Morphotaxonomy of powdery mildew fungus (Golovinomyces cichoracearum DC) on Helianthus petiolaris

Moth mullein (Verbascum blattaria) is an herbaceous plant belonging to the Scrophulariaceae family. It has alternate, simple leaves on stiffly, erect, green stems. Flowers are yellow or white, borne in summer through fall, and is increasingly used in gardens in low-maintenance borders. During the fall of 2009, 4-month-old plants grown in a greenhouse near Torino (northern Italy) showed signs and symptoms of an unknown powdery mildew. The adaxial leaf surfaces were covered with white mycelia and conidia, while the abaxial surfaces were less infected. As the disease progressed, infected leaves turned yellow and wilted. Mycelia were also observed on stems, petioles, and flower calyxes of inflorescences. Powdery mildew was observed on moth mullein naturally diffused in Italian flora and on V. blattaria var albiflorum cv. White Blush. The same symptoms and signs were observed in summer 2010 on V. blattaria plants grown in a garden near Biella. Conidia were hyaline, elliptical, borne in short chains (as many as five conidia per chain), and measured 35 × 22 (29 to 42 × 19 to 24) μm. Conidiophores were erect with a cylindrical foot cell measuring 147 × 11 (93 to 177 × 10 to 12) μm, followed by one to two shorter cells measuring 23 × 11 (15 to 33 × 10 to 12) μm. Fibrosin bodies were absent. Chasmothecia were not observed in the collected samples. The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS4/ITS6 and sequenced (1) (GenBank Accession No. HQ316555). The 542-bp amplicon had 99% homology with the sequence of Golovinomyces cichoracearum (GenBank Accession No. EU819552. Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of healthy V. blattaria plants. Five plants were inoculated, while the same number of noninoculated plants served as a control. Plants were maintained at temperatures from 19 to 25°C. Fifteen days after inoculation, symptoms and signs of powdery mildew developed on inoculated plants. The conidial morphology of the powdery mildew fungus that developed on inoculated plants was identical to the conidial morphology observed in the original fungus. Noninoculated plants remained healthy. The pathogenicity test was carried out twice. G. cichoracearum, formerly Erysiphe verbasci (synonym E. cichoracearum), has been reported on V. blattaria in Hungary, Romania, and the former USSR (2,3). In conclusion, to our knowledge, it is the first report of G. cichoracearum affecting moth mullein in northern Italy. The economic importance of this disease is at present limited in Italy because of limited planting of this host. However, the ecological characteristics and flowering of V. blattaria make it interesting for low-maintenance gardens. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) K. Amano. Host Range and Geographical Distribution of the Powdery Mildew Fungi. Japan Scientific Societies Press. Tokyo, 1986. (3) U. Braun. The Powdery Mildews (Erysiphales) of Europe. Gustav Fischer Verlag, Stuttgart, Germany, 1995.

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First Report of Powdery Mildew Caused by Golovinomyces cichoracearum on Sonchus asper in China

Plant Disease ◽

10.1094/pdis-01-12-0033-pdn ◽

2012 ◽

Vol 96 (5) ◽

pp. 766-766 ◽

Cited By ~ 2

Author(s):

D. Pei ◽

X. Xu ◽

Y. Feng ◽

C. Li

Keyword(s):

Powdery Mildew ◽

Antibacterial Properties ◽

Its Sequence ◽

Conidial Suspension ◽

Powdery Mildew Fungus ◽

Sonchus Asper ◽

First Report ◽

Its Sequence Analysis ◽

Golovinomyces Cichoracearum ◽

Asteraceae Family

Sonchus asper is an exotic annual herb belonging to the Asteraceae family. Crude extracts of S. asper leaves have antiphlogistic and antibacterial properties. In May 2011, severe infection of powdery mildew was observed on S. asper in Henan Province, a central area of China. Symptoms began as small, nearly circular white spots that later enlarged and coalesced. As the disease progressed, white mycelia covered the entire plant, including the inflorescence. The voucher specimens are kept at the Key Laboratory of Plant-Microbe Interaction, Shangqiu Normal University. Conidiophores were erect, 108 to 220 × 10 to 12 μm, and composed of a cylindrical foot cell followed by two to three short cells. Nipple-shaped appressoria were formed on ectophytic mycelia. Conidia were hyaline and cylindrical, without distinct fibrosin bodies, and ranging from 29 to 42 × 19 to 24 μm. Long, unbranched germ tubes were formed from the ends of the conidia. These morphological characteristics suggested that the powdery mildew fungus is the anamorph of Golovinomyces cichoracearum (1,2). Chasmothecia were not observed in the collected samples. To confirm the identification, the internal transcribed spacer (ITS) region of the rDNA was amplified with ITS1 and ITS4 primers (4) and sequenced. The ITS sequence obtained was assigned Accession No. JQ010848 in GenBank, and had 99% similarity to two ITS sequences from different G. cichoracearum accessions (HM449077 and AY739111). The ITS sequence analysis further verified that the causal agent of the powdery mildew on S. asper was G. cichoracearum. Pathogenicity was confirmed by inoculating five healthy plants of S. asper with a conidial suspension (105 conidia/ml) from the infected plants, with five noninoculated plants serving as control. Inoculated plants developed the original powdery mildew symptoms after 10 days, whereas control plants remained healthy. G. cichoracearum (synonym Erysiphe cichoracearum) is a cosmopolitan powdery mildew fungus, parasitic on numerous plant species in the Asteraceae family. It was reported to be infecting S. asper in Bulgaria (3). To our knowledge, this is the first report of G. cichoracearum infections on S. asper in China. S. asper is one of the most important Chinese herbal medicines. The sudden appearance of powdery mildew caused by G. cichoracearum on this plant could result in substantial production loss of S. asper unless fungicide applications are employed. References: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (2) R. T. A. Cook and U. Braun. Mycol. Res. 113:616, 2009. (3) G. Negrean and C. M. Denchev. Mycologia Balcanica, 2004, 1:63. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990.

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Disruption of barley immunity to powdery mildew by an in-frame Lys-Leu deletion in the essential protein SGT1

Genetics ◽

10.1093/genetics/iyaa026 ◽

2020 ◽

Vol 217 (2) ◽

Cited By ~ 1

Author(s):

Antony V E Chapman ◽

Matthew Hunt ◽

Priyanka Surana ◽

Valeria Velásquez-Zapata ◽

Weihui Xu ◽

...

Keyword(s):

Powdery Mildew ◽

Fungal Pathogens ◽

Novel Mutation ◽

Exome Capture ◽

Resistance Locus ◽

Hordeum Vulgare L ◽

Powdery Mildew Fungus ◽

Pathogen Effectors ◽

Cell Processes ◽

Disease Resistances

Abstract Barley (Hordeum vulgare L.) Mla (Mildew resistance locus a) and its nucleotide-binding, leucine-rich-repeat receptor (NLR) orthologs protect many cereal crops from diseases caused by fungal pathogens. However, large segments of the Mla pathway and its mechanisms remain unknown. To further characterize the molecular interactions required for NLR-based immunity, we used fast-neutron mutagenesis to screen for plants compromised in MLA-mediated response to the powdery mildew fungus, Blumeria graminis f. sp. hordei. One variant, m11526, contained a novel mutation, designated rar3 (required for Mla6 resistance3), that abolishes race-specific resistance conditioned by the Mla6, Mla7, and Mla12 alleles, but does not compromise immunity mediated by Mla1, Mla9, Mla10, and Mla13. This is analogous to, but unique from, the differential requirement of Mla alleles for the co-chaperone Rar1 (required for Mla12 resistance1). We used bulked-segregant-exome capture and fine mapping to delineate the causal mutation to an in-frame Lys-Leu deletion within the SGS domain of SGT1 (Suppressor of G-two allele of Skp1, Sgt1ΔKL308–309), the structural region that interacts with MLA proteins. In nature, mutations to Sgt1 usually cause lethal phenotypes, but here we pinpoint a unique modification that delineates its requirement for some disease resistances, while unaffecting others as well as normal cell processes. Moreover, the data indicate that the requirement of SGT1 for resistance signaling by NLRs can be delimited to single sites on the protein. Further study could distinguish the regions by which pathogen effectors and host proteins interact with SGT1, facilitating precise editing of effector incompatible variants.

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Biological relationship of cucumis virus-3 and powdery mildew fungus in bottle gourd

Cellular and Molecular Life Sciences ◽

10.1007/bf01923021 ◽

1978 ◽

Vol 34 (3) ◽

pp. 336-337 ◽

Cited By ~ 1

Author(s):

M. A. Qureshi ◽

C. D. Mayee

Keyword(s):

Powdery Mildew ◽

Bottle Gourd ◽

Powdery Mildew Fungus ◽

Biological Relationship ◽

Relationship Of

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Powdery Mildew Fungus on Cucurbits in the Transvaal Province of South Africa

Nature ◽

10.1038/209938a0 ◽

1966 ◽

Vol 209 (5026) ◽

pp. 938-938 ◽

Cited By ~ 2

Author(s):

G. J. M. A. GORTER

Keyword(s):

South Africa ◽

Powdery Mildew ◽

Powdery Mildew Fungus

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Erysiphe trifolii Causing Powdery Mildew of Lentil (Lens culinaris)

Plant Disease ◽

10.1094/pdis-93-8-0797 ◽

2009 ◽

Vol 93 (8) ◽

pp. 797-803 ◽

Cited By ~ 22

Author(s):

Renuka N. Attanayake ◽

Dean A. Glawe ◽

Frank M. Dugan ◽

Weidong Chen

Keyword(s):

Powdery Mildew ◽

Pacific Northwest ◽

The United States ◽

Morphological Characters ◽

Grain Legumes ◽

Its Sequences ◽

Powdery Mildew Fungus ◽

The Pacific ◽

Soybean Genotypes ◽

Erysiphe Trifolii

The taxonomy of the powdery mildew fungus infecting lentil in the Pacific Northwest (PNW) of the United States was investigated on the basis of morphology and rDNA internal transcribed spacer (ITS) sequences. Anamorphic characters were in close agreement with descriptions of Erysiphe trifolii. However, teleomorphs formed chasmothecial appendages with highly branched apices, whereas E. trifolii has been described as producing flexuous or sometimes loosely branched appendages. Branched appendages have been described in Erysiphe diffusa, a fungus reported from species of Lens, Glycine, and Sophora, raising the possibility that the PNW fungus could be E. diffusa. Examination of morphological characters of an authentic specimen of E. trifolii from Austria determined that it included chasmothecial appendages resembling those seen in PNW specimens. Furthermore, ITS sequences from five powdery mildew samples collected from lentils in PNW greenhouses and fields from 2006 to 2008 were identical to one another, and exhibited higher similarity to sequences of E. trifolii (99%) than to those of any other Erysiphe spp. available in GenBank. Parsimony analysis grouped the lentil powdery mildew into a clade with Erysiphe baeumleri, E. trifolii, and E. trifolii–like Oidium sp., but indicated a more distant relationship to E. diffusa. In greenhouse inoculation studies, the lentil powdery mildew fungus did not infect soybean genotypes known to be susceptible to E. diffusa. The pathogenicity of E. trifolii on lentil was confirmed using modified Koch's postulates. This is the first report of E. trifolii infecting lentil. E. diffusa and E. trifolii have different host ranges, so the discovery of E. trifolii on lentil has implications both for determining species of powdery mildews on cool-season grain legumes, and in disease management.

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BAX INHIBITOR-1 Is Required for Full Susceptibility of Barley to Powdery Mildew

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-23-9-1217 ◽

2010 ◽

Vol 23 (9) ◽

pp. 1217-1227 ◽

Cited By ~ 58

Author(s):

Ruth Eichmann ◽

Melanie Bischof ◽

Corina Weis ◽

Jane Shaw ◽

Christophe Lacomme ◽

...

Keyword(s):

Cell Death ◽

Powdery Mildew ◽

Gene Silencing ◽

Defense Responses ◽

Negative Control ◽

Cellular Level ◽

Virus Induced Gene Silencing ◽

Powdery Mildew Fungus ◽

Basal Resistance ◽

Enhanced Resistance

BAX INHIBITOR-1 (BI-1) is one of the few proteins known to have cross-kingdom conserved functions in negative control of programmed cell death. Additionally, barley BI-1 (HvBI-1) suppresses defense responses and basal resistance to the powdery mildew fungus Blumeria graminis f. sp. hordei and enhances resistance to cell death–provoking fungi when overexpressed in barley. Downregulation of HvBI-1 by transient-induced gene silencing or virus-induced gene silencing limited susceptibility to B. graminis f. sp. hordei, suggesting that HvBI-1 is a susceptibility factor toward powdery mildew. Transient silencing of BI-1 did not limit supersusceptibility induced by overexpression of MLO. Transgenic barley plants harboring an HvBI-1 RNA interference (RNAi) construct displayed lower levels of HvBI-1 transcripts and were less susceptible to powdery mildew than wild-type plants. At the cellular level, HvBI-1 RNAi plants had enhanced resistance to penetration by B. graminis f. sp. hordei. These data support a function of BI-1 in modulating cell-wall-associated defense and in establishing full compatibility of B. graminis f. sp. hordei with barley.

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Ampelomyces strains isolated from diverse powdery mildew hosts in Japan: Their phylogeny and mycoparasitic activity, including timing and quantifying mycoparasitism of Pseudoidium neolycopersici on tomato

PLoS ONE ◽

10.1371/journal.pone.0251444 ◽

2021 ◽

Vol 16 (5) ◽

pp. e0251444

Author(s):

Márk Z. Németh ◽

Yuusaku Mizuno ◽

Hiroki Kobayashi ◽

Diána Seress ◽

Naruki Shishido ◽

...

Keyword(s):

Powdery Mildew ◽

Host Plants ◽

Morphological Characteristics ◽

Post Inoculation ◽

Powdery Mildew Fungus ◽

Rdna Its ◽

Pseudoidium Neolycopersici ◽

Tomato Powdery Mildew ◽

Internal Transcribed Spacer Rdna ◽

Complete Collapse

A total of 26 Ampelomyces strains were isolated from mycelia of six different powdery mildew species that naturally infected their host plants in Japan. These were characterized based on morphological characteristics and sequences of ribosomal DNA internal transcribed spacer (rDNA-ITS) regions and actin gene (ACT) fragments. Collected strains represented six different genotypes and were accommodated in three different clades of the genus Ampelomyces. Morphology of the strains agreed with that of other Ampelomyces strains, but none of the examined characters were associated with any groups identified in the genetic analysis. Five powdery mildew species were inoculated with eight selected Ampelomyces strains to study their mycoparasitic activity. In the inoculation experiments, all Ampelomyces strains successfully infected all tested powdery mildew species, and showed no significant differences in their mycoparasitic activity as determined by the number of Ampelomyces pycnidia developed in powdery mildew colonies. The mycoparasitic interaction between the eight selected Ampelomyces strains and the tomato powdery mildew fungus (Pseudoidium neolycopersici strain KTP-03) was studied experimentally in the laboratory using digital microscopic technologies. It was documented that the spores of the mycoparasites germinated on tomato leaves and their hyphae penetrated the hyphae of Ps. neolycopersici. Ampelomyces hyphae continued their growth internally, which initiated the atrophy of the powdery mildew conidiophores 5 days post inoculation (dpi); caused atrophy 6 dpi; and complete collapse of the parasitized conidiphores 7 dpi. Ampelomyces strains produced new intracellular pycnidia in Ps. neolycopersici conidiophores ca. 8–10 dpi, when Ps. neolycopersici hyphae were successfully destroyed by the mycoparasitic strain. Mature pycnidia released spores ca. 10–14 dpi, which became the sources of subsequent infections of the intact powdery mildew hyphae. Mature pycnidia contained each ca. 200 to 1,500 spores depending on the mycohost species and Ampelomyces strain. This is the first detailed analysis of Ampelomyces strains isolated in Japan, and the first timing and quantification of mycoparasitism of Ps. neolycopersici on tomato by phylogenetically diverse Ampelomyces strains using digital microscopic technologies. The developed model system is useful for future biocontrol and ecological studies on Ampelomyces mycoparasites.

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Effective Management of Cucumber Powdery Mildew with Essential Oils

Agriculture ◽

10.3390/agriculture11111177 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1177

Author(s):

Yasser S. Mostafa ◽

Mohamed Hashem ◽

Ali M. Alshehri ◽

Saad Alamri ◽

Ebrahem M. Eid ◽

...

Keyword(s):

Powdery Mildew ◽

Essential Oils ◽

Disease Incidence ◽

Its Region ◽

Dry Weight ◽

Positive Control ◽

Powdery Mildew Fungus ◽

Membrane Injury ◽

Cucumber Powdery Mildew

This research evaluated the efficacy of essential oils in the management of cucumber powdery mildew. Essential oils of lemongrass, lemon, thyme, peppermint, abundance blend, purification blend, and thieves blend were tested in vitro and under greenhouse conditions in two separate experiments. The effects of essential oils were tested against powdery mildew disease at concentrations of 1.0–2.5 mL/L, and the consequent impact of the oils on plant growth was evaluated. Powdery mildew fungus, Podosphaera xanthii, was identified using sequencing of the ITS region. The essential oils significantly reduced disease incidence up to 77.3% compared with the positive control (p < 0.5). Moreover, the essential oils increased the plant length (up to 187 cm), leaf area (up to 27.5 cm2), fresh weight (up to 123 g), dry weight (up to 22.5 g), number of flowers (16.3), and metabolite content compared with the positive control (p < 0.5). Cell membrane injury decreased significantly in the oil-treated pants (p < 0.5), indicating the protective effect of essential oils. This study recommends the application of essential oils in an appropriate dose (2.5 mL/L) to protect cucumber plants against powdery mildew. Overdose of the oils (more than 2.5 mL/L) should be avoided due to adverse effects.

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