Mycelium

About: Mycelium is a research topic. Over the lifetime, 8923 publications have been published within this topic receiving 170993 citations.

Fungal lipid accumulation and development of mycelial structures by two arbuscular mycorrhizal fungi

Abstract: We monitored the development of intraradical and extraradical mycelia of the arbuscular mycorrhizal (AM) fungi Scutellospora calospora and Glomus intraradices when colonizing Plantago lanceolata. The occurrence of arbuscules (branched hyphal structures) and vesicles (lipid storage organs) was compared with the amounts of signature fatty acids. The fatty acid 16:1omega5 was used as a signature for both AM fungal phospholipids (membrane constituents) and neutral lipids (energy storage) in roots (intraradical mycelium) and in soil (extraradical mycelium). The formation of arbuscules and the accumulation of AM fungal phospholipids in intraradical mycelium followed each other closely in both fungal species. In contrast, the neutral lipids of G. intraradices increased continuously in the intraradical mycelium, while vesicle occurrence decreased after initial rapid root colonization by the fungus. S. calospora does not form vesicles and accumulated more neutral lipids in extraradical than in intraradical mycelium, while the opposite pattern was found for G. intraradices. G. intraradices allocated more of its lipids to storage than did S. calospora. Thus, within a species, the fatty acid 16:1omega5 is a good indicator for AM fungal development. The phospholipid fatty acid 16:1omega5 is especially suitable for indicating the frequency of arbuscules in the symbiosis. We propose that the ratio of neutral lipids to phospholipids is more important than is the presence of vesicles in determining the storage status of AM fungi.

Observations on the extra-matrical mycelium of a vesicular-arbuscular endophyte

Abstract: Information is presented about the morphology of the extra-matrical mycelium and the extent of its connexion with a vesicular-arbuscular endophyte in mycorrhizal roots. The number of hyphal connexions varied from 2·6 to 21·1 per mm. root length according to the season, environment and manurial treatment. The possible interpretation of these results is discussed.

The growth of the extramatrical mycelium of ectomycorrhizal fungi and the growth response of Pinus sylvestris L.

Abstract: SUMMARY Nine ectomycorrhizal fungi have been studied for their effect on the growth of Pinus sylvestris L. seedlings. The plants were kept growing for six months in root chambers with a changeable volume. All seedlings were cultivated under conditions of low substrate nutrient concentrations and they became strongly infected within a short time. We demonstrated the existence of an important negative correlation between the extent of the fungal development and the growth of the host plants. In most studies this reduced growth is attributed to an energy drain by the fungus. Fungi producing large amounts of fungal tissue are more energy consuming than species which only develop a sparse mycelium. However we suggest that also nitrogen acquisition by the plants might be altered by the fungus. Certain fungi probably retain a considerable amount of nitrogen for their own growth, thus reducing the amount transported to the host plant. A decreased N transport finally results in a slower growth. In this study the extramatrical mycelium in the rooting substrate was determined by wet oxidation and by nitrogen determination. This component of the fungal biomass showed the biggest variation among the different mycobiont species. The results are discussed in relation to the culture technique employed.

Fungal Biology: Understanding the Fungal Lifestyle

Abstract: Introduction. Part 1. The Fungal Lifestyle. 2. The Mycelium. 3. The Substrate. 4. Nutrients. Part 2. 5. Water: Living with Desiccation. 6. Oxygen and Lack of it. 7. Using Light. 8. Withstanding Extremes of Temperature. 9. Competitive: Living with Neighbours. Part 3. 10. From Trophophase to Idiophase. 11. Nuclear Relationships. 12. Spores: Dispersive Propagules. 13. Spore Germination: Starting a New Colon. 14. Fungi and Man: Interacting with our Lifestyle.

Morphological and Physiological Differentiation in Streptomyces

Abstract: A GENERAL INTRODUCTION TO STREPTOMYCES The names of many organisms reflect their special biological properties. The name Streptomyces describes a unique morphology, albeit inaccurately: The word means “chain fungus,” although streptomycetes are undoubtedly bona fide gram-positive bacteria. The branching hyphae characteristic of Streptomyces vegetative growth form a complex substrate mycelium (Fig. 1a, b) that penetrates and solubilizes organic debris, typically in soil, by the action of extracellular hydrolytic enzymes. The inherent immobility of the mycelium is counterproductive to distribution, a problem solved (as in eukaryotic molds) by spore formation (Fig. 1c, d). Long chains of spores (often containing >50 spores) usually form from specialized aerial hyphae, which themselves apparently develop mainly by cannibalizing the vegetative mycelium. At this vulnerable stage in development, when the lysing mycelium might easily be consumed by invading motile microorganisms, it is not surprising to find that chemical defense mechanisms are employed. Indeed, nearly all of the thousands of known antibiotics are made by streptomycetes and molds, usually at a time coinciding with that of aerial mycelium formation. The idea has developed that genes for antibiotic production may therefore be subject to at least some of the regulatory mechanisms involved in setting off aerial mycelium formation and that studies of the one will provide information about the other. In this paper descriptions of growth and morphological differentiation (first two sections) are followed by a summary of Streptomyces genetic phenomena and tools and their use in analyzing sporulation. The section, Physiological Differentiation: Production of Secondary Metabolites deals...