Studying the response to drought stress of keystone epiphytes such as tank bromeliads is essential to better understand their resistance capacity to future climate change. The objective was to test whether there is any variation in the carbon, water and nutrient status among different leaf ontogenetic stages in a bromeliad rosette subjected to a gradient of drought stress. We used a semi-controlled experiment consisting in a gradient of water shortage in Aechmea aquilega and Lutheria splendens. For each bromeliad and drought treatment, three leaves were collected based on their position in the rosette and several functional traits related to water and nutrient status, and carbon metabolism were measured. We found that water status traits (relative water content, leaf succulence, osmotic and midday water potentials) and carbon metabolism traits (carbon assimilation, maximum quantum yield of photosystem II, chlorophyll and starch contents) decreased with increasing drought stress, while leaf soluble sugars and carbon, nitrogen and phosphorus contents remained unchanged. The different leaf ontogenetic stages showed only marginal variations when subjected to a gradient of drought. Resources were not reallocated between different leaf ontogenetic stages but we found a reallocation of soluble sugars from leaf starch reserves to the root system. Both species were capable of metabolic and physiological adjustments in response to drought. Overall, this study advances our understanding of the resistance of bromeliads faced with increasing drought stress and paves the way for in-depth reflection on their strategies to cope with water shortage. This article is protected by copyright. All rights reserved.

中文翻译：

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干旱对附生水箱凤梨科叶片个体发育阶段资源分配和保护的影响

研究关键附生植物（如坦克凤梨科植物）对干旱胁迫的反应对于更好地了解它们对未来气候变化的抵抗能力至关重要。目的是测试在经历干旱胁迫梯度的凤梨莲座丛中不同叶片个体发育阶段的碳、水和营养状况是否存在任何变化。我们使用了半控制实验，包括 Aechmea aquilega 和 Lutheria splendens 的缺水梯度。对于每个凤梨科植物和干旱处理，根据它们在莲座丛中的位置和与水和营养状况相关的几个功能特征收集三片叶子，并测量碳代谢。我们发现水分状况性状（相对含水量、叶肉质、渗透势和中午水势）和碳代谢性状（碳同化、光系统 II 的最大量子产量、叶绿素和淀粉含量）随着干旱胁迫的增加而降低，而叶片可溶性糖和碳、氮和磷含量保持不变。当遭受干旱梯度时，不同的叶片个体发育阶段仅表现出边际变化。资源没有在不同的叶子个体发育阶段之间重新分配，但我们发现可溶性糖从叶子淀粉储备到根系统重新分配。这两个物种都能够响应干旱进行代谢和生理调整。全面的，这项研究增进了我们对凤梨科植物面临日益加剧的干旱压力的抗性的理解，并为深入思考它们应对缺水的策略铺平了道路。本文受版权保护。版权所有。