TITLE

The isochorismate pathway is negatively regulated by salicylic acid signaling in O3-exposed Arabidopsis

AUTHOR(S)
Ogawa, Daisuke; Nakajima, Nobuyoshi; Tamaoki, Masanori; Aono, Mitsuko; Kubo, Akihiro; Kamada, Hiroshi; Saji, Hikaru
PUB. DATE
August 2007
SOURCE
Planta;Aug2007, Vol. 226 Issue 5, p1277
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Ozone (O3), a major photochemical oxidant, causes leaf injury in plants. Plants synthesize salicylic acid (SA), which is reported to greatly affect O3 sensitivity. However, the mechanism of SA biosynthesis under O3 exposure remains unclear. Plants synthesize SA either by a pathway involving phenylalanine as a substrate or another involving isochorismate. To clarify how SA is produced in O3-exposed Arabidopsis, we examined the activities of phenylalanine ammonia lyase (PAL) and isochorismate synthase (ICS), which are components of the phenylalanine and isochorismate pathways, respectively. Exposure of Arabidopsis to O3 enhanced the accumulation of SA and the increase of ICS activity but did not affect PAL activity. In sid2 mutants, which have a defect in ICS1, the level of SA and the activity of ICS did not increase in response to O3 exposure. These results suggest that SA is mainly synthesized from isochorismate in Arabidopsis. Furthermore, the level of ICS1 expression and the activity of ICS during O3 exposure elevated in plants deficient for SA signaling ( npr1 and eds5 mutants and NahG transgenics). Treatment of plants with SA also suppressed the enhancement of ICS1 expression by O3. These results suggest that SA synthesis is negatively regulated by SA signaling.
ACCESSION #
26492051

 

Related Articles

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics