Hornwort stomata do not respond actively to exogenous and environmental cues

摘要: Backgrounds and aims Because stomata in bryophytes occur on sporangia, they are subject to different developmental evolutionary constraints from those leaves of tracheophytes. No conclusive experimental evidence exists the responses hornwort exogenous stimulation. Methods Responses abscisic acid (ABA), desiccation, darkness plasmolysis were compared with tracheophyte leaves. Potassium ion concentrations guard cells adjacent analysed by X-ray microanalysis, ontogeny sporophytic intercellular spaces was tracheophytes cryo-scanning electron microscopy. Key results The apertures open early development thereafter remain open. In hornworts, treatments, based measurements >9000 stomata, produced only a slight reduction aperture dimensions after desiccation plasmolysis, no changes following ABA treatments darkness. tracheophytes, all these resulted complete stomatal closure. similar epidermal under at times. small response probably mechanical and/or stress spongy chlorophyllose cells, affecting cells. contrast their nascent gas-filled counterparts across hornworts initially liquid filled. Conclusions Our experiments demonstrate lack physiological regulation opening closing support accumulating structural that primarily involved sporophyte spore discharge rather than photosynthesis-related gaseous exchange. run counter notion acquisition active control movements as proposed previous mosses.