Graminicolous powdery mildew fungi as new natural hosts of Ampelomyces mycoparasites

1997 ◽  
Vol 75 (4) ◽  
pp. 680-683 ◽  
Author(s):  
Levente Kiss
Keyword(s):  
Powdery Mildew ◽  
Poa Pratensis ◽  
Blumeria Graminis ◽  
Erysiphe Graminis ◽  
Natural Occurrence ◽  
Powdery Mildews ◽  
Two Samples ◽  
Natural Hosts ◽  
Powdery Mildew Fungi ◽  
Cultivated Species

The natural occurrence of Ampelomyces mycoparasites is reported for the first time in hyphae, conidiophores, and immature cleistothecia of Blumeria graminis (syn. Erysiphe graminis), the causal agent of cereal and grass powdery mildews. During a 4-year search for Ampelomyces on leaves of different wild and cultivated species of the Gramineae infected with powdery mildews in Hungary, Ampelomyces was recorded in only two samples that represent 5% of the collected monocotyledons. The host plants of B. graminis parasitized by Ampelomyces were Hordeum murinum and Poa pratensis. The pycnidia of Ampelomyces were present in only 3–10% of the powdery mildew mycelia. These observations suggest that (i) the natural occurrence of Ampelomyces mycoparasites on monocotyledons infected with powdery mildews is rare compared with their repeatedly reported incidence on dicotyledons infected with different powdery mildew fungi, and (ii) they probably do not have any significant role in the natural control of B. graminis in the field. Key words: Ampelomyces, Blumeria graminis, Erysiphe graminis, Gramineae, hyperparasitism, mycoparasitism.

FURTHER OBSERVATIONS ON THE MECHANISM OF GERMINATION OF THE CONIDIA OF VARIOUS SPECIES OF POWDERY MILDEW AT LOW HUMIDITY

1945 ◽  
Vol 23c (6) ◽  
pp. 198-211 ◽  
Author(s):  
Harold J. Brodie
Keyword(s):  
Powdery Mildew ◽  
Osmotic Pressure ◽  
Special Function ◽  
Outer Part ◽  
Potassium Nitrate ◽  
Erysiphe Graminis ◽  
Powdery Mildews ◽  
Erysiphe Polygoni ◽  
Powdery Mildew Fungi ◽  
Low Humidity

Collected data from the observations of the author and others indicate that nine species of powdery mildew fungi, obtained from 21 different hosts, have been examined with regard to germination of the conidia at various humidities. Of these species, four, viz., Erysiphe Polygoni DC., E. graminis DC., Uncinula Salicis (DC.) Wint., and Microsphaera Alni (DC) Wint., seem beyond doubt to produce conidia capable of germinating at low humidity. Five species do not tolerate low humidity, according to published information.Conidia of Erysiphe graminis, detached from the conidiophore but adhering in chains, do not germinate in as high proportion as separate conidia from the same sample; also, the longer the chain, the lower the percentage of germination. In chains it is usually the end conidia that germinate, not those in intercalary position. These observations are discussed in the light of the theory previously-put forward by the author to explain the germination of powdery mildew conidia at low humidity.The apparent osmotic pressures of the cell sap of conidia of two powdery mildews were determined by plasmolysis with potassium nitrate. For Erysiphe Polygoni, the figure obtained was 63 atm., and for E. graminis Hordei Marchal, 68 atm. These figures are higher than any previously recorded in the literature seen by the author. The significance of this high osmotic pressure is discussed.Study of the papillae that regularly appear on the end of conidia of E. graminis indicates that they are special structures with a special function and should not be considered as germ pores. It is suggested that the conidium wall is two-layered, at least in the region between adjacent conidia. Rupture of the outer part of the wall in a ring at the septum may serve to disjoin the conidia and form the papilla.

Changes in sterol composition with ontogeny of Blumeria graminis conidia

2000 ◽  
Vol 78 (10) ◽  
pp. 1288-1293 ◽  
Author(s):  
Jérôme Muchembled ◽  
Anissa Lounès-Hadj Sahraoui ◽  
Anne Grandmougin-Ferjani ◽  
Michel Sancholle
Keyword(s):  
Powdery Mildew ◽  
Plant Pathogen ◽  
Total Sterol ◽  
Sterol Composition ◽  
Blumeria Graminis ◽  
Erysiphe Graminis ◽  
Qualitative And Quantitative ◽  
Wheat Powdery Mildew

The total sterol composition of conidia of the obligate plant pathogen Blumeria (= Erysiphe) graminis f.sp. tritici has been analysed as a function of their ontogeny during sporulation. Two main classes of sterols were characterized: 24-ethylsterols (24-ethylcholesta-5,22-dienol, 24-ethylcholesterol, and Δ5-avenasterol) and 24-methylsterols (24-methylenecholesterol and episterol). Our results show that sterol composition is greatly modified during ontogeny of B. graminis conidia both at the qualitative and quantitative levels. In particular, 24-methylsterols, e.g., 24-methylenecholesterol and episterol, are the major sterols in old conidia whereas 24-ethylsterols, e.g., 24-ethylcholesta-5,22-dienol, 24-ethylcholesterol, and Δ5-avenasterol, are the main sterols in young conidia.Key words: Erysiphe, wheat powdery mildew, sterols, ontogeny.

scholarly journals Ecological Basis of the Interaction betweenPseudozyma flocculosaand Powdery Mildew Fungi

2010 ◽  
Vol 77 (3) ◽  
pp. 926-933 ◽  
Author(s):  
Walid Hammami ◽  
Candy Quiroga Castro ◽  
Wilfried Rémus-Borel ◽  
Caroline Labbé ◽  
Richard R. Bélanger
Keyword(s):  
Powdery Mildew ◽  
Fluorescent Protein ◽  
Close Relative ◽  
Tomato Plants ◽  
Powdery Mildews ◽  
Biocontrol Activity ◽  
Cellobiose Lipids ◽  
Powdery Mildew Fungi ◽  
Green Fluorescent ◽  
Ecological Basis

ABSTRACTIn this work, we sought to understand how glycolipid production and the availability of nutrients could explain the ecology ofPseudozyma flocculosaand its biocontrol activity. For this purpose, we compared the development ofP. flocculosato that of a close relative, the plant pathogenUstilago maydis, under different environmental conditions. This approach was further supported by measuring the expression ofcyp1, a pivotal gene in the synthesis of unique antifungal cellobiose lipids of both fungi. On healthy cucumber and tomato plants, the expression ofcyp1remained unchanged over time inP. flocculosaand was undetected inU. maydis. At the same time, green fluorescent protein (GFP) strains of both fungi showed only limited green fluorescence on control leaves. On powdery mildew-infected cucumber leaves,P. flocculosainduced a complete collapse of the pathogen colonies, but glycolipid production, as studied bycyp1expression, was still comparable to that of controls. In complete contrast,cyp1was upregulated nine times whenP. flocculosawas applied toBotrytis cinerea-infected leaves, but the biocontrol fungus did not develop very well on the pathogen. Analysis of the possible nutrients that could stimulate the growth ofP. flocculosaon powdery mildew structures revealed that the complex Zn/Mn played a key role in the interaction. Other related fungi such asU. maydisdo not appear to have the same nutritional requirements and hence lack the ability to colonize powdery mildews. Whether production of antifungal glycolipids contributes to the release of nutrients from powdery mildew colonies is unclear, but the specificity of the biocontrol activity ofP. flocculosatoward Erysiphales does appear to be more complex than simple antibiosis.

scholarly journals A Pattern Recognition Tool for Quantitative Analysis of In Planta Hyphal Growth of Powdery Mildew Fungi

2005 ◽  
Vol 18 (9) ◽  
pp. 906-912 ◽  
Author(s):  
U. Seiffert ◽  
P. Schweizer
Keyword(s):  
Growth Rate ◽  
Pattern Recognition ◽  
Quantitative Analysis ◽  
Powdery Mildew ◽  
Growth Rates ◽  
Fungal Pathogens ◽  
Hyphal Growth ◽  
Blumeria Graminis ◽  
In Planta ◽  
Powdery Mildew Fungi

The development of fungal pathogens can be quantified easily at the level of spore germination or penetration. However, the exact quantification of hyphal growth rates after initial, successful host invasion is much more difficult. Here, we report on the development of a new pattern recognition software (HyphArea) for automated quantitative analysis of hyphal growth rates of powdery mildew fungi on plant surfaces that usually represent highly irregular and noisy image backgrounds. By using HyphArea, we measured growth rates of colonies of the barley powdery mildew, Blumeria graminis f. sp. hordei, on susceptible and induced-resistant host plants. Hyphal growth was not influenced by the resistance state of the plants up to 48 h postinoculation. At later time points, growth rate increased on susceptible plants, whereas it remained restricted on induced-resistant plants. This difference in hyphal growth rate was accompanied by lack of secondary haustoria formation on induced-resistant plants, suggesting that induced resistance in barley against Blumeria graminis is caused mainly by reduced penetration rates of primary as well as secondary appressoria leading, finally, to fewer and lessdeveloped fungal colonies. No evidence was found for reduced nutrient-uptake efficiency of the primary haustoria in induced-resistant leaves, which would be expected to have resulted in reduced hyphal growth rates during the first 48 h of the interaction.

scholarly journals First records of powdery mildew fungi (Erysiphales) on four medicinal plants in Taiwan

2020 ◽  
Author(s):  
Yu-Wei Yeh ◽  
Pei-Yi Chou ◽  
Hsin-Yu Hou ◽  
Roland Kirschner
Keyword(s):  
Powdery Mildew ◽  
Medicinal Plants ◽  
Species Identification ◽  
Host Plants ◽  
New Records ◽  
Its Sequences ◽  
New Host ◽  
Powdery Mildews ◽  
Eryngium Foetidum ◽  
Powdery Mildew Fungi

Abstract Background Production of medicinal plants in Taiwan is not only hampered by international market competition, but also lack of knowledge of their pathogens, such as powdery mildew fungi (Erysiphales, Ascomycota). Records of these fungi in Taiwan originate from few researchers for the last one hundred years and are still incomplete. Since powdery mildews in tropical/subtropical environments do not develop the sexual stages with morphologically diagnostic characteristics, internal transcribed spacer sequences (ITS) of the ribosomal RNA genes obtained from the asexual stages have become important modern tools for species identification. Results Powdery mildews on four medicinal plants from educational and ornamental plantations in Taiwan were identified based on the anamorph morphology and ITS sequences. Three powdery mildews on medicinal plants are new records for Taiwan, Arthrocladiella mougeotii on Lycium chinense, Erysiphe lespedezae on Uraria crinita, and E. lonicerae on Lonicera japonica. Eryngium foetidum is a new host for Erysiphe heraclei hitherto known on other host plants in Taiwan. Eryngium foetidum and Uraria crinita are new host plants for powdery mildews worldwide. Only specific field collection of the pathogens yielded the new records, not checking plant specimens in a phanerogam herbarium. The pathogens did not cause death of the host plants, but appeared to enhance stress by infection of mature leaves. Conclusions Taxonomic study of powdery mildews in Taiwan results into new host records of economically important medicinal plants in Taiwan with potential consequences for plant production and quarantine and also shows that host records are quite incomplete worldwide. Although ITS sequences were useful for species identification, the lack of data for several species on the same host genus on the one hand and the low variation between closely related species on the other indicate the need for further study.

scholarly journals Natural Occurrence of Microsphaera pulchra and Phyllactinia guttata on Two Cornus Species

Plant Disease ◽  
1998 ◽  
Vol 82 (4) ◽  
pp. 383-385 ◽  
Author(s):  
Leigh Ann Klein ◽  
Mark T. Windham ◽  
Robert N. Trigiano
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
Natural Occurrence ◽  
Cornus Florida ◽  
Supplementary Data ◽  
Eastern United States ◽  
Pathogen Identification ◽  
Foliar Disease ◽  
Histological Studies ◽  
Powdery Mildew Fungi

Powdery mildew has become a common foliar disease of Cornus florida and other dogwood species in the eastern United States during the last several years. This study was conducted to determine the identity of powdery mildew fungi on C. florida and C. amomum. Ascocarps of Microsphaera pulchra and Phyllactinia guttata occurred singly and together on both C. florida and C. amomum leaves. M. pulchra ascocarps occurred at a higher density than P. guttata ascocarps on C. florida leaves, whereas P. guttata ascocarps occurred more frequently than M. pulchra ascocarps on C. amomum leaves. Histological studies, however, did not provide supplementary data of infection by the powdery mildew species that occurred less frequently on the leaves of each dogwood species. M. pulchra did not penetrate the cells of C. amomum, and likewise P. guttata did not enter through stomata of C. florida leaves. The presence of ascocarps of both species was not the result of infection of the dogwoods by both pathogens. The ascocarps of M. pulchra probably became airborne and then settled on the C. amomum leaves. Similarly, the ascocarps of P. guttata landed on C. florida leaves. These results emphasize the importance of correct pathogen identification using several criteria such as ascocarp morphology, host-pathogen relationships, distribution of the pathogen, conidial morphology, and histology.

Genome Expansion and Gene Loss in Powdery Mildew Fungi Reveal Tradeoffs in Extreme Parasitism

Science ◽  
2010 ◽  
Vol 330 (6010) ◽  
pp. 1543-1546 ◽  
Author(s):  
Pietro D. Spanu ◽  
James C. Abbott ◽  
Joelle Amselem ◽  
Timothy A. Burgis ◽  
Darren M. Soanes ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Life Style ◽  
Living Plant ◽  
Powdery Mildews ◽  
Primary And Secondary Metabolism ◽  
Core Set ◽  
Barley Powdery Mildew ◽  
Dicotyledonous Plants ◽  
Powdery Mildew Fungi ◽  
Species Specific

Powdery mildews are phytopathogens whose growth and reproduction are entirely dependent on living plant cells. The molecular basis of this life-style, obligate biotrophy, remains unknown. We present the genome analysis of barley powdery mildew, Blumeria graminis f.sp. hordei (Blumeria), as well as a comparison with the analysis of two powdery mildews pathogenic on dicotyledonous plants. These genomes display massive retrotransposon proliferation, genome-size expansion, and gene losses. The missing genes encode enzymes of primary and secondary metabolism, carbohydrate-active enzymes, and transporters, probably reflecting their redundancy in an exclusively biotrophic life-style. Among the 248 candidate effectors of pathogenesis identified in the Blumeria genome, very few (less than 10) define a core set conserved in all three mildews, suggesting that most effectors represent species-specific adaptations.

scholarly journals First records of powdery mildew fungi (Erysiphales) on medicinal plants in Taiwan

2021 ◽  
Author(s):  
Yu-Wei Yeh ◽  
Pei-Yi Chou ◽  
Hsin-Yu Hou ◽  
Roland Kirschner
Keyword(s):  
Powdery Mildew ◽  
Medicinal Plants ◽  
Species Identification ◽  
Host Plants ◽  
New Records ◽  
Its Sequences ◽  
New Host ◽  
Powdery Mildews ◽  
Eryngium Foetidum ◽  
Powdery Mildew Fungi

Abstract Background: Production of medicinal plants in Taiwan is not only hampered by international market competition, but also lack of knowledge of their pathogens, such as powdery mildew fungi (Erysiphales, Ascomycota). Records of these fungi in Taiwan originate from few researchers for the last one hundred years and are still incomplete. Since powdery mildews in tropical/subtropical environments rarely develop the sexual stages with morphologically diagnostic characteristics, internal transcribed spacer sequences (ITS) of the ribosomal RNA genes obtained from the asexual stages have become important modern tools for species identification.Results: Powdery mildews on medicinal plants from educational and ornamental plantations in Taiwan were identified based on the anamorph morphology and ITS sequences. Four powdery mildews on medicinal plants are new records for Taiwan, Arthrocladiella mougeotii on Lycium chinense, Erysiphe glycines on Pueraria lobata, Erysiphe lespedezae on Bauhinia sp., Desmodium caudatum, and Uraria crinita, and E. lonicerae on Lonicera japonica. Eryngium foetidum is a new host for Erysiphe heraclei hitherto known on other host plants in Taiwan. Eryngium foetidum and Uraria crinita are new host plants for powdery mildews worldwide. Only specific field collection of the pathogens yielded the new records, not checking plant specimens in a phanerogam herbarium. The pathogens did not cause death of the host plants, but appeared to enhance stress by infection of mature leaves.Conclusions: Taxonomic study of powdery mildews in Taiwan results into new host records of economically important medicinal plants in Taiwan with potential consequences for plant production and quarantine and also shows that host records are quite incomplete worldwide. Although ITS sequences were useful for species identification, the lack of data for several species on the same host genus on the one hand and the low variation between closely related species on the other indicate the need for further study.

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