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Summoning the wind: Hydrodynamic cooperation of forcibly launched fungal spores

Author
Roper, Marcus; Seminara, Agnese; Cobb, Ann; Dillard, Helene; Pringle, Anne
Abstract
The forcibly launched spores of the crop pathogen \emph{Sclerotinia sclerotiorum} must eject through many centimeters of nearly still air to reach the flowers of the plants that the fungus infects. Because of their microscopic size, individually ejected spores are quickly brought to rest by drag. In the accompanying fluid dynamics video we show experimental and numerical simulations that demonstrate how, by coordinating the nearly simultaneous ejection of hundreds of thousands of spores,\emph{Sclerotinia} and other species of apothecial fungus are able to sculpt a flow of air that carries spores across the boundary layer and around intervening obstacles. Many spores are sacrificed to create this flow of air. Although high speed imaging of spore launch in a wild isolate of the dung fungus \emph{Ascobolus} shows that the synchronization of spore ejections is self-organized, which could lead to spores delaying their ejection to avoid being sacrificed, simulations and asymptotic analysis show that near the fruit body, ejected spores form a sheet-like jet that advances across the fruit body as more spores are ejected. Spores maximize both their range and their contribution to the cooperative range enhancement by ejecting on the arrival of the sheet.
Sponsorship
Miller Institute for Basic Research in Sciences. European Union Framework 7.
Date Issued
2009-10-16Subject
Biomechanics; Cooperation; Fountain; Spore