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The extensin multigene family responds differentially to superoxide or hydrogen peroxide in tomato cell cultures
Author(s) -
Wisniewski Jean-Pierre,
Cornille Patrick,
Agnel Jean-Pierre,
Montillet Jean-Luc
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)00315-4
Subject(s) - superoxide , digitonin , biochemistry , superoxide dismutase , hydrogen peroxide , microbiology and biotechnology , chemistry , xanthine oxidase , gene expression , oxidase test , enzyme , biology , gene
Changes in extensin gene expression were examined in cultured tomato cells following treatments leading to the production of activated oxygen species. Digitonin, a steroid glycoalkaloid compound, has been shown to trigger a rapid and transient production of superoxide anion, O −⋅ 2 . 6 h after application of 50 or 100 μM of digitonin, the accumulation of four extensin transcripts (1.5, 2.6, 4.0 and 6.1 kb) was observed. Superoxide dismutase strongly inhibited the digitonin‐mediated response, suggesting a key role of O −⋅ 2 in the signalling cascade. Furthermore, cells treated with enzymatically produced O −⋅ 2 generated by xanthine oxidase (0.015 U/ml) gave a similar extensin response and again, SOD exerted a strong inhibitory effect on the response. On the other hand, H 2 O 2 (2 mM) or the enzymatic H 2 O 2 generator, glucose oxidase (0.34 U/ml), elicited the accumulation of only three of the four transcripts (1.5, 2.6 and 4.0 kb), indicating that the corresponding genes could be regulated either by H 2 O 2 or O −⋅ 2 but that the gene encoding the 6.1 kb transcript was exclusively expressed in response to O −⋅ 2 . Finally, it was shown that lipid peroxidation, which was only induced when cells were exposed to H 2 O 2 , did not participate in the AOS‐mediated gene expression for extensin. It can be concluded from these results that tomato cells are able to discriminate H 2 O 2 from O −⋅ 2 and they probably sense the latter by the specific oxidation of an extracellular component.