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14 Jun 2018

No Plants No Food

Everything we eat either comes directly or indirectly from plants, and the spread of plant diseases and pests that damage our food crops can cost global agriculture $540 billion a year.

Foraging for wild plants and animals was the first strategy we used to sustain ourselves as Homo sapiens, and today, about 85 percent of our calorie intake comes from about 20 different species of plants.

About 2,000 to 9,000 years ago, traditional farmers developed the main plant crops part of our current diet: wheat (Triticum aestivum), rice (Oryza sativa), and maize (Zea mays).

But it’s not just these staple crops that satisfy our hunger – think about all the fruit and vegetables we so easily pluck from our supermarkets or enjoy in restaurants… Guacamole, chocolate, beer and wine - these all start with a plant!      

However, increased transport of plant material throughout the world is spreading plant diseases and threatening the health of plants and therefore, compromising our food supply.

Dr Edward Liew is a Senior Research Scientist at the Royal Botanic Garden Sydne and he leads a team of scientists at the PlantClinic who are at the forefront of researching, identifying and controlling thousands of plant diseases.

Plant pathology, the study of plant diseases, is so important for food safety and food security
Senior Research Scientist, Dr Edward Liew.
Over 20 years’ experience studying deadly plant diseases

Dr Liew has worked among the world’s leaders in his field to produce some of the most fundamental and practical research on Fusarium and Phytophthora, two of the most prominent pathogens that cause plant diseases.

“For over 20 years I have helped identify and understand the evolution of fungi and their diseases to better inform disease management, both in the cultivated and natural environments, and to enhance our conservation efforts across Australia’s fragile ecosystem,” Dr Liew said.

Dr Liew also features on the second episode of our new Branch Out podcast, No Plants No Food, where he takes listeners into the labs of the PlantClinic and deep into the microscopic world of deadly plant diseases.

When a plant disease goes bananas…

A prominent example of how a lethal plant disease can threaten our food supply, and the agricultural industry, is the Panama disease that nearly wiped out the Gros Michel banana in the 1950’s.

“It was called Panama disease because it was first diagnosed in Panama and it is a type of Fusarium wilt, caused by the fungal pathogen Fusarium oxysporum f. sp. cubense (Foc),” Dr Liew said. 

“It attacks the roots and vascular system, which is like the ‘plumbing system’ of plants, and it is resistant to fungicide and cannot be controlled chemically,” Dr Liew said.

This ruthless disease nearly wiped out entire plantations of the Gros Michel banana in Panama, Costa Rica, Guatemala, Colombia and Ecuador.

Following this catastrophic event, the Cavendish banana was discovered and is the most popular cultivated banana today. However, the Cavendish is only immune to the strain of the fungus that destroyed the Gros Michel in the 50’s.

New strains of Panama disease currently threaten the production of our most popular banana today
Senior Research Scientist, Dr Edward Liew.
The plant disease detectives at the PlantClinic are on the case!

Dr Liew and the scientists at the PlantClinic provide a wide range of plant disease diagnostics and pathogen detection services to the public, industry and government agencies.

“Like us, when plants are sick, they develop a range of different symptoms such as leaf spots, wilting or root rot,” Dr Liew said.

“However, the real problem is all happening at the microscopic level and it involves quite a bit of detective work and utilising DNA technologies. I often tell my team to put on their CSI hat!” Dr Liew said.

Stopping the attack on our Watermelons 

A recent project at the PlantClinic involved establishing the presence and cause of Fusarium wilt in major watermelon producing regions of Australia.

“We studied the geographic distribution of the pathogen and its host range to identify the number and distribution of biological races present,” Dr Liew said.

“This study we did on pathogen dynamics will assist crop production practices, resistant breeding strategies and other control measures to ensure the growth of the Australian watermelon industry,” Dr Liew said.

Branch Out and subscribe to our podcast 

Go deeper into the fascinating and microscopic world of plant diseases with Dr Ed Liew in the second episode of our Branch Out podcast: No Plants No Food.

You can subscribe to Branch Out on the Apple podcast app or Android podcast app. If you like the show, please leave a rating, review and share it with your followers on social media. 

If you want to know more about how world leading scientists are developing solutions to the world’s most critical environmental and biodiversity issues, please head to our science page.

Category: Science
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