The gene for pollinator preference

press release of March 28, 2007

Petunia belongs to those plants that count on insect pollinators to ensure their reproduction, which in this case are the diurnal bumblebees and nocturnal butterflies. Biologists at the National Centre of Competence in Research (NCCR) Plant Survival have found that modifying a single gene is sufficient to change the capacity to attract one pollinator over another. These results have recently been published in the journal The Plant Cell*.

Professor Cris Kuhlemeier's team at the University of Bern have been studying the genetics of petunia for long enough to make this member from the potato or tomato family a veritable model plant. Maria Elena Hoballah, an entomologist and ecologist, holds a postdoctoral position in this research group and has a passion for plant-insect relationships. With her colleague Thomas Gübitz, an evolutionary biologist and geneticist, she was able to demonstrate that a gene involved in determining petal colour (AN2) plays a major role in attracting pollinators.

"The AN2 gene expression is responsible for the production of anthocyanin pigmentation, explains the biologist. It is the anthocyanins that give the Petunia integrifolia flower its red-violet colour, to which the bumblebee Bombus terrestris is particularly attracted. On the other hand, when the AN2 is not expressed, the flower does not produce anthocyanins and remains white. It will then be visited by nocturnal butterflies such as the hawkmoth Manduca sexta."  Therefore, changing the expression of one single gene creates a major shift in the pollinator preference from one flower species to another.

To carry out this study, it was necessary to combine competences in molecular biology and field ecology. Such a mixture is rarely found within the same research group, but happens to be part of the distinctive features of the NCCR Plant Survival, a national network of researchers that is managed from the University of Neuchâtel.

Maria Elena Hoballah, Thomas Gübitz and colleagues first proceeded with laboratory experiments in order to produce petunia varieties in which the AN2 gene is expressed or not. They then carried out pollination tests in greenhouses and in Uruguay where two wild petunia species grow and have the same differences in colour: violet for Petunia integrifolia and white for Petunia axillaris.

However, pollinator attraction does not end with colour. The researchers are hoping to extend their genetic studies to include other attraction factors for petunia such as morphology, scent and the production of nectar, the substance that insects receive as a reward for their contribution towards the plant's reproduction.

*Original article: Single Gene-Mediated Shift in Pollinator Attraction in Petunia
Maria Elena Hoballah, Thomas Gübitz, Jeroen Stuurman, Larissa Broger, Mario Barone, Therese Mandel, Alexandre Dell'Olivo, Maeva Arnold, and Cris Kuhlemeier


Dr. Maria Elena Hoballah
Universität Bern
Tél. 031 631 37 77

Dr. Thomas Gübitz
Universität Bern
Tél. 031 631 37 66