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The left‑right asymmetry of South African butterfly lilies (genus Wachendorfia) has been regarded as a classic evolutionary puzzle for more than a century. Due to the mirror-image arrangement of the floral parts, the plants achieve efficient cross pollination. The molecular basis of this arrangement has now been uncovered by an international team led by the University of Potsdam. Their study in collaboration with the University of Cape Town and Wageningen University has been published in “Science”.
The researchers show that in Wachendorfia species a “supergene” determines whether plants consistently develop styles and stamens that are bent to the left or to the right. This supergene contains two key factors, which independently control the orientation of stamens and styles and thus enable the precise, mirror image positioning of the reproductive organs.
“Our results show that two tightly linked genes act together to ensure that pollen is deposited at exactly those positions on the bodies of pollinators from which it can be picked up again by the respective mirror image floral form,” explains first author Dr Haoran Xue, bioinformatician at the Institute of Biochemistry and Biology at the University of Potsdam. “This supergene couples the orientation of style and stamen so tightly that the plants remain reliably dependent on cross pollination – an elegant mechanism to promote genetic diversity.”
