We investigated ascospore discharge in the perithecial fungus, Gibberella zeae. In a wind tunnel study that simulated constant rain and varying day and night lengths, the rate of ascospore release was approximately 8-30% greater under light than in complete darkness. Under constant light, ascospore discharge occurred at maximal rates at relative humidity levels greater than 92%. When perithecia were placed under conditions of high external osmolarity, ascospore discharge was significantly reduced. Ascospores were discharged from asci along with droplets of fluid, the epiplasm, from within the ascus. Analysis of discharged epiplasmic fluid by GC-MASS Spectrometry revealed that mannitol was the major simple sugar component of the fluid. Activity of mannitol dehydrogenase, which catalyzes the conversion of fructose to mannitol, was higher in protein extracts from mature perithecia than in extracts from vegetative tissue. Several inhibitors of K(+) and Ca(++) ion channels inhibited ascospore discharge, which suggested that ascospore discharge resulted from the buildup of turgor pressure generated by ion fluxes and mannitol accumulation.
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mBio
June 2024
National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.
Fungal Biol
December 2023
Department of Chemistry and Biochemistry, Mount St. Joseph University, Cincinnati, OH, 45233, USA.
Unlike the mechanism of ballistospore discharge, which was not solved until the 1980s, the operation of asci as pressurized squirt guns is relatively straightforward and was understood in the nineteenth century. Since then, mycologists have sought to understand how structural adaptations to asci have allowed the ascomycetes to expel spores of different shapes and sizes over distances ranging from a few millimeters to tens of centimeters. These modifications include the use of valves at the tips of asci that maintain ascus pressure and expel spores at the highest speeds, and gelatinous appendages that connect spores after release and create larger projectiles with greater momentum than single spores.
View Article and Find Full Text PDFFront Microbiol
November 2023
Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden.
Spores are important as dispersal and survival propagules in fungi. In this study we investigated the variation in number, shape, size and germination mode of ascospores in , the only species of the genus known to fruit in the autumn. Based on the observation of five samples, we first discovered significant variation in the shape and size of ascospores in .
View Article and Find Full Text PDFEnviron Microbiol
December 2022
Key Laboratory of Agricultural Microbiology, College of Plant Protection, Shandong Agricultural University, Tai'an, China.
Vesicular trafficking is a conserved material transport process in eukaryotic cells. The GGA family proteins are clathrin adaptors that are involved in eukaryotic vesicle transport, but their functions in phytopathogenic filamentous fungi remain unexplored. Here, we examined the only GGA family protein in Fusarium graminearum, FgGga1, which localizes to both the late Golgi and endosomes.
View Article and Find Full Text PDFFungal Genet Biol
November 2022
Université Paris-Saclay, INRAE, UR BIOGER, 91120 Palaiseau, France. Electronic address:
Little is known about the impact of host immunity on sexual reproduction in fungal pathogens. In particular, it is unclear whether crossing requires both sexual partners to infect living plant tissues. We addressed this issue in a three-year experiment investigating different scenarios of Zymoseptoria tritici crosses according to the virulence ('vir') or avirulence ('avr') of the parents against a qualitative resistance gene.
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