The fastest flights in nature: high-speed spore discharge mechanisms among fungi

• Published in: PloS one 2008-09, Vol.3 (9), p.e3237-e3237
• Main Authors: Yafetto, Levi, Carroll, Loran, Cui, Yunluan, Davis, Diana J, Fischer, Mark W F, Henterly, Andrew C, Kessler, Jordan D, Kilroy, Hayley A, Shidler, Jacob B, Stolze-Rybczynski, Jessica L, Sugawara, Zachary, Money, Nicholas P
• Format: Article
• Language: English
• Subjects: Asci; Ascobolus; Ballistics; Cameras; Cell Biology/Microbial Physiology and Metabolism; Cell Biology/Morphogenesis and Cell Biology; Discharge; Dung; Empirical analysis; Fungi; Fungi - physiology; Fusarium graminearum; Herbivores; High speed; Hydrologic data; Hydrostatic pressure; Hyphae; Identification methods; Indoor air quality; Information processing; Mathematical models; Measuring instruments; Microbiology/Microbial Growth and Development; Microbiology/Microbial Physiology and Metabolism; Microscopy, Video - methods; Models, Biological; Models, Theoretical; Movement; Osmosis; Plant diseases; Reproducibility of Results; Reptiles & amphibians; Scientific imaging; Spectrophotometry - methods; Spectroscopy; Sporangia; Spores; Spores, Fungal - physiology; Turgor; Velocity; Video data; Viscous drag
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0003237

A variety of spore discharge processes have evolved among the fungi. Those with the longest ranges are powered by hydrostatic pressure and include "squirt guns" that are most common in the Ascomycota and Zygomycota. In these fungi, fluid-filled stalks that support single spores or spore-filled sporangia, or cells called asci that contain multiple spores, are pressurized by osmosis. Because spores are discharged at such high speeds, most of the information on launch processes from previous studies has been inferred from mathematical models and is subject to a number of errors. In this study, we have used ultra-high-speed video cameras running at maximum frame rates of 250,000 fps to analyze the entire launch process in four species of fungi that grow on the dung of herbivores. For the first time we have direct measurements of launch speeds and empirical estimates of acceleration in these fungi. Launch speeds ranged from 2 to 25 m s(-1) and corresponding accelerations of 20,000 to 180,000 g propelled spores over distances of up to 2.5 meters. In addition, quantitative spectroscopic methods were used to identify the organic and inorganic osmolytes responsible for generating the turgor pressures that drive spore discharge. The new video data allowed us to test different models for the effect of viscous drag and identify errors in the previous approaches to modeling spore motion. The spectroscopic data show that high speed spore discharge mechanisms in fungi are powered by the same levels of turgor pressure that are characteristic of fungal hyphae and do not require any special mechanisms of osmolyte accumulation.