DNA and the plant family tree
In December 2014 Kew's DNA and Tissue Bank contained over 50,000 samples of DNA from plants and a large collection of silica dried tissue. Preparing DNA samples for the bank involves crushing plant tissue in a mixture of liquids that extract the DNA but precipitate proteins. The mixture is then spun in a centrifuge which separates it into layers. The layer containing DNA is recovered and cold alcohol is added to precipitate the DNA. After purification, the DNA is stored at -80°C.
Why store DNA?
The development of the technology to analyse and sequence DNA over the past 30 years or so, has revolutionised some of the traditional areas of Kew’s plant science and research, including how we think about and understand the plant family tree.
Kew’s scientists use data obtained from DNA sequences to study how different groups of plants are related to one another, identify plants, or examine the genetic variation among individuals of rare plant. While undertaking this work they store the DNA they extract in DNA banks to provide a reference collection for future study.
Mapping the tree of life
Comparing DNA sequences of different plant species reveals likely evolutionary relationships and so has some advantages over subjectively looking at plant characteristics as a classification method. The technique is throwing up some unusual relationships between plants. For example, the sacred lotus (Nelumbo nucifera) has turned out to be unrelated to the water lilies it closely resembles. Instead it is a close relative of the London plane tree (Platanus x acerifolia).
A barcode for every plant
Kew is involved in a project that aims to one day enable scientists to identify any plant by means of a ‘DNA barcode’. The Consortium for the Barcode of Life is an international initiative that aims to promote and develop DNA barcoding as a standard for identifying species. Scientists have found that the sequences of one or two particular DNA regions are effective for identifying animal, plant and fungal species. Although it sounds far-fetched, the hope is that one day it might be possible to create a hand-held device that everyone could use to quickly identify all organisms while working in the field or hiking in the park.
Working in partnership
South Africa’s Cape has the highest recorded species diversity of any similarly sized temperate or tropical region in the world. More than 9,000 plant species grow in 90,000 km, more than in the entire British Isles.
Kew experts are working with scientists at the South Africa National Biodiversity Institute (SANBI) and universities in Johannesburg and Cape Town to create a DNA bank in South Africa to house genetic material from the country’s plants. This is vital work; 1,700 of the Cape Floral region species alone are threatened with extinction. Meanwhile, some scientists believe climate change could drastically alter the distribution of Africa’s plants.
Contact the DNA and Tissue Bank
DNA Bank Administrator
Royal Botanic Gardens, Kew
Surrey TW9 3AB