Meeting Abstract
Complex sensory suites often underlie critical questions in organismal biology because of their profound influence on the ecology and evolution of species. However, the majority of sensory system research has been focused only on animals leaving questions about early sensory system evolution, which require broad comparative frameworks, unanswered. To better understand the evolution and integration of early sensory systems we have turned to the ‘early diverging lineage’ of fungi, which include the Blastocladiomycota. These fungi have retained a single-celled propagule called a zoospore. They are highly motile, diploid cells that use either phototaxis or chemotaxis to control their swimming. Here, we describe the first multimodal sensorimotor system in fungi, simultaneously integrating light and chemical cues to control dispersal and settlement in unicellular zoospores. We find that only the zoospores of Allomyces arbusculus exhibit both phototaxis and chemotaxis, and that closely related Allomyces species do not share this multisensory system. This diversity of sensory modalities within Allomyces provides a rare example of a genus showing rapid sensory system evolution in response to the gain or loss of individual senses. Taking advantage of this newfound framework, we use pharmacological knockdowns to reveal that multisensory systems in Allomyces co-opt new ion channels in order to integrate novel senses into existing behaviors. These studies into zoospore biology reveal deceptively complex sensory systems and variation hidden in these previously unassuming unicellular fungi. Understanding how these systems evolve and contribute to diversification is a step towards a deeper understanding of how organisms perceive, interact, and adapt to their environments.
