School of Molecular Sciences, The University of Western Australia, Crawley, WA 6009, Australia; Research School of Biology, The Australian National University, Acton, ACT 2601, Australia.
Research School of Biology, The Australian National University, Acton, ACT 2601, Australia; Kings Park and Botanic Garden, The Botanic Gardens and Park Authority, West Perth, WA 6005, Australia; Department of Ecology, Environment & Evolution, La Trobe University, Victoria 3086, Australia.
Fitoterapia. 2018 Apr;126:78-82. doi: 10.1016/j.fitote.2017.09.022. Epub 2017 Sep 28.
Until recently, (methylthio)phenols as natural products had only been reported from bacteria. Now, four representatives of this class of sulfurous aromatic compounds have been discovered as semiochemicals in the orchid Caladenia crebra, which secures pollination by sexual deception. In this case, field bioassays confirmed that a 10:1 blend of 2-(methylthio)benzene-1,4-diol (1) and 4-hydroxy-3-(methylthio)benzaldehyde (2) sexually attracts the male thynnine wasp Campylothynnus flavopictus (Tiphiidae:Thynnineae), the exclusive pollinator of C. crebra. Here we show with field bioassays that another undescribed species of Campylothynnus (sp. A) is strongly sexually attracted to a 1:1 blend of compounds 1 and 2, which elicits very high attempted copulation rates (88%). We also confirm that this Campylothynnus species is a pollinator of Caladenia attingens subsp. attingens. Chemical analysis of the flowers of this orchid revealed two (methylthio)phenols, compound 2 and 2-(methylthio)phenol (3), as candidate semiochemicals involved in pollinator attraction. Thus, (methylthio)phenols are likely to be more widely used than presently known. The confirmation of this Campylothynnus as a pollinator of C. attingens subsp. attingens at our study sites was unexpected, since elsewhere this orchid is pollinated by a different thynnine wasp (Thynnoides sp). In general, sexually deceptive Caladenia only use a single species of pollinator, and as such, this unusual case may offer a tractable study system for understanding the chemical basis of pollinator switching in sexually deceptive orchids.
直到最近，（甲基硫代）酚类物质作为天然产物仅在细菌中被报道。现在，作为兰花 Caladenia crebra 半化学物质的此类含硫芳香化合物的四个代表已经被发现，该兰花通过性欺骗来确保授粉。在这种情况下，野外生物测定证实，2-（甲基硫代）苯-1,4-二醇（1）和 4-羟基-3-（甲基硫代）苯甲醛（2）的 10:1 混合物以性方式吸引雄性 Thynnine wasp Campylothynnus flavopictus（Tiphiidae：Thynnineae），这是 C. crebra 的唯一传粉者。在这里，我们通过野外生物测定表明，另一种未描述的 Campylothynnus 物种（sp. A）强烈地被 1:1 的化合物 1 和 2 的混合物吸引，这会引起非常高的交配尝试率（88％）。我们还证实，这种 Campylothynnus 物种是 Caladenia attingens subsp. attingens 的传粉者。对这种兰花花朵的化学分析揭示了两种（甲基硫代）酚，化合物 2 和 2-（甲基硫代）苯酚（3），作为参与传粉者吸引的候选半化学物质。因此，（甲基硫代）酚类物质可能比目前已知的更为广泛地使用。在我们的研究地点，确认这种 Campylothynnus 是 C. attingens subsp. attingens 的传粉者是出乎意料的，因为在其他地方，这种兰花是由不同的 Thynnoides wasp（Thynnoides sp）授粉的。一般来说，性欺骗性的 Caladenia 只使用一种传粉者物种，因此，这种不寻常的情况可能为理解性欺骗性兰花传粉者转换的化学基础提供了一个可行的研究系统。
