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Abstract Body

Phytophthora zoospores display klinokinetic behaviour in response to a chemoattractant

Michiel Kasteel^1,2, Joris Sprakel³, Tharun Rajamuthu^1,2, Tijs Ketelaar¹ & Francine Govers²

¹Laboratory of Cell Biology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen the Netherlands; ²Laboratory of Phytopathology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, the Netherlands; ³Laboratory of Biochemistry, Wageningen University & Research, Stippeneng 4, 6708 WE, Wageningen, the Netherlands

Phytophthora infestans, the causal agent of potato late blight, makes use of dispersal agents called zoospores to rapidly spread and infect. Being motile, these zoospores have been thought to actively track down their hosts using chemical cues such as sugars, amino acids and isoflavonoids. In this study, we used high speed cameras to track zoospores over time and have quantified key trajectory parameters to describe their response to glutamic acid (Glu). We find zoospores to adapt their native run-and-tumble state in response to Glu by greatly increasing the frequency at which they turn. When simulated, we find tuneable tumble frequencies to be sufficient to explain aggregation, implying zoospores to have access to a klinokinetic accumulation strategy to aggregate. We used the same experimental set-up to monitor zoospores of a mutant compromised in heterotrimeric G-protein signalling, and show that their aberrant swimming behaviour is not due to a defect in Glu-chemotaxis, but to aberrantly high and consistent tumbling frequencies.