Fungal Spore Germination: Insights from the Molecular Genetics ofAspergillus nidulansandNeurospora crassa

d’Enfert, Christophe

doi:10.1006/fgbi.1997.0975

Cited by 197 publications

(134 citation statements)

References 67 publications

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“…Mannitol and, to a lesser extent, trehalose may be used as sources of carbon to enable the rapid production of glycerol (11). However, glycerol accumulation during the germination of ⌬mpdA spores was not different from that for the germination of wild-type spores (Fig.…”

Section: Resultsmentioning

confidence: 93%

Mannitol Is Required for Stress Tolerance inAspergillus nigerConidiospores

et al. 2003

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D-Mannitol is the predominant carbon compound in conidiospores of the filamentous fungus Aspergillus niger and makes up 10 to 15% of the dry weight. A number of physiological functions have been ascribed to mannitol, including serving as a reserve carbon source, as an antioxidant, and to store reducing power. In this study, we cloned and characterized the A. niger mpdA gene, which encodes mannitol 1-phosphate dehydrogenase (MPD), the first enzyme in the mannitol biosynthesis pathway. The mpdA promoter contains putative binding sites for the development-specific transcription factors BRLA and ABAA. Furthermore, increased expression of mpdA in sporulating mycelium suggests that mannitol biosynthesis is, to a certain extent, developmentally regulated in A. niger. Inactivation of mpdA abolished mannitol biosynthesis in growing mycelium and reduced the mannitol level in conidiospores to 30% that in the wild type, indicating that MPD and mannitol 1-phosphate phosphatase form the major metabolic pathway for mannitol biosynthesis in A. niger. The viability of spores after prolonged storage and germination kinetics were normal in an mpdA null mutant, indicating that mannitol does not play an essential role as a reserve carbon source in A. niger conidia. However, conidiospores of a ⌬mpdA strain were extremely sensitive to a variety of stress conditions, including high temperature, oxidative stress and, to a lesser extent, freezing and lyophilization. Since mannitol supplied in the medium during sporulation repaired this deficiency, mannitol appears to be essential for the protection of A. niger spores against cell damage under these stress conditions. Polyols or polyhydroxyalcohols are present in all organisms, from bacteria to animals. In particular, plants and fungi are known to accumulate high levels of polyols intracellularly, up to several hundred millimoles per liter. The filamentous fungus Aspergillus niger produces a number of different polyols, including glycerol, erythritol, and D-mannitol (41). The intracellular concentrations of the individual polyols in A. niger depend on growth conditions and developmental stage, suggesting that polyols have important functions in fungal physiology.The hexitol D-mannitol is accumulated by vascular plants (37) and many fungal species (21). In A. niger conidiospores, D-mannitol is the predominant carbon-containing compound and makes up 10 to 15% of the dry weight (41). The metabolic pathway for mannitol biosynthesis in ascomycete and deuteromycete fungi most likely consists of two steps (19) (Fig. 1). Fructose 6-phosphate is reduced to mannitol 1-phosphate by NAD ϩ -dependent mannitol 1-phosphate dehydrogenase (MPD), followed by the dephosphorylation of mannitol 1-phosphate, which is catalyzed by mannitol 1-phosphate phosphatase (MPP), yielding mannitol. The presence of MPD and MPP in several fungi, such as A. niger (22), Aspergillus nidulans (34), and Alternaria alternata (18), has been demonstrated, but these enzymes are also responsible for mannitol biosynthesis in protozoa...

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Section: Resultsmentioning

confidence: 93%

Mannitol Is Required for Stress Tolerance inAspergillus nigerConidiospores

et al. 2003

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“…It occurs simultaneously with the resumption of numerous metabolic activities including respiration, and RNA and protein synthesis and results in a cell whose diameter is two to several times that of the resting conidia [15,16,18]. The last stage is the polarized growth which ends with the formation of a germ tube [13]. After 4 h in culture media, microconidia of all the three Fusarium species are in the second phase of the germination because isotropic growth is evident but no nuclear division or germ tube emergence can be observed (see Fig 4,5 and 6).…”

Section: Discussionmentioning

confidence: 99%

“…Germination is generally triggered by nutrient sensing and is characterized by conidial swelling, adhesion, nuclear reorganization, and formation of a germ tube that is often used to define the limit between conidial germination and vegetative growth [13,14]. In addition to the marked difference in metabolic activity, ungerminated conidia differ from germlings in their biochemical composition, redox status, cell organization and structure and composition of the cell wall [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Photodynamic treatment with phenothiazinium photosensitizers kills both ungerminated and germinated microconidia of the pathogenic fungi Fusarium oxysporum, Fusarium moniliforme and Fusarium solani

Menezes

Tonani

Bachmann

et al. 2016

Journal of Photochemistry and Photobiology B: Biology

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Photodynamic treatment with phenothiazinium photosensitizers kills both ungerminated and germinated microconidia of the pathogenic fungi Fusarium oxysporum, Fusarium moniliforme and Fusarium solani.http://researchonline.ljmu.ac.uk/4233/ Article LJMU has developed LJMU Research Online for users to access the research output of the University more effectively. Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Users may download and/or print one copy of any article(s) in LJMU Research Online to facilitate their private study or for non-commercial research. You may not engage in further distribution of the material or use it for any profit-making activities or any commercial gain.The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription. increased the membrane permeability and APDT with NMBN or S137 increased the lipid peroxidation in microconidia of the three Fusarium species. These findings expand the understanding of photodynamic inactivation of filamentous fungi with phenothiazinium PS.

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“…However, addition of cAMP to these conidia resulted in significant mobilization of trehalose and accelerated germination. In Saccharomyces cerevisiae, trehalose breakdown requires activation of the neutral trehalase, mediated by cAMP-dependent protein kinase A and possibly Ca 2+ (Souza et al, 2002;d'Enfert 1997;de Almeida et al, 1997). The inability of adenylate-cyclasedeficient N. crassa mutants to mobilize trehalose during germination also indicates that cAMP signalling is required for activation of neutral trehalase (de Pinho et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

Trehalose metabolism is important for heat stress tolerance and spore germination of Botrytis cinerea

2006

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To analyse the role of trehalose as stress protectant and carbon storage compound in the grey mould fungus Botrytis cinerea, mutants defective in trehalose-6-phosphate synthase (TPS1) and neutral trehalase (TRE1) were constructed. The Dtps1 mutant was unable to synthesize trehalose, whereas the Dtre1 mutant showed elevated trehalose levels compared to the wild-type and was unable to mobilize trehalose during conidial germination. Both mutants showed normal vegetative growth and were not affected in plant pathogenicity. Growth of the Dtps1 mutant was more heat sensitive compared to the wild-type. Similarly, Dtps1 conidia showed a shorter survival under heat stress, and their viability at moderate temperatures was strongly reduced. In germinating wild-type conidia, rapid trehalose degradation occurred only when germination was induced in the presence of nutrients. In contrast, little trehalose breakdown was observed during germination on hydrophobic surfaces in water. Here, addition of cAMP to conidia induced trehalose mobilization and accelerated the germination process, probably by activation of TRE1. In accordance with these data, both mutants showed germination defects only in the presence of sugars but not on hydrophobic surfaces in the absence of nutrients. The data indicate that in B. cinerea trehalose serves as a stress protectant, and also as a significant but not essential carbon source for germination when external nutrients are low. In addition, evidence was obtained that trehalose 6-phosphate plays a role as a regulator of glycolysis during germination.

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Fungal Spore Germination: Insights from the Molecular Genetics ofAspergillus nidulansandNeurospora crassa

Cited by 197 publications

References 67 publications

Mannitol Is Required for Stress Tolerance inAspergillus nigerConidiospores

Mannitol Is Required for Stress Tolerance inAspergillus nigerConidiospores

Photodynamic treatment with phenothiazinium photosensitizers kills both ungerminated and germinated microconidia of the pathogenic fungi Fusarium oxysporum, Fusarium moniliforme and Fusarium solani

Trehalose metabolism is important for heat stress tolerance and spore germination of Botrytis cinerea

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