| Title: | Drakolide Structure-activity Relationships for Sexual Attraction of Zeleboria Wasp Pollinator |
| Author(s): | Bohman B; Tan MMY; Flematti GR; Peakall R; |
| Address: | "School of Molecular Sciences, the University of Western Australia, Crawley, WA, 6009, Australia. Department of Plant Protection Biology, the Swedish University of Agricultural Sciences, 234 56, Lomma, Sweden. Research School of Biology, The Australian National University, ACT, Canberra, 2600, Australia. School of Molecular Sciences, the University of Western Australia, Crawley, WA, 6009, Australia. rod.peakall@anu.edu.au. Research School of Biology, The Australian National University, ACT, Canberra, 2600, Australia. rod.peakall@anu.edu.au" |
| DOI: | 10.1007/s10886-021-01324-4 |
| ISSN/ISBN: | 1573-1561 (Electronic) 0098-0331 (Linking) |
| Abstract: | "Orchids pollinated by sexual deception lure their specific male pollinators by sex pheromone mimicry. Despite the growing list of chemically diverse semiochemicals known to be involved, the chemical basis and flexibility of this extreme pollinator specificity are not fully understood. One promising but rarely applied tool is the synthesis and field testing of chemically related variants for investigating the structural specificity of the pheromone mimics. Here, we build on the discovery of the unusual semiochemical blend used by Drakaea micrantha to sexually lure its male Zeleboria thynnine wasp pollinator. This blend consists of a beta-ketolactone (drakolide) and two specific hydroxymethylpyrazines, presumably drawn from two distinct biosynthetic pathways. Here, we synthesized and tested the activity of various stereo- and structural isomers of the naturally occurring drakolide. Our study confirmed that in blends with the two pyrazines, both a mixture of stereoisomers, and the specific stereoisomer of the natural drakolide, elicit high rates of landings and attempted copulations. However, in the absence of pyrazines, both the number of responses and the level of sexual attraction were significantly reduced. When structural analogs were substituted for the natural drakolide, attractiveness and degree of sexual behaviour varied but were generally reduced. Based on our findings, and prior knowledge that related hydroxymethylpyrazines are active in other Drakaea spp., we conclude that the dual sex pheromone mimicry of D. micrantha likely evolved via initial changes in just one of the two biosynthetic pathways. Most plausibly, this involved modifications in the drakolides, with the pyrazines as a 'pre-adaption' enhancing the sexual response" |
| Keywords: | Animals Flowers/physiology Male *Orchidaceae/chemistry Pollination/physiology *Sex Attractants/chemistry/pharmacology Structure-Activity Relationship *Wasps/physiology Drakaea Drakolide Pollination chemistry Pyrazine Sexual deception beta-Ketolactone; |
| Notes: | "MedlineBohman, Bjorn Tan, Monica M Y Flematti, Gavin R Peakall, Rod eng LP130100162/australian research council/ DP150102762/australian research council/ DE160101313/australian research council/ 2022/02/01 J Chem Ecol. 2022 Mar; 48(3):323-336. doi: 10.1007/s10886-021-01324-4. Epub 2022 Jan 31" |
