Unveiling the Role of NUDIX Hydrolase in Fungal Infection

Researchers from The Australian National University (ANU), in partnership with scientists from Germany and the United States, have identified a potent “weapon” employed by numerous pathogenic fungi to infect staple food crops like rice and corn. This discovery may lead to novel approaches for enhancing global food security.

Fungi, similar to humans, often depend on plants for sustenance. This fungal dependence negatively affects crop yields, with annual losses attributed to fungal diseases estimated to be between 10 and 23%.

The international research team identified an enzyme, classified as a “NUDIX hydrolase,” that many fungal pathogens utilize as a virulence factor to induce disease in plants. These findings have been published in the journal Science.

By elucidating the function of this enzyme in plant infection, the researchers propose that it may be possible to develop more disease-resistant rice varieties, along with other fruit and vegetable crops, that possess enhanced self-defense mechanisms.

This research could significantly improve food security, particularly in regions where rice and corn are essential dietary components. The US Department of Agriculture notes that rice serves as the primary staple food for over half the global population.

Much of our work focused on the pathogenic fungus Magnaporthe oryzae, which causes rice blast disease. Rice is a critically important food staple, and losses from rice blast could feed 60 million people each year.”

Simon Williams, Associate Professor, Australian National University

Dr. Carl McCombe, the lead author who conducted this research during his PhD studies at ANU, explained that the disease-promoting enzyme can penetrate plant cells and target a crucial signaling molecule responsible for sensing phosphate, an essential nutrient for plant viability.

The enzyme, he stated, effectively “hijacks” vital molecular pathways, deceiving the plant into perceiving a phosphate deficiency, which triggers a starvation-like response. This allows the pathogen to circumvent the plant's inherent immune defenses and cause disease.

In collaboration with colleagues at the Australian Nuclear Science and Technology Organisation, we were able to reveal the structure of the enzyme in detail using a technique called X-ray crystallography. Understanding what the enzyme looks like gave us critical insights into how it is used by pathogens to attack plants.”

Dr. Carl L. McCombe, Postdoctoral Researcher, California Institute of Technology

Associate Professor Williams, who oversaw the ANU research team's involvement, mentioned that besides engineering crops with improved immune responses, the research could also lead to methods for disabling the enzyme's “hijacking effect,” analogous to controlling it with an on/off switch.

Our research also reveals that the NUDIX hydrolase is used as a ‘weapon’ by many different fungi, including ones that are responsible for causing anthracnose disease in fruit, vegetable, and seed crops. These diseases impact crop production in foods such as mangoes, melons, corn, and chickpeas – produce that Australians enjoy daily. This suggests our work also has implications to safeguard other important fruit and vegetable staples.”

Simon Williams, Associate Professor, Australian National University

Associate Professor Williams stated that these findings provide a blueprint for creating new strategies for disease management.

“This could involve engineering the plant’s immune system to detect the enzyme or block its function. This could help farmers protect their crops and secure global food supplies,” Williams said.