. Wheat grains with different grades of infection could be readily detected by Seed Immunoblot Binding Assay (SIBA). Karnal bunt infected wheat seeds when kept for vigour testing on nitrocellulose paper, formed a coloured imprint after the paper was immunoprocessed. The SIBA would not only be a better Indication of teliospores load on seed but also quality of seed in terms of vigour. This method is expected to be useful in routine monitoring of wheat lots for the presence of KB teliospores.     

Sugarcane glycoproteins bind to surface,specific ligands and modify cytoskeleton arrangement of Ustilago scitaminea teliospores

Abstract

Inoculation of sugarcane plants, cv. Jaronu 60-5, with teliospores of Ustilago scitaminea increased the production of sugarcane glycoproteins of high molecular mass (HMMG) and decreased the amount of those of mid-molecular mass (MMMG) recovered from stalks cell-free extracts. Whereas sugarcane glycoprotein of healthy plants totally inhibited the production of fungal mycelium from teliospores, mycelium growth was slightly affected by MMMG, and drastically diminished by HMMG obtained from inoculated plants. The adhesion of sugarcane glycoproteins to fungal teliospores produced cell aggregation. This effect was clearly reduced by incubating teliospores in buffer containing HMMG or MMMG previously digested with invertase. Sugarcane arginase associated to MMMG was retained by teliospores, whereas the enzymatic activity associated to HMMG from inoculated plants increased. Chitinase was not significantly retained by teliospores. Only HMMG and MMMG obtained from healthy plants were able to inhibit cell polarity in some extent. Smut induced changes in the composition of HMMG and MMMG. Some of these new glycoproteins are able to inhibit cell polarity. Since receptors, isolated from the cell wall of smut teliospores, were eluted from activated agarose beads by N-acetyl-D-glucosamine, we concluded that the peptide fraction of HMMG and MMMG bind to this amino sugar in the polysaccharide moiety of smut ligands.     

A new species of <Emphasis Type="Italic">Puccinia</Emphasis> (Pucciniales,Basidiomycota) and new records of rust fungi from Panama

A new species of Puccinia with diorchidioid teliospores is described from Urochloa decumbens (Poaceae) in Panama. It differs from the other known species of Puccinia with diorchidioid teliospores by uredinia with paraphyses and urediniospores with 3–4 scattered germ pores. Twenty-one known species of rust fungi are cited for Panama for the first time. Alveolaria cordiae is a poorly known species which is reported, described and illustrated in detail for the first time on Cordia spinescens in Panama.     

The Development of an In Vitro Host-Pathogen System Consisting of Maize Seedling Segments Infected with Ustilago maydis

The nodal segments of 7-day-old seedlings of maize were inoculated with sporidia of Ustilago maydis. At different times after inoculation (day 0 to day 9), the nodal segments were explanted to tissue culture media containing Benomyl. On one of the media, segments explanted at day 1 or later responded with the formation of galls carrying roots. In such galls Ustilago could complete its life cycle and form teliospores. Explantation at day 0 never led to gall or teliospore formation. Thefindings are discussed with respect to the possible presence of mycoboethins.     

Independent Inheritance of Genes Governing Virulence and the Production of a Polypeptide in Ustilago hordei*

Detergent soluble polypeptides from teliospores of Ustilago hordei were examined by two-dimensional isoelectric focusing-polyacrylamide gel electrophoresis. A relatively prominent polypeptide (M.W. 28,000, P¹ 6.8) was found in extracts of teliospores from two isolates that were avirulent on the barley cultivar ‘Plush’ but was not detected in extracts from two isolates that were virulent on this cultivar. The polypeptide was also detected in extracts from teliospores of an F₁, hybrid between one of the virulent and one of the avirulent isolates. Haploid cultures from five meiotic tetrads, isolated from the F₁ hybrid, were backcrossed to haploids from the virulent parent to determine the pathogenicity of each strain. The polypeptide segregated among the 20 progeny as if under the control of a single, dominant allele. The gene governing virulence on ‘Plush’ was not linked to the gene governing the segregating polypeptide.     

A new species, Dicheirinia panamensis, and new records of rust fungi from Panama

Based on a recent fieldwork in Panama, 25 species of rust fungi and several new hosts are reported for the first time from this country. Among the new records is one new species, Dicheirinia panamensis on Cojoba rufescens (Fabaceae). It differs from known species in the genus Dicheirinia by the presence of uredinia and telia without paraphyses, irregularly tuberculate urediniospores with two germ pores on the flattened sides, and tuberculate teliospores formed by three probasidial cells, subtended by a pedicel with three hyaline, apical cells. Taxonomical novelty: Dicheirinia panamensis J.R. Hern.,M. Piepenbr. and Vega Rios.     

New geographic distribution records and assumed microcyclic life cycle of Triphragmiopsis jeffersoniae (Pucciniales)

Triphragmiopsis jeffersoniae was found on Jeffersonia dubia in Sapporo, Japan, in 2003. This was the first geographic distribution record of the fungus out of its native distribution range in continental Far East Asia. This fungus was found also in Nikko, Japan, in 2011. Triphragmiopsis jeffersoniae formed Aecidium-type sori and tripartite teliospores subtended by a pedicel. In the early spring, the fungus formed telia with or without Aecidium-type sori on petioles of emerging host leaves. Subsequently clusters of Aecidium-type sori were formed on the abaxial leaf surface. These sori did not repeat; but they were soon densely surrounded by telia. Both the Aecidium-type sori and telia were densely crowded and no small isolated telia were formed. The assumption that the spores from Aecidium-type sori do not have infective ability was confirmed by inoculation experiments and microscopic observations for the Japanese materials. The Aecidium-type spore germlings failed to invade the Jeffersonia leaf either directly or through a stoma under the experimental conditions. Thus, T. jeffersoniae was assumed to have microcyclic life cycle, comprising the functional teliospores and the non-functional Aecidium-type aeciospores.     

Comparative studies on the teliospore morphology and ontogeny ofSpumula serispora,spec. nova,andRavenelia texensis (Uredinales,Raveneliaceae)

A new rust fungus,Spumula serispora, is described. The morphology of the teliospores and the telia was studied. In the teliospores ofS. serispora andS. quadrifida, the type species of the genus, sterile cells could be found, which are comparable to apical cells of otherRaveneliaceae. Similar sterile cells were also present in the telial heads ofRavenelia texensis. The ontogeny of the teliospores ofS. serispora and the teliospore heads ofRavenelia texensis was studied and compared. In both species the ontogeny of the spores heads was similar. InR. texensis hygroscopic cysts sustaining the spore heads were produced by division and not by conversion of basal sterile cells of the teliospore heads.Part 114 of the series Studies inHeterobasidiomycetes.     

Uromycladium tepperianum, the gall rust fungus from Falcataria moluccana in Malaysia and Indonesia

Batai (Falcataria moluccana) is a valuable tree species for forest plantations in Malaysia and Indonesia. Since 1993, a gall rust disease has caused severe damage to all growth stages, from seedlings in the nursery to mature trees in the field. To identify the fungus causing gall rust disease on F. moluccana in Malaysia and Indonesia, study of the mode of infection and changes in the anatomy of infected cells were carried out in the anatomy laboratory. The disease in Malaysia and Indonesia is caused by Uromycladium tepperianum. The fungus produces three longitudinally ridged teliospores on each head, with spores measuring 13–20 μm wide and 17–28 μm long. The fungus is microcyclic, completing its entire life cycle on F. moluccana. This study confirmed that the teliospores themselves cannot infect the host. Under favorable conditions, about 10 h after inoculation, teliospores germinate to produce basidiospores that form penetration pegs about 6 h later, and it is this peg which penetrates the host cells directly through the epidermis. Pycnia, recognized as small brown pustules, break through the epidermis about 7 days after inoculation.     

Einsatz von V. lecanii als biologisches Schädlingsbekämpfungsmittel gegen den Bohnenrostpilz U. appendiculatus var. appendiculatus im Feld und im Gewächshaus

The use of Verticillium lecanii as a biological control agent against the bean rust fungus Uromyces appendiculatus var. appendiculatus in the field and in the glasshouse The deuteromycete V. lecanii parasites uredo- and teliospores of the bean-rust-fungus U. appendiculatus var. appendiculatus. We investigated the conditions for the use of the hyperparasite as biological control agent in the field and in glasshouses. The growth rate of the hyperparasite was 0,3 cm per day at 25 °C. Under suitable conditions in the lab (25 °C, 100 % r. h.) it took about 20 days to invade 100 % of uredospores and 65 % of teliospores. We failed to prevent the spread of bean-rust-fungus spores in the field, but we succeeded in the glasshouse by 68 %, compared to the untreated controls, using the hyperparasite V. lecanii as biological control agent.     

Studies on the Host Range of the Hyperparasite Aphanocladium album

The uredospores of the 14 rust species tested and an Ascochyta, sp. were heavily parasitized by A. album. The teliospores of 3 Ustilaginales species were slightly parasitized. Some other important plant parasites were inhibited at distance, some others did not show any damage.     

<Emphasis Type="Italic">Phragmidium</Emphasis> species parasitizing species of Rosaceae in Tibet,China, with descriptions of three new species

Phragmidum spp. are rust fungi that are serious pathogens of plants in the Rosaceae. We characterized 15 Phragmidium species from Tibet, including 12 previously described and 3 new species. All the taxa, including the three new species (Ph. chayuensis, Ph. cibanum, Ph. zangdongii) are described and illustrated based on morphological characteristics. These taxa have multi-celled teliospores with firm pedicels. Phragmidium chayuensis is characterized by (5)7–9-celled teliospores with short papillae. Phragmidium cibanum is characterized by smooth teliospores that are distinctly constricted at the septa. Phragmidium zangdongii is characterized by large uredinia and 11–13-celled teliospores. Five types of urediniospore-surface structures were identified based on the gross shape of ornamentations and their distribution on the urediniospore wall. Molecular sequence data from the LSU rDNA analysis showed that the new taxa formed distinct clades independent from previously recorded species represented by LSU rDNA sequence data. The phylogenetic tree indicated that Phragmidium species are highly host specific.     

Initiation of Meiotic Recombination in Ustilago maydis

A central feature of meiosis is the pairing and recombination of homologous chromosomes. Ustilago maydis, a biotrophic fungus that parasitizes maize, has long been utilized as an experimental system for studying recombination, but it has not been clear when in the life cycle meiotic recombination initiates. U. maydis forms dormant diploid teliospores as the end product of the infection process. Upon germination, teliospores complete meiosis to produce four haploid basidiospores. Here we asked whether the meiotic process begins when teliospores germinate or at an earlier stage in development. When teliospores homozygous for a cdc45 mutation temperature sensitive for DNA synthesis were germinated at the restrictive temperature, four nuclei became visible. This implies that teliospores have already undergone premeiotic DNA synthesis and suggests that meiotic recombination initiates at a stage of infection before teliospores mature. Determination of homologous recombination in plant tissue infected with U. maydis strains heteroallelic for the nar1 gene revealed that Nar⁺ recombinants were produced at a stage before teliospore maturation. Teliospores obtained from a spo11Δ cross were still able to germinate but the process was highly disturbed and the meiotic products were imbalanced in chromosomal complement. These results show that in U. maydis, homologous recombination initiates during the infection process and that meiosis can proceed even in the absence of Spo11, but with loss of genomic integrity.     

Ravenelia cenostigmatis, a new rust fungus from Brazil

Ravenelia cenostigmatis is described as a new species of plant rust (Uredinales) onCenostigma gardnerianum (Caesalpiniaceae) from Brazilian Cerrado. Teliospore heads ofR. cenostigmatis exhibit an unusually complex structure with four different kinds of cells: teliospore cells, sterile apical cells (intercalary between pedicel hyphae and teliospores), sterile hygroscopic cysts, and morphologically distinct border cells. The last are flattened, elaborately ornamented and probably sterile cells that are wedged between the teliospores and the cysts.Ravenelia cenostigmatis probably belongs to a natural assemblage of ravenelias that occur on caesalpiniaceous hosts and exhibit similar morphological traits. Part 179 of the series “Studies in Heterobasidiomycetous Fungi” of the Botanical Institute, University of Tübingen