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Differentiation inside multicelled macroconidia of Fusarium culmorum during early germination
Gilma S Chitarra1, Pieter Breeuwer, Frans M Rombouts
1Laboratory of Food Microbiology,Wageningen University, Biotechnion, P.O. Box 8129, 6703 HD, Wageningen, The Netherlands.
Abstract:
Multicelled conidia are formed by many fungal species, but germination of these spores is scarcely studied. Here, the germination and the effects of antimicrobials on multicompartment macroconidia of Fusarium culmorum were investigated. Germ-tube formation was mostly from apical compartments. The intracellular pH (pH(in)) of the different individual cells of the macroconidia was monitored during germination. The pH(in) varied among different compartments and during different stages of germination. The internal pH was lowest in ungerminated cells and rose during germ-tube formation and was highest in new germ tubes. Antifungal compounds affect the pH(in) and differentiation of the conidia. The pH(in) inside the macroconidial compartments was lowered very fast in the presence of nystatin (1 and 4 microg/ml). At sublethal doses (0.3 microg/ml), the apical compartments were preferentially targeted showing lower pH(in) values. The reduced germination capacity of apical compartments under these conditions was compensated by an increased germination capacity of middle compartments.
Insights
Investigating fungal spore germination reveals that intracellular pH (pH(in)) changes dynamically during macroconidia development. Antimicrobials like nystatin disrupt this pH balance, impacting fungal differentiation and spore germination.
Area of Science:
- Mycology
- Fungal Physiology
- Antimicrobial Research
Background:
- Multicelled fungal spores (macroconidia) are common, yet their germination is poorly understood.
- Understanding macroconidia germination is crucial for controlling fungal pathogens.
Purpose of the Study:
- To investigate the germination process of Fusarium culmorum macroconidia.
- To determine the role of intracellular pH (pH(in)) during germination.
- To examine the effects of antifungal compounds on macroconidia germination and pH(in).
Main Methods:
- Monitoring intracellular pH (pH(in)) in individual macroconidial compartments during germination.
- Treating macroconidia with varying concentrations of nystatin.
- Assessing germination capacity and germ-tube formation.
Main Results:
- Germ-tube formation primarily occurred from apical compartments.
- Intracellular pH (pH(in)) varied significantly between compartments and germination stages, rising during germ-tube formation.
- Nystatin rapidly decreased macroconidial pH(in). Sublethal doses preferentially affected apical compartments, leading to compensatory germination in middle compartments.
Conclusions:
- Intracellular pH (pH(in)) is a critical factor regulating macroconidia germination in Fusarium culmorum.
- Antifungal agents like nystatin disrupt fungal differentiation by altering intracellular pH.
- Targeting specific compartments within macroconidia offers a potential strategy for antifungal development.
