An international team of 279 scientists from institutions worldwide has produced a ‘tree of life’ for flowering plants, which accounts for around 90% of all known plant life on land.
The genomic tree, according to the Natural History Museum in London, is the most comprehensive of its kind ever made.
Using 1.8 billion letters of genetic code from more than 9500 species covering almost 8000 known flowering plant genera, this incredible achievement sheds new light on the evolutionary history of flowering plants and their rise to ecological dominance on Earth.
“What’s really cool is that the DNA doesn’t have to be super high quality,” says Norm Wickett, a professor of biological sciences at Clemson University in South Carolina.
“That means we can go back to plant collections made 100 years ago or 200 years ago and take what DNA is left and match it to our probes and to get these sequences out of these plants.”
The study’s authors believe the data will aid future attempts to identify new species, refine plant classification, uncover new medicinal compounds, and conserve plants in the face of climate change and biodiversity loss.
This major milestone for plant science, which involved 138 organisations internationally, was built on 15 times more data than any comparable studies of the flowering plant.
The sheer amount of data unlocked by this research, which would take a single computer 18 years to process, is a huge stride towards building a ‘tree of life’ for all 330,000 known species of flowering plants – a massive undertaking.
Dr Sandra Knapp, research botanist at the Natural History Museum, said understanding how flowering plants dominated soon after their origin 140 million years ago has baffled scientists, including Charles Darwin, for generations. Darwin was mystified by the sudden appearance of such diversity in the fossil record, calling it an “abominable mystery”.
Utilising 200 fossils, the authors scaled their tree of life to time, revealing how flowering plants evolved across geological time. They found that early flowering plants did indeed explode in diversity, giving rise to more than 80% of the major lineages today shortly after their origin.
However, this trend then declined to a steadier rate for the next 100 million years until another surge in diversification about 40 million years ago, coinciding with a global decline in temperatures. These new insights can help today’s scientists understand how and why species diversify.
For this study, new genomic techniques were developed to magnetically capture hundreds of genes and hundreds of thousands of letters of genetic code from every sample. This enabled the sequencing of a wide diversity of plant material, old and new, even when the DNA was badly damaged.
The team even analysed extinct plants, such as the Guadalupe Island olive tree (Hesperelaea palmeri), which has not been seen alive since 1875 but was sequenced from dried plant material preserved in the herbarium. In fact, 511 of the species sequenced are already at risk of extinction.
The vast treasure troves of dried plant material in the world’s herbarium collections, which comprise nearly 400 million scientific specimens of plants, some obtained as far back as the 19th century, can now be studied genetically using these techniques.
In addition to material sourced from herbaria across 48 countries, the team also benefited from publicly available data for more than 1 species, highlighting the value of open science to future genomic research.
Open access to this new tree and the data that underpins it could have enormous potential in future biodiversity research. Scientists can use the tree to understand and predict how pests and diseases will affect UK plants in the future, for example, or assess which plant species may include molecules with medicinal potential.
