20 years of DNA Research Celebrated at Royal Botanic Gardens, Kew
Embargoed 00.01 BST Saturday 27 April 2013
Thanks to pioneering work led by Kew scientists, plants were the first major group of organisms to be re-classified based on genetic studies; all organisms have now been re-classified based on such evidence, following the lead work on plants
In 2013 the DNA Bank at the Royal Botanic Gardens, Kew is celebrating its 20th anniversary. This whirring freezer in the Jodrell Laboratory is home to a large set of samples, but there are an original set of about 200 DNA samples that 20 years ago helped to revolutionise botany – changing scientists’ understanding of how the world’s flowering plants (angiosperms) were related and resulting in a major reclassification important for unlocking the potential in plants for human use. Today, Kew’s DNA Bank is the oldest and largest of its kind in the world, with more than 42,000 samples of wild plant DNA, representing some 34,000 plant species.
This effort to unravel relationships between all flowering plants based on genetic data was carried out by a global consortium of scientists, the Angiosperm Phylogeny Group, which was led by Kew’s Professor Mark Chase.
Traditionally, plant taxonomy was based on morphology, the physical appearance of plants. Plants were classified according to their overall similarity: those that closely resembled one another were grouped together.
In the early 1990s, DNA sequencing, which was then cutting-edge technology, made it possible for scientists at Kew to start comparing plant species according to their DNA and assessing them for genetic similarities. The results were truly surprising, revealing relationships between the most unlikely sets of species.
Plane trees, common on our city streets, turned out to be related to the iconic national flower of South Africa, the protea; another surprising relative of the plane tree was the sacred lotus plant; and what’s more the lotus was not related to the waterlily, which it so closely resembled. Straggly hedgerow weed, the nettle, was close kin to the regal rose, and the exotic, much-loved flowers of orchids were related to the vegetables asparagus and onion.
Professor Mark Chase, Keeper of the Jodrell, who pioneered DNA research at Kew, says, “Previously, researchers had managed to sort out some of the puzzles created by evolution, such as the fact that cacti and spurges were, in spite of their similar appearance, distantly related, but they missed a large number of fairly important relationships, such as those mentioned above. Not everything changed, but those things that did change were quite unexpected and have had significant implications.”
For the first time, botanists were able to begin building an accurate evolutionary ‘tree of life’. They were able to deduce the order in which groups of plants diverged from each other as they evolved. In addition, by using fossils to date certain events (like palm fossils from 92 million years ago to establish a minimum age for the palm family), then it became possible to date the origins of groups for which there are no relevant fossils, and this use of a “molecular clock” has revolutionised concepts of how extant diversity has evolved and when.
Our survival on the planet has depended to a large extent on the benefits we reap from plants – medicinal, food, fuel, clothing and shelter. Knowing the pattern of plants’ evolution is a great advantage because it allows scientists to tap into the predictive power of genetics to more easily distinguish plants most likely to be beneficial to people in the future. It can also help inform conservation programmes. The loss of a species without close relatives results in a greater loss of genetic information than the extinction of a species with many related species.
Professor Mark Chase says, “When we started out, the work was painstaking as the technology was so primitive. It took a whole year to sequence just one gene. Today we can do the same work in a few hours. This ability to deal with huge amounts of data has been key to ramping up the speed and scale of our efforts to increase our understanding of the world’s plants. This speed is vital when we are losing so many plant species, around one fifth over the next century, before we have even had an opportunity to study them for their potential uses and benefits.”
As for the future of DNA research at Kew, Kew is involved in the Consortium for the Barcode of Life, that aims to one day enable scientists to identify any plant by means of a ‘DNA barcode’ (a small section of DNA). Scientists have found that the sequences of one or two particular DNA regions are effective for identifying animal, plant and fungal species.
Adds Professor Mark Chase, “Although it sounds far fetched, the hope is that one day it might be possible to create a hand-held device, like a mobile phone, that everyone could use to quickly identify plants while working in the field or hiking in the countryside. This would certainly accelerate our exploration of the plant world.”
Researchers at Kew are also delving into the DNA of fungi to create the first genetic library of UK fungi. Fungi are one of the most diverse and least understood groups of organisms, but they are absolutely fundamental to ecosystems: they recycle waste and dead matter, are responsible for fermentation (e.g. beer, bread, cheese) and provide plants with nutrients. These DNA samples will be integrated into Kew’s DNA Bank in the near future.
Recent advances in DNA sequencing (the so-called “next generation sequencing” or NGS) are again completely revolutionising the amount of DNA data available. At first, NGS was too expensive to be applied broadly, but now it has become much cheaper and the computing techniques needed to collect and analyse such huge amounts of data have become available. Whereas previously a large data set consisted of 4-8 genes per species in the analysis it is now possible to have hundreds or thousands of genes per species.
Professor Mark Chase says, “Fortunately, the early results of such studies support those of the earlier work, so we do not expect another re-classification of plants will be needed, but these vast amounts of information have many other uses. The DNA samples used in the earlier studies are still in good condition and can used in such genomic studies.”
Media enquiries: Royal Botanic Gardens, Kew press office +44 (0)20 8332 5607 or email@example.com
Images are available to download from http://www.kew.org/press/images/dna_bank_annivesary.html
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An audio podcast about 20 years of DNA research at Kew is also available. It features interviews with Professor Mark Chase, Keeper of the Jodrell and David Simpson, Acting Keeper of the Herbarium http://www.kew.org/video-galleries/video/the-truth-about-plants.htm
Notes to editors:
• The instrumental set of 200 DNAs that kick-started the Angiosperm Phylogeny Group research project included species such as the Venus flytrap (Dionaea muscipula) and the northern bluethread (Burmannia biflora, a plant species that parasitises fungi). Both of these represent groups of plants that previous researchers had found difficult to place, carnivorous and parasitic plants
• Other notable specimens saved in the DNA Bank include the St Helena olive, which is extinct in wild. The last individual died on the island in 2004 http://www.kew.org/plants-fungi/Nesiota-elliptica.htm
• The DNA bank holds between 8-14% of all known wild plant species
• More than 7,000 genera are covered, more than half of the c. 13,000 already described (a genus is a category of biological classification ranking between the family and the species level of classification, containing genetically closely related species)
• Almost all families of flowering plants (angiosperms) are represented
• Around 2,000 requests for DNA bank material are handled every year – researchers all over the world use the DNA samples stored at Kew
• The reorganisation of Kew’s Herbarium collection to conform to the DNA-based APG system will be completed by the end of 2013
• More about fungal DNA barcoding at Kew http://www.kew.org/science-research-data/directory/projects/FungalDNABarcoding.htm
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