Nitric oxide is induced by wounding and influences jasmonic acid signaling in Arabidopsis thaliana.
Nitric oxide (NO) has been associated with plant defense responses during microbial attack, and with induction and/or regulation of programmed cell death. Here, we addressed whether NO participates in wound responses in Arabidopsis thaliana (L.) Heynh. Real-time imaging by confocal laser-scanning microscopy in conjunction with the NO-selective fluorescence indicator 4,5-diaminofluorescein diacetate (DAF-2 DA) uncovered a strong NO burst after wounding or after treatment with JA. The NO burst was triggered within minutes, reminiscent of the oxidative burst during hypersensitive responses. Furthermore, we were able to detect NO in plants (here induced by wounding) by means of electron paramagnetic resonance measurements using diethyldithiocarbamate as a spin trap. When plants were treated with NO, Northern analyses revealed that NO strongly induces key enzymes of jasmonic acid (JA) biosynthesis such as allene oxide synthase (AOS) and lipoxygenase (LOX2). On the other hand, wound-induced AOS gene expression was independent of NO. Furthermore, JA-responsive genes such as defensin (PDF1.2) were not induced, and NO induction of JA-biosynthesis enzymes did not result in elevated levels of JA. However, treatment with NO resulted in accumulation of salicylic acid (SA). In transgenic NahG plants (impaired in SA accumulation and/or signaling), NO did induce JA production and expression of JA-responsive genes. Altogether, the presented data demonstrate that wounding in Arabidopsis induces a fast accumulation of NO, and that NO may be involved in JA-associated defense responses and adjustments.
Huang
Xi
X
Institute of Biochemical Plant Pathology, GSF--National Research Center for Environment and Health, 85764 Oberschleissheim, Germany.
Stettmaier
Kurt
K
Michel
Christa
C
Hutzler
Peter
P
Mueller
Martin J
MJ
Durner
Jörg
J
D017360:Arabidopsis / Q000737:chemistry* / Q000378:metabolism*; D003517:Cyclopentanes / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018613:Microscopy, Confocal; D009569:Nitric Oxide / Q000096:biosynthesis*; D054883:Oxylipins; D019441:Plant Epidermis / Q000166:cytology / Q000648:ultrastructure; D018515:Plant Leaves / Q000737:chemistry / Q000235:genetics; D015398:Signal Transduction; D014947:Wounds and Injuries / Q000378:metabolism*
D003517:Cyclopentanes; D054883:Oxylipins; D009569:Nitric Oxide; C011006:jasmonic acid