Mycelium

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

Early stages in colonization of Allium porrwn (leek) roots by the vesicular—arbuscular mycorrhizal fungus, Glomus versiforme

Abstract: SUMMARY Leek (Allium porrum L. cv. Titan) roots wore colonized by the vesicular arbuscular (VA) mycorrhizal fungus Glomus versiforme (Daniels and Trappe) Berch. External hyphae were of varying sizes and had a single-layered wall surrounding a vacuolate cytoplasm. Intra-hyphal hyphae were frequent in the extraradical mycelium. Some external hyphae formed small branches which initiated simple appressoria over the outer tangential wall of epidermal cells. Appressoria were multinucleate and possessed many structures which we have interpreted to be bacterium-like organclles (BLOs). Infection hyphae formed by appressoria penetrated the radial cell walls of epidermal cells and were surrounded by an electron dense substance and host cell wall. Epidermal and cortical cells reacted frequently by forming cell wall thickenings. Hyphae in the exodermis formed coils which were surrounded by host plasma membrane but not host cell wall, and had many nuclei and BLOs.

Reduction of organic and inorganic selenium compounds by the edible medicinal basidiomycete Lentinula edodes and the accumulation of elemental selenium nanoparticles in its mycelium

Abstract: We report for the first time that the medicinal basidiomycete Lentinula edodes can reduce selenium from inorganic sodium selenite (SeIV) and the organoselenium compound 1,5-diphenyl-3-selenopentanedione-1,5 (DAPS-25) to the elemental state, forming spherical nanoparticles. Submerged cultivation of the fungus with sodium selenite or with DAPS-25 produced an intense red coloration of L. edodes mycelial hyphae, indicating accumulation of elemental selenium (Se0) in a red modification. Several methods, including transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and X-ray fluorescence, were used to show that red Se0 accumulated intracellularly in the fungal hyphae as electron-dense nanoparticles with a diameter of 180.51±16.82 nm. Under designated cultivation conditions, shiitake did not reduce selenium from sodium selenate (SeVI).

Translocation of C^(14)-Labeled Compounds in Mycorrhizae and It Implications in Interplant Nutrient Cycling

Abstract: Loblolly pine (Pinus taeda L.) seedlings were grown axenically in mycorrhizae synthesis cultures with either the symbiont Pisolithus tinctorius (Pers.) Coker and Couch or Thelephora terrestris (Ehrh.) Fr. Glassware was designed to allow synthesis of mycorrhizae on two seedlings physically separated except for a bridge formed between the two root systems by mycorrhizal fungus mycelium. Glucose—C14 and sucrose—C14 were used as tracers to investigate movement of labeled compounds from mycorrhizal roots to external mycelium, from external mycelium to roots and from one root system to the other via shared mycelium. Whether applied to foliage as glucose—C14 or sucrose—C14, C14 was readily translocated to pine roots. Transport of C14 from mycorrhizal roots to external hyphae of T. terrestris up to a distance of 12 cm was shown, but only slight movement of C14 occurred into external hyphae of P. tinctorius. The introduction of glucose—C14 and sucrose—C14 to isolated strands of T. terrestris resulted in the movement of C14 from strands to roots. Movement of isotope from one seedling to the other via mutually—shared mycelium did not occur in the synthesis cultures; however, C14 movement between root systems artifically linked by mycelial strands indicated that interplant exchange can take place. Evidence suggests that mycorrhizal fungi such as T. terrestris could be effective in the exchange of organic and possibly other materials between root systems in an ecosystem.

Specific induction of a cuticle-degrading protease of the insect pathogenic fungus Metarhizium anisopliae

Abstract: Summary: The insect pathogenic fungus Metarhizium anisopliae produces several extracellular cuticle-degrading proteases and evidence is consistent that one of these, a chymoelastase PR1, is a determinant of pathogenicity. We have shown previously that the wide-domain regulatory circuits of carbon and nitrogen derepression regulate PR1 production. In the present work we have established in addition that PR1 is specifically induced by insect cuticle, but not by other soluble or insoluble proteinaceous substrates. The feeding of elastin or collagen to derepressed established mycelium (starved for carbon and nitrogen) did not enhance PR1 production significantly and the soluble proteins BSA and gelatin rapidly and completely repressed PR1. The carbohydrate polymers cellulose and xylan gave derepressed basal levels of PR1. However, addition of locust cuticle enhanced PR1 production to a level approximately 10-fold that of derepressed mycelium. In order to establish if the enhancing effect of insect cuticle on PR1 production was due to specific induction or merely a reflection of enhanced growth on this insoluble dual carbon and nitrogen source, ergosterol was used as a measure of fungal growth. Expressing enzyme activity per mg dry weight showed that PR1 production in cuticle cultures increased approximately five- and ninefold after 12 and 24 h growth compared with elastin-grown cultures. Thus, the substantial increase in PR1 production on cuticle was shown not to be a function of fungal growth and this confirms that PR1 is induced by a component of insect cuticle; we believe this is the first report of induction by a specific substrate for any microbial protease.