Weeding out bad grasses

Volume 6 Number 7 July 12 - August 8 2010

Dr Murphy in his ‘laboratory’ - the Royal Botanic Gardens.
Dr Murphy in his ‘laboratory’ - the Royal Botanic Gardens.

Growing up on Phillip Island, Dan Murphy’s ‘classrooms’ were beaches and bushland reserves. These days he is a botanist at the National Herbarium of Victoria who is lucky enough to call the Royal Botanic Gardens Melbourne his laboratory. Dr Murphy studies the evolutionary history of plants and is driving a project tracking the DNA of weeds that has significant implications for Australia’s bio-security, as Fiona Willan reports.

It all started with a chance encounter with a Venus Fly Trap at the age of 10.

Dr Dan Murphy was at a local market when he spotted the carnivorous plant – and was awed by its ability to quickly snap shut and trap insect prey. He fell “so head over heels” that he was inspired to build his own greenhouse in his parent’s backyard.

“I became so fascinated with carnivorous plants that I started collecting them,” Dr Murphy says. “I had hundreds of them in my greenhouse.”

Dr Murphy developed an interest in nature and biodiversity from a young age. School holidays were spent volunteering at Phillip Island’s famous Penguin Parade – weighing penguins and watching closely as scientists went about their research. He was also fascinated by evolution, inspired by a schoolteacher who was a “dinosaur nut” and would take the class on field trips to cut dinosaur fossils out of rocks.

From a childhood spent among plants and animals, it seems an almost natural progression that Dr Murphy went on to work as a scientist. After studying botany at the University of Melbourne “because it was definitely the most appropriate course for what I wanted to do”, Dr Murphy (BSc 1995 BSc Hons 1996 PhD 2001) became a botanist at the National Herbarium of Victoria, where he studies the evolutionary history of plants and describes new species. 

This information plays an important role in plant conservation as “you can’t preserve something if you don’t know it exists to begin with”. His focus is on investigating how different plants relate to each other and answering questions about their evolutionary history and, in turn, broader questions about evolution.

A key investigative tool Dr Murphy uses to do this is DNA sequencing. He is currently driving a major project that involves DNA tracking of weeds and grasses, which has significant implications for Australia’s bio-security.

 The project aims to stop new species being introduced to Australia and becoming weeds, by identifying foreign grasses from their DNA.

 “Grasses for non-specialists – or even for specialists – are almost impossible to tell apart, unless they’re flowering,” Dr Murphy explains. He has been working on developing a plant DNA database that will enable scientists across the world to identify grasses.

“Say if Quarantine finds a piece of paper with grass seeds embedded in it – we’ll be  able to get a fragment of the plant, grind it up, get the DNA out and sequence the DNA to tell what the plant is.”

DNA sequencing is a relatively new scientific tool in botany – it has been used in this field for only around 15 years – and analysing grass DNA is just part of what Dr Murphy does.

He employs a range of other research methods to investigate plant evolution – including analysing basic historical information, recording details of plant populations and collecting samples.

Dr Murphy has a particular interest in the evolution of acacias – the biggest plant group in Australia – and his research into this group has led to the biggest discovery of his career to date.

While completing his PhD, Dr Murphy was among a group of researchers to make a discovery that would force botanists to re-examine the evolution of acacias as they knew it. They found that acacia, as it was traditionally known, was not one single genus as scientists had previously thought. In fact, it was actually divided into five different genera.

“This discovery completely changed our whole concept of evolution of the group,” Dr Murphy says. “When we found that the plants we called acacias actually aren’t that closely related…we had to change the naming and classifying of the plants, and this was very controversial because this group is so large and well known all around the world.”

Dr Murphy is now leading a research project investigating the interactions between plants and other organisms, using acacias in Australia as a model organism. Working with researchers from other fields of science, he is using the evolutionary history of acacias to obtain evolutionary information on other organisms, such as insects and bacteria.  For Dr Murphy, part of the beauty of working in botany is that there are still many stones left unturned.

“There are many new species out there. In botany, there’s still a lot to discover,” he says.  “I’m learning something new every day – there aren’t many professions where you can say that.”

http://www.unimelb.edu.au/alumni/