The structure and histochemistry of sclerotia ofSclerotinia minor Jagger

Summary A detailed histochemical investigation was carried out on rind, cortical and medullary hyphae of sclerotia ofSclerotinia minor Jagger. Four developmental stages, including mature sclerotia, were studied. The walls and septa of all hyphae contained chitin and -1,3 glucans, while those of the rind contained in addition, a melanin-like pigment. An extracellular matrix, which accumulated around cortical and medullary hyphae, consisted primarily of -1,3 glucans, although another polysaccharide, which could not be identified by histochemical methods, was also present. Phenolic material was deposited around the extracellular matrix and in the few interhyphal spaces that remained at maturity. Glycogen was present throughout the cytoplasm of hyphae of the cortex and medulla, at all stages of their differentiation. Polyphosphate granules were laid down within small vacuoles and as sclerotia matured, became most common in the cortical region. Protein bodies developed rapidly in cortical and medullary hyphae until at maturity, they were the most obvious interhyphal feature. These bodies were either round or elongated in shape, the elongated ones often lying parallel to the long axis of the hyphae, and in close association with strands of endoplasmic reticulum. No lipid reserves were detected.Mrs. S.Lowry.     

Effect of Sclerotial Damage of Sclerotinia sclerotiorum on the Mycoparasitic Activity of Trichoderma hamatum

Damaged sclerotia of Sclerotinia sclerotiorum buried in soil infested with Trichoderma hamatum isolate TMCS - 3 were degraded rapidly when the medulla of sclerotia was com pletely exposed by the feeding activity of larvae of the fungus gnat Bradysia coprophila. These heavily damaged sclerotia also enhanced , in vitro, the growth of TMCS - 3 . Growth of TMCS - 3 in liquid culture was studied using different carbon sources as substrates , including sclerotia of S. sclerotiorum. Significantly more biomass of TMCS - 3 was recovered using sclerotia as a substrate compared to other carbon sources tested . Exudates from sclerotia whose melanized rinds had been completely removed by feeding larvae accelerated the germination of conidia of TMCS - 3 . Concentrations of amino acids , carbohydrates and proteins in the sclerotial exudates were not increased as damage to sclerotia was increased . Exudation of electrolytes was higher in undamaged than damaged sclerotia . Glucanase activity of TMCS - 3 was slightly increased when the fungus was exposed to damaged sclerotia . However , chitinase activity was not increased by damaging the sclerotia . Larval damage altered the sclerotia not only physically but also chemically , thereby enhancing the activity of the fungus T. hamatum.     

Identification of Armillaria species associated with Polyporus umbellatus using ITS sequences of nuclear ribosomal DNA

The sclerotia of Polyporus umbellatus were collected from three locations in Japan and three locations in China. All the collected sclerotia were adhered to by rhizomorphs of the symbionts. When the sclerotium of P. umbellatus was cross sectioned, the internal part of the sclerotium was cream colored, and many black regions surrounding the invading rhizomorphs were observed. The surrounding zone contained string-like, gelatinous masses composed of hyphae, and its outside was brown in color. All isolates were similar in colony morphology and grew well on PDA medium with well-developed rhizomorphs. All the isolates showed typical morphology of Armillaria. The isolated fungi were identified via the ITS region of the nuclear ribosomal DNA sequence. Phylogenetic analysis based on the neighbor-joining method showed that all the isolates clustered with fungi belonging to Armillaria species. Among them, five species (A. sinapina, A. calvescens, A. gallica, A. cepistipes, and A. nabsnona) and the symbiont formed a highly supported clade. We report on the case where Armillaria has a relationship in the sclerotium of Polyporus umbellatus.     

Armillaria luteobubalina mycelium develops air pores that conduct oxygen to rhizomorph clusters

Armillaria luteobubalina produces air pores in culture. They consist of two parts: a basal region of tissue elevated to form a mound covered with a rind continuous with that of the colony, but perforated; and an apical region of long parallel hyphae, cemented together by scattered patches of extracellular material. This forms a hydrophobic structure that is elevated above the general level of the mycelial crust and does not easily become waterlogged. Air pores develop near the inoculum plug shortly after inoculation, arising directly from the mycelium, and rhizomorphs are initiated from them. The air pore contains a complex system of gas space connecting the atmosphere with the central canal of each rhizomorph. The tissue beneath the melanised colony crust also contains gas space, especially near air pores. This is also connected with the gas space of each rhizomorph and of each air pore. Measurements with oxygen electrodes show that air pores and their associated rhizomorphs conduct oxygen. The average oxygen conductance of a group of air pores with associated rhizomorphs, within agar blocks, but with rhizomorph apices cut off, was about 700 × 10⁻¹² m³ s⁻¹, equivalent to about 200 × 10⁻¹² m³ s⁻¹ for each air-pore. We conclude that the air pores conduct oxygen into the gas space below the pigmented mycelium of the colony, where the rhizomorphs - which also conduct oxygen - originate. A. luteobubalina thus has a complex aerating system which allows efficient diffusion of oxygen into rhizomorphs, and this is likely to facilitate extension of inoculum into low-oxygen environments.     

Influence of inocula and grains on sclerotia biomass and carotenoid yield of<Emphasis Type="Italic"> Penicillium</Emphasis> sp. PT95 during solid-state fermentation

Various inocula and grains were evaluated for carotenoid production by solid-state fermentation using Penicillium sp. PT95. Millet medium was more effective in both sclerotia growth and carotenoid production than other grain media. An inoculum in the form of sclerotia yielded higher sclerotia biomass compared to either a spore inoculum or a mycelial pellet inoculum. Adding wheat bran to grain medium favored the formation of sclerotia. However, neither the inoculum type nor addition of wheat bran resulted in a significant change in the carotenoid content of sclerotia. Among grain media supplemented with wheat bran (wheat bran:grain =1:4 w/w, dry basis), a medium consisting of rice and wheat bran gave the highest sclerotia biomass (15.10 g/100 g grain), a medium consisting of buckwheat and wheat bran gave the highest content of carotenoid in sclerotia (0.826 mg/g dry sclerotia), and a medium consisting of millet and wheat bran gave the highest carotenoid yield (11.457 mg/100 g grain).     

Changes during development in the permeability of sclerotia ofSclerotinia minor to an apoplastic tracer

Summary Sclerotia ofSclerotinia minor produced in culture are permeable to the apoplastic tracer sulphorhodamine G (SR) in early stages of their development, but become impermeable as the rind differentiates at the onset of maturation. Reduction in permeability corresponds with deposition of the dark brown pigment in the rind cell walls rather than initiation of the rind as a distinct surface layer. Fluorochrome permeation into cut sclerotia indicates that, while the rind is the primary barrier, the walls and extracellular matrix of the cortex and medulla of mature sclerotia also impede SR movement. Some cells take up fluorochrome into the protoplast. This indicates enhanced proton pumping activity at the cell surface, which suppresses ionisation of the fluorochrome, allowing it to cross the plasma membrane and accumulate in the hyphae. In intact sclerotia such hyphae are very rare and were detected only at one stage of development. However, in cut sclerotia at the two earliest stages of development most of the hyphae near the cut surface accumulated SR and it is possible that this is due to proton pumping activity induced by wounding.Abbreviations ECM extracellular matrix - SR sulphorhodamine G     

猪苓菌核结构性质的研究

利用光学显微镜和电子显微镜对猪苓菌核的结构及其发育进行了研究。组成猪苓菌核的菌丝与平板培养或发酵培养的猪苓菌丝比较,具有多分枝、融合频率高、菌丝形态不规则等特点。猪苓菌核表现了高度的结构分化,有表皮、表皮下层、疏松菌丝层和结构菌丝之分,结构菌丝是组成菌核的主要成分,疏松菌丝层类似一般菌核的髓,但大小、位置在菌核中变化较大。菌核的个体繁殖是由母体菌核的一束或几柬菌丝突破表皮而萌发产生新的菌核;较系统的观察了猪苓菌核细胞分裂及其菌丝内部结构的变化。     

New lichenicolous, muscicolous, corticolous and lignicolous taxa of Burgoa s. l. and Marchandiomyces s. l. (anamorphic Basidiomycota), a new genus for Omphalinafoliacea, and a catalogue and a key to the non-lichenized, bulbilliferous basidiomycetes

A catalogue and a key to the non-lichenized, bulbilliferous basidiomycetes are given. The new genus Burgella is described for the lichenicolous B. flavoparmeliae, phylogenetically close to Sistotrema oblongisporum and Multiclavula. The genera Pneumatospora and Tricellulortus are placed in synonymy of Minimedusa, the new combination M. obcoronata is proposed, and the new facultative lichenicolous M. pubescens is described. The new facultative lichenicolous Burgoa angulosa is phylogenetically close to the generic type B. verzuoliana, whilst the new B. moriformis and B. splendens are provisionally included in the genus Burgoa. A Burgoa-like species in the Ceratobasidiaceae is left unnamed. Two new species of Marchandiomyces, M. buckii and M. nothofagicola, are described. As Marchandiomyces aurantiacus is phylogenetically more close to Erythricium than to Marchandiomyces, it is proposed to exclude it from that genus and to use the holomorphic generic name Marchandiobasidium for both anamorph and teleomorph of this species. The new genus Marchandiomphalina is introduced for the lichenized Omphalina foliacea, a taxon phylogenetically close to Marchandiobasidium. Taxonomic novelties Burgella Diederich & Lawrey; B. flavoparmeliae Diederich & Lawrey; Burgoa angulosa Diederich, Lawrey & Etayo; B. moriformis Diederich, Ertz & Coppins; B. splendens Diederich & Coppins; Marchandiomphalina Diederich, Lawrey & Binder; Marchandiomphalina foliacea (P. M. J?rg.) Diederich, Lawrey & Binder; Marchandiomyces buckii Diederich & Lawrey; M. nothofagicola Diederich & Lawrey; Minimedusa pubescens Diederich, Lawrey & Heylen; M. obcoronata (B. Sutton, Kuthub. & Muid) Diederich & Lawrey