Plants may have weathered dinosaur extinction by doubling their DNA

Thanks to a genetic quirk, many flowering plants survived the asteroid impact that wiped out the dinosaurs and many other species, scientists say in a new study.

Published Friday in the journal Cell, researchers from Ghent University and the Belgium biotechnology research institute VIB detail their intensive analysis of hundreds of plant genomes. A striking pattern stands out within the data: Major waves of genome duplication often coincided with some of the most turbulent periods in Earth's history, including the mass extinction event triggered by the asteroid strike 66 million years ago.

That's because plants carrying extra copies of their genetic material may have been better equipped to endure dramatic temperature swings and even sudden environmental collapses.

Most living organisms inherit two sets of chromosomes, one from each parent, but plants frequently undergo whole-genome duplication, in which their entire genetic code is copied. The process can produce plants with multiple chromosome sets, known as polyploidy.

While common in crops like bananas and wheat, polyploidy can have drawbacks in the wild. Larger genomes demand more resources and can increase the risk of genetic problems. Many duplicated genomes disappear over evolutionary time because of these costs.

But in ancient flowering plants, researchers found the duplicated genes that did persist were often linked to severe ecological stress. The genomes of 470 flowering plant species were compared with fossil evidence from 44 ancient plants to estimate during which precise periods these duplication events may have occurred.

Those periods included the asteroid impact that eliminated non-avian dinosaurs, intervals of global cooling that disrupted ecosystems and the Paleocene-Eocene Thermal Maximum, a rapid warming episode that scientists often study as a possible parallel for modern climate change.

"Whole-genome duplication is often seen as an evolutionary dead end in stable environments," says author Yves Van de Peer, a bioinformatics and genome biology professor at Ghent University. "But in harsh situations, it can provide unexpected advantages."

Duplicated genomes may have given plants greater flexibility to adapt because extra gene copies can evolve new functions or help organisms tolerate environmental stressors such as heat and drought.

The findings may also carry implications for the present day as global temperatures continue to rise.

"While the current climate is warming at a much faster rate, what we see from the past suggests that polyploidy may help plants cope with these stressful conditions," Van de Peer said in a press release.