McAdam Scott A M, Manandhar Anju, Rimer Ian M, Aros-Mualin Daniela
Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA.
Plant Physiol. 2025 May 30;198(2). doi: 10.1093/plphys/kiaf238.
Most ferns are adapted to lower-light environments and have relatively low rates of leaf gas exchange compared with seed plants. Recent studies suggest that certain fern groups adapted to full sun, yet ever-wet, environments have evolved novel stomatal regulatory mechanisms, particularly in response to light, enabling higher rates of leaf gas exchange. Among these lineages, the genus Equisetum, a morphologically and ecologically distinctive group of ferns, remains poorly understood in terms of stomatal physiology. Here, we investigated stomatal control by light in Equisetum by combining observations of stomatal conductance in the field with measurements of canopy conductance in a controlled environment and stem-level gas exchange responses to varying wavelengths and intensities of light. We found that Equisetum stomatal closure in the dark occurs over 5 min, which is extremely fast compared with other ferns. Additionally, Equisetum has lost a stomatal response to red-light, with stomata exclusively regulated by blue-light. This novel regulation of stomata by blue-light and rapid stomatal closure in the dark results in strong co-ordination between canopy conductance and light intensity at the end of the day. Our results have implications for understanding the regulation of stomata by light and suggest that there is considerable ecologically relevant diversity in stomatal regulation within ferns.
与种子植物相比，大多数蕨类植物适应低光照环境，叶片气体交换速率相对较低。最近的研究表明，某些适应全日照但常年湿润环境的蕨类植物群体已经进化出了新的气孔调节机制，特别是对光的响应，从而能够实现更高的叶片气体交换速率。在这些谱系中，木贼属是一类形态和生态上独特的蕨类植物，但在气孔生理学方面仍了解甚少。在这里，我们通过结合田间气孔导度的观测、控制环境中冠层导度的测量以及茎水平对不同波长和光强的气体交换响应，研究了木贼属植物中光对气孔的控制。我们发现，木贼属植物在黑暗中气孔关闭发生在5分钟内，与其他蕨类植物相比非常快。此外，木贼属植物已经失去了对红光的气孔响应，气孔仅受蓝光调节。这种蓝光对气孔的新调节以及黑暗中快速的气孔关闭导致了一天结束时冠层导度和光强之间的强协调。我们的结果对于理解光对气孔的调节具有启示意义，并表明蕨类植物在气孔调节方面存在相当多与生态相关的多样性。
