State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, China.
Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.
Physiol Plant. 2024 Mar-Apr;176(2):e14253. doi: 10.1111/ppl.14253.
Ferns are primitive vascular plants with diverse morphologies and structures. Plant anatomical traits and their linkages can reflect adaptation to the environment; however, these remain are still poorly understood in ferns. The main objective of this study was to explore whether there was structural coordination among and within organs in fern species. We measured 16 hydraulically related anatomical traits of pinnae, petioles, and roots of 24 representative fern species from the tropical and subtropical forest understory and analyzed trait correlation networks. In addition, we examined phylogenetic signals for the anatomical traits and analyzed co-evolutionary relationships. These results indicated that stomatal density and all petiole anatomical traits exhibited significant phylogenetic signals. Evolutionary correlations were observed between the tracheid diameter and wall thickness of the petiole and between the water transport capacity of the petiole and stomatal density. Conversely, anatomical traits of roots (e.g., root diameter) showed no phylogenetic signals and were not significantly correlated with those of the pinnae and petioles, indicating a lack of structural coordination between the below- and above-ground organs. Unlike angiosperms, vein density is unrelated to stomatal density or pinna thickness in ferns. As root diameter decreased, the cortex-to-stele diameter ratio decreased significantly (enhanced water absorption) in angiosperms but remained unchanged in ferns. These differences lead to different responses of ferns to climate change and improve our knowledge of the water adaptation strategies of ferns.
蕨类植物是具有多样化形态和结构的原始维管植物。植物解剖学特征及其相互关系可以反映对环境的适应；然而，这些在蕨类植物中仍然知之甚少。本研究的主要目的是探讨蕨类植物各器官之间和内部是否存在结构协调性。我们测量了来自热带和亚热带森林林下的 24 种有代表性的蕨类植物的羽片、叶柄和根的 16 个水力相关解剖特征，并分析了特征关联网络。此外，我们还检查了解剖特征的系统发育信号，并分析了协同进化关系。这些结果表明，气孔密度和所有叶柄解剖特征都表现出显著的系统发育信号。叶柄导管直径和细胞壁厚度之间以及叶柄水分运输能力和气孔密度之间观察到进化相关性。相反，根的解剖特征（例如，根直径）没有系统发育信号，也与羽片和叶柄的解剖特征没有显著相关性，这表明地下和地上器官之间缺乏结构协调性。与被子植物不同，叶脉密度与蕨类植物的气孔密度或羽片厚度无关。随着根直径的减小，被子植物的皮层-中柱直径比显著降低（增强了水分吸收），而蕨类植物则保持不变。这些差异导致蕨类植物对气候变化的不同反应，并提高了我们对蕨类植物水分适应策略的认识。
