Prats Kyra A, Roddy Adam B, Brodersen Craig R
School of the Environment, Yale University, 195 Prospect St, New Haven, CT 06511, USA.
New York Botanical Garden, 2900 Southern Blvd, Bronx, NY 10458, USA.
AoB Plants. 2024 Jul 20;16(4):plae041. doi: 10.1093/aobpla/plae041. eCollection 2024 Jul.
Stomatal anatomy and behaviour are key to managing gas exchange fluxes, which require coordination with the plant vascular system to adequately supply leaves with water. Stomatal response times and regulation of water loss are generally understudied in ferns, especially across habits (i.e. epiphytic and terrestrial) and habitats (i.e. wet mesic and dry xeric environments). Our objectives were to (i) determine if hydraulic and anatomical traits that control water use are correlated with their habitats (i.e. xeric, mesic) and habits (i.e. epiphytic, terrestrial) for ferns and lycophytes across taxa, and (ii) explore how those traits and others like average leaf water residence time correlate with stomatal function using a subset of closely related species. Epiphytic species had lower vein densities than terrestrial species, while xeric species had higher vein densities than mesic species. Xeric ferns also had smaller stomata than mesic ferns but had similar stomatal densities. Further, in a subset of mesic and xeric ferns, the xeric ferns had higher maximum stomatal conductance and water content, as well as shorter average stomatal opening responses to light intensity, but stomatal closing times did not differ. Finally, shorter stomatal opening and closing responses were correlated with shorter water residence time. Our study highlights anatomical and physiological differences between ferns and lycophytes, which may partially explain habitat preference based on their optimization of light and water.
气孔的解剖结构和行为是控制气体交换通量的关键，这需要与植物维管系统协调，以便为叶片充分供水。蕨类植物中，气孔的响应时间和水分流失调节通常未得到充分研究，尤其是在不同习性（即附生和陆生）和生境（即湿润中生和干旱旱生环境）中。我们的目标是：（i）确定控制水分利用的水力和解剖学特征是否与其生境（即旱生、中生）和习性（即附生、陆生）相关，涉及蕨类植物和石松类植物的各个分类群；（ii）使用一组亲缘关系密切的物种，探讨这些特征以及其他特征（如平均叶片水分停留时间）如何与气孔功能相关。附生植物的叶脉密度低于陆生植物，而旱生植物的叶脉密度高于中生植物。旱生蕨类植物的气孔也比中生蕨类植物小，但气孔密度相似。此外，在中生和旱生蕨类植物的一个子集里，旱生蕨类植物具有更高的最大气孔导度和含水量，以及对光强的平均气孔开放响应时间更短，但气孔关闭时间没有差异。最后，较短的气孔开放和关闭响应与较短的水分停留时间相关。我们的研究突出了蕨类植物和石松类植物之间的解剖学和生理学差异，这可能部分解释了它们基于对光和水的优化而形成的生境偏好。
