title: The Arabidopsis-related halophyte Thellungiella halophila: boron tolerance via boron complexation with metabolites?
abstract: Tolerance to boron (B) is still not completely understood. We tested here the hypothesis that Thellungiella halophila, an Arabidopsis thaliana-related 'extremophile' plant, with abundance of B in its natural environment, is tolerant to B, and examined the potential mechanisms of this tolerance. With 1-10 mm B applied ([B](ext)) to Thellungiella and Arabidopsis grown in hydroponics, the steady-state accumulated B concentration ([B](int)) in the root was below [B](ext), and was similar in both, suggesting both extrude B actively. Whether grown in soil or hydroponically, the shoot [B](int) was higher in Arabidopsis than in Thellungiella, suggesting more effective net B exclusion by Thellungiella root. Arabidopsis exhibited toxicity symptoms including reduced shoot fresh weight (FW), but Thellungiella was not affected, even at similar levels of shoot-accumulated [B](int) (about 10 to 40 mm B in 'shoot water'), suggesting additional B tolerance mechanism in Thellungiella shoot. At [B](ext) = 5 mm, the summed shoot concentration of the potentially B-binding polyhydroxyl metabolites (malic acid, fructose, glucose, sucrose and citric acid) in Arabidopsis was below [B](int) , but in Thellungiella it was over twofold higher than [B](int) , and therefore likely to allow appreciable 1:2 boron-metabolite complexation in the shoot. This, we suggest, is an important component of Thellungiella B tolerance mechanism.
authors: The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors: Netta Li
authors: NL
authors: Lamdan
authors: Ziv
authors: Z
authors: Attia
authors: Nava
authors: N
authors: Moran
authors: Menachem
authors: M
authors: Moshelion
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D018533:Biomass; D001895:Boron / Q000032:analysis / Q000378:metabolism / Q000633:toxicity*; D019607:Brassicaceae / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D019343:Citric Acid / Q000032:analysis / Q000378:metabolism; D005632:Fructose / Q000032:analysis / Q000378:metabolism; D005947:Glucose / Q000032:analysis / Q000378:metabolism; D018527:Hydroponics; D008293:Malates / Q000032:analysis / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D055051:Salt-Tolerant Plants / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D012987:Soil; D013312:Stress, Physiological / Q000187:drug effects / Q000502:physiology*; D013395:Sucrose / Q000032:analysis / Q000378:metabolism
chemical_list: D008293:Malates; D012987:Soil; D019343:Citric Acid; D005632:Fructose; D013395:Sucrose; C030298:malic acid; D005947:Glucose; D001895:Boron