Application of glutathione to roots selectively inhibits cadmium transport from roots to shoots in oilseed rape.
Glutathione is a tripeptide involved in various aspects of plant metabolism. This study investigated the effects of the reduced form of glutathione (GSH) applied to specific organs (source leaves, sink leaves, and roots) on cadmium (Cd) distribution and behaviour in the roots of oilseed rape plants (Brassica napus) cultured hydroponically. The translocation ratio of Cd from roots to shoots was significantly lower in plants that had root treatment of GSH than in control plants. GSH applied to roots reduced the Cd concentration in the symplast sap of root cells and inhibited root-to-shoot Cd translocation via xylem vessels significantly. GSH applied to roots also activated Cd efflux from root cells to the hydroponic solution. Inhibition of root-to-shoot translocation of Cd was visualized, and the activation of Cd efflux from root cells was also shown by using a positron-emitting tracer imaging system (PETIS). This study investigated a similar inhibitory effect on root-to-shoot translocation of Cd by the oxidized form of glutathione, GSSG. Inhibition of Cd accumulation by GSH was abolished by a low-temperature treatment. Root cells of plants exposed to GSH in the root zone had less Cd available for xylem loading by actively excluding Cd from the roots. Consequently, root-to-shoot translocation of Cd was suppressed and Cd accumulation in the shoot decreased.
Department of Biological Production, Faculty of Bioresource Sciences, Akita Prefectural University, 241-438 Kaidobata-Nishi, Shimoshinjo-Nakano, Akita, Japan. sinnaka@akita-pu.ac.jp
Shin-ichi
S
Nakamura
Nobuo
N
Suzui
Toshinori
T
Nagasaka
Fumiya
F
Komatsu
Noriko S
NS
Ishioka
Sayuri
S
Ito-Tanabata
Naoki
N
Kawachi
Hiroki
H
Rai
Hiroyuki
H
Hattori
Mitsuo
M
Chino
Shu
S
Fujimaki
D001692:Biological Transport; D029688:Brassica napus / Q000187:drug effects / Q000378:metabolism*; D002104:Cadmium / Q000378:metabolism* / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D005978:Glutathione / Q000494:pharmacology*; D010084:Oxidation-Reduction; D059828:Plant Cells / Q000187:drug effects / Q000378:metabolism; D053147:Plant Exudates / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects* / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects* / Q000378:metabolism; D013696:Temperature; D052584:Xylem / Q000187:drug effects / Q000378:metabolism; D015032:Zinc / Q000378:metabolism
D053147:Plant Exudates; D002104:Cadmium; D005978:Glutathione; D015032:Zinc