title: Threshold response of stomatal closing ability to leaf abscisic acid concentration during growth.
abstract: Leaf abscisic acid concentration ([ABA]) during growth influences morpho-physiological traits associated with the plant's ability to cope with stress. A dose-response curve between [ABA] during growth and the leaf's ability to regulate water loss during desiccation or rehydrate upon re-watering was obtained. Rosa hybrida plants were grown at two relative air humidities (RHs, 60% or 90%) under different soil water potentials (-0.01, -0.06, or -0.08MPa) or upon grafting onto the rootstock of a cultivar sustaining [ABA] at elevated RH. Measurements included [ABA], stomatal anatomical features, stomatal responsiveness to desiccation, and the ability of leaves, desiccated to varying degrees, to recover their weight (rehydrate) following re-watering. Transpiration efficiency (plant mass per transpired water) was also determined. Soil water deficit resulted in a lower transpiration rate and higher transpiration efficiency at both RHs. The lowest [ABA] was observed in well-watered plants grown at high RH. [ABA] was increased by soil water deficit or grafting, at both RHs. The growth environment-induced changes in stomatal size were mediated by [ABA]. When [ABA] was increased from the level of (well-watered) high RH-grown plants to the value of (well-watered) plants grown at moderate RH, stomatal responsiveness was proportionally improved. A further increase in [ABA] did not affect stomatal responsiveness to desiccation. [ABA] was positively related to the ability of dehydrated leaves to rehydrate. The data indicate a growth [ABA]-related threshold for stomatal sensitivity to desiccation, which was not apparent either for stomatal size or for recovery (rehydration) upon re-watering.
authors.affiliation: Department of Food Science, Århus University, Kirstinebjergvej 10, DK-5792, Årslev, Denmark.
authors.forename: Habtamu
authors.initials: H
authors.lastname: Giday
authors.affiliation: Institute for Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich, D-52425 Jülich, Germany.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Fanourakis
authors.affiliation: Department of Food Science, Århus University, Kirstinebjergvej 10, DK-5792, Årslev, Denmark.
authors.forename: Katrine H
authors.initials: KH
authors.lastname: Kjaer
authors.affiliation: Department of Agroecology-Crop Health, Århus University, Forsøgsvej 1, 4200 Slagelse, Denmark.
authors.forename: Inge S
authors.initials: IS
authors.lastname: Fomsgaard
authors.affiliation: Department of Food Science, Århus University, Kirstinebjergvej 10, DK-5792, Årslev, Denmark CO.Ottosen@agrsci.dk.
authors.forename: Carl-Otto
authors.initials: CO
authors.lastname: Ottosen
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D003890:Desiccation; D006813:Humidity; D054046:Plant Stomata / Q000502:physiology*; D018526:Plant Transpiration; D027826:Rosa / Q000502:physiology*; D012987:Soil; D014867:Water / Q000502:physiology*
chemical_list: D012987:Soil; D014867:Water; D000040:Abscisic Acid
keywords: Evaporative demand; grafting; rehydration; relative air humidity; soil water deficit; stomatal closure; stomatal malfunction; stomatal size; transpiration; transpiration efficiency.