極端な高温乾燥環境で樹木が生存する仕組みを解明 (How Hardy Tree Species Thrives Under Extreme Dry-Heat Conditions)

2026-03-03 中国科学院(CAS)

中国科学院西双版納熱帯植物園(XTBG)の研究チームは、乾燥と高温が長期間続く環境でも生存できる樹木Pistacia weinmanniifoliaの適応メカニズムを解明した。研究では、雲南省の極端な乾熱谷、湿潤な熱帯雨林、中間環境の3地域に生育する個体群を比較し、葉の形態、光合成色素量、表皮ワックス構造などを分析した。その結果、この樹種は気孔機能と葉表面ワックスの協調的調節によって乾熱ストレスに適応していることが判明した。乾熱環境では葉面積比と光合成色素が減少する一方、気孔密度は変えず気孔サイズを拡大し、蒸散による冷却効率を高めていた。またアルコール系ワックスの生成増加により光反射と水分蒸発抑制を強化していた。これらの形態・化学的特性の統合が、極端な乾燥高温環境への持続的耐性を支えていることが示された。

<関連情報>

統合された気孔ワックス特性は、長期にわたる乾燥熱環境に対するピスタシア・ウェインマニフォリアの持続的な耐性を付与する Integrated stomatal-wax traits confer sustained tolerance of Pistacia weinmanniifolia to prolonged dry-heat environment

Boqin Zheng, Ajoronor Samuel Ewhea, Han Zhang, Guowei Zheng, Juan Guo, Donghai Li, Defeng Feng, Mingda Zhang, Chaolei Yang, Yanqiang Jin, Bo Tian

Plant Physiology and Biochemistry  Available online 10 February 2026

DOI:https://doi.org/10.1016/j.plaphy.2026.111126

極端な高温乾燥環境で樹木が生存する仕組みを解明 (How Hardy Tree Species Thrives Under Extreme Dry-Heat Conditions)

Highlights

  • Investigating plant dry-heat adaptation strategies through three climatic gradients.
  • Plants employ a integrated “cool-save-protect” strategy to cope with combined dry-heat stress.
  • Increasing the stomatal size rather than density can enhance heat dissipation efficiency.
  • The formation of wax crystals reduces solar absorptance to cool the leaves.
  • Wax crystals minimize water loss, while compositional changes enhance the capture of water vapor.

Abstract

Compound drought-heat events are becoming the dominant driver of tree mortality under rapid climate change. However, the functional-trait syndromes that allow woody species to survive prolonged dry-heat stress remain unresolved. We quantified leaf morphology, photosynthetic pigments, stomatal architecture, and wax micro-morphology and chemistry in Pistacia weinmanniifolia populations inhabiting three contrasting climates in south-western China: (i) dry-heat (the dry-hot valley in Jisha River, JSR), (ii) humid-heat (the tropical rainforest in Xishuangbanna Tropical Botanical Garden, XSBN), and (iii) an intermediate transitional site (the evergreen broadleaf forest in Chengjiang, CJ). Compared with plants grown in XSBN, JSR plants displayed a 60% lower specific leaf area, 44–60% lower chlorophyll content, a 36% higher carotenoid-to-chlorophyll ratio, a 65% larger individual stomatal area without altered stomatal density, a 198% increase 1-Octacosanol coverage, which dominates in platelet-like wax crystals. The data reveal a coordinated stomatal-wax strategy: enlarged, but not more numerous, stomata facilitate heat dissipation, while a highly reflective, alcohol-rich wax layer reduces radiative load and cuticular transpiration. This functional integration explains the exceptional tolerance of P. weinmanniifolia to sustained dry-heat extremes and provides a mechanistic framework for predicting species persistence under future compound climate stresses.

1304森林環境
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