Diagnosing karnal bunt

Karnal bunt is disease of wheat caused by the fungus Tilletia indica and was first discovered in northern India in 1930. It has since spread to other parts of India, Pakistan, Afghanistan, Nepal, Iraq, Iran, Mexico, South Africa and southern and eastern parts of the United States.

It is currently absent from Australia; featuring as a category two pest in the Emergency Plant Pest Response Deed. Preferring cool and humid conditions, our climate would be suitable for it to spread if it became established here, which would have a major economic impact on our wheat industry and exports.

Stringent quarantine regulations on the imports of new wheat varieties or breeding lines for sowing, as well as enforcing cleanliness of imported agricultural machinery, helps to manage the risk of karnal bunt entering the country.

For growers, it’s difficult to detect karnal bunt in the field. Only a few seeds on each head are attacked by the disease. The symptoms became more evident during processing when the grain is replaced with powdery dark spores that emit a strong and fishy odour.

To help Australia respond efficiently to a suspected incursion of karnal bunt, Dr Mui-Keng Tan from Industry & Investment New South Wales and her project team have recently completed over three years of research which will enable quick and accurate diagnosis in the laboratory. The new protocol is currently with the Sub-Committee of Plant Health Diagnostic Standards (SPHDS) for validation, and hopefully endorsement as an accepted international diagnostic standard.

One of the project’s objectives was to incorporate the most sensitive and appropriate tool in the enhanced protocol. Mui-Keng says, “the endorsement of the tool by SPHDS will reflect its recognition of the value of biotechnology advancement in plant diagnosis which is so evident in medical and veterinary diagnosis”.

Completing the project hasn’t always been easy sailing. Mui-Keng’s team faced many hurdles along the way, including the first and most challenging part of the project which was to develop a robust protocol that would withstand the rigours of an international ring test. Mui-Keng and the team also found it difficult geographically. Working on CRC projects, often means project team members are located in different states. In this case, Mui-Keng was in New South Wales and working with Ms Dominie Wright based in Perth at the Department of Agriculture and Food, Western Australia. To overcome this obstacle the team used every opportunity (CRC Science Exchange 2007, National Workshop March 2008 at EMAI, overseas training workshops August 2008 in UK and Italy) to discuss and plan, particularly for the international ring test.

The international ring test had to fit in with the work schedules of participating laboratories. Datelines for the completion of the ring test had to be moved a couple of times, giving the project team a feeling of uncertainty about the outcome as the project approached its due date. As the results slowly filtered in, Mui-Keng was pleased to see the results from the laboratories that had undertaken training in the protocol in contrast to those that had not. Mui-Keng was also very happy with the way the project team worked stating that the project team were able to overcome their challenges with sheer hard work and patience.

When undertaking a complex scientific project, there are also rewards. Mui-Keng found the most gratifying part of her project was the very kind and generous contribution of spore materials and knowledge from scientists working on bunt in Australia and overseas. She believes this generosity was critical to the success of the project. These scientists include Dr Indu Sharma, Dr Roger Shivas, Dr Michael Priest, Mr Yi Jianping, Dr John Brennan, Dr Gordon Murray, Dr L Carris, Kerrie Wratten, Dr John McDonald and Dr S Christiansen. Mui-Keng also gives high praise to the technical officer in the project, Ms Aida Ghalayini, who she says was a pleasure and delight to work with.

Mui-Keng was extremely relieved and very happy when the final report was submitted to the CRC. She was very pleased that the objectives of the project had been achieved. She also said the sense of elation far exceeded the many moments of frustration during the course of the project.

So what’s next for Mui-Keng now that she’s successfully completed her project with the CRC? She is exploring projects in wheat research and currently pursuing support for the innovative application of molecular technology to study the molecular basis (at the gene level) of phenotype variation for two wheat traits. Everyone at the CRC wishes her and the project team the best of luck with their future research activities, and hopes they have similar successful outcomes.