PLANT PHYSIOLOGY , Vol 112, Issue 1 217-227, Copyright © 1996 by American Society of Plant Biologists
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WHOLE PLANT, ENVIRONMENTAL, AND STRESS PHYSIOLOGY |
Aluminum Tolerance Acquired during Phosphate Starvation in Cultured Tobacco Cells
Y. Yamamoto, K. Masamoto, S. Rikiishi, A. Hachiya, Y. Yamaguchi and H. Matsumoto
Research Institute for Bioresources, Okayama University, Kurashiki 710, Japan (Y. Yamamoto, S.R., A.H., Y. Yamaguchi, H.M.)
Al toxicity in cultured tobacco cells (Nicotiana tabacum L. cv Samsun;
nonchlorophyllic cell line SL) has been investigated in nutrient medium. In
this system, Al and Fe(II) (ferrous ion) in the medium synergistically
result in the accumulation of both Al and Fe, the peroxidation of lipids,
and eventually death in cells at the logarithmic phase of growth (+P
cells). A lipophilic antioxidant, N,N[prime]-diphenyl-p-phenylenediamine,
protected +P cells from the peroxidation of lipids and from cell death,
suggesting that a relationship exists between the two. Compared with +P
cells, cells that had been starved of Pi (-P cells) were more tolerant to
Al, accumulated 30 to 40% less Al and 70 to 90% less Fe, and did not show
any evidence of the peroxidation of lipids during Al treatment. These
results suggest that -P cells exhibit Al tolerance because their plasma
membranes are protected from the peroxidation of lipids caused by the
combination of Al and Fe(II). It seems likely that the exclusion of Fe from
-P cells might suppress directly Fe-mediated peroxidation of lipids.
Furthermore, since -P cells accumulated [beta]-carotene, it is proposed
that this carotenoid pigment might function as a radical-trapping
antioxidant in the plasma membrane of cells starved of Pi.
