title: Histidine promotes the loading of nickel and zinc, but not of cadmium, into the xylem in Noccaea caerulescens.
abstract: Histidine is known to be involved in Ni hyperaccumulation. Recently, histidine-dependent xylem loading of Ni and Zn has been demonstrated in the Zn/Ni/Cd hyperaccumulator, Noccaea caerulescens. Here we tested the hypothesis whether Cd xylem loading is histidine-dependent, too. In contrast to that of Ni and Zn, the xylem loading of Cd was not affected by exogenous histidine. Histidine accumulation in root cells appears to facilitate the radial transport of Ni and Zn, but not Cd, across the roots. This may be due to the relatively high preference of Cd for coordination with sulfur over coordination with nitrogen, in comparison with Ni and Zn.
authors.affiliation: a Laboratory of Root Physiology; Timiryazev Institute of Plant Physiology; Russian Academy of Sciences; Moscow, Russia.
authors.forename: Anna D
authors.initials: AD
authors.lastname: Kozhevnikova
authors.forename: Ilya V
authors.initials: IV
authors.lastname: Seregin
authors.forename: Rudo
authors.initials: R
authors.lastname: Verweij
authors.forename: Henk
authors.initials: H
authors.lastname: Schat
mesh_terms: D001693:Biological Transport, Active / Q000187:drug effects; D019607:Brassicaceae / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002104:Cadmium / Q000378:metabolism*; D006639:Histidine / Q000378:metabolism* / Q000494:pharmacology; D009532:Nickel / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D052584:Xylem / Q000187:drug effects / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism*
chemical_list: D002104:Cadmium; D006639:Histidine; D009532:Nickel; D015032:Zinc
keywords: Noccaea caerulescens; cadmium; histidine; hyperaccumulation; xylem loading