Mycelium

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

The mycorrhizal nodules of podocarps

Abstract: Re-examination of the root nodules of New Zealand species of Dacrydium, Phyllocladus and Podocarpus and of Agathis australis (Araucariaceae) has confirmed that they are short roots upon which a new cortex is developed annually for several years. This cortex is normally occupied by phycomycetous mycelium, but this is not the cause of the nodules for in P. dactydioides they formed normally towards the close of the seedling's first year in fungus-free cultures. However, fungal infection is necessary to sustain growth in natural soils. Infected seedlings of P. totara attained a dry weight nearly seven times that of uninfected seedlings over 2 years; with P. dactydioides a fourfold difference developed in 1 year. The endophytic mycelium bore vesicles and arbuscles and made only transitory growth into agar. It appeared therefore to be the same as that forming mycorrhizas with most forest plants. The nodules are considered to be an adaptation to accommodate mycorrhizal fungi upon which growth normally depends, and thus to be functionally equivalent to the short roots of pines.

Fungi Associated with Several Developmental Stages of Heterodera glycines From an Alabama Soybean Field Soil

Abstract: An examination of young, swollen, cream-colored cysts of Heterodera glycines Ichinohe attached to root surfaces and of white, newly exposed females partly immersed within roots of Alabama-grown soybeans [Glycine max (L.) Merr.] revealed the presence of a number of fungal pathogens. Fungi most frequently isolated from these stages of development were: Chaetomium cochliodes Palliser, Exophiala pisciphila McGinnis & Ajello, Fusarium oxysporum Schlecht, F. solani (Mart.) Sacc., Phytophthora cinnamoni Rands, Pythium sp., a sterile mycelium, and Trichosporon beigelii (Kuchenm. & Rabenh.) Vuill. Fifty percent of the cream-colored cysts were infected as compared to 20 percent of the younger white, lens-shaped females. An examination of sausage-shaped females within roots and brown cysts from soil indicated that two and 70 percent respectively were invaded by fungi. Results indicated that a progressive increase in fungal colonization occurred with nematode development. Some overlapping of the

Streptofactin, a novel biosurfactant with aerial mycelium inducing activity from Streptomyces tendae Tü 901/8c

Abstract: Streptomyces tendae Tu 901/8c produces an extracellular hydrophobic peptide, termed streptofactin. The compound was isolated from conditioned agar medium and characterized. Streptofactin is a mixture of structurally related peptides with the major components ranging in size from 1003 m/z to 1127 m/z. Extracellular application of the purified peptide restored the capacity to form aerial mycelium in mutants defective in morphological development. Surface activity measurements revealed that streptofactin decreased the surface tension of water from 72.0 mN m−1 to 39.4 mN m−1 and achieved a critical micelle concentration value of 36 mg l−1. The properties of streptofactin suggest that it plays a structural role in aerial mycelium development and supports the erection of aerial hyphae by lowering the surface tension of water films enclosing the colonies. A model for aerial mycelium formation which represents a novel mechanism for the adaption to environmental changes in Streptomyces is proposed.

Hemibiotrophic infection of Pisum sativum by Colletotrichum truncatum

Abstract: The infection of pea (Pisum sativum) by Colletotrichum truncatum was studied by light and electron microscopy. These investigations were facilitated by use of an Argenteum pea mutant, which has a readily detachable epidermis. Infection pegs emerging from appressoria penetrated epidermal cells directly. Large intracellular primary hyphae formed a dense stromatic mycelium confined within a single epidermal cell. Primary mycelia gave rise to thinner secondary hyphae which radiated into surrounding cells and caused extensive wall dissolution. Melanized sclerotia developed in the centre of chlorotic water-soaked lesions. Acervuli were not observed. Epidermal cells survived initial penetration by primary hyphae, as shown by their ability to plasmolyse and accumulate Neutral red, but all infected cells were dead when the secondary hyphae had formed. Six cultivars of pea were susceptible, but seven other legumes were resistant. A single isoform of polygalacturonase with a pI of 8·3 and apparent Mr of 40000 was purified from culture filtrates and the TV-terminal amino acid sequence determined. The relevance of the results to the taxonomy of C. truncatum and the relationships between infection process and host range are discussed.