title: A role for nickel in osmotic adjustment in drought-stressed plants of the nickel hyperaccumulator Stackhousia tryonii Bailey.
abstract: The hypothesis that hyperaccumulation of certain metals in plants may play a role in osmotic adjustment under water stress (drought) was tested in the context of nickel hyperaccumulator Stackhousia tryonii. Field-collected mature plants of S. tryonii, grown in native ultramafic soil, were pruned to soil level and the re-growth exposed to five levels of water stress (20, 40, 60, 80 and 100% field capacity; FC) for 20 weeks. Water stress had significant (P<0.05) influence on growth (biomass), water potential and shoot Ni concentrations, with progressively more impact as water stress was increased from 80 to 40% FC. Shoot Ni concentration increased significantly from 3,400 microg g(-1) dry weight (at 100% FC) to 9,400 microg g(-1) dry weight (at 20% FC). Assuming that Ni is uniformly distributed through the shoot tissue, the Ni concentration could account for 100% at the 80 and 60% FC conditions, and 50% at the 40 and 20% FC conditions of plant osmotic regulation. The results are consistent with a role of Ni in osmotic adjustment and protection of S. tryonii plants against drought.
authors.affiliation: Primary Industries Research Centre, School of Biological and Environmental Sciences, Central Queensland University, 4702 Rockhampton, Queensland, Australia.
authors.forename: Naveen P
authors.initials: NP
authors.lastname: Bhatia
authors.forename: Alan J M
authors.initials: AJ
authors.lastname: Baker
authors.forename: Kerry B
authors.initials: KB
authors.lastname: Walsh
authors.forename: David J
authors.initials: DJ
authors.lastname: Midmore
mesh_terms: D000222:Adaptation, Physiological; D017632:Asbestos, Serpentine; D001692:Biological Transport; D019684:Magnoliopsida / Q000254:growth & development / Q000502:physiology*; D009532:Nickel / Q000378:metabolism*; D009994:Osmolar Concentration; D018520:Plant Shoots / Q000378:metabolism; D012987:Soil; D014867:Water / Q000502:physiology; D014882:Water-Electrolyte Balance / Q000502:physiology*
chemical_list: D017632:Asbestos, Serpentine; D012987:Soil; D014867:Water; D009532:Nickel