As Australia faces rising temperatures and more frequent heatwaves, researchers at The Australian National University (ANU) are working to better understand how extreme heat affects one of the country’s most important crops: wheat. 

For researchers John Mackenzie and Andrew Scafaro from the Research School of Biology, the question is not simply whether heat reduces yields — that is already well understood. The challenge is understanding why some wheat varieties cope better with extreme heat than others, and whether those biological traits could help breeders develop more heat-resilient crops for the future. 

Using controlled-environment experiments at ANU, the team exposed different wheat genotypes to simulated multi-day heatwaves and tracked how the plants responded before, during and after heat stress. The research is part of a larger effort – that includes 3 seasons of field work - funded by the GRDC. 

The wheat varieties used in the study were selected from a larger breeding program based on strong field performance under hotter conditions. The ANU researchers are now taking a deeper look into the biology behind that performance. 

One of the key findings so far relates to Rubisco, a critical protein involved in photosynthesis and plant growth. 

Initial findings show that while all wheat varieties experienced reductions in Rubisco abundance following heat stress, some retained significantly more of the protein than others. That difference may help explain why certain wheat lines perform better under heatwaves than other lines. 

The team believes this could eventually provide breeders with a biological marker for heat tolerance, helping speed up the identification and selection of wheat varieties better suited to hotter Australian growing conditions. 

Importantly, the research is also exploring how these traits could be measured at scale in real-world breeding programs. The team linked their measurements to advanced hyperspectral scanning technology, which may allow breeders to rapidly assess crops in the field and identify promising heat-tolerant lines more efficiently. 

For Australian agriculture, the implications are significant. 

Wheat is one of Australia’s largest and most economically important crops, but it is also highly vulnerable to rising temperatures. Research already shows that wheat yields decline substantially with increasing heat, even in the absence of drought. 

As climate conditions continue to shift, improving crop resilience will become increasingly important for maintaining productivity, supporting regional farming communities and strengthening long-term food security. 

“Even if emissions stopped tomorrow, we are already locked into further warming,” Andrew said. “We need to better understand the biology that allows crops to keep performing in hotter growing environments.” 

The work will be shared at the 47th New Phytologist Symposium, Extreme Heat: extending the thermal limits of life, alongside other ANU researchers investigating how plants and ecosystems respond to rising temperatures.