Increased abscisic acid levels in transgenic tobacco over-expressing 9 cis-epoxycarotenoid dioxygenase influence H2O2 and NO production and antioxidant defences.

Abscisic acid (ABA) regulates the plant's adaptive responses to abiotic stresses. Over-expression of the 9-cis-epoxycarotenoid dioxygenase gene (SgNCED1) in the transgenic tobaccos increased ABA content and tolerance to drought and salt stresses. H2O2 and nitric oxide (NO) contents were enhanced in guard cells and mesophyll cells of the transgenic plants, accompanied with increased transcripts and activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR). The enhancements of H2O2 and NO and transcripts and activities of antioxidant enzymes in the transgenic plants were blocked by pre-treatments with inhibitor of ABA biosynthesis, scavengers of H2O2 and NO, and inhibitors of NADPH oxidase and NO synthase-like (NOS-like). The elevated production of NO in the transgenic plants was blocked by scavenger of H2O2 and inhibitors of NADPH oxidase, whereas H2O2 level was not affected by scavenger of NO and inhibitor of NOS-like, indicating that H2O2 is essential for the elevated production of NO. The results demonstrate that the increased drought and salt tolerance in the transgenic plants is associated with ABA-induced production of H2O2 via NADPH oxidase and NO via NOS-like, which sequentially induce transcripts and activities of SOD, CAT, APX and GR.

[1]  Jianhua Zhang,et al.  Mitogen-Activated Protein Kinase Is Involved in Abscisic Acid-Induced Antioxidant Defense and Acts Downstream of Reactive Oxygen Species Production in Leaves of Maize Plants1 , 2006, Plant Physiology.

[2]  D. Kim,et al.  Transgenic Plants of Creeping Bent Grass Harboring the Stress Inducible Gene, 9-cis-epoxycarotenoid dioxygenase, are Highly Tolerant to Drought and NaCl Stress , 2005, Plant Growth Regulation.

[3]  Xiaorong Wan,et al.  Regulation of ABA level and water-stress tolerance of Arabidopsis by ectopic expression of a peanut 9-cis-epoxycarotenoid dioxygenase gene. , 2006, Biochemical and biophysical research communications.

[4]  J. Hancock,et al.  Hydrogen peroxide is a common signal for darkness- and ABA-induced stomatal closure in Pisum sativum. , 2004, Functional plant biology : FPB.

[5]  J. Zeevaart,et al.  The 9-cis-epoxycarotenoid cleavage reaction is the key regulatory step of abscisic acid biosynthesis in water-stressed bean. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[6]  Jianhua Zhang,et al.  Nitric oxide induced by hydrogen peroxide mediates abscisic acid-induced activation of the mitogen-activated protein kinase cascade involved in antioxidant defense in maize leaves. , 2007, The New phytologist.

[7]  Jinfen Yang,et al.  Overexpressing SgNCED1 in Tobacco Increases ABA Level, Antioxidant Enzyme Activities, and Stress Tolerance , 2008, Journal of Plant Growth Regulation.

[8]  Radhika Desikan,et al.  A new role for an old enzyme: Nitrate reductase-mediated nitric oxide generation is required for abscisic acid-induced stomatal closure in Arabidopsis thaliana , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[9]  L. Lamattina,et al.  Nitric oxide plays a central role in determining lateral root development in tomato , 2004, Planta.

[10]  Jianhua Zhang,et al.  Water stress-induced abscisic acid accumulation triggers the increased generation of reactive oxygen species and up-regulates the activities of antioxidant enzymes in maize leaves. , 2002, Journal of experimental botany.

[11]  A. Thompson,et al.  Ectopic expression of a tomato 9-cis-epoxycarotenoid dioxygenase gene causes over-production of abscisic acid. , 2000, The Plant journal : for cell and molecular biology.

[12]  Bingru Huang,et al.  Nitric oxide is involved in abscisic acid-induced antioxidant activities in Stylosanthes guianensis. , 2005, Journal of experimental botany.

[13]  J. Hancock,et al.  Nitric oxide synthesis and signalling in plants. , 2008, Plant, cell & environment.

[14]  M. M. Bradford.  A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. , 1976, Analytical biochemistry.

[15]  Zhi-li Liu,et al.  Effects of Abscisic Acid on Antioxidant Systems of Stylosanthes guianensis (Aublet) Sw. under Chilling Stress , 2005 .

[16]  J. Hancock,et al.  ABA-induced NO generation and stomatal closure in Arabidopsis are dependent on H2 O2 synthesis. , 2006, The Plant journal : for cell and molecular biology.

[17]  K. Cline,et al.  Molecular characterization of the Arabidopsis 9-cis epoxycarotenoid dioxygenase gene family. , 2003, The Plant journal : for cell and molecular biology.

[18]  K. Shinozaki,et al.  Regulation of drought tolerance by gene manipulation of 9-cis-epoxycarotenoid dioxygenase, a key enzyme in abscisic acid biosynthesis in Arabidopsis. , 2001, The Plant journal : for cell and molecular biology.

[19]  William J. Davies,et al.  Root Signals and the Regulation of Growth and Development of Plants in Drying Soil , 1991 .

[20]  Jianhua Zhang,et al.  Cross-talk between calcium and reactive oxygen species originated from NADPH oxidase in abscisic acid-induced antioxidant defence in leaves of maize seedlings. , 2003, Plant, cell & environment.

[21]  K. Shinozaki,et al.  A stress-inducible gene for 9-cis-epoxycarotenoid dioxygenase involved in abscisic acid biosynthesis under water stress in drought-tolerant cowpea. , 2000, Plant physiology.

[22]  C. Foyer,et al.  ASCORBATE AND GLUTATHIONE: Keeping Active Oxygen Under Control. , 1998, Annual review of plant physiology and plant molecular biology.

[23]  Jianhua Zhang,et al.  Involvement of plasma-membrane NADPH oxidase in abscisic acid- and water stress-induced antioxidant defense in leaves of maize seedlings , 2002, Planta.

[24]  C. Larsson,et al.  [52] Preparation of high-purity plasma membranes , 1987 .

[25]  J. Zeevaart,et al.  Overexpression of a 9-cis-Epoxycarotenoid Dioxygenase Gene in Nicotiana plumbaginifolia Increases Abscisic Acid and Phaseic Acid Levels and Enhances Drought Tolerance1 , 2002, Plant Physiology.

[26]  Jihua Wang,et al.  A simple colorimetric method for determination of hydrogen peroxide in plant tissues , 2006, Plant Growth Regulation.

[27]  J. Hancock,et al.  ABA, hydrogen peroxide and nitric oxide signalling in stomatal guard cells. , 2003, Journal of experimental botany.

[28]  Rongchen Wang,et al.  Nitrite Acts as a Transcriptome Signal at Micromolar Concentrations in Arabidopsis Roots1[W][OA] , 2007, Plant Physiology.

[29]  E. Nambara,et al.  Abscisic acid biosynthesis and catabolism. , 2005, Annual review of plant biology.

[30]  J. Zeevaart,et al.  Characterization of the 9-cis-epoxycarotenoid dioxygenase gene family and the regulation of abscisic acid biosynthesis in avocado. , 2000, Plant physiology.

[31]  Z. Guo,et al.  Differential responses of antioxidative system to chilling and drought in four rice cultivars differing in sensitivity. , 2006, Plant physiology and biochemistry : PPB.

[32]  J. Hancock,et al.  Hydrogen peroxide and nitric oxide as signalling molecules in plants. , 2002, Journal of experimental botany.

[33]  Jinfen Yang,et al.  Cloning of a 9-cis-epoxycarotenoid dioxygenase gene (SgNCED1) from Stylosanthes guianensis and its expression in response to abiotic stresses , 2007, Plant Cell Reports.

[34]  M. Robertson,et al.  Gene Expression Regulated by Abscisic Acid and its Relation to Stress Tolerance , 1994 .