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Video: See fungal spores fly

In a remarkable display of cooperation, specialized fungi eject spores sitting atop their fruiting bodies at high speeds in rapid succession to generate a miniature wind current that carries their progeny 20 times farther than a single spore could travel on its own. Spore puffs from Sclerotinia sclerotiorumImage: M. RoperCombining mathematical theory with high speed video, a team led by applied mathematician linkurl:Marcus Roper;http://math.berkeley.edu/%7Emroper/www/Home.html of the University

Sep 27, 2010
Jef Akst
In a remarkable display of cooperation, specialized fungi eject spores sitting atop their fruiting bodies at high speeds in rapid succession to generate a miniature wind current that carries their progeny 20 times farther than a single spore could travel on its own.
Spore puffs from Sclerotinia sclerotiorum
Image: M. Roper
Combining mathematical theory with high speed video, a team led by applied mathematician linkurl:Marcus Roper;http://math.berkeley.edu/%7Emroper/www/Home.html of the University of California, Berkeley, watched as Sclerotinia sclerotiorum -- a pathogenic fungus that infects the flowers of crop plants -- performed this impressive reproductive feat, which involves the ejection of fungal spores from some 100,000 separate sacs, known as asci. The team also demonstrated how the cooperating spores can evade obstacles by riding the air current they create. Their results are reported in this week's Proceedings of the National Academy of Sciences (PNAS). The explosion seems to be triggered by a few "pioneering" spores that eject spontaneously, Roper explained, and the rest seem to be initiated by mechanical communication among the different asci. The outcome is a very rapid wave of ejections, resulting in a sheet-like jet of air that carries the spores more than 10 centimeters. "In addition to being very beautiful," he said, "it actually turns out that this particular way of triggering the puff avoids unfair distribution of cooperative benefits." That is, no one spore can cheat the system, and ride the currents created by the others without doing its own part to maximize the distance traveled for all. "What's keeping them from cheating is built into the physics."
Spores eject from the top of a fruiting body of the fungus Sclerotinia sclerotiorum, slowed down to one fifth of its natural speed, to show the structure of the jet of air created by the spores.
Video courtesy of Marcus Roper
A high speed film showing the same species of fungus ejecting its spores. The left panel shows the spores illuminated with a ~1mm thick laser light sheet. The right panel displays the speed of the spores, computed using a technique called particle image velocimetry (PIV).
Video courtesy of Mahesh Bandi, Agnese Seminara and Marcus Roper
The ejection of spores from a related fungus, Ascobolus furfuraceus. The spores are black specks, which disappear when the spores are ejected.
Video courtesy of Marcus Roper
M. Roper, et al., "Dispersal of fungal spores on a cooperatively generated wind," PNAS, www.pnas.org/cgi/doi/10.1073/pnas.1003577107, 2010.
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[22nd July 2010]