Confirmation of a Link between Fungal Pigmentation, Turgor Pressure, and Pathogenicity Using a New Method of Turgor Measurement

Money, Nicholas P.; Howard, Richard J.

doi:10.1006/fgbi.1996.0037

Cited by 123 publications

(81 citation statements)

References 37 publications

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“…In contrast, Glycera jaw melanin is organized into 200-nm-thick tablets arranged perpendicular to the long axis of the jaw. 4 We know of only one other instance, melanized fungal cell walls (18,38,39), in which interactions between constituent melanins suffice to maintain structural integrity after all other molecules have been removed. The mechanism of this long range stabilization of melanins of Glycera jaw is not yet understood but probably involves linkages between melanin particles.…”

Section: Discussionmentioning

confidence: 99%

Melanin and Glycera Jaws

Moses

Harreld

Stucky

et al. 2006

Journal of Biological Chemistry

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Section: Discussionmentioning

confidence: 99%

Melanin and Glycera Jaws

Moses

Harreld

Stucky

et al. 2006

Journal of Biological Chemistry

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“…6, 2007 MINIREVIEW 355 ular in plant infection, the fungal cell uses considerable turgor pressure to overcome physical barriers, such as the outer wall of the plant epidermis (58,80,132). However, tip growth can occur in the absence of cytoplasmic turgor pressure (78,79), and it was suggested that additional cytoskeleton-based mechanisms might exert force on the tip (47,50,77).…”

Section: Fig 4 Motility Of Early Endosomes Along Microtubules In Usmentioning

confidence: 99%

Hyphal Growth: a Tale of Motors, Lipids, and the Spitzenkörper

2007

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Filamentous fungi are a large and evolutionarily successful group of organisms of enormous ecological importance (27,114). Fungi also have a considerable impact on our economy because they serve as bio-factories for the industrial production of proteins (90,130) and because many fungi are human and plant pathogens that pose a threat to public health and agriculture (1,105,124).The basic unit of a filamentous fungus is the hypha, which usually consists of a chain of elongated cells that expand at the apex of the tip cell (10,41,115). Hyphal tip growth is characterized by the initial establishment of one growth site, which is followed by its continuous maintenance. This growth mode is different from budding in the yeast Saccharomyces cerevisiae.Here a short period of polarized apical growth is followed by extended isotrophic growth, which allows delivery of cell wall material over the entire bud surface and which leads to the almost spherical daughter cell (28,68). In contrast, hyphal growth results in an elongated tip cell, which raises new requirements. Among these is the long-distance transport between the subapical part and the apex of the tip cell. It is thought that microtubule (MT)-based motors, including kinesin-1 and kinesin-3, deliver vesicles and growth supplies over long distances to the hyphal tip (see below). However, in agreement with the described differences between hyphal growth and budding, these motors are not even encoded by the genome of S. cerevisiae.Hyphal growth is accompanied by the secretion of exoenzymes that participate in lysis of the substrate or are involved in the synthesis of the fungal cell wall (3, 42). The cell wall can be considered as an extracellular matrix consisting mainly of a meshwork of polysaccharides and manno-proteins that shelters the cell and resists the internal turgor pressure to maintain the shape of the hypha (112).It is currently thought that growth of fungal hyphae is mediated by cytoskeleton-based polar exocytosis at the hyphal tip and cytoplasmic expansion forces that push the cytoplasm against the flexible apical wall (summarized in reference 7). This model is in part based on the phenotypic similarities between fungal cells and plant cells that grow at their tips, such as pollen tubes or root hairs (36). However, phylogenetic comparison of rRNA or conserved proteins demonstrates that fungi are more closely related to animals (6, 131), and there is evidence for amoeboid motility of fungal cells (50). In this article, I will summarize recent results from different fields of fungal cell biology that are instrumental for understanding hyphal tip growth. This includes research on the Spitzenkör-per, the polarisome, the role of the cytoskeleton in endo-and exocytosis, the cellular function of sterol-rich plasma membrane domains, and the mechanism that generates the force for extension of the hypha. Finally, I will integrate all of these results from different fungal systems in a model for hyphal tip growth, and I will end the review by providing directions for ...

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“…This is somewhat surprising, as M. graminicola penetrates its host by stomata, whereas melanization is reported to be very important for generating turgor pressure in the appressoria of appressorium-forming fungal plant pathogens like M. grisea and Colletotrichum lagenarium (32,38,46,63). The melanin biosynthesis pathway in fungi is also well characterized (47,66), and expression of three melanin biosynthesis genes was reduced only at the onset of germination in the Fus3 orthologous mutants of C. lagenarium, suggesting the involvement of this ortholog in melanization of appressoria (62).…”

Section: Vol 8 2009mentioning

confidence: 99%

Gα and Gβ Proteins Regulate the Cyclic AMP Pathway That Is Required for Development and Pathogenicity of the Phytopathogen Mycosphaerella graminicola

et al. 2009

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We identified and functionally characterized genes encoding three G␣ proteins and one G␤ protein in the dimorphic fungal wheat pathogen Mycosphaerella graminicola, which we designated MgGpa1, MgGpa2, MgGpa3, and MgGpb1, respectively. Sequence comparisons and phylogenetic analyses showed that MgGPA1 and MgGPA3 are most related to the mammalian G␣ i and G␣ s families, respectively, whereas MgGPA2 is not related to either of these families. On potato dextrose agar (PDA) and in yeast glucose broth (YGB), MgGpa1 mutants produced significantly longer spores than those of the wild type (WT), and these developed into unique fluffy mycelia in the latter medium, indicating that this gene negatively controls filamentation. MgGpa3 mutants showed more pronounced yeast-like growth accompanied with hampered filamentation and secreted a dark-brown pigment into YGB. Germ tubes emerging from spores of MgGpb1 mutants were wavy on water agar and showed a nested type of growth on PDA that was due to hampered filamentation, numerous cell fusions, and increased anastomosis. Intracellular cyclic AMP (cAMP) levels of MgGpb1 and MgGpa3 mutants were decreased, indicating that both genes positively regulate the cAMP pathway, which was confirmed because the WT phenotype was restored by adding cAMP to these mutant cultures. The cAMP levels in MgGpa1 mutants and the WT were not significantly different, suggesting that this gene might be dispensable for cAMP regulation. In planta assays showed that mutants of MgGpa1, MgGpa3, and MgGpb1 are strongly reduced in pathogenicity. We concluded that the heterotrimeric G proteins encoded by MgGpa3 and MgGpb1 regulate the cAMP pathway that is required for development and pathogenicity in M. graminicola.

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Confirmation of a Link between Fungal Pigmentation, Turgor Pressure, and Pathogenicity Using a New Method of Turgor Measurement

Cited by 123 publications

References 37 publications

Melanin and Glycera Jaws

Melanin and Glycera Jaws

Hyphal Growth: a Tale of Motors, Lipids, and the Spitzenkörper

Gα and Gβ Proteins Regulate the Cyclic AMP Pathway That Is Required for Development and Pathogenicity of the Phytopathogen Mycosphaerella graminicola

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