Ecotypic Variation in Leaf Thermoregulation and Heat Tolerance but Not Thermal Safety Margins in Tropical Trees
Middleby, Kali B., Cheesman, Alexander W., Hopkinson, Richard, Baker, Leesa, Ramirez Garavito, Sebastian, Breed, Martin F., and Cernusak, Lucas A. (2025) Ecotypic Variation in Leaf Thermoregulation and Heat Tolerance but Not Thermal Safety Margins in Tropical Trees. Plant, Cell & Environment, 48 (1). pp. 649-663.
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Abstract
To avoid reaching lethal temperatures during periods of heat stress, plants may acclimate either their biochemical thermal tolerance or leaf morphological and physiological characteristics to reduce leaf temperature (Tleaf). While plants from warmer environments may have a greater capacity to regulate Tleaf, the extent of intraspecific variation and contribution of provenance is relatively unexplored. We tested whether upland and lowland provenances of four tropical tree species grown in a common garden differed in their thermal safety margins by measuring leaf thermal traits, midday leaf-to-air temperature differences (∆Tleaf) and critical leaf temperatures defined by chlorophyll fluorescence (Tcrit). Provenance variation was species- and trait-specific. Higher ∆Tleaf and Tcrit were observed in the lowland provenance for Terminalia microcarpa, and in the upland provenance for Castanospermum australe, with no provenance effects in the other two species. Within-species covariation of Tcrit and ∆Tleaf led to a convergence of thermal safety margins across provenances. While future studies should expand the number of provenances and species investigated, our findings suggest that lowland and upland provenances may not differ substantially in their vulnerability to heat stress, as determined by thermal safety margins, despite differences in operating temperatures and Tcrit.
| Item ID: | 84397 |
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| Item Type: | Article (Research - C1) |
| ISSN: | 1365-3040 |
| Keywords: | ecotypic variation, intraspecific trait variation, leaf temperature, provenance, thermal safety margin, thermal tolerance,tropical forest |
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| Copyright Information: | This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. © 2024 The Author(s). Plant, Cell & Environment published by John Wiley & Sons Ltd. |
| Funders: | Australian Research Council (ARC) |
| Projects and Grants: | ARC LP190100484 |
| Date Deposited: | 01 Jan 2025 23:25 |
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