[
International Worm Meeting,
2021]
Olfaction plays an important role in threat perception in higher organisms. To understand the role of olfaction in host survival, we studied interaction of C. elegans with Pseudomonas aeruginosa, a bacterium commonly found in the same ecological niche as this nematode. P. aeruginosa acts as a pathogen against C. elegans, colonizing its gut and reducing its survival. It is known that C. elegans actively detects and avoids P. aeruginosa (Zhang et al. Nature 2005). We have identified two volatiles produced by P. aeruginosa that elicit a behavioural response in C. elegans. One of the chemicals is an attractant and the other is a repellent for C. elegans. The amphid neurons AWA, AWB and AWC are mainly responsible for detecting volatile odorants. While AWA and AWC detect attractants, AWB is responsible for detecting repellents. By studying calcium dynamics in olfactory neurons, we have identified specific neurons which detect volatiles from P. aeruginosa. Through qPCR analysis, we have observed induction of P. aeruginosa specific immune response genes upon exposure to the volatile repellent. The induction of immune response genes is dependent on functional olfactory neurons. Further, pre-exposure of worms to the identified repellent also increases their survival on Pseudomonas aeruginosa lawn. Keywords: Host-microbe interactions, Olfaction, Chemotaxis, Immune response, Pseudomonas aeruginosa, Volatiles