Griffith University-led research is discovering the genetic diversity of Chickpea/Ascochyta Blight, the major pathogen threat to Australia’s billion-dollar chickpea industry.
Published in Microbial Genomics, the collaboration with the New South Wales Department of Primary Industries, South Australian Research and Development Institute and Curtin University has catalogued the genetic sequences of the causal fungus Ascochyta rabiei within all major chickpea production regions across Australia and identified the most destructive members.
“Ascochyta rabiei is a necrotrophic fungus that kills the living cells of its host chickpea plant and then feeds on the dead matter, which leads to huge amounts of fungicides are being sprayed onto the crops multiple times every year,” said lead researcher Dr Ido Bar, from the Centre of Planetary Health and Food Security.
“Ascochyta blight can result in complete chickpea crop failure and is evolving fast, causing increased disease even on our most resistant chickpea varieties.
He said the increased severity of the disease was likely caused by adaptation within the fungal population to select for fitter and more aggressive individuals.
Six years of monitoring has established a comprehensive collection of thousands of members of the fungal population from all major Australian chickpea production regions, which researchers are now using to search for the sections within the fungal genome that enable it to aggressively infect the plant causing severe disease and subsequently compare results with other regions of the world.
“Understanding the molecular diversity within the fungus populations and the frequency and distribution of population members that have adapted to overcome host resistance across agroecological regions is key to adapting farming practices and in managing the disease,” said co-lead researcher Professor Rebecca Ford, from the Centre of Planetary Health and Food Security.
“This research found that Australian A. rabiei population is far less genetically diverse than in other populations worldwide, yet contains very aggressive varieties, able to cause severe damage on our currently grown chickpea species.
“As a result, we are now able to identify and supply the most aggressive members of the fungal populations to chickpea breeders to help them select for the most resistant new varieties.
“This research is a crucial first step to identifying specific areas within the fungal genome that lead to severe aggressive disease and studying the way the fungus attacks the chickpea host, both of which are essential to better inform management practices, such as when and what fungicides to spray.
Dr Bar said the discovery of distinct genetic sequences associated with high and low aggressiveness would enable the development of molecular tools to help in early detection of the pathogen.
“This will aid in the development of disease management and control strategies and providing crucial information to the national chickpea breeding program.”
“While we’ll always be one step behind the fungus, this work allows the chickpea industry to develop the knowledge and tools to reduce the risk of Ascochyta Blight disease and helps ensure the industry prospers into the future.”