PLANT PHYSIOLOGY , Vol 109, Issue 4 1191-1197, Copyright © 1995 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
Induction of Nopaline Synthase Promoter Activity by H2O2 Has No Direct Correlation with Salicylic Acid
Z. Dai and G. An
Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340 (Z.D., G.A.)
Transgenic tobacco (Nicotiana tabacum L.) plants carrying a fusion between
the nopaline synthase (nos) promoter and chloramphenicol acetyltransferase
(CAT) reporter gene (cat) were tested for their response to treatment with
H2O2. The nos promoter-driven CAT activity increased significantly by
addition of H2O2, reaching the maximum level at 15 mM. Kinetic analysis for
CAT activity showed that induction by H2O2 was similar to that of methyl
jasmonate (MJ), but was much slower than induction by salicylic acid (SA).
Time-course experiments for mRNA level also revealed that the response to
H2O2 treatment was similar to that of MJ. The nos promoter displayed a
rapid and transient induction of mRNA with SA treatment, with the maximum
levels occurring at 3 h, whereas the levels induced by H2O2 or MJ treatment
increased continuously during the 11-h experimental period. The
antioxidants N-acetyl-L-cysteine and catechol did not alter the SA effect.
The responses of the nos promoter to H2O2, MJ, and wounding were
significantly reduced by deletions of the CAAT box region and the sequence
between -112 and -101. However, these deletions did not significantly alter
the SA response. This suggests that H2O2 may have a different mechanism
from that of SA for inducing nos promoter activity.
