title: Artificially decreased vapour pressure deficit in field conditions modifies foliar metabolite profiles in birch and aspen.
abstract: Relative air humidity (RH) is expected to increase in northern Europe due to climate change. Increasing RH reduces the difference of water vapour pressure deficit (VPD) between the leaf and the atmosphere, and affects the gas exchange of plants. Little is known about the effects of decreased VPD on plant metabolism, especially under field conditions. This study was conducted to determine the effects of artificially decreased VPD on silver birch (Betula pendula Roth.) and hybrid aspen (Populus tremula L.×P. tremuloides Michx.) foliar metabolite and nutrient profiles in a unique free air humidity manipulation (FAHM) field experiment during the fourth season of humidity manipulation, in 2011. Long-term exposure to decreased VPD modified nutrient homeostasis in tree leaves, as demonstrated by a lower N concentration and N:P ratio in aspen leaves, and higher Na concentration and lower K:Na ratio in the leaves of both species in decreased VPD than in ambient VPD. Decreased VPD caused a shift in foliar metabolite profiles of both species, affecting primary and secondary metabolites. Metabolic adjustment to decreased VPD included elevated levels of starch and heptulose sugars, sorbitol, hemiterpenoid and phenolic glycosides, and α-tocopherol. High levels of carbon reserves, phenolic compounds, and antioxidants under decreased VPD may modify plant resistance to environmental stresses emerging under changing climate.
authors.affiliation: University of Eastern Finland, Department of Environmental and Biological Sciences, PO Box 111, 80101 Joensuu, Finland jenna.lihavainen@uef.fi.
authors.forename: Jenna
authors.initials: J
authors.lastname: Lihavainen
authors.affiliation: University of Eastern Finland, Department of Environmental and Biological Sciences, PO Box 111, 80101 Joensuu, Finland.
authors.forename: Markku
authors.initials: M
authors.lastname: Keinänen
authors.affiliation: University of Eastern Finland, Department of Environmental and Biological Sciences, PO Box 111, 80101 Joensuu, Finland.
authors.forename: Sarita
authors.initials: S
authors.lastname: Keski-Saari
authors.affiliation: University of Eastern Finland, Department of Environmental and Biological Sciences, PO Box 111, 80101 Joensuu, Finland.
authors.forename: Sari
authors.initials: S
authors.lastname: Kontunen-Soppela
authors.affiliation: University of Tartu, Institute of Ecology and Earth Sciences, Lai 40, 51005 Tartu, Estonia.
authors.forename: Anu
authors.initials: A
authors.lastname: Sõber
authors.affiliation: University of Eastern Finland, Department of Environmental and Biological Sciences, PO Box 111, 80101 Joensuu, Finland.
authors.forename: Elina
authors.initials: E
authors.lastname: Oksanen
mesh_terms: D000975:Antioxidants / Q000032:analysis / Q000378:metabolism; D029662:Betula / Q000378:metabolism*; D006027:Glycosides / Q000032:analysis / Q000378:metabolism; D006813:Humidity; D010636:Phenols / Q000032:analysis / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism*; D032107:Populus / Q000378:metabolism*; D013012:Sorbitol / Q000032:analysis / Q000378:metabolism; D013213:Starch / Q000032:analysis / Q000378:metabolism; D024502:alpha-Tocopherol / Q000032:analysis / Q000378:metabolism
chemical_list: D000975:Antioxidants; D006027:Glycosides; D010636:Phenols; D013012:Sorbitol; D013213:Starch; D024502:alpha-Tocopherol
keywords: Betula; GC-MS; Populus; VPD.; metabolite profiling; mineral nutrients; relative humidity