• Drought‐induced xylem embolism is considered to be one of the main factors driving mortality in woody plants worldwide. Although several structure–functional mechanisms have been tested to understand the anatomical determinants of embolism resistance, there is a need to study this topic by integrating anatomical data for many species.
• We combined optical, laser, and transmission electron microscopy to investigate vessel diameter, vessel grouping, and pit membrane ultrastructure for 26 tropical rainforest tree species across three major clades (magnoliids, rosiids, and asteriids). We then related these anatomical observations to previously published data on drought‐induced embolism resistance, with phylogenetic analyses.
• Vessel diameter, vessel grouping, and pit membrane ultrastructure were all predictive of xylem embolism resistance, but with weak predictive power. While pit membrane thickness was a predictive trait when vestured pits were taken into account, the pit membrane diameter‐to‐thickness ratio suggests a strong importance of the deflection resistance of the pit membrane. However, phylogenetic analyses weakly support adaptive coevolution.
• Our results emphasize the functional significance of pit membranes for air‐seeding in tropical rainforest trees, highlighting also the need to study their mechanical properties due to the link between embolism resistance and pit membrane diameter‐to‐thickness ratio. Finding support for adaptive coevolution also remains challenging.

中文翻译：

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将干旱引起的木质部栓塞抗性与新热带树木的木材解剖特征联系起来。

• 干旱引起的木质部栓塞被认为是导致全世界木本植物死亡的主要因素之一。尽管已经测试了多种结构功能机制来理解抗栓塞性的解剖学决定因素，但仍需要通过整合许多物种的解剖学数据来研究该主题。
• 我们结合了光学，激光和透射电子显微镜，研究了横跨三个主要进化枝（木兰类，罗氏类和星状类）的26种热带雨林树种的容器直径，容器分组和基坑膜超微结构。然后，我们将这些解剖学观察结果与先前发表的有关干旱引起的栓塞性抗性的数据进行了系统发育分析。
• 血管直径，血管分组和凹膜超微结构均能预测木质部栓塞阻力，但预测能力较弱。当考虑到保留的凹坑时，凹坑膜的厚度是一种预测性状，但凹坑膜的直径与厚度之比表明，凹坑膜的抗挠性非常重要。但是，系统发育分析很少支持自适应协同进化。
• 我们的结果强调了坑膜对热带雨林树木播种的功能重要性，并强调了由于抗栓性与坑膜直径与厚度之比之间的联系，还需要研究其力学性能。寻找对自适应协同进化的支持也仍然具有挑战性。