Use of Freeze Substitution for TEM Studies of Fungal Spores

Since its initial use to fix fungal hyphae (1), plunge freezing followed by freeze substitution has become the “gold standard” for TEM studies of fungal hyphae and spores. In this presentation we discuss results we have obtained using plunge freezing and freeze substitution to fix various types of spores produced by plant pathogenic fungi. Examples include basidiospores and aeciospores of rust fungi, teliospores of rust and smut fungi and conidia of a variety of ascomycetes and deuteromycetes.Generally speaking, plunge freezing followed by freeze substitution usually yields best results when spore diameter does not exceed 10-15 μm. However, in a number of cases we (2) have obtained good to excellent results with much larger spores. A key to good freezing appears to be direct exposure of spores to liquid propane during plunging. We have had best results by placing spores on small pieces of dialysis membrane and then plunging these membranes. In most cases the spores remain attached to membranes throughout the freezing, substitution, infiltration and embedment procedures.

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Survival and probability of transmission of plant pathogenic fungi through the digestive tract of honey bee workers

Apidologie ◽

10.1007/s13592-019-00697-6 ◽

2019 ◽

Vol 50 (6) ◽

pp. 871-880 ◽

Cited By ~ 1

Author(s):

Jorgiane B. Parish ◽

Eileen S. Scott ◽

Raymond Correll ◽

Katja Hogendoorn

Keyword(s):

Digestive Tract ◽

Honey Bee ◽

Honey Bees ◽

Plant Pathogens ◽

Fungal Spores ◽

Pathogenic Fungi ◽

Colletotrichum Acutatum ◽

Plant Pathogenic Fungi ◽

The Mean ◽

Honey Bee Workers

AbstractHoney bees, Apis mellifera, have been implicated as vectors of plant pathogens. However, the survival of spores of plant pathogenic fungi through the digestive tract of workers has not been investigated. As workers defecate outside the hive, transport of hives could give rise to biosecurity concerns if fungal spores remain viable following passage through the digestive tract. To determine the likelihood that honey bees serve as vectors, this study investigated the viability of spores of Botrytis cinerea and Colletotrichum acutatum after passing through the digestive tract of summer and autumn worker bees. For both fungi, the mean viability of spores in faeces suspensions was less than one percent of the initial dose fed to the bees. Although survival was low, the large number of workers per hive implies a high probability of transmission of viable spores through honey bee faeces. Hence, in the case of economically important fungal diseases, transported hives could be a source of inoculum and quarantine restrictions should be considered.

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Impact of Cryo Techniques on Cytological Studies of Plant Pathogenic Fungi and their Hosts

Microscopy and Microanalysis ◽

10.1017/s1431927600035868 ◽

2000 ◽

Vol 6 (S2) ◽

pp. 674-675 ◽

Cited By ~ 1

Author(s):

R. J. Howard ◽

T. M. Bourett ◽

K. E. Duncan

Keyword(s):

Electron Microscope ◽

Freeze Substitution ◽

Pathogenic Fungi ◽

Extracellular Matrices ◽

Direct Result ◽

Aqueous Environment ◽

Specimen Preparation ◽

Plant Pathogenic Fungi ◽

Chemical Methods ◽

Transmission Electron

Cryo techniques of specimen preparation have become the standard for cytological studies of biological specimens. From the pioneering work of Feder and Sidman, and Zalokar, the now ubiquitous application of freeze substitution for transmission electron microscope studies of fungi was a direct result of work reported in 1979. Since then, cryopreparative methods have also become the standard for SEM studies and may, for certain purposes, replace conventional methods of fixation for light microscopy as well. Undoubtedly, there are instances where non-cryo methods might be preferred, or where comparisons of results using cryo vs. chemical fixations can provide unique information. On the whole, however, the advantages offered to mycologists and plant pathologists by cryo fixation over any chemical methods are many, and include (a) the opportunity to preserve specimens in a non-aqueous environment, (b) preservation of labile structures such as certain organelles, extracellular matrices, or various cellular content such as ions or that of vacuoles, (c) preservation of cells in a more life-like state,

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Putative Rust Fungal Effector Proteins in Infected Bean and Soybean Leaves

Phytopathology ◽

10.1094/phyto-11-15-0310-r ◽

2016 ◽

Vol 106 (5) ◽

pp. 491-499 ◽

Cited By ~ 14

Author(s):

Bret Cooper ◽

Kimberly B. Campbell ◽

Hunter S. Beard ◽

Wesley M. Garrett ◽

Nazrul Islam

Keyword(s):

Plant Cell ◽

Crop Production ◽

Rust Fungus ◽

Fungal Spores ◽

Pathogenic Fungi ◽

Rust Fungi ◽

Effector Proteins ◽

Glycoside Hydrolases ◽

Data Set ◽

Soybean Leaves

The plant-pathogenic fungi Uromyces appendiculatus and Phakopsora pachyrhizi cause debilitating rust diseases on common bean and soybean. These rust fungi secrete effector proteins that allow them to infect plants, but their effector repertoires are not understood. The discovery of rust fungus effectors may eventually help guide decisions and actions that mitigate crop production loss. Therefore, we used mass spectrometry to identify thousands of proteins in infected beans and soybeans and in germinated fungal spores. The comparative analysis between the two helped differentiate a set of 24 U. appendiculatus proteins targeted for secretion that were specifically found in infected beans and a set of 34 U. appendiculatus proteins targeted for secretion that were found in germinated spores and infected beans. The proteins specific to infected beans included family 26 and family 76 glycoside hydrolases that may contribute to degrading plant cell walls. There were also several types of proteins with structural motifs that may aid in stabilizing the specialized fungal haustorium cell that interfaces the plant cell membrane during infection. There were 16 P. pachyrhizi proteins targeted for secretion that were found in infected soybeans, and many of these proteins resembled the U. appendiculatus proteins found in infected beans, which implies that these proteins are important to rust fungal pathology in general. This data set provides insight to the biochemical mechanisms that rust fungi use to overcome plant immune systems and to parasitize cells.

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Aecidium peristrophes , a new record for Pakistan

Mycotaxon ◽

10.5248/135.275 ◽

2020 ◽

Vol 135 (2) ◽

pp. 275-280

Author(s):

N.S. Afshan ◽

M. Riaz ◽

A. Saqib

Keyword(s):

Plant Species ◽

New Record ◽

Pathogenic Fungi ◽

Rust Fungi ◽

Plant Pathogenic Fungi ◽

Hedera Helix

During a survey of plant pathogenic fungi of Khanspur, Thandiani, and adjacent areas, two plant species—Hedera helix (Araliaceae) and Peristrophe sp. (Acanthaceae)—were found to be infected with rust fungi. After careful morphological and anatomical observations, these rusts were identified as Aecidium hederae and A. peristrophes, with A. peristrophes reported as a new record for Pakistan.

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Freeze substitution fixation of fungal reproductive structures and spores

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100156936 ◽

1989 ◽

Vol 47 ◽

pp. 990-991

Author(s):

C. W. Mims ◽

E. A. Richardson

Keyword(s):

Plant Pathogens ◽

Freeze Substitution ◽

Uranyl Acetate ◽

Chemical Fixation ◽

Dialysis Membrane ◽

Razor Blade ◽

Thin Sections ◽

Reproductive Structures ◽

Dry Down ◽

Diamond Knife

The advantages of freeze substitution fixation over conventional chemical fixation for preservation of ultrastructural details in fungi have been discussed by various authors. As most ascomycetes, basidiomycetes and deuteromycetes do not fix well using conventional chemical fixation protocols, freeze substitution has attracted the attention of many individuals interested in fungal ultrastructure. Thus far most workers using this technique on fungi have concentrated on thin walled somatic hyphae. However, in our laboratory we have experimented with the use of freeze substitution on a variety of fungal reproductive structures and spores with promising results.Here we present data on freeze substituted samples of sporangia of the zygomycete Umbellopsis vinacea, basidia of Exobasidium camelliae var. gracilis, developing teliospores of the smut Sporisorium sorghi, germinating teliospores of the rust Gymnosporangium clavipes, germinating conidia of the deuteromycete Cercosporidium personatum, and developing ascospores of Ascodesmis nigricans.Spores of G. clavipes and C. personatum were deposited on moist pieces of sterile dialysis membrane where they hydrated and germinated. Asci of A. nigricans developed on pieces of dialysis membrane lying on nutrient agar plates. U. vinacea was cultured on small pieces of agar-coated wire. In the plant pathogens E. camelliae var. gracilis and S. sorghi, a razor blade was used to remove smal1 pieces of infected host issue. All samples were plunged directly into liquid propane and processed for study according to Hoch.l Samples on dialysis membrane were flat embedded. Serial thin sections were cut using a diamond knife, collected on slot grids, and allowed to dry down onto Formvar coated aluminum racks. Sections were post stained with uranyl acetate and lead citrate.

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Development of genome editing technologies for plant pathogenic fungi

Japanese Journal of Phytopathology ◽

10.3186/jjphytopath.86.264 ◽

2020 ◽

Vol 86 (4) ◽

pp. 264

Author(s):

T. ARAZOE

Keyword(s):

Genome Editing ◽

Pathogenic Fungi ◽

Plant Pathogenic Fungi

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Comparative Fungicidal Activity of some Pure and Nanoemulsion Monoterpenes Effects on Soil Borne Plant Pathogenic Fungi

Journal of Plant Protection and Pathology ◽

10.21608/jppp.2018.43962 ◽

2018 ◽

Vol 9 (10) ◽

pp. 707-713

Author(s):

Mona Abdelrasoul ◽

G. Amer

Keyword(s):

Fungicidal Activity ◽

Pathogenic Fungi ◽

Plant Pathogenic Fungi

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Fungal Phytotoxins in Sustainable Weed Management

Current Medicinal Chemistry ◽

10.2174/0929867324666170426152331 ◽

2018 ◽

Vol 25 (2) ◽

pp. 268-286 ◽

Cited By ~ 4

Author(s):

Maurizio Vurro ◽

Angela Boari ◽

Francesca Casella ◽

Maria Chiara Zonno

Keyword(s):

Weed Management ◽

Pathogenic Fungi ◽

Mechanisms Of Action ◽

Limiting Factors ◽

Integrated Weed Management ◽

Plant Pathogenic Fungi ◽

Design Strategies ◽

Disease Etiology ◽

Chemical Structures ◽

Toxic Metabolites

Fungal phytotoxins are natural secondary metabolites produced by plant pathogenic fungi during host–pathogen interactions. They have received considerable particular attention for elucidating disease etiology, and consequently to design strategies for disease control. Due to wide differences in their chemical structures, these toxic metabolites have different ecological and environmental roles and mechanisms of action. This review aims at summarizing the studies on the possible use of these metabolites as tools in biological and integrated weed management, e.g. as: novel and environmentally friendly herbicides; lead for novel compounds; sources of novel mechanisms of action. Moreover, the limiting factors for utilizing those metabolites in practice will also be briefly discussed.

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First record of Pestalotiopsis spp. from affected leaves of mastic shrubs (Pestacia lentiscus L.) in northeastern of Libya.

International Journal of Bioassays ◽

10.21746/ijbio.2016.08.004 ◽

2016 ◽

Vol 5 (08) ◽

pp. 4744

Author(s):

Zahra Ibrahim El-Gali

Keyword(s):

Signs And Symptoms ◽

Pathogenic Fungi ◽

First Record ◽

Plant Pathogenic Fungi ◽

Pistacia Lentiscus ◽

Plant Materials ◽

Al Jabal Al Akhdar ◽

First Time

This study was carried out to identify the unknown different symptoms and their causes as plant pathogenic fungi from Al-Jabal Al-Akhdar District. Plant materials with fungal signs and symptoms were collected and examined. The main fungi consistently isolated from symptomatic leaves and twigs were Pestalotiopsis spp. Morphology, colony characteristics, and pathogenicity of the isolates were examined. My report the occurrence of Pestalotiopsis spp. on leaves of mastic (Pistacia lentiscus) for the first time in Libya.

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