Vast DNA Tree of Life For Plants Revealed By Global Science Team

An international team of scientists used 1.8 billion letters of genetic code from more than 9,500 species covering almost 8,000 known flowering plant genera to create the most up-to-date understanding of the flowering plant tree of life. The research has been published in the journal Nature. Phys.Org reports: The major milestone for plant science, led by [Royal Botanic Gardens, Kew] and involving 138 organizations internationally, was built on 15 times more data than any comparable studies of the flowering plant tree of life. Among the species sequenced for this study, more than 800 have never had their DNA sequenced before. 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 by Kew's Tree of Life Initiative.

The flowering plant tree of life, much like our own family tree, enables us to understand how different species are related to each other. The tree of life is uncovered by comparing DNA sequences between different species to identify changes (mutations) that accumulate over time like a molecular fossil record. Our understanding of the tree of life is improving rapidly in tandem with advances in DNA sequencing technology. 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, orders of magnitude more than earlier methods. A key advantage of the team's approach is that it enables a wide diversity of plant material, old and new, to be sequenced, even when the DNA is badly damaged. The vast treasure troves of dried plant material in the world's herbarium collections, which comprise nearly 400 million scientific specimens of plants, can now be studied genetically.

Across all 9,506 species sequenced, more than 3,400 came from material sourced from 163 herbaria in 48 countries. Additional material from plant collections around the world (e.g., DNA banks, seeds, living collections) have been vital for filling key knowledge gaps to shed new light on the history of flowering plant evolution. The team also benefited from publicly available data for more than 1,900 species, highlighting value of the open science approach to future genomic research. Flowering plants alone account for about 90% of all known plant life on land and are found virtually everywhere on the planet -- from the steamiest tropics to the rocky outcrops of the Antarctic Peninsula. Utilizing 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 that exist 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 would have fascinated Darwin and will surely help today's scientists grappling with the challenges of understanding how and why species diversify. A list of 'remarkable species' included in the flowering plant tree of life is embedded below the article.

Looking ahead, the study's authors believe this 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.

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