Effects of osmotic stress on antioxidant enzymes activities in leaf discs of P<sub>SAG12</sub>-<em>IPT</em> modified gerbera

^{Key Laboratory of Horticultural Plant Development and Biotechnology, Department of Horticulture, Zhejiang University, Hangzhou 310029, China}

^{Institute of Biotechnology, Zhejiang University, Hangzhou 310029, China}

^{Department of Horticulture, Zhejiang Forestry University, Lin’an 311300, China}

^{Corresponding Author}

†E-mail:nc.ude.ujz@uhzjhz

Received 2006 Sep 26; Accepted 2007 Feb 8.

Abstract

Leaf senescence is often caused by water deficit and the chimeric gene P_SAG12-IPT is an auto-regulated gene delaying leaf senescence. Using in vitro leaf discs culture system, the changes of contents of chlorophylls, carotenoids, soluble protein and thiobarbituric acid reactive substance (TBARS) and antioxidant enzymes activities were investigated during leaf senescence of P_SAGl2-IPT modified gerbera induced by osmotic stress compared with the control plant (wild type). Leaf discs were incubated in 20%, 40% (w/v) polyethylene glycol (PEG) 6 000 nutrient solution for 20 h under continuous light [130 µmol/(m^{·s)]. The results showed that the contents of chlorophylls, carotenoids and soluble protein were decreased by osmotic stress with the decrease being more pronounced at 40% PEG, but that, at the same PEG concentration the decrease in the transgenic plants was significantly lower than that in the control plant. The activities of superoxide dismutase (SOD), catalases (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and dehydroascorbate reductase (DHAR) were stimulated by PEG treatment. However, the increases were higher in P}_SAG12-IPT transgenic plants than in the control plants, particularly at 40% PEG treatment. Lipid peroxidation (TBARS content) was increased by PEG treatment with the increase being much lower in transgenic plant than in the control plant. It could be concluded that the increases in the activities of antioxidant enzymes including SOD, CAT, APX, GPX and DHAR were responsible for the delay of leaf senescence induced by osmotic stress.

Keywords: Antioxidant enzymes, Gerbera, Leaf disc, Leaf senescence, Osmotic stress, P_SAG12-IPT

Abstract

References

1. Allen RG, Balin AKOxidative influence on development and differentiation: an overview of a free radical theory of development. Free Radic Biol Med. 1989;6(6):631–661. doi: 10.1016/0891-5849(89)90071-3.] [[PubMed][Google Scholar]
2. Alscher RG, Erturk N, Heath LSRole of superoxide dismutases in controlling oxidative stress in plants. J Exp Bot. 2002;53(372):1331–1341. doi: 10.1093/jexbot/53.372.1331.] [[PubMed][Google Scholar]
3. Aziz A, Larher FOsmotic stress induced changes in lipid composition and peroxidation in leaf discs of Brassica napus L. J Plant Physiol. 1998;153(5):754–762.[PubMed][Google Scholar]
4. Behera SK, Nayak L, Biswal BSenescing leaves possess potential for stress adaptation: the developing leaves acclimated to high light exhibit increased tolerance to osmotic stress during senescence. J Plant Physiol. 2003;160(2):125–131. doi: 10.1078/0176-1617-00791.] [[PubMed][Google Scholar]
5. Bradford MMA rapid and sensitive method for the quantitation of micogram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976;72(1-2):248–254. doi: 10.1016/0003-2697(76)90527-3.] [[PubMed][Google Scholar]
6. de Haan JB, Cristiano F, Iannello R, Bladier C, Kelner MJ, Kola IElevation in the ratio of Cu/Zn-superoxide dismutase to glutathione peroxidase activity induces features of cellular senescence and this effect is mediated by hydrogen peroxide. Hum Mol Genet. 1996;5(2):283–292. doi: 10.1093/hmg/5.2.283.] [[PubMed][Google Scholar]
7. Dertinger U, Schaz U, Schulz EDAge-dependence of the antioxidative system in tobacco with enhanced glutathione reductase activity or senescence-induced production of cytokinins. Physiol Plant. 2003;119(1):19–29. doi: 10.1034/j.1399-3054.2003.00095.x.[PubMed][Google Scholar]
8. Dong HZ, Li WJ, Tang W, Li ZH, Zhang DM, Niu YHYield, quality and leaf senescence of cotton grown at varying planting dates and plant densities in the Yellow River Valley of China. Field Crops Res. 2006;98(2-3):106–115. doi: 10.1016/j.fcr.2005.12.008.[PubMed][Google Scholar]
9. Foyer CH, Lelandais M, Kunert KJPhotooxidative stress in plants. Physiol Plant. 1994;92(4):696–717. doi: 10.1034/j.1399-3054.1994.920422.x.[PubMed][Google Scholar]
10. Gan S, Amasino RMInhibition of leaf senescence by autoregulated production of cytokinin. Science. 1995;270(5244):1986–1988. doi: 10.1126/science.270.5244.1986.] [[PubMed][Google Scholar]
11. Gan S, Amasino RMMaking sense of senescence. Plant Physiol. 1997;113(2):313–319.[Google Scholar]
12. Guo YF, Gan SSLeaf senescence: signals, execution, and regulation. Current Topics in Developmental Biology. 2005;71:83–112.[PubMed][Google Scholar]
13. Huguet-Robert V, Sulpice R, Lefort C, Maerskalck V, Emery N, Larher FRThe suppression of osmoinduced proline response of Brassica napus L. var oleifera leaf discs by polyunsaturated fatty acids and methyljasmonate. Plant Sci. 2003;164(1):119–127. doi: 10.1016/S0168-9452(02)00343-6.[PubMed][Google Scholar]
14. Jandrew J, Clark DGSelectively induced nutrient deficiency in transgenic P_SAG12-IPT, P_SAG13-IPT and P_SAG12-Kn1 petunias. HortSci. 2001;36:518–519.[PubMed][Google Scholar]
15. Lascano HR, Antonicelli GE, Luna CM, Melchiorre MN, Gómez LD, Racca RW, Trippi VS, Casano LMAntioxidant system response of different wheat cultivars under drought: field and in vitro studies. Aust J Plant Physiol. 2001;28(11):1095–1102.[PubMed][Google Scholar]
16. Li WX, Zhang M, Yu HQStudy on hypobaric storage of green asparagus. J Food Eng. 2006;73(3):225–230. doi: 10.1016/j.jfoodeng.2005.01.024.[PubMed][Google Scholar]
17. Lichtenthaler HKChlorophylls and carotenoids: pigments of photosynthetic biomembranes. Meth Enzymol. 1987;148:350–382.[PubMed][Google Scholar]
18. Ludewig F, Sonnewald UHigh CO₂-mediated down-regulation of photosynthetic gene transcripts is caused by accelerated leaf senescence rather than sugar accumulation. FEBS Letters. 2000;479(1-2):19–24. doi: 10.1016/S0014-5793(00)01873-1.] [[PubMed][Google Scholar]
19. McCabe MS, Garratt LC, Schepers F, Jordi WJRM, Stoopen GM, Davelaar E, van Rhijn JHA, Power JB, Davey MREffects of P_SAG12-IPT gene expression on development and senescence in transgenic lettuce. Plant Physiol. 2001;127(2):505–516. doi: 10.1104/pp.127.2.505.] [[Google Scholar]
20. Mignotte B, Vayssiere JLMitochondria and apoptosis. Eur J Biochem. 1998;252(1):1–15. doi: 10.1046/j.1432-1327.1998.2520001.x.] [[PubMed][Google Scholar]
21. Nakano Y, Asada KHydrogen peroxide scanvenged by ascorbated specific peroxidase in spinach chloroplast. Plant Cell Physiol. 1981;22(5):867–880.[PubMed][Google Scholar]
22. Nickel RS, Cunningham BAImproved peroxidase assay method using Ieuco 2,3,6-trichlcroindophenol and application to comparative measurements of peroxidase catalysis. Anal Biochem. 1969;27(2):292–299. doi: 10.1016/0003-2697(69)90035-9.] [[PubMed][Google Scholar]
23. Pastori GM, Rio LANatural senescence of pea leaves, an activated oxygen-mediated function for peroxisomes. Plant Physiol. 1997;113(2):411–418.[Google Scholar]
24. Patra HL, Kar M, Mishre DCatalase activity in leaves and cotyledons during plant development and senescence. Biochem Physiol. 1978;172(4):385–390.[PubMed][Google Scholar]
25. Shalata A, Tal MThe effect of salt stress on lipid peroxidation and antioxidants in the leaf of the cultivated tomato and its wild salt-tolerant relative Lycopersicon pennellii . Physiol Plant. 1998;104(2):169–174. doi: 10.1034/j.1399-3054.1998.1040204.x.[PubMed][Google Scholar]
26. Shibanuma M, Kuroki T, Nose KStimulation by hydrogen peroxide of DNA synthesis, competence family gene expression and phosphorylation of a specific protein in quiescent Balb/3T3 cells. Oncogene. 1990;5(7):1025–1032.[PubMed][Google Scholar]
27. Stewart RC, Bewley JDLipid peroxidation associated with accelerated aging of soybean axes. Plant Physiol. 1980;65(2):245–248.[Google Scholar]
28. Sun YFree radicals, antioxidant enzymes, and carcinogenesis. Free Radic Biol Med. 1990;8(6):583–599. doi: 10.1016/0891-5849(90)90156-D.] [[PubMed][Google Scholar]
29. Thomas JC, Smigoli AC, Bohnert HJLight-inducible expression of ipt from Agrobacterium tumefaciens results in cytokinin accumulation and osmotic stress symptoms in transgenic tobacco. Plant Mol Biol. 1995;27(2):225–235. doi: 10.1007/BF00020179.] [[PubMed][Google Scholar]
30. Toit ES, Robbertse PJ, Niederwieser JG. Temperature regime during bulb production affects foliage and flower quality of Lachenalia cv. Ronina pot plants. Scientia Horticulturae. 2004;102(4):441–448.[PubMed]
31. Turtola S, Rousi M, Pusenius J, Yamaji K, Heiska S, Tirkkonen V, Meier B, Riitta JTGenotypic variation in drought response of willows grown under ambient and enhanced UV-B radiation. Environmental and Experimental Botany. 2006;56(1):80–86. doi: 10.1016/j.envexpbot.2005.01.007.[PubMed][Google Scholar]
32. Wang J, Letham DS, Cornish E, Stevenson KRStudies of cytokinin action and metabolism using tobacco plants expressing either the ipt or the GUS gene controlled by a chalcone synthase promoter I developmental features of the transgenic plants. Plant Physiol. 1997;24(5):661–672.[PubMed][Google Scholar]
33. Zhu ZJ, Gerendas J, Bendixen R, Schinner K, Tabrizi H, Sattelmacher B, Hansen UPDifferent tolerance to light stress in NO₃^{and NH}₄^-grownPhaseolus vulgaris L. Plant Biol. 2000;2(5):558–570. doi: 10.1055/s-2000-7498.[PubMed][Google Scholar]