A source of variation in moths’ sex pheromones – A single mutation in an enzyme accounts for variation of sex pheromones
February 14, 2013
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Functional impact of the mutation of the 453rd amino acid residue of the pheromone gland specific fatty-acyl reductase on its activity. The pie charts represent the relative abundance of products.
Pheromones are central to the mating systems of a wide range of organisms, and reproductive isolation between closely related species is often achieved by subtle differences in pheromone composition. In moths, the use of structurally similar components in different blend ratios is usually sufficient to impede gene flow between species. To date, however, the genetic changes associated with variation and divergence in pheromone signals remain largely unknown.
Using the emerging model system Ostrinia, we show the functional consequences of mutations in the protein-coding region of the pheromone biosynthetic fatty-acyl reductase gene pgFAR. Heterologous expression confirmed that pgFAR orthologs encode enzymes exhibiting different substrate specificities. When taking natural ratios of pheromone precursors into account, our data reveal that pgFAR substrate preference provides a good explanation of how species-specific ratios of pheromone components are obtained among Ostrinia species. Site-directed mutagenesis experiments substantiate the idea that amino acid polymorphisms underlie subtle or drastic changes in pgFAR substrate preference.
Altogether, this study identifies the reduction step as a potential source of variation in pheromone signals in the moth genus Ostrinia.
Jean-Marc Lassance, Marjorie A. Liénard, Binu Antony, Shuguang Qian, Binu Antony, Takeshi Fujii, Jun Tabata, Yukio Ishikawa, Christer Löfstedt, “Functional consequences of sequence variation in the pheromone biosynthetic gene pgFAR for Ostrinia moths,” Proceedings of the National Academy of Sciences of the United States of America (PNAS). Online Edition: 2013/2/12 (Japan time), doi: 10.1073/pnas.1208706110.