Facilitated by the SciLifeLab National Bioinformatics Infrastructure (NBIS) and the National Genomics Infrastructure (NGI), researchers from Stockholm University, Uppsala University, Durham University (United Kingdom), University of Granada (Spain), and the University of Seville (Spain), have revealed the architecture and evolution of a supergene behind efficient cross-pollination, and thus, solved a more than century old mystery.
Ever since the 16th century, scientists have known that some plant species are distylous, meaning that they have two types of flowers that differ reciprocally in the length of their male and female sexual organs. Darwin was the first person to suggest that this kind of architecture could facilitate efficient cross-pollination by insects. Geneticists could show that the two types of flowers were controlled by a supergene – a single chromosomal region containing a large cluster of genes – but for more than a century, the architecture of this supergene had been veiled in mystery.
Now, in a recent study led by SciLifeLab Fellow alumna Tanja Slotte (Professor at Stockholm University), an international team of researchers has sequenced this supergene in the wild flaxseed species Linum tenue, by using modern DNA sequencing methods. Surprisingly, the supergene varied in length, with the dominant form containing around 260,000 more base pairs than the recessive form. These 260,000 base pairs contains several genes likely to cause the length variation in sexual organs.
”These results were really surprising to us, because a similar genetic makeup of the supergene that governs distyly has previously been identified in another system, primroses, where it evolved completely independently,” said Tanja Slotte, in a press release from Stockholm University.
”Not only has evolution repeatedly led to similar variation in the flowers of primroses and flaxseed species, it has also relied on a similar genetic solution to achieve this feat,” said Juanita Gutiérrez-Valencia, PhD student at Stockholm University and first author of the study.
The study, published in Current Biology, demonstrate the exceptional power of evolution and its ability to find convergent solutions, such as highly efficient cross-pollinating mechanisms.
”Distyly is ultimately a mechanism for efficient cross-pollination. Understanding pollination mechanisms is particularly important today given climate change and challenges faced by both plant and insect pollinator populations,” says Tanja Slotte.
The project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 757451).