When an asteroid struck Earth 66 million years ago, it eliminated all non-avian dinosaurs and roughly one-third of life on the planet. Many flowering plants, however, survived. A new study published in Cell suggests that accidental duplications of entire genomes may help explain how—and raises questions about whether the same mechanism could help plants cope with climate change today.
Most organisms carry two sets of chromosomes, one from each parent. In flowering plants, however, many species carry additional sets as a result of random whole-genome duplication, a condition known as polyploidy. Cultivated bananas, for example, have three sets of chromosomes, while wheat can have as many as six.
Whole-genome duplication occurs relatively frequently in plants and comes with real costs. Larger genomes require more nutrients to maintain, increase the risk of harmful mutations, and can affect fertility. For these reasons, only a small fraction of duplicated genomes are retained and passed down through generations in the wild. On the other hand, genome duplications can increase genetic variation and allow genes to evolve new functions—changes that may help plants better tolerate stress such as heat or drought.
To understand why some duplicated genomes persist while most do not, Yves Van de Peer of Ghent University and his team analyzed the genomes of 470 flowering plant species, constructing one of the largest datasets of its kind. They identified blocks of genes appearing in nearly identical pairs—a marker of past whole-genome duplication events—and compared that data with information from 44 plant fossils to estimate when those duplications occurred.
The analysis revealed a clear pattern. Duplicated genes that persisted over time tended to originate during major periods of environmental upheaval, including the asteroid-triggered mass extinction 66 million years ago, several periods of global cooling when ecosystems collapsed, and the Paleocene-Eocene Thermal Maximum (PETM) approximately 56 million years ago—a period of rapid global warming.
"Whole-genome duplication is often seen as an evolutionary dead end in stable environments," said Van de Peer. "But in harsh situations, it can provide unexpected advantages."
The findings help explain a long-standing puzzle of why polyploidy is common in flowering plants yet only a small number of duplicated genomes survive over millions of years. Under extreme conditions, traits that are normally disadvantageous—such as maintaining a larger, more complex genome—may become beneficial.
The PETM is of particular interest given current conditions. During that period, global temperatures rose by approximately 5 to 9°C over roughly 100,000 years, a scale of warming comparable to projections for today. "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 added.
Most organisms carry two sets of chromosomes, one from each parent. In flowering plants, however, many species carry additional sets as a result of random whole-genome duplication, a condition known as polyploidy. Cultivated bananas, for example, have three sets of chromosomes, while wheat can have as many as six.
Whole-genome duplication occurs relatively frequently in plants and comes with real costs. Larger genomes require more nutrients to maintain, increase the risk of harmful mutations, and can affect fertility. For these reasons, only a small fraction of duplicated genomes are retained and passed down through generations in the wild. On the other hand, genome duplications can increase genetic variation and allow genes to evolve new functions—changes that may help plants better tolerate stress such as heat or drought.
To understand why some duplicated genomes persist while most do not, Yves Van de Peer of Ghent University and his team analyzed the genomes of 470 flowering plant species, constructing one of the largest datasets of its kind. They identified blocks of genes appearing in nearly identical pairs—a marker of past whole-genome duplication events—and compared that data with information from 44 plant fossils to estimate when those duplications occurred.
The analysis revealed a clear pattern. Duplicated genes that persisted over time tended to originate during major periods of environmental upheaval, including the asteroid-triggered mass extinction 66 million years ago, several periods of global cooling when ecosystems collapsed, and the Paleocene-Eocene Thermal Maximum (PETM) approximately 56 million years ago—a period of rapid global warming.
"Whole-genome duplication is often seen as an evolutionary dead end in stable environments," said Van de Peer. "But in harsh situations, it can provide unexpected advantages."
The findings help explain a long-standing puzzle of why polyploidy is common in flowering plants yet only a small number of duplicated genomes survive over millions of years. Under extreme conditions, traits that are normally disadvantageous—such as maintaining a larger, more complex genome—may become beneficial.
The PETM is of particular interest given current conditions. During that period, global temperatures rose by approximately 5 to 9°C over roughly 100,000 years, a scale of warming comparable to projections for today. "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 added.