Rapid Reversible heat-induced Inhibition of Photosynthesis (RRHIP): Possible traits for crop improvement

Start year: 2025

Summary: There are many efforts trying to modify photosynthesis in crops for increased food production. Key to these efforts is understanding the limiting factors in photosynthesis under real world conditions, which include heat and moisture stress conditions. Pilot work exploring desert plants in Australia, revealed evidence for two distinct responses to extreme heat stress. In particular, the photosystem II (PSII) is known to be particularly sensitive to high temperatures. Consistent with a strong inhibition of PSII, we observed essentially complete loss of variable chlorophyll fluorescence at high leaf temperatures in these species. Surprisingly, though, variable fluorescence completely recovered as temperature decreased overnight, suggesting a new mechanism for tolerance to elevated temperatures that we term Rapid Reversible heat-induced Inhibition of Photosynthesis (RRHIP). The overall objectives of the project are to test possible mechanisms for RRHIP and assess if RRHIP traits and genetic determinants are potentially useful targets for crop improvement. The Australian component of this work will focus on extremophile plants in the central Australian desert, where Traditional Custodians and joint managers of Uluru-Kata Tjuta National Park (UKTNP) want to understand how their plants are coping under hotter droughts with climate change.