Unlocking the Evolutionary History of Flowering Plants Through DNA Mapping

2024-04-30 23:15:19

Groundbreaking research maps the genetic relationships of over 9,500 species of flowering plants, creating an advanced tree of life that improves our understanding of their evolutionary history and their potential uses in various scientific fields. Credit: twoday.co.il.com

The largest tree of life ever for flowering plants was built by the succession of

DNA

DNA, or deoxyribonucleic acid, is a molecule composed of two long strands of nucleotides that coil around each other to form a double helix. It is the hereditary material in humans and almost all other organisms that carries genetic instructions for development, functioning, growth, and reproduction. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).

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species

A species is a group of living organisms that share a set of common characteristics and are able to breed and produce fertile offspring. The concept of a species is important in biology as it is used to classify and organize the diversity of life. There are different ways to define a species, but the most widely accepted one is the biological species concept, which defines a species as a group of organisms that can interbreed and produce viable offspring in nature. This definition is widely used in evolutionary biology and ecology to identify and classify living organisms.

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A study recently published in the journal Nature, written by an international team of 279 researchers, including three scientists from the New York Botanical Garden (NYBG), offers the latest insights into the evolutionary and genetic relationships among flowering plants. These plants make up about 90 percent of all known plant species.

Using 1.8 billion letters of genetic code from more than 9,500 species covering nearly 8,000 genera of plants (groups of closely related species), the research team was able to create the most detailed tree of life – a graphic depiction of sexual relationships similar to a genealogical family tree. – to date for this group of plants, shedding new light on the evolutionary history of flowering plants and their rise to ecological dominance on Earth. The authors of the study believe that the data will help in future attempts to identify new species, refine the classification of plants, reveal new medicinal compounds and preserve plants in the face of double biodiversity and climate crises.

Contributing to this major landmark in plant science are Fabian Michelangelo, Ph.D., Absess Curator of Tropical Botany and Director of NYBG’s Institute of Systematic Botany; Gregory M. Plunkett, Ph.D., Director and Curator of NYBG’s Coleman Program for Molecular Systematics; and John D. Mitchell, NYBG Affiliate Scientist.

An international team of researchers, including three New York Botanical Garden (NYBG) scientists, used the genetic code of more than 9,500 flowering plant species to create the most detailed evolutionary tree of life for this plant group to date. Credit: RBG Kew

“While the main goals of this large-scale project were to understand the relationships of all types of flowering plants, it also sheds light on the timing of key events in the evolution of complex flower forms and life histories,” said Dr. Michelangelo. Large ones like this can provide context for conservation strategies, sustainable agriculture, and many other applications that need basic knowledge of biodiversity. Understanding how organisms are related is the building block of all biodiversity science and applications.”

The research team – led by the Royal Botanic Gardens, Kew, and involving 138 international organizations – used 15 times more data than any parallel study on the flowering plant tree of life. Among the species included in the study, the DNA of more than 800 had never been recorded before. The vast amount of data unlocked by this research, which would take a single computer 18 years to process, is a huge step toward building a tree of life for all 330,000 known species of flowering plants.

ran over Michelangelo and Plunkett and Mr. Mitchell provided expertise on the plant families they study as well as expertly identified specimens for a variety of plant groups, with a large proportion coming from the tropical plant family Melastomataceae, which is Dr. Michelangelo’s specialty, and the Apiaceae (parsley or carrot) families. and Araliaceae (ginseng), which Dr. Plunkett studies.

Opening historical herbal samples for innovative research

The flowering plant tree of life, much like a family tree, allows scientists to understand how different species are related to each other. The tree of life is revealed by comparing DNA sequences between different species to identify changes (mutations) that accumulate over time like a molecular fossil record. Science’s understanding of the tree of life is rapidly improving along with advances in DNA sequencing technology. For this research, new genomic techniques were developed for the magnetic capture of hundreds of genes and hundreds of thousands of letters of genetic code from each sample, orders of magnitude greater than previous methods.

A major advantage of the team’s approach is that it allows sequencing a wide variety of plant material, old and new, even when the DNA is severely damaged. It is now possible to genetically explore the vast treasure troves of dried and preserved plants in the world’s herbarium collections, which include nearly 400 million specimens. Using such samples, the team successfully recorded a sequence of sand (Arnaria globiflora) was collected almost 200 years ago in Nepal and despite the poor quality of his DNA, they managed to place him on the tree of life. The team even analyzed extinct plants, such as the Guadalupe Island olive (Hesperelaea palmeri), which has not been seen alive since 1875. In fact, 511 of the listed species are already endangered, according to the Red List, the authoritative collection of the world’s threatened plant, fungal and animal species maintained by the International Union for Conservation of Nature.

Of all 9,506 species sequenced, over 3,400 came from material derived from 163 grasses in 48 countries. Additional material from plant collections around the world such as DNA banks, seeds and living collections have been essential to fill key knowledge gaps to shed new light on the evolutionary history of the flowering plant. The team also benefits from publicly available data for over 1,900 species, highlighting the value of the open science approach to future genomic research.

Illuminating Darwin’s “Abominable Mystery”.

Flowering plants make up about 90% of all known plant life on land and are found almost everywhere on Earth – from the steamiest tropical regions to the rocky outcrops of the Antarctic Peninsula. Still, our understanding of how these plants came to dominate the scene shortly after their discovery has puzzled scientists for generations, including Charles Darwin. Flowering plants originated more than 140 million years ago, after which they quickly overtook other vascular plants, including their closest living relatives – the gymnosperms, non-flowering plants that have naked seeds such as cycads, conifers and ginkgos.

Darwin was stunned by the seemingly sudden appearance of such diversity in the fossil record. In an 1879 letter to Joseph Dalton Hooker, his close confidant and director of the Royal Botanic Gardens, Kew, he wrote, “The rapid development so far as we can judge of all higher plants in recent geological time is a hideous mystery.”

Using 200 fossils, the researchers grew their tree of life into time, revealing how flowering plants evolved over geologic time. They found that early flowering plants exploded in diversity, giving rise to over 80 percent of the major lineages that exist today shortly after their origin. However, this trend then declined to a more stable rate over the next 100 million years until another spike in diversity about 40 million years ago, coinciding with a global decrease in temperatures. These new insights would have fascinated Darwin and will surely help today’s scientists face the challenges of understanding how and why species diverge.

Assembling such an extensive tree of life would have been impossible without the cooperation of scientists from all over the world. In total, 279 authors were involved in the study, representing many different nationalities from 138 organizations in 27 countries. International collaborators shared their unique botanical expertise, as well as valuable plant specimens from around the world that could not have been obtained without their help. The comprehensive nature of the tree is in no small part a result of this broad partnership.

“Efforts like this show how the international scientific community can come together to collaborate and produce something that no single research group or institution can do alone,” said Dr. Michelangelo.

Good use of the flowering plant tree

The flowering plant tree of life has enormous potential in the study of biodiversity. This is because, just as the properties of an element can be predicted based on its position on the periodic table, the position of a species on the tree of life allows scientists to predict its properties. The new data will therefore be valuable for improving many areas of science and beyond.

To enable this, the tree and all the data underlying it became openly and freely accessible to both the public and the scientific community, including through the Kew Tree of Life Explorer. The authors of the study believe that such open access is the key to democratizing access to scientific data worldwide.

Open access will also help scientists make the best use of data, such as combining it with artificial intelligence to predict which plant species might contain molecules with medicinal potential. Similarly, the Tree of Life can be used to better understand and predict how pests and diseases may affect the world’s plants in the future. Ultimately, the authors note, data applications will be driven by the ingenuity of scientists.