By tracing how a gene mutation over 100 million years ago led flowers to make male and female parts in different ways, research by University of Leeds plant scientists has uncovered a snapshot of evolution in progress.
In a number of plants, the gene involved in making male and female organs has duplicated to create two, very similar, copies.
In rockcress (Arabidopsis), one copy still makes male and female parts, but the other copy has taken on a completely new role: it makes seed pods shatter open.
In snapdragons (Antirrhinum), both genes are still linked to sex organs, but one copy makes mainly female parts, while still retaining a small role in male organs – but the other copy can only make male.
The findings published in the Proceedings of the National Academy of Sciences (PNAS) Online Early Edition provide a perfect example of how diversity stems from such genetic 'mistakes'.
The research also opens the door to further investigation into how plants make flowers.
“Snapdragons are on the cusp of splitting the job of making male and female organs between these two genes, a key moment in the evolutionary process,” says lead researcher Professor of Plant Development, Brendan Davies.
“More genes with different roles give an organism added complexity and open the door to diversification and the creation of new species.”
By tracing back through the evolutionary ‘tree' for flowering plants, the researchers calculate the gene duplication took place around 120 million years ago. But the mutation which separates how snapdragons and rock cress use this extra gene happened around 20 million years later.
The researchers have discovered that the different behaviour of the gene in each plant is linked to one amino acid.
Although the genes look very similar, the proteins they encode don't always have this amino acid. When it is present, the activity of the protein is limited to making only male parts.
When the amino acid is not there, the protein is capable of interacting with a range of other proteins involved in flower production, enabling it to make both male and female parts, according to a University of Leeds press release.