Simplifying the Odor Landscape

Abstract

The vast number of detectable odors makes matching olfactory receptors (ORs) to their ligands a daunting task. Krautwurst and colleagues have hypothesized that this process can be simplified by focusing on those odorants that are perceptually relevant food odors. In this issue of Chemical Senses, they use this framework to identify highly sensitive receptors for 2 key food odorants found in red wine and onions, that activate broadly tuned OR1A1 and narrowly tuned OR2M3, respectively. This work provides further evidence for the advantage of screening receptors against ecologically relevant odors, and we discuss it in the context of current limitations in OR screening methods.

Keywords: genetic variability; key food odors; odor; olfaction; onion; wine.

Figure 1.

KFOs as the best ligands for ORs. (A) Proportion of receptors responding in the published literature when tested against KFOs or other odors. A chi-square test demonstrates a significant difference between these 2 groups (P < 0.001). (B) Distribution of EC50s for published OR/odor pairs, colored by whether Dunkel et al. (2014) identify the odor as a KFO. Arrows indicate EC50s for the “prune” and “onion” odors identified in this issue.

Figure 2.

ORs in the reference genome may not be the most common or most functional variant. The version of OR10A6 in the hg19 reference genome is nonfunctional in cell culture and has an allele frequency of 20% in the 1000 genomes population (Abecasis et al. 2010). In contrast, a variant with a single amino acid change (L287P) responds to geranyl acetate in cell culture and occurs more frequently in the population (Mainland J, unpublished data).