SACHA PFEIFFER, HOST:
When Earth faces its next cataclysm, some plants appear to have a time-tested strategy to survive. Science reporter Ari Daniel has our story.
ARI DANIEL, BYLINE: Most people have two sets of chromosomes, one set from each parent, whereas...
YVES VAN DE PEER: Strawberries, for example, they have eight sets of chromosomes.
DANIEL: Yves Van de Peer is a plant biologist at Ghent University in Belgium. This phenomenon is called polyploidy, where an organism has more than two sets of chromosomes stuffed into every cell - in other words, a whole genome duplication. And it's pretty common actually, especially in plants.
VAN DE PEER: It's a mutational event. You end up basically with a new cell with twice the amount of DNA than the normal plant cell (ph).
DANIEL: The plant species may do OK for a while, but this wholesale duplication of the genome is error prone.
VAN DE PEER: Usually, there is reduced fertility because you have more chromosomes to deal with, which then is problem for cell division.
DANIEL: And that tends to be a problem for survival, leading often ultimately to extinction. And yet, polyploidy is everywhere we look today. What's the deal?
VAN DE PEER: The polyploid paradox has kept me puzzling for a long time.
DANIEL: Van de Peer and his colleagues decided to try to unravel the riddle. Their first step involved gathering all 470 flowering plant genomes that have been sequenced, a mix of wild species and agricultural crops from all over the world. The research team scoured the DNA of those plants for evidence of genome duplication events that occurred long ago.
VAN DE PEER: Not all the plants showed it.
DANIEL: But some did, and the researchers used the fossil record to help determine when each duplication event happened. And here's what they found.
VAN DE PEER: These whole genome duplications, they do not occur randomly. They are clustered in time.
DANIEL: In particular, they cluster during periods characterized by environmental upheaval over the last 150 million years.
VAN DE PEER: For example, important cooling periods on our planet or global warming on our planet.
DANIEL: Or perhaps most dramatically, some 66 million years ago when an asteroid collided with Earth, darkening the skies which likely wiped out the dinosaurs and over half of all plant species.
VAN DE PEER: Plants were suddenly no longer adapted.
DANIEL: Most plants, that is because it turns out for all their baggage, polyploid plants excel at surviving environmental stress, like prolonged changes in temperature or light level.
VAN DE PEER: They might be better in doing photosynthesis, for example, because they have more genes to capture the little light that is still there. And so they have an advantage over a lot of other plant lineages.
DANIEL: Polyploid plants are like an insurance policy. Most of the time, they fade away, but during extreme turmoil, they win out. The research is published in the journal Cell. Sandra Pitta is a plant biotechnologist at the University of Buenos Aires who wasn't involved in this study.
SANDRA PITTA: Well, the paper really is very rigorous, and it gives us a lot of hope in a way.
DANIEL: Hope because our planet is again facing a changing climate, one that polyploid plants may well endure. These findings will also help plant breeders like Pitta.
PITTA: If polyploidism (ph) help them resist more different types of stresses, well, that is really useful to me.
DANIEL: As for Yves Van de Peer, he thinks he may have finally solved that pesky paradox.
VAN DE PEER: I feel like I can retire now because this is sort of the culmination of - yeah, of 25 years of work.
DANIEL: Sometimes a seeming dead end can actually pay off in the future. For NPR News, I'm Ari Daniel.
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