光強度が植物の熱・寒冷ストレス耐性に影響(Light Intensity Alters Plants’ Tolerance to Heat and Cold Stress)

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2025-06-23 中国科学院(CAS)

中国科学院西双版納熱帯植物園(XTBG)などの研究チームは、植物の温度耐性が光の強さによって大きく変化することを明らかにしました。従来は暗所でクロロフィル蛍光(Fv/Fm)を用いて評価されてきましたが、実際の環境では高温と強光、低温と弱光が同時に生じるため、この方法では過大評価となる可能性があります。研究では20種の樹木を対象に光強度下での光合成系II(PSII)の耐熱性および耐寒性を測定。強光はほぼすべての種で耐熱性を低下させ、弱光は全種で耐寒性を低下させました。AmaxやEmaxが高い種、葉が厚い種は光による損傷への耐性が高いことも判明。この結果は、気候変動下での植物の脆弱性評価における新たな視点を提供します。

<関連情報>

樹冠植物種における暑熱および寒冷ストレス時の耐熱性を変化させる光強度 Light Intensity Alters Thermal Tolerance During Heat and Cold Stress in Canopy Plant Species

Qin Nie, Shiyu Dai, Jianwei Feng, Nawatbhrist Kitudom, Zexin Fan, Zhongfei Li, Hua Lin
Plant, Cell & Environment  Published: 15 June 2025
DOI:https://doi.org/10.1111/pce.70002

ABSTRACT

Climate change increases extreme weather events like heat waves and cold waves. Understanding plant thermal tolerance is essential for assessing their safety. Measuring the Fv/Fm after dark thermal treatments is a common way to evaluate photosynthetic thermal tolerance, but it differs from real-world conditions with light–temperature covariation. To investigate how light influences thermal tolerance measurement, we tested the photosynthetic thermal tolerance of 20 naturally growing canopy species from Xishuangbanna Tropical Botanical Garden under various light intensities. We found that weak light (300 μmol·m²·s¹) triggered species-specific responses in heat tolerance, while strong light (1000 μmol·m²·s¹) reduced heat tolerance across all tested species, except for Psidium guajava in T50_h. Weak light (200 μmol·m²·s¹) significantly reduced the cold tolerance of all 10 tested species. The species with higher gas exchange rate (Emax and Amax) were more resistant to light-induced damage under heat stress. Leaf thickness mitigated the reduction of heat tolerance caused by strong light and provided physical photoprotection under cold stress. These findings highlight the importance of considering both species-specific photoprotective capacities and ecological realism when evaluating photosynthetic thermal limits. This study helps us understand plant adaptation strategies and predict ecosystem responses to climate change.

生物環境工学
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