Prestigious scientific journal Nature releases a new paper “Phylogenomics and the rise of the angiosperms’ which forms part of Kew’s Tree of Life Initiative. The paper redefines our understanding of the evolutionary history of flowering plants and will allow us to answer key questions about plants in the future.
The paper results from a large-scale, international collaboration involving 279 scientists from 27 countries. CUBG’s Assistant Curator and palm specialist, Dr Ángela Cano, was a co-author on paper, and explains more about these findings:
“The study sampled over 8,000 plant genera, which combined, represent the broad diversity of flowering plants (angiosperms). The samples were gathered from a range of sources, including many from herbarium specimens – highlighting the importance of these invaluable collections. Some of these herbarium specimens were collected hundreds of years ago making this also a collaboration with collectors across time.”
DNA was extracted from these samples and sequenced using a novel technique, with the goal of building the tree of life of all flowering plants. The evolutionary tree of life underpins the biological sciences, providing a fundamental roadmap for exploring and predicting patterns of diversity. Mapping it is a huge and important undertaking, with various diagrams having been built over the centuries since Darwin first proposed the idea.
Ángela says: “Building the tree of life is a mission which has been attempted multiple times, each time implementing the latest scientific methods.
It was first done based on morphological traits – where related plants showed similar structures. This was followed by DNA analysis, comparing a handful of short DNA fractions either from the chloroplast or the nuclear genomes present in plant cells. More recently, the most ambitious push (2019) was sequencing and comparing the entire chloroplast genome of around 1,000 species.
However, this Plant and Fungal Trees of Life Project (PAFTOL) study pushes the boundaries even further. It involved sequencing 353 genes from the DNA of the nucleus, providing significantly more in-depth information. Also, it was applied to a 15-fold increase in plant species.
The results are significant for a number of reasons:
They confirm what was already known about the evolutionary relationships of most flowering plants.
They also clarify some relationships between plants which previously weren’t properly understood.
They also show important rearrangements in the classification of some major plant lineages. These are mainly within the Rosids, a large group of around 70,000 related plants which include more than a quarter of all flowering plants. Across all flowering plants, 12 orders (such as the Cucurbitales – where the cucumber is classified) and 10 families (including Asteraceae – the Daisy family) will require rearrangements according to the results of this study.
Finally, they also highlight some relationships that still need resolving, despite the huge technical improvements in analysis.”
“The paper demonstrates, yet again, the enduring power of botanical collections for scientific discovery.”
One of the highlights of this work for Ángela is the re-definition of the order where palms are classified.
“When it comes to the history of plant classification, palms were originally the only members of the order Arecales. On the basis of analyses of plastid genomes, this order was then redefined to include the family Dasypogonaceae (a small family endemic to Australia). However now, our most recent study based on nuclear DNA does not support this change. Therefore, palms are again exclusive members of Arecales. As a palm specialist, having collected many of the palm samples used in this study from remote localities in the Americas, I am delighted that these results confirm what I and other palm specialists have known for decades – the wonderful uniqueness of the palms!”
CUBG’s Curator, Professor Sam Brockington says: “I’d like to congratulate Angie and the other members of the PAFTOL collaboration for an extremely important paper that redefines our understanding of the relationships among the major plant lineages. The precise circumscription of the Arecales has long been a contentious issue, and it is fitting that the important samples that Angie has collected over a career dedicated to studying palms, are an essential contribution to this work. The paper demonstrates, yet again, the enduring power of botanical collections for scientific discovery.”
Read more about this story from Royal Botanic Gardens, Kew here.
