Role of nitric oxide in hydrogen peroxide-dependent induction of abiotic stress tolerance by brassinosteroids in cucumber

• Published in: Plant, cell and environment cell and environment, 2011-02, Vol.34 (2), p.347-358
• Main Authors: CUI, JIN-XIA, ZHOU, YAN-HONG, DING, JIAN-GANG, XIA, XIAO-JIAN, SHI, KAI, CHEN, SHUANG-CHEN, ASAMI, TADAO, CHEN, ZHIXIANG, YU, JING-QUAN
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Biological and medical sciences; brassinosteroids; Brassinosteroids - pharmacology; confocal laser‐scanning microscopy; Cucumis sativus; Cucumis sativus - drug effects; Cucumis sativus - enzymology; Cucumis sativus - genetics; Cucumis sativus - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant - drug effects; Glutathione Reductase - genetics; Glutathione Reductase - metabolism; Hydrogen; hydrogen peroxide; Hydrogen Peroxide - analysis; Hydrogen Peroxide - metabolism; Microscopy, Confocal; Nitric oxide; Nitric Oxide - analysis; Nitric Oxide - metabolism; Plant Growth Regulators - metabolism; Plant Growth Regulators - pharmacology; Plant Leaves - enzymology; Plant Leaves - genetics; Plant Leaves - metabolism; Plant Proteins - genetics; Plant Proteins - metabolism; reactive oxygen species; Seedlings - drug effects; Seedlings - enzymology; Seedlings - genetics; Seedlings - metabolism; Signal Transduction; Steroids, Heterocyclic - pharmacology; Stress; stress tolerance; Triazoles - pharmacology
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/j.1365-3040.2010.02248.x

Brassinosteroids (BRs) can induce plant tolerance to a variety of abiotic stresses by triggering the generation of H₂O₂ as a signalling molecule in cucumber leaves. Whether nitric oxide (NO) also plays a signalling role and, if so, what is the relationship between NO and H₂O₂ in BR-induced stress tolerance are unknown. Involvement of NO and H₂O₂ in BR-induced tolerance was examined. NO accumulation and defence related gene transcripts were monitored by confocal laser-scanning microscopy and qRT-PCR, respectively. NO content was elevated after treatment with 24-epibrassinolide (EBR) and reduced with the inhibition of BR biosynthesis. EBR-induced NO production was blocked by pre-treatment with inhibitor of NADPH oxidase and a reactive oxygen species scavenger. On the other hand, EBR-induced H₂O₂ generation was not sensitive to NO scavenger or inhibitor of NO production. Scavenging or inhibition of NO production inhibited EBR-induced tolerance to photo-oxidative and cold stress and partly blocked EBR-induced expression and activities of several antioxidant enzymes. Pre-treatment of the exogenous NO precursor, on the other hand, led to both increased stress tolerance and increased expression of antioxidant enzymes. These results strongly suggest that NO plays an important role in H₂O₂-dependent induction of plant stress tolerance by BR.