title: To open or to close: species-specific stomatal responses to simultaneously applied opposing environmental factors.
abstract: Plant stomatal responses to single environmental factors are well studied; however, responses to a change in two (or more) factors - a common situation in nature - have been less frequently addressed. We studied the stomatal responses to a simultaneous application of opposing environmental factors in six evolutionarily distant mono- and dicotyledonous herbs representing different life strategies (ruderals, competitors and stress-tolerators) to clarify whether the crosstalk between opening- and closure-inducing pathways leading to stomatal response is universal or species-specific. Custom-made gas exchange devices were used to study the stomatal responses to a simultaneous application of two opposing factors: decreased/increased CO2 concentration and light availability or reduced air humidity. The studied species responded similarly to changes in single environmental factors, but showed species-specific and nonadditive responses to two simultaneously applied opposing factors. The stomata of the ruderals Arabidopsis thaliana and Thellungiella salsuginea (previously Thellungiella halophila) always opened, whereas those of competitor-ruderals either closed in all two-factor combinations (Triticum aestivum), remained relatively unchanged (Nicotiana tabacum) or showed a response dominated by reduced air humidity (Hordeum vulgare). Our results, indicating that in changing environmental conditions species-specific stomatal responses are evident that cannot be predicted from studying one factor at a time, might be interesting for stomatal modellers, too.
authors.affiliation: Institute of Technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia.
authors.forename: Ebe
authors.initials: E
authors.lastname: Merilo
authors.affiliation: Institute of Technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia.
authors.forename: Indrek
authors.initials: I
authors.lastname: Jõesaar
authors.affiliation: Institute of Technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia.|Division of Plant Biology, Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014, Helsinki, Finland.
authors.forename: Mikael
authors.initials: M
authors.lastname: Brosché
authors.affiliation: Institute of Technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia.
authors.forename: Hannes
authors.initials: H
authors.lastname: Kollist
mesh_terms: D017360:Arabidopsis / Q000502:physiology*; D002245:Carbon Dioxide; D004777:Environment; D005740:Gases; D006813:Humidity; D008027:Light; D010788:Photosynthesis; D054046:Plant Stomata / Q000502:physiology*; D018526:Plant Transpiration; D006109:Poaceae / Q000502:physiology*; D015398:Signal Transduction; D013045:Species Specificity; D014026:Nicotiana / Q000502:physiology*; D014867:Water
chemical_list: D005740:Gases; D014867:Water; D002245:Carbon Dioxide
keywords: Arabidopsis thaliana; Hordeum vulgare; Nicotiana tabacum; Thellungiella salsuginea; Triticum aestivum; crosstalk; environmental factors; stomata