Overexpression of a cytoplasm-localized allene oxide synthase promotes the wound-induced accumulation of jasmonic acid in transgenic tobacco

Overexpression of a cytoplasm-localized allene oxide synthase promotes the wound-induced... Jasmonic acid (JA) is involved in regulating the expression of certain plant defense genes and response to various stresses. JA biosynthesis is hypothesized to occur both in chloroplasts and the cytoplasm. In order to test whether or not a cytosol-localized allene oxide synthase (AOS) can promote JA biosynthesis, transgenic tobacco plants containing a flax AOS cDNA without a chloroplast transit sequence under the control of a tetracycline-inducible promoter were generated. Induction of the flax AOS gene in transgenic plants with chlor-tetracycline (Tc) led to the expression of the flax AOS mRNA and protein, which resulted in high level of metabolism of 13(S)-hydroperoxyoctadecatrienoic acid (13(S)-HPOT) and formation of 12-oxo-phytodienoic acid (12-O-PDA). Subcellular fractionation demonstrated that the flax AOS protein and activity were associated with the cytosol. Overexpression of the flax AOS in induced transgenic plants did not increase JA levels in healthy, undamaged leaf tissues. However, in wounded tissues overexpressing a flax AOS, levels of JA and the transcript of a pathogenesis-related gene (PR-1) dramatically increased when compared to those not expressing the flax AOS. Analysis of the release of wound-induced C6 volatiles showed that the level of (Z)-3-hexen-1-ol decreased about 30% due to overexpression of the cytoplasm-localized AOS, while (Z)-3-hexenal and (Z)-3-hexenyl acetate appeared not to be significantly altered. The data indicate that cytoplasmic AOS responds to wounding by increasing the levels of the wound-induced JA which in turn directly or indirectly enhances the expression of plant defense genes. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant Molecular Biology Springer Journals

Overexpression of a cytoplasm-localized allene oxide synthase promotes the wound-induced accumulation of jasmonic acid in transgenic tobacco

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Publisher
Kluwer Academic Publishers
Copyright
Copyright © 1999 by Kluwer Academic Publishers
Subject
Life Sciences; Biochemistry, general; Plant Sciences; Plant Pathology
ISSN
0167-4412
eISSN
1573-5028
D.O.I.
10.1023/A:1006253927431
Publisher site
See Article on Publisher Site

Abstract

Jasmonic acid (JA) is involved in regulating the expression of certain plant defense genes and response to various stresses. JA biosynthesis is hypothesized to occur both in chloroplasts and the cytoplasm. In order to test whether or not a cytosol-localized allene oxide synthase (AOS) can promote JA biosynthesis, transgenic tobacco plants containing a flax AOS cDNA without a chloroplast transit sequence under the control of a tetracycline-inducible promoter were generated. Induction of the flax AOS gene in transgenic plants with chlor-tetracycline (Tc) led to the expression of the flax AOS mRNA and protein, which resulted in high level of metabolism of 13(S)-hydroperoxyoctadecatrienoic acid (13(S)-HPOT) and formation of 12-oxo-phytodienoic acid (12-O-PDA). Subcellular fractionation demonstrated that the flax AOS protein and activity were associated with the cytosol. Overexpression of the flax AOS in induced transgenic plants did not increase JA levels in healthy, undamaged leaf tissues. However, in wounded tissues overexpressing a flax AOS, levels of JA and the transcript of a pathogenesis-related gene (PR-1) dramatically increased when compared to those not expressing the flax AOS. Analysis of the release of wound-induced C6 volatiles showed that the level of (Z)-3-hexen-1-ol decreased about 30% due to overexpression of the cytoplasm-localized AOS, while (Z)-3-hexenal and (Z)-3-hexenyl acetate appeared not to be significantly altered. The data indicate that cytoplasmic AOS responds to wounding by increasing the levels of the wound-induced JA which in turn directly or indirectly enhances the expression of plant defense genes.

Journal

Plant Molecular BiologySpringer Journals

Published: Oct 19, 2004

References

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