Genetic mechanism reveals key secret behind disease infection in crops

Researchers have discovered a key genetic mechanism behind how pathogens infect crops, leading to new strategies for breeding resistant crop varieties against other pathogens carrying the same genetic mechanism.

Led by researchers from the Center for Crop and Disease Management (CCDM), a national center co-supported by GRDC and Curtin University, as well as collaborators from the Curtin Health Innovation Research Institute, CSIRO, University of Nottingham (United Kingdom) and INRAe (France), the team identified and validated the function of a specific DNA sequence linked to genes responsible for damage in wheat.

By studying the genetic mechanism of Parastagonospora nodorum, the fungus responsible for Septoria nodorum leaf spot (SNB) in wheat, the research team was able to confirm that a transcription factor called Pf2 binds to a specific DNA consensus sequence. In doing so, Pf2 activates adjacent genes to produce necrotrophic effectors, molecules responsible for inducing damage in wheat.

Former CCDM doctoral student. Student Dr Evan John and Associate Professor Kar-Chun Tan, along with their research team, hope to transfer this knowledge to other diseases to improve the identification of necrotrophic effectors and other virulence-associated genes . These results are published in the journal PLOS Pathogens.

“This discovery of the DNA consensus sequence is of great importance for disease resistance research, because it means we now know how the pathogen’s effectors are activated to attack a plant,” said Dr. John.

“What’s exciting about this research is that it can be used as a regulatory model, because the same Pf2 transcription factor is found in other fungal pathogens that cause diseases such as wheat yellow spot , blackleg and canola black spot. According to our current knowledge, it seems that Pf2 functions by the same mechanism. »

Associate Professor Tan said that for many years, researchers have been looking for effectors in pathogen genomes, but narrowing them down to a short list of candidates can be difficult.

“Now, knowing the genetic code of the DNA sequence targeted by Pf2, we can narrow down the potential effector genes associated with the specific DNA consensus sequence and prioritize these genes for effector discovery,” said Dr. Associate Professor Tan.

“Finding effectors is a big win, because it means we can then find the corresponding susceptible gene in the crop and help breeders using effector-assisted selection on crops, providing growers with varieties with improved resistance to diseases.”

Professor Mark Gibberd, Director of CCDM, said he was proud of the path taken by this CCDM research team to achieve such an important scientific result which will lead to better varieties for growers.

“This discovery took eight years. A few years ago the team had discovered the transcription factor and knew it regulated effectors, but they didn’t know how it regulated them,” Professor Gibberd said.

“By persisting with countless challenges, they got to the bottom of the scientific mystery and came to a conclusion that will help improve disease resistance not only in wheat, but potentially in canola diseases as well.

“This research is an example of CCDM’s ability to work deeply and collaboratively on in-depth research to ensure Australian agriculture is a world leader in grain production research and innovation.”