Dehydroascorbate uptake is impaired in the early response of Arabidopsis plant cell cultures to cadmium.
The balance between antioxidants, such as ascorbate (ASC) and glutathione, and oxidative reactive oxygen species (ROS) is known to play a pivotal role in the response of plant cells to abiotic stress. Here cell cultures of Arabidopsis thaliana were investigated with regard to their response to elevated levels of cadmium. At concentrations <100 microM, Cd induces a rapid and concentration-dependent H(2)O(2) accumulation. This response could be inhibited by diphenylene iodonium (DPI, 20 microM). Reverse transcription-PCR analysis of three RBOH (respiratory burst oxidase homologues) genes showed an increased transcription of RBOHF after 15 min. No change in ASC concentration was observed during the first 3 h after Cd addition. In contrast, glutathione levels completely diminished within 1 h. This drop could be attributed to an increase in phytochelatin 4. At the plasma membrane, Cd further induced a significant decrease in dehydroascorbate (DHA) uptake activity (up to 90% inhibition after 4 h). This decrease is not present when cells are treated with LaCl(3) before exposure to CdCl(2). LaCl(3) is a typical inhibitor of Ca channels and prevents Cd uptake in these cells as well as the Cd-induced ROS production. Therefore, these results appear to indicate that Cd uptake is a prerequisite for the change in DHA transport activity. However, DPI did not prevent the drop in DHA uptake activity present in Cd-treated Arabidopsis cells, indicating that this response seems to be independent of the Cd-induced H(2)O(2) production.
Horemans
Nele
N
Department of Biology, Plant Physiology, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium. nele.horemans@ua.ac.be
Raeymaekers
Tine
T
Van Beek
Kim
K
Nowocin
Anna
A
Blust
Ronny
R
Broos
Katleen
K
Cuypers
Ann
A
Vangronsveld
Jaco
J
Guisez
Yves
Y
D017360:Arabidopsis / Q000187:drug effects* / Q000378:metabolism; D001205:Ascorbic Acid / Q000378:metabolism; D002104:Cadmium / Q000378:metabolism / Q000494:pharmacology*; D019256:Cadmium Chloride / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D003683:Dehydroascorbic Acid / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007811:Lanthanum / Q000494:pharmacology; D009861:Onium Compounds / Q000494:pharmacology; D054811:Phytochelatins / Q000378:metabolism
D004791:Enzyme Inhibitors; D009861:Onium Compounds; D002104:Cadmium; C028521:lanthanum chloride; C007517:diphenyleneiodonium; D007811:Lanthanum; D054811:Phytochelatins; D006861:Hydrogen Peroxide; D005978:Glutathione; D019256:Cadmium Chloride; D001205:Ascorbic Acid; D003683:Dehydroascorbic Acid