Current advances in molecular mycology

Molecular Microbiology, 2007

It is a challenge in biology to explore the molecular and cellular mechanisms necessary to form a complex three-dimensional structure composed of different cell types. Interesting models to study the underlying processes are fungi that can transform their wire-like hyphal filaments into complex and sometimes container-like fruit bodies. In the past, the role of developmental triggers and transcription factors was a major focus of research on fungal model organisms. In this issue of Molecular Microbiology, Nowrousian and collaborators report that fruit body development of the model organism Sordaria macrospora includes a novel player, a specific membrane protein of the endoplasmic reticulum that is not required for vegetative growth. This finding represents an important step towards connecting regulation of development with the coordinated changes in cellular compartments.

Molecular Genetics And Genomics, 1979

The initiation of monokaryotic fruiting in the basidiomycetous fungus Schizophyllum commune has been observed to occur spontaneously, in response to biochemical substances, and following mechanical injury. The responses to these three stimuli are genetically separable and under polygenic control.

Mycologia, 2016

This article describes the evolution of the field of fungal morphogenesis, its beginning at the end of the 19th century and its exponential growth during the second half of the 20th century, continuing until the present day. The main theme correlates biological progress with the advent of new technologies. Accordingly the article describes the discovery of apical growth, the fibrillar nature of the fungal wall, the chemistry of the cell wall, the search for biochemical pathways in morphogenesis, the discovery of the Spitzenkörper, the apical gradient of wall synthesis, key highlights in ultrastructural research, the development of mathematical models particularly the vesicle supply center (VSC) model, the revolution brought about by molecular biology and unique discoveries such as the hydrophobins and c-tubulin and some the latest triumphs of the marriage between molecular genetics and confocal microscopy. Credit is given to the investigators responsible for all the advances.

Biology and Applications, 2005

2003

Plant pathology has made significant progress over the years, a process that involved overcoming a variety of conceptual and technological hurdles. Descriptive mycology and the advent of chemical plant-disease management have been followed by biochemical and physiological studies of fungi and their hosts. The later establishment of biochemical genetics along with the introduction of DNA-mediated transformation have set the stage for dissection of gene function and advances in our understanding of fungal cell biology and plant-fungus interactions. Currently, with the advent of high-throughput technologies, we have the capacity to acquire vast data sets that have direct relevance to the numerous subdisciplines within fungal biology and pathology. These data provide unique opportunities for basic research and for engineering solutions to important agricultural problems. However, we also are faced with the challenge of data organization and mining to analyze the relationships between fungal and plant genomes and to elucidate the physiological function of pertinent DNA sequences. We present our perspective of fungal biology and agriculture, including administrative and political challenges to plant protection research.

Mycosphere

Fungi are ubiquitousthey are found in any conceivable environment, i.e., both aquatic and terrestrial habitats. They remain one of the most diverse groups of organisms on Earth. Because fungi are heterotrophic, they obtain their nutrients by colonizing their substrates with a vegetative mass of hyphae called mycelium. These hyphae secrete enzymes that digest nutrients locked in colonized substrates, after which the nutrients are then absorbed by the hyphae. Not only do hyphae constitute the mycelium of fungi, but they also form other structuresmycelial strand, mycelial cords, and rhizomorphsthrough which fungi are able to spread in their environment in search of new substrates to colonize. The aim of this present paper is to explore the structure of mycelial cords and rhizomorphs. Rhizomorphs are among the most complex organs produced by fungi. They are root-like structures constituted by a series of differentiated tissues each with distinctive hyphal type, orientation, size, and function. Thus, rhizomorphs are produced as a result of a coordinated growth of millions of bundled hyphae. Rhizomorph-forming fungi thrive in nutrient-poor environment and are known to cause devastating destruction to homes and plantations. Because rhizomorphs serve as exploratory organs, and they enhance the survival of rhizomorph-forming fungi in plantations and homes, farmers, homeowners, attorneys, and even mycologists and plant pathologists, need to understand and appreciate their potential to wreak havoc that results in huge annual financial losses.

2004

In mycelial fungi the formation of hyphal branches is the only way in which the number of growing points can be increased. Cross walls always form at right angles to the long axis of a hypha, and nuclear division is not necessarily linked to cell division. Consequently, no matter how many nuclear divisions occur and no matter how many cross walls are formed there will be no increase in the number of hyphal tips unless a branch arises. Evidently, for the fungi, hyphal branch formation is the equivalent of cell division in animals, plants and protists. The position of origin of a branch, and its direction and rate of growth are the crucial formative events in the development of fungal tissues and organs. Kinetic analyses have shown that fungal filamentous growth can be interpreted on the basis of a regular cell cycle, and encourage the view that a mathematical description of fungal growth might be generalised into predictive simulations of tissue formation. An important point to empha...

Fungal Diversity, 2002

Succession is one of the most widely known ecological concepts. It is intuitive and yet extremely complex. There have been many fungal succession studies on a wide diversity of substrates and yet we still know very little about the mechanisms that drive succession. Direct methods of observing fungal succession (change in occupation of space by thalli) use destructive techniques and therefore change in mycelia in a point in space over time cannot be observed. However, these direct destructive methods, with appropriate replication, are extremely useful for discovering general patterns of succession. Indirect methods often observe only the fruit body sequence on a substrate. These studies can also be extremely useful, but need to be interpreted with caution. In addition the underlying assumption that sporulation reflects changes in mycelial occupation of space in the substrate needs to be considered carefully.

Molecular Biology Intelligence Unit

I n mycelial fungi the formation of hyphal branches is the only way in which the number of growing points can be increased. Cross walls always form at right angles to the long axis of a hypha, and nuclear division is not necessarily linked to cell division. Consequently, no matter how many nuclear divisions occur and no matter how many cross walls are formed there will be no increase in the number of hyphal tips unless a branch arises. Evidently, for the fungi, hyphal branch formation is the equivalent of cell division in animals, plants and protists. The position of origin of a branch, and its direction and rate of growth are the crucial formative events in the development of fungal tissues and organs. Kinetic analyses have shown that fungal filamentous growth can be interpreted on the basis of a regular cell cycle, and encourage the view that a mathematical description of fungal growth might be generalised into predictive simulations of tissue formation. An important point to emphasise is that all kinetic analyses published to date deal exclusively with physical influences on growth and branching kinetics (like temperature, nutrients, etc.). In this chapter we extrapolate from the kinetics so derived to deduce how the biological control events might affect the growth vector of the hyphal apex to produce the patterns of growth and branching that characterise fungal tissues and organs. This chapter presents: (i) a review of the published mathematical models that attempt to describe fungal growth and branching; (ii) a review of the cell biology of fungal growth and branching, particularly as it relates to the construction of fungal tissues; and (iii) a section in which simulated growth patterns are developed as interactive three-dimensional computer visualisations in what we call the Neighbour-Sensing model of hyphal growth. Experiments with this computer model demonstrate that geometrical form of the mycelium emerges as a consequence of the operation of specific locally-effective hyphal tip interactions. It is not necessary to impose complex spatial controls over development of the mycelium to achieve particular morphologies. Kinetics of Mycelial Growth and Morphology Kinetic analyses show that fungal filamentous growth can be interpreted on the basis of a regular cell cycle, and in this section we review published mathematical models that attempt to describe fungal growth and branching in the vegetative (mycelial) phase. Measurement Methodologies Measurements of hyphal diameter, hd, and hyphal length, hl, allow hyphal volume, hv, to be calculated, which when multiplied by the average density of the composite hyphal material, ρ, gives an estimate of biomass, X. Taking these measurements over a series of time intervals enable hyphal extension rate, E, and the rate of increase of biomass to be calculated. Currently, automated image analysis systems permit real-time analysis of these microscopic parameters, 1 and some of these analyses suggest that hyphal tips grow in pulses, 2 although this is debatable, 3 particularly because the observations use video techniques and the pixelated image generated by both analogue and digital cameras will cause pulsation artefacts. 4 The most important macroscopic parameter is total biomass. Total hyphal length is proportional to total biomass, if hd and ρ are assumed to be constant, but measurement can be difficult. Nondestructive mass measurement is rarely feasible and in most cases separating the mycelium from the substratum is difficult (and sometimes impossible). Acuña et al 5 developed a neural network that they trained to correlate colony radius with colony biomass. However, this relationship is only relevant to circular mycelia and measurements in two dimensions.

FEMS Microbiology Letters, 2006

The basidiomycete fungus Schizophyllum commune has been utilised as a model system for examining the genetic regulation of sexual reproduction, a process that culminates in the production of mushrooms in this and many other related species. Recent studies have suggested that conserved elements of the cyclic AMP (cAMP) signalling pathway play a role in the control of mushroom development in S. commune. The small G-protein Ras also appears to impinge on the process, either by inputting into the cAMP pathway, or by acting in parallel. The molecular connections between nutrient sensing and mushroom development are now beginning to be examined.