AFTER a year where pulse crops have been under intense pressure from fungal disease which have bred prolifically in the wet conditions Australian lentil producers will be delighted in a research breakthrough in the fight to combat the damaging legume disease ascochyta blight.
Researchers from the Centre for Crop and Disease Management (CCDM), in collaboration with the South Australian Research and Development Institute (SARDI) have made an important discovery of a gene in the fungal pathogen causing ascochyta blight that triggers disease resistance in lentils.
The breakthrough will help researchers to better identify the fungal disease gene infecting lentil crops via a laboratory test similar to the PCR COVID-19 test.
The research has flipped conventional thinking on disease management on its head.
Researchers found that some lentil varieties carried a gene that was able to recognise a key fungal protein normally responsible for disease development, which instead triggered a defence response, leaving certain lentil varieties asymptomatic.
CCDM researcher and co-author Bernadette Henares said this was different to the usual approach to genetic improvement of crops where plant breeders try to breed out the genes involved in response to toxic proteins from the pathogen.
"This is exciting news as it has led to the development of a laboratory test - similar to the PCR-based COVID-19 test - that has potential to inform growers which variety of lentil to grow for maximum resistance, based on the fungal gene that is present in the paddock," Dr Henares said.
Further into the future she said the test could be deployed in paddock.
"The laboratory test has potential, with a little further work, to be deployed as an in-field test, and is showing promise in becoming an essential decision-support tool for growers to use when selecting their lentil varieties."
Dr Henares said the research identified there are two types of the ascochyta pathogen - pathotype 1 which doesn't cause disease on PBA Hurricane XT, PBA Hallmark XT, PBA Bolt and other varieties that carry the same resistance, but does cause disease on Nipper.
The other type, pathotype 2, is damaging to PBA Hurricane XT, PBA Hallmark XT and PBA Bolt, but not Nipper.
It means that accurate identification of the pathogen can make all the difference in terms of varietal choice.
"If we can diagnose which pathotype of ascochyta is in the grower's paddock or stubble, then we can let them know, for example, if PBA Hurricane XT might be susceptible to the ascochyta pathotype that is present in their paddock, and suggest they choose a different variety."
CCDM researcher and report co-author Lars Kamphuis said this discovery has helped to explain, in part, why certain lentil varieties have come and gone.
"We've been collecting samples of lentil ascochyta from across Australia since 2013," Dr Kamphuis said.
"Analysis has shown that pathotype 1 was the predominant one at a time when the variety Nipper was popular," he said.
"Then other varieties were introduced, with varieties such as PBA Bolt, PBA Hallmark XT and PBA Hurricane XT gaining a lot of popularity from 2016 onwards, which resulted in pathotype 2 becoming the more dominant pathotype.
"Both pathotypes have been found across the lentil cropping regions of southern Australia, but one will dominate over the other when a certain lentil variety is grown."
The CCDM is a national centre co-supported by the Grains Research and Development Corporation (GRDC) and Curtin University.