Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada.
Nicholas School of the Environment, Duke University, Durham, North Carolina, USA.
Plant Cell Environ. 2021 Jul;44(7):2321-2330. doi: 10.1111/pce.13990. Epub 2021 Jan 13.
The heat tolerance of photosystem II (PSII) may promote carbon assimilation at higher temperatures and help explain plant responses to climate change. Higher PSII heat tolerance could lead to (a) increases in the high-temperature compensation point (T ); (b) increases in the thermal breadth of photosynthesis (i.e. the photosynthetic parameter Ω) to promote a thermal generalist strategy of carbon assimilation; (c) increases in the optimum rate of carbon assimilation P and faster carbon assimilation and/or (d) increases in the optimum temperature for photosynthesis (T ). To address these hypotheses, we tested if the T , T and T PSII heat tolerances were correlated with carbon assimilation parameters for 21 plant species. Our results did not support Hypothesis 1, but we observed that T may be used to estimate the upper thermal limit for T at the species level, and that community mean T may be useful for approximating T . The T and T heat tolerance metrics were positively correlated with Ω in support of Hypothesis 2. We found no support for Hypotheses 3 or 4. Our study shows that high PSII heat tolerance is unlikely to improve carbon assimilation at higher temperatures but may characterize thermal generalists with slow resource acquisition strategies.
PSII（光系统 II）的耐热性可能会促进高温下的碳同化，并有助于解释植物对气候变化的响应。较高的 PSII 耐热性可能导致：(a) 高温补偿点 (T) 的增加；(b) 光合作用热宽（即光合参数 Ω）的增加，以促进碳同化的热广适策略；(c) 最佳碳同化率 P 的增加以及更快的碳同化和/或 (d) 光合作用最佳温度 (T) 的增加。为了验证这些假说，我们测试了 21 种植物物种的 PSII 耐热性与碳同化参数之间的相关性。我们的结果不支持假设 1，但我们观察到 T 可以用来估计物种水平上 T 的上限，而群落平均 T 可以用来近似 T。T 和 T 的耐热性指标与 Ω 呈正相关，支持假设 2。我们没有发现假设 3 或 4 的支持。我们的研究表明，高 PSII 耐热性不太可能提高高温下的碳同化，但可能以缓慢资源获取策略为特征的热广适物种。
