How do the spores responsible for downy mildew “swim”?

  • Research
Published on May 14, 2022 Updated on May 16, 2022
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Zoospore
Zoospore False colored SEM Image of a zoospore of the water mold Phytophthora. © Quang D. Tran, Eric Galiana, Philippe Thomen, Céline Cohen, François Orange, Fernando Peruani, Xavier Noblin
The article "Coordination of two opposite flagella allows high-speed swimming and active turning of individual zoospores", published in eLife, has been highlighted by CNRS and Science.

Abstract of the article
Phytophthora species cause diseases in a large variety of plants and represent a serious agricultural threat, leading, every year, to multibillion dollar losses. Infection occurs when their biflagellated zoospores move across the soil at their characteristic high speed and reach the roots of a host plant. Despite the relevance of zoospore spreading in the epidemics of plant diseases, individual swimming of zoospores have not been fully investigated. It remains unknown about the characteristics of two opposite beating flagella during translation and turning, and the roles of each flagellum on zoospore swimming. Here, combining experiments and modeling, we show how these two flagella contribute to generate thrust when beating together, and identify the mastigonemes-attached anterior flagellum as the main source of thrust. Furthermore, we find that turning involves a complex active process, in which the posterior flagellum temporarily stops, while the anterior flagellum keeps on beating and changes its gait from sinusoidal waves to power and recovery strokes, similar to Chlamydomonas’s breaststroke, to reorient its body to a new direction. Our study is a fundamental step toward a better understanding of the spreading of plant pathogens’ motile forms, and shows that the motility pattern of these biflagellated zoospores represents a distinct eukaryotic version of the celebrated ‘run-and-tumble’ motility class exhibited by peritrichous bacteria.

Reference
Coordination of two opposite flagella allows high-speed swimming and active turning of individual zoospores. Quang D. Tran, Eric Galiana, Philippe Thomen, Céline Cohen, François Orange, Fernando Peruani, Xavier Noblin. eLife, le 3 mai 2022. DOI : https://doi.org/10.7554/eLife.71227.sa0