The involvement of lipid peroxide-derived aldehydes in aluminum toxicity of tobacco roots.
Oxidative injury of the root elongation zone is a primary event in aluminum (Al) toxicity in plants, but the injuring species remain unidentified. We verified the hypothesis that lipid peroxide-derived aldehydes, especially highly electrophilic alpha,beta-unsaturated aldehydes (2-alkenals), participate in Al toxicity. Transgenic tobacco (Nicotiana tabacum) overexpressing Arabidopsis (Arabidopsis thaliana) 2-alkenal reductase (AER-OE plants), wild-type SR1, and an empty vector-transformed control line (SR-Vec) were exposed to AlCl(3) on their roots. Compared with the two controls, AER-OE plants suffered less retardation of root elongation under AlCl(3) treatment and showed more rapid regrowth of roots upon Al removal. Under AlCl(3) treatment, the roots of AER-OE plants accumulated Al and H(2)O(2) to the same levels as did the sensitive controls, while they accumulated lower levels of aldehydes and suffered less cell death than SR1 and SR-Vec roots. In SR1 roots, AlCl(3) treatment markedly increased the contents of the highly reactive 2-alkenals acrolein, 4-hydroxy-(E)-2-hexenal, and 4-hydroxy-(E)-2-nonenal and other aldehydes such as malondialdehyde and formaldehyde. In AER-OE roots, accumulation of these aldehydes was significantly less. Growth of the roots exposed to 4-hydroxy-(E)-2-nonenal and (E)-2-hexenal were retarded more in SR1 than in AER-OE plants. Thus, the lipid peroxide-derived aldehydes, formed downstream of reactive oxygen species, injured root cells directly. Their suppression by AER provides a new defense mechanism against Al toxicity.
Yin
Lina
L
Tottori University, Koyama, Minami 4-101, Tottori 680-8553, Japan.
Mano
Jun'ichi
J
Wang
Shiwen
S
Tsuji
Wataru
W
Tanaka
Kiyoshi
K
D000447:Aldehydes / Q000378:metabolism*; D000535:Aluminum / Q000633:toxicity*; D017360:Arabidopsis / Q000201:enzymology; D029681:Arabidopsis Proteins / Q000378:metabolism; D016923:Cell Death; D006861:Hydrogen Peroxide / Q000378:metabolism; D015227:Lipid Peroxidation; D008054:Lipid Peroxides / Q000378:metabolism*; D018384:Oxidative Stress; D018517:Plant Roots / Q000187:drug effects* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000378:metabolism; D014026:Nicotiana / Q000187:drug effects / Q000378:metabolism*
D000447:Aldehydes; D029681:Arabidopsis Proteins; D008054:Lipid Peroxides; D006861:Hydrogen Peroxide; D000535:Aluminum