Overview

Morphological specialization (production of differentiated gametangia) has little relevance to mating in fungi based on the haploid phase. Indeed, specialized cells for mating are found only in filamentous Ascomycotina and even here a single individual produces both male and female structures. Nonetheless, most species have genetic barriers to self-fertilization and only individuals with different mating types can engage in sexual reproduction. Ascomycotina have just two mating types but...

Neurospora A Gateway to Biology

In 1843, a luxuriant growth of a pink-orange fungus was observed on bread in the bakeries of Paris. This fungus was subsequently recognized as a common contaminant of bakeries and it came to be known as the pink bread mold. On September 1, 1923, an earthquake followed by fire struck Tokyo. The strange sight of a pink-orange growth that developed on almost all burnt trees and vegetation amazed the residents. Examination showed that the orange colored growth was due to the profuse production of...

A

Action spectrum pigmentation, 163 sporulation, 166, 167, 168 Alcohol fermentation, 81 Alternaria solani, detoxification of saponin, 59 Amylase, 155 Anamorph, 232 Appressorium, 38, 54-55 Arbuscular mycorrhiza, 38 Armillaria bulbosa, largest and oldest fungus, 3 method of testing individualism of colony, 3-6 Ascus, 70, 226, 228 ascospore, 70, 73, 76 Ascus, 67, 226 ascospore, 69-77, 226 Asexual reproduction, basic strategy, 107 Aspergillus nidulans, 15, 21-23, 30, 107 Autoradiographic imaging of...

Carbon Sources in Environment

As the temperature begins to rise in a compost heap, the mesophilic microflora is succeeded by thermophilic microflora (Hedger and Hudson, 1974). Therefore, the availability of soluble carbon sources (sugars, amino acids and organic acids) will decrease and the carbon source available to thermophilic fungi will mainly be the polysaccharide constituents of the biomass, chiefly cellulose and hemicelluloses. Not surprisingly, thermophilic fungi are therefore especially well adapted for...

Info

Figure 3.3 Technique to study translocation of 14C-sucrose by root and mycorrhizal tissue. (From Burnett, Fundamentals of Mycology (1976), London Arnold.) mycelium and spores. One useful technique is to grow mycorrhizal fungi on hairy roots induced by infection with the bacterium Agrobacterium rhizogenes. Hairy roots are maintained aseptically in media containing ampicillin. This technique has led to the development of an in vitro collection of AM fungi and has been particularly useful for...

Xylanases

Several thermophilic fungi are exceptionally high producers of xylanases with the application in the bio-bleaching of wood pulp for paper manufacture. They are generally single-chain glycoproteins, ranging from 6 to 80 kDa, active between a pH of 4.5 to 6.5, and at temperatures between 55 to 65 C. Xylanases are co-induced with cellulases by natural substrates or inferior quality filter-paper containing hemicelluloses. Thermoascus aurantiacus and Paecilomyces varioti are exceptionally high...

Part II

Interactions of Fungi with Other Organisms Two organisms don't enter into symbiosis to give something to the partner, but in order to take as much advantage of the partner as possible. Some fungi live in symbiotic association with cells of higher plants and algae. The mycorrhizal and the lichen-forming fungi are two examples of mutualism. The main physiological basis for this mutualism is bi-directional nutrient transfer. The photosynthetic partner supplies the fungus with sugars and the fungus...

Concluding Remarks

A persistent multinuclear condition is a unique feature of fungi. There is as yet no evidence that the multinuclear condition confers an observable advantage of rapid growth rate. Considering that synthesis of a DNA molecule requires chemical energy, the question arises as to why fungi have so many nuclei. Indeed, this question has not received any serious thought or experiment to find an explanation. One possibility could be that the fungi store nitrogen and phosphorus in an organic form (DNA)...

Composts

Compost is decomposed plant debris prepared by gathering refuse material in a heap to hasten the decay of the material and reduce its bulk. The heat produced in the heaped mass of garbage, plant residues, herbivore dung and kitchen and municipal waste kills pests, mesophilic microorganisms and drives off toxic ammonia. The process of production of organic manure by composting is an unwitting exploitation of thermophilic microorganisms. A similar exploitation of thermophilic fungi is in the...

Q

Figure 2.5 (A) Diagram of clamp formation in hypha of a Basidiomycotina. Each cell of the dikaryon has two nuclei of both types. (B) Nuclear types had clamps not formed. (From Ingold and Hudson, The Biology of Fungi (1993), Chapman and Hall. With permission of Kluwer Academic Publishers.) air channels within fruit bodies) and SC7 but not SC3 (which coats aerial hyphae and hyphae at the surface of fruit bodies) whereas on a hydrophobic surface the nuclei were separated (13 to 16 m) and the...

Parasexual Recombination

A consequence of heterokaryosis is the parasexual cycle, discovered in Aspergillus nidu-lans by G. Pontecorvo (see Davis, 2003). The parasexual cycle involves the fusion of two genetically unlike nuclei to form a transient diploid nucleus. During subsequent multiplication of the diploid nucleus, a rare event of mitotic crossing-over occurs and members of each homologous pair of chromosomes assort independently of other pairs. The conidia produced during the cycle are genetically different from...

Trehalase

The substrate of the enzyme trehalase is trehalose, commonly called mushroom or fungal sugar. It is a disaccharide composed of two glucose units joined by an a,1 1 glycosidic bond (Figure 10.8). Remarkable effects of trehalose on the protection of membranes and thermostabilization of enzymes has been found (Crowe et al., 1992). Bharadwaj and Maheshwari (1999) chose the enzyme trehalase (which hydrolyzes trehalose) for a comparative investigation in a thermophilic and a mesophilic fungus....

Discovery Of Intraspecies Variability

Figure 13.1 Infection types produced by wheat stem rust, Puccinia graminis var. tritici, on differential varieties of wheat. 0, Entirely immune. 0 , Practically immune. 1, Extremely resistant. 2, Moderately resistant. 3, Moderately susceptible. 4, Completely susceptible. Tracing from Stakman and Harrar (1957). Author Two labels for 0, please verify. Is 0 correct Would 0a be better Figure 13.1 Infection types produced by wheat stem rust, Puccinia graminis var. tritici, on differential varieties...

Metabolic Rate

In 1920, Kurt Noack of Germany compared the metabolic rates of thermophilic and mesophilic fungi at different temperatures. Using the volume of carbon dioxide evolved over time as a measure of the metabolic rate, he compared Thermoascus aurantiacus (a thermophilic fungus) with Penicillium glaucum (a mesophilic fungus), both grown in identical media. The quantity of carbon dioxide released by the mesophilic fungus in 24 hours was equivalent to 67 of its dry weight at 15 C and 133 at 25 C. Noack...

Chromosome Numbers

The genome size of fungi varies from 15 to 45 megabases (Mb or millions of nucleotide pairs of DNA). This genome is smaller than that of other eukaryotes and consequently fungal chromosomes in the vegetative phase are at the limit of resolution of a light microscope. However, in the exceptionally large meiotic cells of certain species belonging to Ascomycotina (e.g., Neurospora), the chromosomes are duplicated and condensed. In such cells, the pachytene stage...

Detection Of Genetic Variation In Populations

Burnett (2003) described a population as a pattern of distribution of individuals with distinctive but comparable morphology and genotypes. A basic requirement for the study of populations is that the fungus is recognized in nature and enough samples are collected over a wide range of geographical distances for inferences. A fungus suited admirably for population studies is Neurospora (Ascomycotina) since it produces distinctive orange conidia that allow its practically unambiguous recognition...

Biochemistry Of Degradation Of Cell Wall Polymers

Lignin is formed by random cross-linking of three monomer phenylpropanoid units p-hydroxycinnamyl (coumaryl) alcohol, 4-hydroxy-3-methoxycinnamyl (coniferyl) alcohol and 3,5-dimethoxy-4-hydroxycinnamyl (sinapyl) alcohol with several different carbon-carbon and carbon-oxygen linkages (Figure 12.2). Lignin encrusts the cellulose microfibrils within plant cell walls, giving the vascular plant the rigidity and protecting the plant from weather, insects and pathogenic organisms. It is remarkable,...

M

Macroconidia, see Neurospora, 65-79 Magnaporthe grisea, 20, 50, 53 Markers, use of genetic in study of life history, 69 in study of senescence, 209, 214-215 restriction fragment length polymorphism, 4, 199-201 random amplified polymorphic DNA, 5, 201 Mating reaction, in Ustilago maydis 124 Mating type, 68 Meiotic events crossing-over, 72 first division segregation, 72 second division segregation, 72 Meiotic silencing by unpaired DNA, 134 Melanin, 54 Mesophilic fungi, 145 Metabolic pathway, 77...

Cushion Of Conidiogenous

Phytophthora

Figure A2 Ascomycotina. (a) A swelling ascus bursting the wall of cleistothecium. (b) Ruptured cleistothecium and ascus. (c) Ascus immediately after discharge of ascospores. (From Ingold, C.T. and Hudson, H.J. (1993). Kluwer Academic Publishers. With permission.) Figure A3 Basidiomycotina. Diagram of basidium development. From Ingold, C.T. and Hudson, H.J. (1993). With kind permission of Kluwer Academic Publishers. Figure A4 Basidiomycotina. Fruit body (sporophore) with cap (pileus) and...

Pilobolus spp

Pilobolus Fungi

A common fungus that grows on the dung of herbivorous animals is Pilobolus (Zygomycotina). The dung contains nitrogen, vitamins, growth factors and minerals and satisfies the fungus' unusual nutritional requirement of a chelated form of iron. The fungus can be grown in media incorporating a decoction of dung or on a synthetic medium containing a complex iron-containing compound called coprogen. Exposure to visible light (380 to 510 nm) triggers the formation of a large bulbous cell called a...

Extracellular Recognition 831 The a Locus

The fusion of sporidia is controlled by two unlinked mating type loci, designated as a and b. Compatible mates have different alleles of genes at both loci. The a mating type locus has two alleles, a1 and a2, that are structurally quite dissimilar even though they are at the same position in the chromosome. This unusual situation of dissimilar mating type genes being present at the same locus in the chromosome is distinguished from the term allele by the term idiomorph. The idiomorphs are...

Nuclear Division Cycle

The cell cycle is divided into four phases G1 phase (between mitosis and the beginning of DNA synthesis), S phase (the period of DNA synthesis), G2 phase (the interval following the S phase and the beginning of mitosis) and M phase (separation of daughter nuclei). The G1, S and G2 phases are typically a longer part of the cell cycle than the M phase (Figure 2.2). Whereas in plant and animal cells the nuclear membrane breaks down during cell division, fungi including yeasts have a closed mitosis...

Conidiation Genes

Macroconidia Neurospora

Mutants of A. nidulans were obtained that are normal in hyphal growth and sexual reproduction but are defective in conidiophore development (Clutterbuck, 1969). Since conidia are not formed, the conidiation mutants are detected by the lack of the wild green color and by their inability to be replica plated a simple technique that allows colonies producing loose conidia in a petri dish to be sampled by pressing a velvet cloth secured over the top of a cylinder and onto the surface of new medium...

References

Hyphal tip growth outstanding questions. In Osiewacz, H.D., ed., Molecular Biology of Fungal Development. New York Marcel Dekker, pp. 29-58. Brasier, C.M. (1984). Inter-mycelial recognition systems in Ceratocystis ulmi, pp. 451-497. In Jennings, D.H. and Rayner, A.D.M., eds., The Ecology and Physiology of the Fungal Mycelium. Cambridge Cambridge University Press. Burnett, J.H. (1976). Fundamentals of Mycology. London Edward Arnold, Chapter 3. Carlile, M.J. (1995)....

Some Striking Fungal Diseases 421 Diseases of Crop Plants

We stop the press, with great regret, to announce that potato murrain has unequivocally declared itself in Ireland. The crops around Dublin are suddenly perishing. Where will Ireland be in the event of a universal potato rot. Gardner's Chronicle, September 13, 1845 The potato was once the staple crop of Ireland and people depended on this single crop as their primary food source. In the late summer of 1845, the fungus (see Appendix) Phytophthora infestans (Straminipila) almost completely...

Classification

Reverse Testicular Atrophy

Classification is the placing of an individual in categories. This not only aids in determining whether it is identical or similar to an already known fungus but also in understanding its evolutionary affiliation. Naming and classification go hand in hand. The modern trend is to classify fungi based on genealogy. Some interpretations of relationships based on their evolutionary sequence conflict with the classification schemes that were developed based on morphological characters. A genus is a...

Detoxification of Saponins

Many plants constitutively produce triterpenoid, steroid or steroidal glycosylated compounds that are generally inhibitory to fungi Figure 4.9 . These are known by the general term saponin because of their soap-like properties, derived from the plant Saponaria officinalis, the extracts of which were once used to make soap Osbourn, 1996 . Saponins make complexes with membrane sterols, resulting in pore formation and leakage of cell constituents. The leaves and green fruits of the tomato plant...

Transformation Procedure

Thermophilic Fungi

Methods were developed for transferring DNA into fungal cells and to select the transformed cells that have taken up this DNA. In the prototype experiment done in Edward Tatum's laboratory, wild type DNA was introduced into an inositol-requiring mutant Figure 9.1 Neurospora crassa growing on a sugarcane factory-waste dump. The genes encoding pink-orange color have been used as a visual reporter system in gene-silencing experiments. Photo courtesy of P. Maruthi Mohan. See color insert following...

Ustilago maydis Mechanisms in Sexual Reproduction

Sexual reproduction in fungi involves the detection of potential mating partners among multiple mating partners present in the environment, coordination of choices by making contact, commitment to a particular mating partner by adhesion, fusion of compatible cells followed by the fusion of gametic nuclei karyogamy and the meiotic division of the diploid nucleus to produce haploid progeny in the form of spores. Where the fusing nuclei differ genetically, the haploid progeny have new combinations...

Early Ideas On Plant Diseases

Chlamydospore

Although wheat rust was sometimes very destructive in Europe, the most generally prevalent disease of wheat was the bunt or the stinking smut Figure 4.1 . In 1750, the Academy of Arts offered a prize for the best dissertation on cause and cure of bunt. It was at that time variously ascribed as due to the use of pigeon droppings, sheep, or horse dung as manure. A French farmer named Matthieu Tillet 1714-1791 put most of these guesses to the test. He divided a piece of land crosswise into five...

Number Of Fungal Species

Previously, a species was defined as a group of individuals having common morphological characters. Based on the degree of discrimination adopted by the taxonomist a scientist who identifies and classifies according to a nomenclature and classification system approximately 70,000 species of fungi have been described based on morphological features such as the structure of conidiophores, the color and the method of formation of spores, the types of ascocarps, the features of basidium and many...

Infection Structures

Animal Cell Under Electron Microscope

Nearly all fungal plant pathogens gain entry into their host via a structure called the appres-sorium. The firm attachment of the appressorium to the hydrophobic host surface prevents lift-off as the infection penetration peg from the underside forces entry through the narrow stomata pore or pierces through the cuticle and cell wall. Mutants of Magnaporthe grisea that are deficient in hydrophobin show reduced pathogenesis Talbot et al., 1996 . Howard et al. 1991 used solutions of polyethylene...

General Features Of Pathogenesis

Phytopathogens Fungi Stomata

Once fungi were recognized as a pathogen, it was understood that disease is a state of altered metabolism of cells and tissues resulting from a reciprocal interaction of a parasite and host, each of which is individually influenced by the environment. The example of a biotrophic fungus for example, a rust fungus can be used to understand what is conveyed by the above diagram and to point to some generic features of pathogenesis. After arriving on the leaf surface, the urediospore germinates if...

Homologous Vs Ectopic Integration Oftransgene

In contrast to yeast, where the transforming DNA molecule commonly integrates at the related sequence by cross over homologous recombination , integration in the filamentous fungi occurs commonly at unrelated sequences heterologous or ectopic recombination . As an example, Figure 9.2 shows the partial restriction map of a circular plasmid carrying Figure 9.2 a Map of plasmid used to obtain HygR transformants of Ascobolus immersus. Black thick lines correspond to hph genes, dotted lines are...

Nuclear Migration

A process as fundamental as nuclear migration can be expected to have common components in different organisms. In fungi, nuclei must migrate at specific times and in predetermined directions for growth of hypha to occur, for spores to be formed and for mating to take place. Nuclei divide in the hyphal tip King and Alexander, 1969 and migrate through septal pores into hyphal compartments. The fungal hypha is therefore an excellent material for studying the rates and mechanisms of long distance...

Mycorrhiza

Root Anatomy Mycorrhizal Aquatic Plants

Land plants never had an independence from fungi for if they had, they could never have colonized land. KA. Pirozynski and D.W. Malloch 1975 About 90 of all terrestrial plants have underground fungal partners known as mycorrhiza, which means fungus-root or a root colonized by a symbiotic fungus. The fungus invades tree roots and obtains nourishment by tapping into the plant's vascular system. The hyphae enmesh the root and extend into the soil particles or leaf-litter, tapping a larger volume...

Cellcell Recognition 821 Mating Types

The fungi grouped in Basidiomycotina are remarkable for having thousands of potential mating partners or mating types. It is of interest to learn how these fungi select a mating partner in the absence of any morphological differentiation. They are remarkable too for having a life cycle in which the nuclei of opposite mating types divide synchronously and remain in close proximity as an n n pair by a special type of hyphal growth called a clamp connection, in which a short hyphal branch grows...

Qk603m34 2005

Taylor amp Francis Group is the Academic Division of T amp F Informa plc. Visit the Taylor amp Francis Web site at http www.taylorandfrancis.com and the CRC Press Web site at http www.crcpress.com Fungi are organisms generally composed of tubes that are invisible to the naked eye. The cells of these tubes are multinucleate and in cytoplasmic continuity. Fungi are among the oldest and largest living organisms, rivaling the mass of a California redwood tree or a blue whale. As the chief agents of...

Cell Wall

Thermophilic Cell Structure

The tubular form of the hypha is an ideal structure for forcing entry into living tissues, for extending through soil or for growing erect to produce propagules and disseminate them into the air. For carrying out these functions, the hypha must generate enormous turgor pressure and have strong cell walls to contain it. If the cell wall is digested by microbial cell wall lytic enzymes, round protoplasts are released. This suggests that the tubular shape of the hypha is due to the rigid cell...

Thermophilic Fungi Eukaryotic Life at High Temperature

It is of interest to study the systematics, distribution, and physiological adaptations of organisms which have been successful in colonizing high temperature environments in order to examine the limits to which evolution can be pushed. From an ecological point of view, high temperature environments usually have relatively simple species composition and short food chains, which make a study of productivity, trophodynam-ics, population fluctuation, and species interaction more simple. From the...

Habitat Life Style And Life Cycle

Neurospora Life Cycle

Neurospora Figure 5.1 is frequently seen growing on stubbles of sugar cane after the canes have been harvested for milling and the agricultural field is burnt Pandit and Maheshwari, 1996 to clear the trash of the cut leaves. In addition to the pink-orange type, a yellow-colored N. intermedia is found in Asia on maize cobs which have been discarded on road-sides, parks or railway tracks after the roasted kernels are eaten by residents. Another species, N. discreta a species thought to be...

Mapping Transcription Network

In the early 1960s, bacterial genetics laid the concept of regulatory circuits controlling expression of genes. In its simplest form, circuits are turned on or off' by the binding of transcription factors or repressors to the upstream regulatory sequences of genes respectively. Expression analysis by microarrays described in the earlier section revealed the co-regulated expression and repression of sometimes hundreds of genes during specific cellular Figure 6.14 A schematic representation of a...

Distribution In Soil

Thermophilic fungi have been isolated from almost any soil, even in the temperate zones, prompting the remark the ubiquitous distribution of organisms, whose minimal temperature for growth exceeds the temperature obtainable in the natural environment from whence they were isolated, still stands as a 'perfect crime' story in the library of biological systems Tendler et al., 1967 . Whether their presence in soil is because of their growth therein or a consequence of dissemination of their spores...

Self Heating of Stored Agricultural Products

Thermophilic Fungi

Thermophilic fungi were discovered as chance contaminants of bread or potato that had been inoculated with garden soil see Cooney and Emerson, 1964 Maheshwari et al., 2000 . Their habitats and growth conditions were discovered when Hugo Miehe 1907 of Germany was drawn to investigate the cause of self-heating and the spontaneous combustion of damp stacks of hay. He studied the role of microbial flora in thermogenesis. From the self-heating haystacks, Miehe isolated several microorganisms,...

Heterothallism Vs Homothallism

Heterothallism Homothallism

The processes leading to fertilization and production of progeny are quite variable in fungi. In the early twentieth century, A.F. Blakeslee found that a large number of morphologically indistinguishable single spore-derived cultures of a species belonging to Mucorales Zygomycotina could be sorted into two types, which he called plus and minus - since the strains could not be morphologically distinguished as male or female. If a plus colony was grown with another plus strain in a petri dish, or...

Meiotic Events

Genetic Recombination Fungi

Lindegren perceived Neurospora as a marvelous organism for genetic analysis as the four products of a single meiosis are packaged as ascospores in a single row in the order of their formation in ascus usually called a tetrad, although in Neurospora the meiotic division is followed by a mitotic division hence, each of the four meiotically produced ascospores are duplicated as sister ascospores, thus an octad . The ascospores are large enough, measuring approximately 29 X 15...

Proteomics And System Biology Modeling

A cell continuously senses environmental stimuli and relays that information inside across membranes to trigger a response. The process of signal transduction occurs by sequential transfer of information via protein-protein interaction. Take the example of a yeast cell growing in a glucose-rich environment suddenly encountering galactose. It senses the change in composition of the carbon source, shuts off the expression of genes required for glucose metabolism and turns on the genes required...

Part I

Pollen Tube Growth Apical

Fungi are composed of microscopic, tube-like structures called hyphae singular hypha which grow on substrates such as leaf litter, fallen timber and herbivore dung. The hypha has the shape of a cylindrical tube of even diameter with a tapering tip that branches subapically, with each branch having a tip of its own. By iteration of this modular unit comprising of a tip and a subapical branch Figure 1.1 , a radiating system of hypha called the mycelium is formed Carlile, 1995 . At places, hyphae...

Mycobiont and Photobiont

The mycobiont is mostly an Ascomycotina. The fungus is the dominant member of the partnership and determines the morphology of the lichen. Based on the chlorophyll content of alga, it was estimated that the alga Nostoc comprises about 5 of the lichen Peltigera. Beneath the algal layer is fungal medulla 400 to 1000 m thick. Electron microscopy shows that alga and fungus are in intimate contact but there is no penetration of algal cells by fungus. Lichen fungi are not specific to their algal...