Australia has three native species of rice all growing in the tropics and savannah. These wild relatives grow in highly arid and highly variable seasonal conditions that will characterise future climate regimes around the world. When grown in Macquarie’s facilities by a team led by Associate Professor Brian Atwell, one endemic species, Oryza australiensis, was shown to tolerate temperatures up to 45 degrees centigrade, while cultivated rice stopped growing.
Using proteomics to study thousands of proteins at once, the research team painstakingly identified twelve protein candidates to explain the tolerance of wild rice to heat. The core target became Rubisco activase, a critical component of photosynthesis; the enzyme was at the time just emerging as a potential ‘weak link’ in plants experiencing heat. On pursuing the function of the protein and the sequence of its parent gene, the team detected a number of critical changes in the gene sequence that had evolved in the wild rice and speculated that this conferred heat tolerance, allowing the wild relatives to fix more carbon and grow faster during heatwaves.
Funding from the project’s research sponsors, Bayer CropScience, helped develop a large body of evidence that has led to the gene sequence being protected by a Macquarie University patent. Bayer CropScience has now supported two rounds of collaborative experiments in Belgium on transgenic plants with this unique Australian gene engineered into host (Oryza sativa) rice lines that are sensitive to heat stress. The Macquarie research team believes this is a key strategy to protect against crop losses from heatwaves.