51 million year old genetic secret to Darwin's theory unlocked by scientists in UK

Scientists from UK have unlocked a 51.7-million-year-old genetic secret related to a landmark theoryproposed by English naturalist Charles Darwin more than 150years ago.

Researchers have identified the cluster of genesresponsible for reproductive traits in the Primula flower.

Darwin hypothesised that some plant species with twodistinct forms of flower, where male and female reproductiveorgans were of differing lengths, had evolved that way topromote out-crossing by insect pollinators.

His ground-breaking insight into the significance of thetwo forms of flower known as ‘pins’ and ‘thrums’ coined theterm ‘heterostyly’, and subsequent studies contributed to thefoundation of modern genetic theory.

Now scientists at the University of East Anglia (UEA) inthe UK have identified exactly which part of these species’ genetic code made them that way, through an event thatoccurred more than 51 million years ago.

“To identify the genes which control the biology noted byDarwin is an exciting moment. Many studies have been done overthe past decades to explore the genetic basis of thisphenomenon but now we have pinpointed the supergene directlyresponsible, the S locus,” said Professor Philip Gilmartinfrom UEA’s School of Biological Sciences.

Supergenes are clusters of closely-associated genes whichare always inherited together as a unit and allow complexbiology to be controlled.

Researchers worked with the Earlham Institute in the UKto map the plant’s 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, whichunderpins biodiversity and food security, he said.

“With challenges such as climate change and its effectson plants, crops and their insect pollinators, it is even moreimportant 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 aclose 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 inthe S locus and mutated to control the position of the antherin the flower.

The study was published in the journal Nature Plants.