Scientists from UK have unlocked a 51.7-million-year-old genetic secret related to a landmark theory proposed by English naturalist Charles Darwin more than 150 years ago.
Researchers have identified the cluster of genes responsible for reproductive traits in the Primula flower.
Darwin hypothesised that some plant species with twodistinct forms of flower, where male and female reproductive organs were of differing lengths, had evolved that way topromote out-crossing by insect pollinators.
His ground-breaking insight into the significance of the two forms of flower known as pins and thrums coined theterm heterostyly, and subsequent studies contributed to the foundation of modern genetic theory.
Now scientists at the University of East Anglia (UEA) in the UK have identified exactly which part of these speciesgenetic code made them that way, through an event that occurred more than 51 million years ago.
To identify the genes which control the biology noted by Darwin is an exciting moment. Many studies have been done overthe past decades to explore the genetic basis of this phenomenon but now we have pinpointed the supergene directly responsible, the S locus, said Professor Philip Gilmartinfrom UEAs School of Biological Sciences.
Supergenes are clusters of closely-associated genes which are always inherited together as a unit and allow complexbiology to be controlled.
Researchers worked with the Earlham Institute in the UK to map the plants genes and sequence the Primula genome tofind the specific gene cluster responsible for creating thediffering flower morphs.
Not only did we identify the supergene but we found itis specific to just one of the flower forms, the thrum. Thisinsight has profound implications for our understanding of akey evolutionary innovation of flowering plants, Gilmartinsaid.
Understanding of the genetics which underpin flowerdevelopment and reproduction of a species broadens ourknowledge about the entire system of pollination, which underpins biodiversity and food security, he said.
With challenges such as climate change and its effectson plants, crops and their insect pollinators, it is even more important to understand pollination mechanisms and how speciescan and will react, Gilmartin said.
In their hunt for the genes controlling heterostyly, researchers also managed to date the original mutation, to51.7 million years ago.
Having found the S locus, they realised the gene was a close relative to another, identified six years ago asresponsible for controlling the identity of petals on aPrimula flower.
At some point this gene duplicated, inserted itself in the S locus and mutated to control the position of the anther in the flower.
The study was published in the journal Nature Plants.