Researchers from CSIRO, Australia's national science agency, have unlocked the most detailed genetic blueprint yet of a major soil-borne crop pathogen — an advance that paves the way for better crop disease management in Australian agriculture.
For the first time, researchers have sequenced and assembled a chromosome-level genome for the fungal pathogen Rhizoctonia solani AG-8, revealing its complex genetic structure.
The fungus causes bare patch disease in wheat, barley and legume crops across Australia, resulting in over $150 million in crop losses each year.
Dr Jonathan Anderson, Principal Research Scientist at CSIRO, said the fungus has long been a challenge for farmers because there are no resistant crop varieties and fungicides often don't work reliably.
"Using new sequencing technology, we discovered that Rhizoctonia solani AG-8 is what's known as dikaryotic — meaning it carries two separate sets of genetic material, called haplotypes, some of which are highly genetically diverse," Dr Anderson said.
In simpler terms, the fungus has two distinct genetic blueprints, which could help explain why it's so hard to control.
"By studying how genes in each haplotype behave when infecting different crops, we found that the two genetic sets may play different roles in how the fungus attacks wheat," Dr Anderson explained.
"This new level of genetic insight into the fungus gives us a powerful foundation to transform how to manage the destructive diseases it causes in the paddock."
The findings lay the foundation for nationwide studies of Rhizoctonia solani populations across Australia's grain growing regions — research that was previously limited by uncertainty around the relationship between the fungus' two genetic sets.
The new genome sequence also supports further research into how the fungus causes bare patch disease in different crops and guides the development of smarter crop management strategies to reduce its impact.
The paper, The fungal pathogen Rhizoctonia solani AG-8 has 2 nuclear haplotypes that differ in abundance , was published in G3: Genes, Genomes, Genetics.
