Local adaptation optimizes photoprotection strategies in a Neotropical legume tree under drought stress.
Local adaptation optimizes photoprotection strategies in a Neotropical legume tree under drought stress.
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DOI：
10.1093/treephys/tpab034
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发表时间：
2021-02
期刊：
影响因子：
4
通讯作者：
Irene Cordero;M. D. Jiménez;J. Delgado;L. Balaguer;J. Pueyo;A. Rincón
中科院分区：
文献类型：
--
作者：
Irene Cordero;M. D. Jiménez;J. Delgado;L. Balaguer;J. Pueyo;A. Rincón
光保护是植物防止过度光照造成光氧化损伤的一种功能机制。当碳同化受到干旱的限制时，这是最重要的，因此，它需要在碳同化和压力避免之间进行权衡。植物对当地可用水的生态适应可以导致不同的光保护策略。为了验证这一点，我们使用了不同种源的刺苏子。昆策(俗称“塔拉”)沿降水梯度。塔拉是一种新热带豆科树种，具有很高的生态和商业价值，生长在日益受到气候变化威胁的干燥热带森林中。在一个普通的花园温室试验中，分析了塔拉种源在3种不同的干旱和小叶固定处理(即光胁迫)下的形态和生理反应。塔拉通过降低气孔导度、蒸散量、光化学效率、碳同化和生长，同时增加结构和化学光保护(小叶角度和用于散热的色素)来迅速响应干旱。关闭小叶是一种有效的光保护策略，对幼苗具有整体的生理好处，因为它减少了蒸发需求，避免了光损害，但也减少了净碳同化机会，从而带来了成本。这些反应取决于种子来源，来自最干旱地区的幼苗表现出最高的脱水耐受性，这表明了当地的适应，并突出了不同环境下不同策略的价值。这种对环境压力反应的可塑性使Tara能够在水资源供应不同的地区茁壮成长。我们的发现增加了对塔拉干旱反应的功能生态控制因素的理解，这可以被用来改善对其分布范围变化的预测，并用于规划这种关键树种的恢复项目。
Photoprotection is a plant functional mechanisms to prevent photooxidative damage by excess light. This is most important when carbon assimilation is limited by drought, and as such, it entails a trade-off between carbon assimilation vs stress avoidance. The ecological adaptation of plants to local water availability can lead to different photoprotective strategies. To test this, we used different provenances of Caesalpinia spinosa (Mol.) Kuntze (commonly known as "tara") along a precipitation gradient. Tara is a Neotropical legume tree with high ecological and commercial value, found in dry tropical forests, which are increasingly threatened by climate change. Morphological and physiological responses of tara provenances were analyzed under three different treatments of drought and leaflet immobilization i.e., light stress, in a common garden greenhouse experiment. Tara quickly responded to drought by reducing stomatal conductance, evapotranspiration, photochemical efficiency, carbon assimilation and growth, while increasing structural and chemical photoprotection (leaflet angle and pigments for thermal dissipation). Leaflet closure was an efficient photoprotection strategy with overall physiological benefits for seedlings as it diminished the evaporative demand and avoided photodamage, but also entailed costs by reducing net carbon assimilation opportunities. These responses depended on seed origin, with seedlings from the most xeric locations showing the highest dehydration tolerance, suggesting local adaptation and highlighting the value of different strategies under distinct environments. This plasticity on its response to environmental stress allows tara to thrive in locations with contrasting water availability. Our findings increase the understanding of the factors controlling the functional ecology of tara in response to drought, which can be leveraged to improve forecasts of changes in its distribution range, and for planning restoration projects with this keystone tree species.