Plasticity of photosynthetic heat tolerance in plants adapted to thermally contrasting biomes |
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| Authors: | Lingling Zhu Keith J. Bloomfield Charles H. Hocart John J.G. Egerton Odhran S. O'Sullivan Aurore Penillard Lasantha K. Weerasinghe Owen K. Atkin |
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| Affiliation: | 1. ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia;2. Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia;3. Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia;4. Faculty of Agriculture, University of Peradeniya, Peradeniya, Sri Lanka |
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| Abstract: | In many biomes, plants are subject to heatwaves, potentially causing irreversible damage to the photosynthetic apparatus. Field surveys have documented global, temperature‐dependent patterns in photosynthetic heat tolerance (P HT); however, it remains unclear if these patterns reflect acclimation in P HT or inherent differences among species adapted to contrasting habitats. To address these unknowns, we quantified seasonal variations in T crit (high temperature where minimal chlorophyll‐a fluorescence rises rapidly, reflecting disruption to photosystem II) in 62 species native to 6 sites from 5 thermally contrasting biomes across Australia. T crit and leaf fatty acid (FA) composition (important for membrane stability) were quantified in three temperature‐controlled glasshouses in 20 of those species. T crit was greatest at hot field sites and acclimated seasonally (summer > winter, increasing on average 0.34 °C per °C increase in growth temperature). The glasshouse study showed that T crit was inherently higher in species from warmer habitats (increasing 0.16 °C per °C increase in origin annual mean maximum temperature) and acclimated to increasing growth temperature (0.24 °C °C?1). Variations in T crit were positively correlated with the relative abundance of saturated FAs, with FAs accounting for 40% of T crit variation. These results highlight the importance of both plastic adjustments and inherent differences determining contemporary continent‐wide patterns in P HT. |
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| Keywords: | adaptation fatty acids high temperature membranes phenotypic plasticity photosystem II thermal tolerance |
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