Sexuality

The wood-inhabiting Ascomycetes and Basidiomycetes are either homothallic or heterothallic (Ryvarden and Gilbertson 1993). Homothallic fungi are self-fertile, that is no second mating type is required for sexual reproduction. Fertilization takes place at the same mycelium.

Many Ascomycetes and about 10% of the Basidiomycetes belong to this type. Heterothallism includes both bipolar and tetrapolar fungi. In bipolar (uni-factorial) species, incompatibility is controlled by a series of multiple alleles at one locus. Any dikaryon has two alleles that segregate at the the basidiospores have one allele and half the other. Compatible matings occur between monokaryons with different mating type factors. The inbreeding level is 50%. The outbreeding level inpopulations of bipolar polypores is over 90%.

In tetrapolar (bifactorial) species, incompatibility is controlled by two se-ries of multiple alleles at two loci on different chromosomes. The twopairs segregate independently at meiosis. Four different mating types rise from one dikaryon. In a fruit body of an isolate, basidiospores of the mating type A,13x, AxBy, AyBx and AyBy develop. These spores germinate to monokaryons. Fully compatible matings of monokaryons (+ in Table 2.5) occur when both factors are heterozygous (A#B#): Ax13„ and AyBy as well as AxBy and AyBx. In addition, there are hemicompatible matings, in which only one factor is different: AO, and A,By as well as AyBy and AxBy.

The inbreeding level is 25%. The outbreeding level is very high. In Schizo-phyllum commune 450 A factors and 90 B factors can combine to over 40,000 mating types (Raper and Miles 1958). Many Ascomycetes and about 25% of the examined Basidiomycetes are bipolar heterothallic (e.g., Oligoporus pla-centa). About 65% Basidiomycetes are tetrapolar (Raper 1966).

Bipolar mating predominates among brown-rot fungi and tetrapolar mating among white-rot fungi (Rayner and Boddy 1988). Of 25 investigated brown-rot polypores, 17 were bipolar, three were tetrapolar, three were heterothallic with type of mating system undetermined, one was homothallic, and one was reported by different authors as bipolar and tetrapolar (Ryvarden and Gilbertson 1993). The biolog-ical significance of heterothallism is that inbreeding is limited and outbreeding is enhanced, promoting gene flow between populations and decreasing the rate of speciation.

Combination and recombination of the genetic material with plasmogamy, karyogamy, and haploidization, but without sexual organs, gamets and changes ofgenerations, can take place by parasexuality, particularly in Deuteromycetes ( Jennings and Lysek 1999). Nuclei of a hypha migrate by anastomosis into another hypha and multiply and spread there. In the case of a heterokaryon,

Comments

Reproduction of Deuteromycetes

F ungi that reproduce asexually (anamorphic fungi ) are either yeasts or Deu-teromycetes. The term "yeast" is descriptive and stands for any fungus that reproduces by budding. Deuteromycetes (Fungi imperfecti, colloquially: molds) is an artificial as-semblage of fungi that reproduce asexually by conidia (conidiospores), either as the only form for propagation (imperfect fungi) or additionally (anamorph) to a sexual reproduction (teleomorph). When both the anamorph and the teleo-morph are known, the fungus is called a holomorph (the whole fungus). The teleomorph may have one (mono-anamorphic) or many (pleo-anamorphic) asexual stages. In other words: Deuteromycetes are the conidia-producing forms of a fungus and may or may not be associated with a teleomorph. Many Deuteromycetes are supposed to have a teleomorph in the Ascomycetes, but they may also have basidiomycetous affinity. Also in the wood-inhabiting Deuteromycetes, the teleomorph often is of ascomycetous a...

What shapes the peer review landscape in ecology?

It was great to be discussing the future of peer review with researchers at the recent peer review panel discussion organised by the British Ecological Society (BES) at their annual conference in Liverpool last week. Jane Hill (Professor of Ecology at the University of York and Chair of BES Publications Committee) chaired the debate, and we heard from Allen Moore (Editor-in-Chief, Ecology and Evolution), Patricia Morse (Managing Editor, American Naturalist ), Nate Sanders (Senior Editor, Journal of Animal Ecology ), Andy Robertson (Senior Vice President & Managing Director, Society Services, Wiley) and me. We started with a discussion of ways in which the publishing process could be opened up, with Allen advocating open science principles and pre-registration of research. Nate also shared his experience in the value of “opening up” research online to get people talking and to generate new ideas. Andy Robertson suggested that partnering w...

Islands

H ow often have you seen those wonderful advertisements inviting you to have a holiday on a tropical island ( Fig. )What is it about islands, whether in the tropics or polar regions, that suggests romance, excitement and adventure? Is it because of a sense of escape from the pressures and stress of a bustling way of life, or the opportunity to savour sun-soaked beaches, or the adventure of rocky unexplored shores, or perhaps the chance of seeing unique island wildlife? It is for all these reasons that there is a growing tourist industry for many islands around the world. The wildlife of islands, especially oceanic islands , has long been of special significance in biology , ecology , conservation and biogeography. Studies of island species have also been of historical significance for evolutionary biology. Many of the world's islands have high levels of endemic flora and fauna; that is, taxa found only on a particular island and no other place. Isla...

Red Streaking

Red Streaking Red-streaking discoloration (known as "Rotstreifigkeit" in Germany) is one of the most common and important damage in seasoning logs and sawn lumber, occurring only in conifers (spruce, pine, fir) and recognized as a distinct con-dition in continental Europe. The stripe-shaped to spotted yellow to reddish-brown discoloration extends in logs from both their bark-covered faces and from their cut ends (Butin 1995; Baum and Bariska 2002) . Stems that are not debarked show a rather flat discoloration and debarked stems exhibit a streakier staining (v. Pechmann et al. 1967). Causal agents are several white-rot Basidiomycetes, in spruce particularly Stereum sanguinolentum (Kleist and Seehann 1997) and Amylostereum areola-turn. In south Germany, Amylostereum chailettii is common (Zycha and Knopf 1963; v. Pechmann et al. 1967). In pine, red streaking is mainly due to Trichap-turn abietinum (Butin 1995). According to Kreisel (1961), S. sanguinolentum and T...

Ecosia ; Ecology Search

https://www.ecosia.org/ How it works You search the web with Ecosia. Ads Search ads generate income for Ecosia. Ecosia uses this income to plant trees. httpecologicaljournal.blogspot.com Ecosia about video

Bioenergetics

T housands of chemical reactions occur throughout the body during each minute of the day. Collec-tively, these reactions are called metabolism. Metab-olism includes chemical pathways that result in the synthesis of molecules (anabolic reactions) as well as the breakdown of molecules (catabolic reactions). Since energy is required by all cells, it is not sur-prising that cells possess chemical pathways that are capable of converting foodstuffs (i.e., fats, proteins, carbohydrates) into a biologically usable form of energy . This metabolic process is termed bioenergetics. In order for you to run, jump, or swim, skeletal muscle cells must be able to continuously extract energy from food nutrients. In fact, the inability to transform energy contained in foodstuffs into usable biological energy would limit performance in endurance activities. The explanation for this is simple. To continue to contract, muscle cells must have a continuous source of energy. When energy is not...

White Rot

W hite-rot research has been reviewed by Ericksson et al. (1990) and Mess-ner et al. (2003). White rot means the degradation of cellulose, hemicellu-loses, and lignin usually by Basidiomycetes and rarely by Ascomycetes, e.g., Kretzschmaria deusta and Xylaria hypoxylon. White rot has been classified by macroscopic characteristics into white-pocket, white-mottled, and white-stringy, the different types being affected by the fungal species, wood species, and ecological conditions. From microscopic and ultrastructural investiga-tions, two main types of white rot have been distinguished (Liese 1970). In the simultaneous white rot ("corrosion rot"), carbohydrates and lignin are almost uniformly degraded at the same time and at a similar rate during all decay stages. Typical fungi with simultaneous white rot are Fomes fomentar-ws, Phellinus igniarius, Phellinus robustus, and Trametes versicolor in standing trees and stored hardwoods (Blanchette 1984a). Wood d...

Soft Rot

The term " soft rot " was originally used by Findlay and Savory (1954) to describe a specific type of wood decay caused by Ascomycetes and Deuteromycetes which typically produce chains of cavities within the S2 layer of soft- and hardwoods in terrestrial and aquatic environments (Liese 1955), for example when the wood-fill in cooling towers became destroyed despite water saturation, and when poles broke, although they were protected against Basidiomvcetes. About 300 species (Seehann et al. 1975) to some 1,600 examples of ascomvcete and deuteromvcete fungi (Eaton and Hale 1993) cause soft rot, e.g., Chaeromium globosurn (Takahashi 1978), Hurnicola spp., Lecythophora hoffrnannii, Monodictys putredinis, Paecilornyces spp., and Thielavia terrestris. Soft-rot fungi differ from brown-rot and white-rot Basidiomycetes by grow-ing mainly inside the woody cell wall trate, starting from the tracheidal lumina., by means of thin perforation hyphae of less than 0.5 pm thickne...

Antagonists, Synergists, and Succession

Interactions (reciprocal effects) between wood fungi have been early investi-gated e.g., by Oppermann (1951) and Leslie et al. (1976), and were described in detail by Rayner and Boddy (1988). Antagonism (competitive reciprocal effect), the mutual inhibition and in a broader sense the inhibition of one organism by others, is based on the pro-duction of toxic metabolites, on mycoparasitism, and on nutrient competition. Antagonisms are investigated as alternative to the chemical protection against tree fungi ("biological forest protection") and against fungi on wood in service ("biological wood protection") (Walchli 1982; Bruce 1992; Holdenrieder and Greig 1998; Phillips-Laing et al. 2003). As early as 1934, Weindling showed the inhibiting effect of Trichoderma species on several fungi. Bjerkandera adusta and Ganoderma species were antagonistic against the causing agent of Plane canker stain disease (Grosclaude et al...

Sexual Reproduction

A specific feature of the sexual reproduction of Ascomycetes and Basid-iomycetes is that plasmogamy of haploid cells and karyogamy of two nuclei (n) to form a diploid nucleus (2n) are separated from each other temporally as well spatially by the dikaryophase (two-nuclei phase, dikaryon, n + n, ===) (Fig.1). A dikaryotic hypha is one with two nuclei that derive from two haploid hyphae, but in which the nuclei are not yet fused by karyogamy. Particularly in Basidiomycetes, the dikaryotic phase is considerably ex-tended. By conjugated division of the two nuclei (conjugated mitosis), by division of the dikaryotic hypha, and by means of a special nucleus migration connested with camp formation both daughter cells become again dikaryotic. Ascomycetes The life cycle of a typical ascomycete is shown in Fig.1 (also Muller and Loeffler 1992; Eaton and Hale 1993; Schwantes 1996; Jennings and Lysek 1999). Haploid (n) spores (A, ascospores or conidia from an anamorph) ge...

Ecological world

Search This Blog