Science and Technology Daily reporter Zhang Mengran
Why is a study of flowers and plants rated as an "incredible achievement"?
An international team of 279 scientists, led by Kew Gardens, published a new paper in the journal Nature on April 24, revealing the latest scientific understanding of the phylogenetic tree of flowering plant germlines.
The study drew on 1.8 billion genetic codes from more than 9,500 species and covered nearly 8,000 known genera of flowering plants (about 60%), unfolding a history of plant evolution for humanity and showing how these plants rose to dominate the planet's ecology.
There is 15 times more data to construct the angiosperm phylogenetic tree than comparable studies, involving the sequencing of more than 9,500 different flowering plants.
Image credit: Kew Gardens
The researchers believe that this valuable data could help identify new species, refine plant taxonomy, discover new medicinal compounds, and protect plants in the face of climate change and biodiversity loss.
"Unlock" historical plant specimens
The phylogenetic tree of flowering plants, like the human family tree, allows for an understanding of the relationships between different species. Phylogenetic trees are discovered by comparing DNA sequences between different species to identify changes (mutations) that accumulate over time, much like examining a "molecular fossil" record.
As DNA sequencing technology advances, so does the understanding of evolutionary trees. In this study, the team developed new genomic technologies that can obtain hundreds of genes and hundreds of thousands of genetic code letters from each sample, orders of magnitude more than earlier methods.
The oldest plant sequenced in the study was a dried plant specimen collected in 1829.
Image credit: Kew Gardens
A key advantage of the new method is the ability to sequence a wide range of old and new plant material, even if the DNA is severely damaged. Herbariums around the world are huge treasures of dried plant material, including nearly 400 million specimens of plant science, containing a wealth of evolutionary information.
The first specimen of Alstonia spectabilis to be sequenced in the study, a species of important medicinal value to the indigenous Tetun people.
Image Credit: Kew Gardens
For example, the team was able to sequence a sample of Sand grass collected in Nepal nearly 200 years ago and place it in a phylogenetic tree despite its poor DNA quality.
For example, they also analysed extinct plants, such as Guadalupe olives. In fact, according to the IUCN Red List of Threatened Species (IUCN), 511 of the sequenced species are at risk of extinction.
Of the 9,506 species that have been sequenced, more than 3,400 species are from 163 herbariums in 48 countries, and others come from plant collections around the world, such as DNA banks, seeds, living collections, and other materials. These are essential to fill key knowledge gaps and understand the evolutionary history of flowering plants.
Solve the mystery that puzzled Darwin
Flowering plants originated more than 140 million years ago, and since then they have rapidly replaced other vascular plants, accounting for about 90% of all known plants on land.
However, generations of scientists, including Charles Darwin, have wondered the situation: why did these plants become dominant so soon after their origins?
Scientists have sequenced the parasitic plant Pilostyles aethiopica, which lives in other plants and is only visible when it blooms. DNA sequencing has reclassified the taxa to which this plant belongs.
Photo credit: Sidonie Bellot/Kew Gardens
In response to the seemingly sudden emergence of diversity in the fossil record, Darwin wrote in 1879 to his close friend Joseph Hooke, director of the Royal Botanic Gardens: "It is a nasty mystery to us that the rapid development of all higher plants in the modern geological period is in our judgment. ”
Now, using 200 fossils, the team has scaled their evolutionary tree over time, revealing how flowering plants evolved over different geological periods. They found that the diversity of early flowering plants did explode, producing more than 80% of the major lineages that exist today shortly after their origins.
The new evolutionary tree reclassifies the family and genus of Pineflower Snakefish, a small tropical tree with exotic fruits.
Image credit: Danilo Tandang
However, this trend declined at a steady rate over the next 100 million years, until about 40 million years ago, when biodiversity surged again and global temperatures fell. These new insights help today's scientists understand how species respond to the challenges of diversity.
Open and shared evolutionary tree "fruits"
The construction of the evolutionary tree of flowering plants is of great significance for the study of biodiversity. Just as one can predict the properties of an element based on its position in the periodic table, the position of a species in the evolutionary tree allows one to predict its properties. As a result, the evolutionary tree contains new data that can help advance many areas of science.
More than 1,900 species of the data used in this study were previously publicly available, which is the value of the open science approach to genomic research.
Further openness to data will also help scientists make the most of these findings in the future, for example by combining them with artificial intelligence (AI) to predict which plant species may contain medicinal molecules. It can also help scientists better understand pests and diseases and predict how they will affect plants in the future.
Researchers say AI has been used to predict which plants contain chemicals that have the potential to treat malaria. The newly constructed evolutionary tree of flowering plants contains a huge data set, providing an opportunity to make more and more accurate predictions to accelerate the discovery of drugs from plants to cure intractable diseases.