agnese seminara - université cote d'Azur, INPHYNI, CNRS - Keywords: spore dispersal, atmosphere, turbulence

agnese seminara - université cote d'Azur, INPHYNI, CNRS - Keywords: spore dispersal, atmosphere, turbulence

Contribution title: The fundamental drivers of fungal spore liberation in the atmosphere

Fungi range from decomposers to symbionts, parasites and pathogens and are among the worst threats (1,2) and at the same time the most fundamental components of many ecosystems (3). Allergenic fungal spores are universally present in the atmosphere; regularly outnumber pollen of 100 or 1000 fold and commonly display seasonal patterns of dispersal affected by meteorological parameters. Emerging fungal diseases are causing some of the most severe extinctions ever witnessed in wild species, and crop pathogens jeopardize food security. Understanding fungal spore dispersal for the health of humans and ecosystems is urgent.

The fungi lack legs or wings for locomotion, but they routinely translocate even across oceans by dispersing their spores, causing the spread of major diseases of crops, animals and humans. Most fungi use spectacular discharge mechanisms to accelerate spores at rates nearly unmatched elsewhere in nature. We demonstrated that discharge is optimized to the slimmest level of precision (4-8) but how and when fungi choose to liberate their spores is largely unknown. Moreover, how this choice affects spore trajectory is unclear: kicked and buffeted by wind and turbulence individual spores follow unpredictable trajectories. We use a combination of stochastic modeling and Lagrangian simulations using weather data to show that the average time a spore spends in the atmosphere (“flight time”) depends on the time of liberation. The second ingredient dictating spore flight time is spore shape. Thus fungi lose control over individual spores but they may still manipulate spore discharge to release the bulk of spores in favorable conditions, i.e. when probability of beneficial trajectories is greatest.

We are currently working towards an understanding of the best environmental parameters that predict spore flight. A statistical prediction of flight time is essential for a fungus to decide the timing of spore liberation that best matches their needs. Some fungi may benefit from dispersing the bulk of their spores as far as possible. Others, that have short-lived spores, must avoid excessive exposure to the elements, which would lead to spore death.

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