Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK.
Philos Trans R Soc Lond B Biol Sci. 2018 Feb 5;373(1739). doi: 10.1098/rstb.2016.0498.
Cryo-scanning electron microscopy shows that nascent intercellular spaces (ICSs) in bryophytes are liquid-filled, whereas these are gas-filled from the outset in tracheophytes except in the gametophytes of Lycopodiales. ICSs are absent in moss gametophytes and remain liquid-filled in hornwort gametophytes and in both generations in liverworts. Liquid is replaced by gas following stomatal opening in hornworts and is ubiquitous in moss sporophytes even in astomate taxa. New data on moss water relations and sporophyte weights indicate that the latter are homiohydric while X-ray microanalysis reveals an absence of potassium pumps in the stomatal apparatus. The distribution of ICSs in bryophytes is strongly indicative of very ancient multiple origins. Inherent in this scenario is either the dual or triple evolution of stomata. The absence, in mosses, of any relationship between increases in sporophyte biomass and stomata numbers and absences, suggests that CO entry through the stomata, possible only after fluid replacement by gas in the ICSs, makes but a minor contribution to sporophyte nutrition. Save for a single claim of active regulation of aperture dimensions in mosses, all other functional and structural data point to the sporophyte desiccation, leading to spore discharge, as the primeval role of the stomatal apparatus.This article is part of a discussion meeting issue 'The Rhynie cherts: our earliest terrestrial ecosystem revisited'.
冷冻扫描电子显微镜显示，在苔藓植物中，初生细胞间隙（ICS）充满液体，而在维管植物中，除石松目植物的配子体外，这些间隙从一开始就是充满气体的。苔藓植物的配子体中没有 ICS，角苔配子体和所有世代的地钱配子体中仍保持充满液体。在角苔中，ICS 中的液体在气孔张开后被气体取代，并且在苔藓植物的孢子体中普遍存在，即使在无气孔的分类群中也是如此。关于苔藓植物水分关系和孢子体重量的新数据表明，后者是等水合的，而 X 射线微分析显示气孔装置中缺乏钾泵。苔藓植物中 ICS 的分布强烈表明它们具有非常古老的多起源。在这种情况下，要么是气孔的双重或三重进化，要么是气孔的双重或三重进化。在苔藓植物中，孢子体生物量和气孔数量的增加之间没有任何关系，也没有任何关系，这表明 CO 通过气孔进入，这只有在 ICS 中的液体被气体取代后才有可能，对孢子体营养的贡献很小。除了在苔藓植物中存在单个关于孔径主动调节的说法外，所有其他功能和结构数据都表明，气孔的主要作用是使孢子体脱水，导致孢子释放。本文是关于“Rhynie cherts：重新审视我们最早的陆地生态系统”的讨论会议的一部分。
