Nitric oxide is involved in cadmium-induced programmed cell death in Arabidopsis suspension cultures.
Exposure to cadmium (Cd(2+)) can result in cell death, but the molecular mechanisms of Cd(2+) cytotoxicity in plants are not fully understood. Here, we show that Arabidopsis (Arabidopsis thaliana) cell suspension cultures underwent a process of programmed cell death when exposed to 100 and 150 microm CdCl(2) and that this process resembled an accelerated senescence, as suggested by the expression of the marker senescence-associated gene12 (SAG12). CdCl(2) treatment was accompanied by a rapid increase in nitric oxide (NO) and phytochelatin synthesis, which continued to be high as long as cells remained viable. Hydrogen peroxide production was a later event and preceded the rise of cell death by about 24 h. Inhibition of NO synthesis by N(G)-monomethyl-arginine monoacetate resulted in partial prevention of hydrogen peroxide increase, SAG12 expression, and mortality, indicating that NO is actually required for Cd(2+)-induced cell death. NO also modulated the extent of phytochelatin content, and possibly their function, by S-nitrosylation. These results shed light on the signaling events controlling Cd(2+) cytotoxicity in plants.
De Michele
Roberto
R
Dipartimento di Biologia, Università degli Studi di Padova, I-35131 Padova, Italy. demicheler@virgilio.it
Vurro
Emanuela
E
Rigo
Chiara
C
Costa
Alex
A
Elviri
Lisa
L
Di Valentin
Marilena
M
Careri
Maria
M
Zottini
Michela
M
Sanità di Toppi
Luigi
L
Lo Schiavo
Fiorella
F
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism; D060387:Ascorbate Peroxidases; D002104:Cadmium / Q000633:toxicity*; D002374:Catalase / Q000378:metabolism; D018929:Cell Culture Techniques; D016922:Cellular Senescence / Q000187:drug effects; D003546:Cysteine Endopeptidases / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism / Q000502:physiology*; D010544:Peroxidases / Q000378:metabolism; D054811:Phytochelatins / Q000494:pharmacology; D015398:Signal Transduction
D029681:Arabidopsis Proteins; D002104:Cadmium; D009569:Nitric Oxide; D054811:Phytochelatins; D006861:Hydrogen Peroxide; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D002374:Catalase; C402082:SAG12 protein, Arabidopsis; D003546:Cysteine Endopeptidases