CYTOLOGICAL STUDIES OF HELMINTHOSPORIUM SATIVUM

1956 ◽  
Vol 34 (3) ◽  
pp. 321-327 ◽  
Author(s):  
S. B. Hrushovetz
Keyword(s):  
Helminthosporium Sativum ◽  
Germ Tubes

Cytological studies of Helminthosporium sativum P.K. & B. showed that a mechanism exists for the perpetuation of heterokaryons. Septa are laid down in such a way that usually the hyphal tips and mycelial cells are initially multinucleate. Hyphal fusions occur in all parts of the colony and nuclei have been observed in the bridging hyphae. Two or more nuclei generally enter the young conidiophore and several nuclei invariably enter the young conidium before the latter is delimited from the conidiophore. The multicellular, multinucleate conidia exhibit polar or bipolar germination but only the nuclei in the terminal cells of the conidium enter the germ tubes; the remaining cells and their nuclei subsequently degenerate. Germination of complete conidiophores or portions of conidiophores was also observed.

OVERWINTERING OF CERTAIN CEREAL PATHOGENS IN ALBERTA

1937 ◽  
Vol 15c (12) ◽  
pp. 547-559 ◽  
Author(s):  
W. R. Foster ◽  
A. W. Henry
Keyword(s):  
Winter Wheat ◽  
Fusarium Culmorum ◽  
Soil Surface ◽  
Freezing And Thawing ◽  
Tilletia Caries ◽  
Helminthosporium Sativum ◽  
Favorable Conditions ◽  
Germ Tubes ◽  
Continuous Freezing ◽  
Hardened Condition

Helminthosporium sativum, Fusarium culmorum, Ophiobolus graminis, Leptosphaeria herpotrichoides, Wojnowicia graminis, Erysiphe graminis, Tilletia caries, and Tilletia foetens readily overwinter under natural conditions at Edmonton, Alberta, Canada. The first five of these overwinter at Edmonton in both spore and vegetative stages and are highly resistant to cold. Even in a non-hardened condition several of them survived severe frost. Young germ tubes of H. sativum for instance continued growth after being frozen solid overnight. Fresh agar cultures of H. sativum, F. culmorum and O. graminis grew vigorously after exposure to sub-zero temperatures. Agar cultures of H. sativum and F. culmorum were viable after a 17-day exposure to temperatures ranging from about 0° F. to —50° F.Conidia of H. sativum proved less resistant to freezing and thawing than to continuous freezing. They survived longer than conidia of F. culmorum and F. graminearum. Mycelia of all foot-rot fungi grown on sterilized barley seeds were viable in one case after three months of continuous freezing, and in another after 40 alternate freezings and thawings. H. sativum and F. culmorum growing in soil survived 61 alternate freezings and thawings.H. sativum, F. culmorum and L. herpotrichoides, retained their viability more readily on the soil surface than when buried at depths of from 2 to 12 in. Well aerated soil seemed to favor the survival of H. sativum, although other factors besides aeration probably are involved. Strains of H. sativum from high latitudes were not better adapted to low temperatures than strains from lower latitudes.The bunt fungi, T. caries and T. foetens, are shown to be capable of overwintering at Edmonton in the form of mycelia in winter wheat. Infection of winter wheat from soil-borne spores may occur in western Canada, but in these experiments soil-borne spores did not survive to infect wheat in the spring.Erysiphe graminis overwinters in the perithecial stage at Edmonton. In the studies made, ascospores were differentiated in the spring, when favorable conditions prevailed and before the first infections of winter wheat were observed.

A SLIDE TECHNIQUE FOR THE STUDY OF FUNGI AND ACTINOMYCETES IN SOIL WITH SPECIAL REFERENCE TO HELMINTHOSPORIUM SATIVUM

1953 ◽  
Vol 31 (6) ◽  
pp. 718-724 ◽  
Author(s):  
S. H. F. Chinn
Keyword(s):  
Special Reference ◽  
Soybean Meal ◽  
Fusarium Culmorum ◽  
Natural Soil ◽  
Penicillium Notatum ◽  
Amended Soils ◽  
Helminthosporium Sativum ◽  
Stachybotrys Atra ◽  
Slide Technique ◽  
Germ Tubes

A slide technique suitable for studying the behavior of fungi and actinomycetes both qualitatively and quantitatively in soil is described. Besides Helminthosporium sativum, eight other fungi and one actinomycete were used to demonstrate the applicability of the method which was used for both natural and soybean meal amended soils. In the natural soil spores of Penicillium notatum, Stachybotrys atra, and the actinomycete only germinated. However, lysis or disintegration of the germ tubes of the two fungi was observed on the fourth day. Growth of the actinomycete was continuous to at least the seventh day. In the amended soil only one fungus failed to germinate. Of those that germinated, only Fusarium culmorum and the actinomycete were capable of continued growth and sporulation. Lysis or disintegration of the germ tubes of the others was noticed on the fourth day.

THE INFLUENCE OF ASSOCIATED MICROORGANISMS ON THE PATHOGENICITY OF HELMINTHOSPORIUM SATIVUM

1956 ◽  
Vol 34 (6) ◽  
pp. 865-874 ◽  
Author(s):  
W. P. Campbell
Keyword(s):  
Soil Temperature ◽  
Soil Fungi ◽  
Trichoderma Viride ◽  
Soil Extract ◽  
The Other ◽  
Internal Parasites ◽  
Helminthosporium Sativum ◽  
Extract Medium ◽  
Germination And Growth ◽  
Germ Tubes

Six species of soil fungi were studied in association with Helminthosporium sativum. Phoma humicola, Epicoccum purpurascens, and Trichoderma viride strongly inhibited the pathogenic activities of H. sativum, while Actinomucor repens, Sclerotinia trifoliorum, and Myrothecium verrucaria were only slightly inhibitory. The pathogenicity of H. sativum was increasingly depressed by each of the six fungi as soil temperature was increased from 15° to 26 °C. The pH shifts which these fungi induced in soil were not sufficient to be considered as a factor in depressing pathogenicity. In plate tests on nonenriched soil-extract medium, S. trifoliorum and A. repens did not appreciably affect H. sativum. The other four fungi all caused distortion and breakdown of the spores, while M. verrucaria and E. purpurascens were found as internal parasites in spores of H. sativum. P. humicola, E. purpurascens, and T. viride caused the breakdown of mycelium of the pathogen, and P. humicola and E. purpurascens were found as internal parasites of the mycelium. The fungi produced substances in the medium which adversely affect the germination and growth of germ tubes of spores of H. sativum. A. repens and S. trifoliorum were least effective, T. viride and P. humicola were intermediate in their action, and E. purpurascens and M. verrucaria were very severely limiting. Two antagonistic mechanisms, antibiosis and direct parasitism, were demonstrated, both of which were responsible for disorganization of the mycelium of the pathogen. Only those fungi that caused disruption of the mycelium were able to depress the pathogenicity of H. sativum appreciably.

STUDIES ON THE SEEDLING DISEASE OF BARLEY CAUSED BY HELMINTHOSPORIUM SATIVUM P.K. & B.

1956 ◽  
Vol 34 (4) ◽  
pp. 653-673 ◽  
Author(s):  
R. A. Ludwig ◽  
R. V. Clark ◽  
J. B. Julien ◽  
D. B. Robinson
Keyword(s):  
Disease Incidence ◽  
Infested Soil ◽  
Disease Development ◽  
Toxic Activity ◽  
Factors Affecting ◽  
Seedling Disease ◽  
Nutrient Salt ◽  
Helminthosporium Sativum ◽  
Treatment Comparisons

A standard sand – cornmeal – nutrient salt medium, for use in the production of artificial inoculum of Helminthosporium sativum, is described. This inoculum induces uniform plant disease development when thoroughly incorporated with the planting soil. The results presented clearly demonstrate the necessity of using a series of infestation levels in studies of factors affecting disease development in artificially infested soil. It is shown that considerable reliance can be placed on treatment comparisons within an experiment but that comparisons between experiments are much less accurate. The role of a toxin (or toxins) in disease development in barley seedlings has been demonstrated. The toxic activity was found to be distinct from that frequently encountered on addition of organic matter to soil. Results obtained suggest that toxin adsorption by the soil may play an important role in reducing disease incidence and severity.

scholarly journals Cell Biology of Conidial Anastomosis Tubes in Neurospora crassa

2005 ◽  
Vol 4 (5) ◽  
pp. 911-919 ◽  
Author(s):  
M. Gabriela Roca ◽  
Jochen Arlt ◽  
Chris E. Jeffree ◽  
Nick D. Read
Keyword(s):  
Neurospora Crassa ◽  
Optical Tweezers ◽  
Cell Biology ◽  
Transmembrane Protein ◽  
Mitogen Activated Protein Kinase ◽  
Cellular Element ◽  
Hyphal Fusion ◽  
Self Recognition ◽  
Mitogen Activated Protein ◽  
Germ Tubes

ABSTRACT Although hyphal fusion has been well documented in mature colonies of filamentous fungi, it has been little studied during colony establishment. Here we show that specialized hyphae, called conidial anastomosis tubes (CATs), are produced by all types of conidia and by conidial germ tubes of Neurospora crassa. The CAT is shown to be a cellular element that is morphologically and physiologically distinct from a germ tube and under separate genetic control. In contrast to germ tubes, CATs are thinner, shorter, lack branches, exhibit determinate growth, and home toward each other. Evidence for an extracellular CAT inducer derived from conidia was obtained because CAT formation was reduced at low conidial concentrations. A cr-1 mutant lacking cyclic AMP (cAMP) produced CATs, indicating that the inducer is not cAMP. Evidence that the transduction of the CAT inducer signal involves a putative transmembrane protein (HAM-2) and the MAK-2 and NRC-1 proteins of a mitogen-activated protein kinase signaling pathway was obtained because ham-2, mak-2, and nrc-1 mutants lacked CATs. Optical tweezers were used in a novel experimental assay to micromanipulate whole conidia and germlings to analyze chemoattraction between CATs during homing. Strains of the same and opposite mating type were shown to home toward each other. The cr-1 mutant also underwent normal homing, indicating that cAMP is not the chemoattractant. ham-2, mak-2, and nrc-1 macroconidia did not attract CATs of the wild type. Fusion between CATs of opposite mating types was partially inhibited, providing evidence of non-self-recognition prior to fusion. Microtubules and nuclei passed through fused CATs.

Gaeumannomyces graminis var. tritici. [Descriptions of Fungi and Bacteria].

1973 ◽  
Author(s):  
J. Walker
Keyword(s):  
Geographical Distribution ◽  
Root Hairs ◽  
Seed Transmission ◽  
Gaeumannomyces Graminis ◽  
Root Infection ◽  
Root Death ◽  
Meristematic Region ◽  
Germ Tubes ◽  
Gaeumannomyces Graminis Var Tritici ◽  
Take All

Abstract A description is provided for Gaeumannomyces graminis var. tritici. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Gramineae, especially Triticum, Hordeum, Secale, Agropyron and several other grass genera and, more rarely, Sorghum and Zea; also recorded from the roots of plants in other families. DISEASE: Take-all of cereals and grasses (also referred to as deadheads or whiteheads, pietin and pied noir (France), Schwarzbeinigkeit and Ophiobolus Fusskrankheit (Germany), Ophiobolusvoetziekt (Netherlands) and others). Root infection is favoured by soil temperature from 12-20°C (Butler, 1961). Ascospore germ tubes penetrate root hairs and the epidermis in the meristematic region (Weste, 1972) leading to plugging of xylem and root death. GEOGRAPHICAL DISTRIBUTION: (CMI Map 334, ed. 3, 1972). Widespread, especially in temperate zones. Africa; Asia (India, Iran, Japan, USSR): Australasia and Oceania; Europe; North America (Canada, USA); South America (Argentina, Brazil, Chile, Colombia, Uruguay). TRANSMISSION: In soil on infected organic fragments, as runner hyphae on roots of cereals and grasses and, under special conditions, by ascospores. Seed transmission very doubtful (47, 3058).

scholarly journals Bright-Field and Fluorescence Microscopic Study of Development of Erysiphe polygoni in Susceptible and Resistant Bigleaf Hydrangea

Plant Disease ◽  
2009 ◽  
Vol 93 (2) ◽  
pp. 130-134 ◽  
Author(s):  
Yonghao Li ◽  
Mark T. Windham ◽  
Robert N. Trigiano ◽  
Sandra M. Reed ◽  
James M. Spiers ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Hyphal Growth ◽  
Early Response ◽  
Resistance Mechanisms ◽  
Colony Development ◽  
Susceptible Cultivar ◽  
Bright Field ◽  
Erysiphe Polygoni ◽  
Infected Cells ◽  
Germ Tubes

Temporal development of Erysiphe polygoni and responses of bigleaf hydrangeas (Hydrangea macrophylla) to the fungal attack were investigated using bright-field and fluorescence microscopy. Conidia germinated 2 h after inoculation (HAI) and formed primary appressoria at the tip of the primary germ tubes within 4 HAI. Secondary germ tubes were initiated from primary appressoria or other parts of conidia 12 HAI. Hyphae developed through elongation of secondary germ tubes, and paired lateral appressoria were formed along hyphae within 2 days after inoculation (DAI). Conidiophores and conidia were formed 5 DAI. In the susceptible cultivar Nikko Blue and the resistant cultivar Veitchii, the fungus established a parasitic relationship, which was indicated by the formation of haustoria under primary appressoria and development of secondary germ tubes at 1 DAI. A hypersensitive response (HR) and accumulation of callose were detected in both resistant and susceptible cultivars at 3 DAI. Resistance to powdery mildew in Veitchii was evident by manifestation of early accumulation of callose, relatively high percentage of necrotic infected cells, and restricted colony development compared to the susceptible cultivar Nikko Blue. Restricting hyphal growth and sporulation by early response of callose accumulation and HR are important resistance mechanisms that could be used in screening hydrangeas for resistance to powdery mildew.

scholarly journals PERKECAMBAHAN UREDOSPORA HEMILEIA VASTATRIX PADA EKSTRAK RIMPANG JAHE DAN KUNYIT SERTA DAUN CENGKEH DAN SIRIH

2006 ◽  
Vol 6 (1) ◽  
pp. 52-58
Author(s):  
Cipta Ginting
Keyword(s):  
Block Design ◽  
Water Extract ◽  
Piper Betle ◽  
Distilled Water ◽  
Control Methods ◽  
Hemileia Vastatrix ◽  
Coffee Leaf Rust ◽  
Randomized Complete Block Design ◽  
Test Treatments ◽  
Germ Tubes

Germination of Hemileia vastatrix uredospores on crude water extracts of zinger and turmeric rhizome and clove and Piper betle leaves.  Coffee leaf rust caused by H. vastatrix especially on Arabica coffee is one of most important diseases in coffee and conventional control methods of leaf coffee rust is still unsatisfactory.  The objective of this study was to determine the effect of crude water extract on the germination of H. vastatrix uredospores.  The study was conducted from January to September 2004 in the Laboratory of Plant Pathology at Unila.  In each test, treatments were arranged in a randomized complete block design with four replications.  Crude water extract was prepared by homogenizing 100 g of material in 100 ml sterilized distilled water.  After being passed through four layers of sterilized cheesecloth, the mixture was defined as the aliquot (100% extract) and dilutions were made with sterile distilled water to obtain concentrations of 2.5 to 10%.  Each of four materials (zinger, turmeric, clove, and Piper betle) was tested separately in five aliquot concentration levels.  One ml of each extract was mixed with 0.25 ml of uredospora suspension (4 x 105 per ml), and 0.2 ml of the mixture was incubated.  The variable was germinated uredospora (%) that was determined under a mikroscope.  The results show that significant reduction in spore germination occurred by  turmeric, clove, and P. betle extracts at > 2.5% and by zinger extract at > 5%.  Some uredospora exposed to plant extract germinated abnormally:  germ tubes shorten, swollen, or malform.

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