Skip to main content
SpringerLink
Log in

The involvement of cytokinins in plant responses to environmental stress

  • Published:
Plant Growth Regulation Aims and scope Submit manuscript

Abstract

Cytokinin (CK) levels tend to decrease under adverse environmental conditions. A general view has emerged that during stress, a reduction of CK supply from the root alters gene expression in the shoot and thereby elicits appropriate responses to ameliorate the effects of stress. However, recent studies have indicated that transcription of many stress-inducible genes can also be caused by CK application. This review attempts to highlight some of these apparently paradoxical findings and to suggest potential approaches for future research in this area. Changes in patterns of gene expression associated with responses to adverse environmental conditions are most probably the end products of hierarchical changes in regulatory controls exercised at hormonal, developmental and morphological levels. We consider possible roles for CKs in affecting overall hormonal balance following the imposition of environmental stresses, and thereby playing a role in systemic responses to stress. Particular attention is devoted to the interactions of CKs with ABA, ethylene, salicylic acid and jasmonates, all of which are known to be involved in plant stress responses. The recent emergence of MAPK-type cascades in mediating responses to several environmental modifications is discussed in relation to their possible modulation by CKs.

Since CKs are likely to elicit their effects at the level of gene expression and stress-induced alterations in gene expression are usually rapid and repeatable, molecular analysis of CK-regulated stress-inducible genes may contribute to enhanced understanding of CK-mediated signal transduction in plants. In this regard, examination of stress responses of transgenic plants with altered levels of endogenous CKs as well as mutants altered in CK metabolism or signalling may be informative. Emerging evidence that CKs may impact on methylation reactions is discussed in relation to the apparent importance of methyl group transfers in the biochemical acclimation to environmental stress.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Similar content being viewed by others

References

  1. Abdullah Z and Ahmad R (1990) Effect of pre-and post-kinetin treatments on salt tolerance of different potato cultivars growing on saline soils. J Agron Crop Sci 165: 94–102

    Google Scholar 

  2. Aharoni N, Blumenfeld A and Richmond AE (1977) Hormonal activity in detached lettuce leaves as affected by leaf water content. Plant Physiol 59: 1169–1173

    Google Scholar 

  3. Ainley WM, McNeil KJ, Hill JW, Lingle WL, Simpson RB, Brenner ML, Nagao RT and Key JL (1993) Regulatable endogenous production of cytokinins up to “toxic” levels in transgenic plants and plant tissues. Plant Mol Biol 22: 13–23

    PubMed  Google Scholar 

  4. Allen GJ and Saunders D (1994) Osmotic stress enhances the competence of Beta vulgaris vacuoles to respond to inositol 1,4,5-trisphosphate. Plant J: 687–695

  5. Amzallag GN, Lerner HR and Poljakoff-Mayber A (1992) Interaction between mineral nutrients, cytokinin and gibberellic acid during growth of Sorghum at high NaCl salinity. J Exp Bot 43: 81–87

    Google Scholar 

  6. Armstrong F, Leung J, Grabov A, Brearly J, Giraudat J and Blatt MR (1995) Sensitivity to abscisic acid of guard-cell K+ channels is suppressed by abi1-1, a mutant Arabidopsis gene encoding a putative protein phosphatase. Proc Natl Acad Sci USA 92: 9520–9524

    PubMed  Google Scholar 

  7. Badenoch-Jones J, Parker CW, Letham DS and Singh S (1996) Effect of cytokinins supplied via the xylem at multiples of endogenous concentrations on transpiration and senescence in derooted seedlings of oat and wheat. Plant Cell Environ 19: 504–516

    Google Scholar 

  8. Bailiss KW, Cocker FM and Cassels AC (1977) The effect of Benlate and cytokinins on the content of tobacco mosaic virus in tomato leaf discs and cucumber mosaic virus in cucumber cotyledon discs and seedlings. Ann Appl Biol 87: 383–392

    Google Scholar 

  9. Balázs E and Király Z (1981) Virus content and symptom expression in Samsun tobacco treated with kinetin and a benzimidazole derivative. Phytopath Z 100: 356–360

    Google Scholar 

  10. Balázs E, Sziráki I, and Király Z (1977) The role of cytokinin in the systemic acquired resistance of tobacco hypersensitive to tobacco mosaic virus. Physiol Plant Pathol 11: 29–37

    Google Scholar 

  11. Banno H, Hirano K, Nakamura T, Irie K, Nomoto S, Matsumoto K and Machida Y (1993) NPK1, a tobacco gene that encodes a protein with a domain homologous to yeast BCK1, STE11, and Byr2 protein kinases. Mol Cell Biol 13: 4745–4752

    PubMed  Google Scholar 

  12. Bano A, Dörffling K, Bettin D and Hahn H (1993) Abscisic acid and cytokinins as possible root-to-shoot signals in xylem sap of rice plants grown in drying soil. Aust J Plant Physiol 20: 109–115

    Google Scholar 

  13. Beardsell MF and Cohen D (1975) Relationships between leaf water status, abscisic acid levels and stomatal resistance in maize and sorghum. Plant Physiol 56: 207–212

    Google Scholar 

  14. Beck E and Wagner BM (1994) Quantification of the daily cytokinin transport from the root to the shoot of Urtica dioica L. Bot Acta 107: 342–348

    Google Scholar 

  15. Beckett RP and Van Staden J (1992) The effect of thidiazuron on the yield of salinity stressed wheat. Ann Bot 70: 47–51

    Google Scholar 

  16. Bengston C, Falk SO and Larson S (1979) Effects of kinetin on transpiration rate and abscisic acid content of water stressed young wheat leaves. Physiol Plant 45: 183–188

    Google Scholar 

  17. Bent AJ, Innes RW, Ecker JR and Staskawicz BJ (1992) Disease development in ethylene insensitive Arabidopsis thaliana infected with virulent and avirulent Pseudomonas and Xanthomonas pathogens. Mol Plant-Microbe Interact 5: 372–378

    PubMed  Google Scholar 

  18. Berridge MJ (1993) Inositol trisphosphate and cell signalling. Nature 361: 315–325

    Article  PubMed  Google Scholar 

  19. Biddington NL and Thomas TH (1978) Influence of different cytokinins on the transpiration and senescence of excised oat leaves. Physiol Plant 42: 369–374

    Google Scholar 

  20. Biddington NL and Dearman AS (1982) The involvement of the root apex and cytokinins in the control of lateral root emergence in lettuce seedlings. Plant Growth Regul 1: 183–193

    Google Scholar 

  21. Blackman PG and Davies WJ (1984) Modification of the CO2responses of maize stomata by abscisic acid and by naturally occurring and synthetic cytokinins. J Exp Bot 35: 174–179

    Google Scholar 

  22. Blackman PG and Davies WJ (1984) Age-related changes in stomatal response to cytokinins and ABA. Ann Bot 54: 121–125

    Google Scholar 

  23. Bögre L, Ligterink W, Herbele-Bors E and Hirt H (1996) Mechanosensors in plants. Nature 383: 489–490

    Article  PubMed  Google Scholar 

  24. Bögre L, Ligterink W, Meskiene I, Barker PJ, Herbele-Bors E, Huskisson NS and Hirt H (1997) Wounding induces the rapid and transient activation of a specific MAP kinase pathway. Plant Cell 9: 75–83

    Article  PubMed  Google Scholar 

  25. Bohnert HJ, Nelson DE and Jensen RG (1995) Adaptations to environmental stress. Plant Cell 7: 1099–1111

    Article  PubMed  Google Scholar 

  26. Bradford KJ (1983) Involvement of plant growth substances in the alteration of leaf gas exchange of flooded tomato plants. Plant Physiol 73: 480–483

    Google Scholar 

  27. Bradford KJ and Trewavas AJ (1994) Sensitivity thresholds and variable time scales in plant hormone action. Plant Physiol 105: 1029–1036

    PubMed  Google Scholar 

  28. Brewster JL, De Valoir T, Dwyer ND, Winter E and Gustin MC (1993) An osmosensing signal transduction pathway in yeast. Science 259: 1760–1763

    PubMed  Google Scholar 

  29. Burrows WJ and Carr DJ (1969) Effects of flooding the root system of sunflower plants on the cytokinin content in the xylem sap. Physiol Plant 22: 1105–1112

    Google Scholar 

  30. Caers M, Rudelsheim P, Van Onckelen H and Horemans S (1985) Effect of heat stress on photosynthetic activity and chloroplast ultrastructure in correlation with endogenous cytokinin concentration in maize seedlings. Plant Cell Physiol 26: 47–52

    Google Scholar 

  31. Cahill DM, Weste GM and Grant BR (1986) Changes in cytokinin concentrartions in xylem extrudate following infection of Eucalyptus marginata Donn ex Sm with Phytophthora cinnamomi Rands. Plant Physiol 81: 1103–1109

    Google Scholar 

  32. Carmi V and Van Staden J (1983) Role of roots in regulating the growth rate and cytokinin content in leaves. Plant Physiol 73: 76–78

    Google Scholar 

  33. Cary AJ, Liu W and Howell SH (1995) Cytokinin action is coupled to ethylene in its effects on the inhibition of root and hypocotyl elongation in Arabidopsis thaliana seedlings. Plant Physiol 107: 1075–1082

    Article  PubMed  Google Scholar 

  34. Chandler PM and Robertson M (1994) Gene expression regulated by abscisic acid and its relation to stress tolerance. Annu Rev Plant Physiol Plant Mol Biol 45: 113–141

    Article  Google Scholar 

  35. Chapin FS III (1991) Integrated responses of plants to stress: a centralised system of physiological responses. Bioscience 41: 29–36

    Google Scholar 

  36. Cheikh N and Jones RN (1994) Disruption of maize kernel growth and development by heat stress. Plant Physiol 106: 45–51

    PubMed  Google Scholar 

  37. Chen C-M, Ertl JR, Leisner SM and Chang C-C (1985) Localization of cytokinin biosynthetic sites in pea plants and carrot roots. Plant Physiol 78: 510–513

    Google Scholar 

  38. Chen Z, Silva H and Klessig DF (1993) Active oxygen species in the induction of plant systemic acquired resistance by salicylic acid. Science 262: 1883–1886

    PubMed  Google Scholar 

  39. Cockburn W, Whitelam GC, Broad A and Smith J (1996) The participation of phytochrome in the signal transduction pathway of salt stress responses in Mesembryanthemum crystallinum L. J Exp Bot 47: 647–653

    Google Scholar 

  40. Conley TR, Sharp RE and Walker JC (1997) Water deficit rapidly stimulates the activity of a protein kinase in the elongation zone of the maize primary root. Plant Physiol 113: 219–226

    PubMed  Google Scholar 

  41. Crane KE and Ross CW (1986) Effects of wounding on cytokinin activity in cucumber cotyledons. Plant Physiol 82: 1151–1152

    Google Scholar 

  42. Crowell DN and Amasino RM (1991) Induction of specific mRNAs in cultured soybean cells during cytokinin or auxin starvation. Plant Physiol 95: 711–715

    Google Scholar 

  43. Darral NM and Wareing PF (1981) The effect of nitrogen nutrition on cytokinin activity and free amino acids in Betula pendula Roth. and Acer pseudoplatanus L. J Exp Bot 32: 369–379

    Google Scholar 

  44. Davenport TL, Jordan WR and Morgan PW (1979) Movement of kinetin and gibberellic acid in leaf petioles during water stress-induced abscission in cotton. Plant Physiol 63: 152–155

    Google Scholar 

  45. Davies WJ, Tardieu F and Trejo CL (1994) How do chemical signals work in plants that grow in drying soil? Plant Physiol 104: 309–314

    PubMed  Google Scholar 

  46. Deikman J and Hammer PE (1995) Induction of anthocyanin accumulation by cytokinins in Arabidopsis thaliana. Plant Physiol 108: 47–57

    PubMed  Google Scholar 

  47. Dérijard B, Hibi M, Wu I-H, Barret T, Su B, Deng T, Karin M and Davis RJ (1994) JNK1: a protein kinase stimulated by UV light and Ha-Ras that binds and phosphorylates the c-Jun activation domain. Cell 76: 1025–1037

    Article  PubMed  Google Scholar 

  48. DeRocher EJ and Bohnert HJ (1993) Development and environmental stress employ different mechanisms in the expression of a plant gene family. Plant Cell 5: 1611–1625

    Article  PubMed  Google Scholar 

  49. Didierjean L, Frendo P, Nasser W, Genot G, Marivet J and Bukard G (1996) Heavy-metal responsive genes in maize: identification and comparison of their expression upon various forms of abiotic stress. Planta 199: 1–8

    Article  PubMed  Google Scholar 

  50. Drüger U and Schönbeck F (1992) Effect of vesicular arbuscular mycorrhizal infection on transpiration, photosynthesis and growth of flax (Linum usitatissimum L.) in relation to cytokinin levels. J Plant Physiol 141: 40–48

    Google Scholar 

  51. Dunlap JR and Binzel ML (1996) NaCl reduces indole-3-acetic acid levels in the roots of tomato plants independent of stress-induced abscisic acid. Plant Physiol 112: 379–384

    PubMed  Google Scholar 

  52. Erdei L and Matsumoto H (1991) Mitigation of symptoms of Ca2+ deficiency by benzyladenine in cucumber: ion levels, polyamines and Ca2+-Mg2+-ATPase. Biochem Physiol Pflanzen 187: 177–188

    Google Scholar 

  53. Espartero J, Pintor-Toro JA and Pardo JM (1994) Differential accumulation of S-adenosylmethionine synthetase transcripts in response to salt stress. Plant Mol Biol 25: 217–227

    PubMed  Google Scholar 

  54. Fußeder A, Wartinger A, Hartung W, Schulze ED and Heilmeier H (1992) Cytokinins in the xylem sap of desert grown almond (Prunus dulcis) trees: daily courses and their possible interactions with abscisic acid and leaf conductance. New Phytol 122: 45–52

    Google Scholar 

  55. Galcheva-Gargova Z, Dérijard B, Wu I-H and Davis RJ (1994) An osmosensing signal transduction pathway in mammalian cells. Science 265: 806–808

    PubMed  Google Scholar 

  56. Galston AW and Kaur-Sawhney R (1995) Polyamines as endogenous growth regulators. In: Davies PJ (ed) Plant Hormones: Physiology, Biochemistry and Molecular Biology, pp 158–178. Dordrecht, The Netherlands: Kluwer Academic Publishers

    Google Scholar 

  57. Gan S and Amasino RM (1995) Inhibition of leaf senescence by autoregulated production of cytokinin. Science 270: 1986–1988

    PubMed  Google Scholar 

  58. Gaudino RJ and Pikaard CS (1997) Cytokinin induction of RNA polymerase I transcription in Arabidopsis thaliana. J Biol Chem 272: 6799–6804

    PubMed  Google Scholar 

  59. Giraudat J, Parcy F, Bertauche N, Gosti F, Leung J, Morris P-C, Bouvier-Durand M and Vartanian N (1994) Current advances in abscisic acid acid and signalling. Plant Mol Biol 26: 1557–1577

    PubMed  Google Scholar 

  60. Giridhar G and Thimann KV (1985) Interaction between senescence and wounding in oat leaves. Plant Physiol 78: 29–33

    Google Scholar 

  61. Goicoechea N, Dolézal K, Antolin MC, Strnad M and Sánchez-Díaz M (1995) Influence of mycorrhizae and Rhizobium on cytokinin content in drought-stressed alfalfa. J Exp Bot 46: 11543–11549

    Google Scholar 

  62. Gosti F, Bertauche N, Vartanian N and Giraudat J (1995) Abscisic acid-dependent and-independent regulation of gene expression by progressive drought in Arabidopsis thaliana. Mol Gen Genet 246: 10–18

    Article  PubMed  Google Scholar 

  63. Griffiths A and Bray EA (1996) Shoot induction of ABA-requiring genes in response to soil drying. J Exp Bot 47: 1525–1531

    Google Scholar 

  64. Gusta LV, Fowler DB and Tyler NJ (1982) The effect of abscisic acid and cytokinins on the cold hardiness of winter wheat. Can J Bot 60: 301–305

    Google Scholar 

  65. Haberlach GT, Budde AD, Sequeira L and Helgeson JP (1978) Modification of the disease resistance of tobacco callus tissues by cytokinins. Plant Physiol 62: 522–525

    Google Scholar 

  66. Han J, Lee J-D, Bibbs L and Ulevitch RJ (1994) A MAP kinase targeted by endotoxin and hyperosmolarity in mammalian cells. Science 265: 808–811

    PubMed  Google Scholar 

  67. Hare PD and Van Staden J (1997) The molecular basis of cytokinin action. Plant Growth Regul 23: 41–78

    Article  Google Scholar 

  68. Hare PD and Van Staden J (1994) Inhibitory effect of thidiazuron on the activity of cytokinin oxidase isolated from soybean callus. Plant Cell Physiol 35: 1121–1125

    Google Scholar 

  69. Hare PD and Van Staden J (1994) Cytokinin oxidase: biochemical features and physiological significance. Physiol Plant 91: 128–136

    Article  Google Scholar 

  70. Hare PD and Cress WA (1996) Tissue-specific accumulation of transcript encoding Δ1-pyrroline-5-carboxylate reductase in Arabidopsis thaliana. Plant Growth Regul 19: 249–256

    Google Scholar 

  71. Hare PD and Cress WA (1997) Metabolic implications of stress-induced proline accumulation in plants. Plant Growth Regul 21: 79–102

    Article  Google Scholar 

  72. Hare PD, Du Plessis S, Cress WA and Van Staden J (1996) Stress-induced changes in plant gene expression: prospects for enhancing agricultural productivity in South Africa. S Afr J Sci 92: 431–439

    Google Scholar 

  73. Hewett EW and Wareing PF (1973) Cytokinins in Populus x robusta: changes during chilling and bud burst. Physiol Plant 28: 393–399

    Google Scholar 

  74. Hirayama T, Ohto C, Mizoguchi T and Shinozaki K (1995) A gene encoding a phosphatidylinositol-specific phospholipase C is induced by dehydration and salt stress in Arabidopsis thaliana. Proc Natl Acad Sci USA 92: 3903–3907

    PubMed  Google Scholar 

  75. Horgan JM And Wareing PF (1980) Cytokinins and the growth responses of seedlings of Betula pendula Roth. and Acer pseudoplatanus L. to nitrogen and phosphorus deficiency. J Exp Bot 311: 525–532

    Google Scholar 

  76. Hubick KT, Taylor JS and Reid DM (1986) The effect of drought on levels of abscisic acid, cytokinins, gibberellins and ethylene in aeroponically-grown sunflower plants. Plant Growth Regul 4: 139–151

    Google Scholar 

  77. Huner NPA, Maxwell DP, Gray GR, Savitch LV, Krol M, Ivanov AG and Falk S (1996) Sensing environmental temperature change through imbalances between energy supply and energy consumption: redox state of photosystem II. Physiol Plant 98: 358–364

    Article  Google Scholar 

  78. Inzé D and Van Montagu M (1995) Oxidative stress in plants. Curr Opin Biotech 6: 153–158

    Article  Google Scholar 

  79. Ishitani M, Nakamura T, Han SY and Takebe T (1995) Expression of the betaine aldehyde dehydrogenase gene in barley in response to osmotic stress and abscisic acid. Plant Mol Biol 27: 307–315

    PubMed  Google Scholar 

  80. Ishitani M, Majumder AL, Bornhouser A, Michalowski CB, Jensen RG and Bohnert HJ (1996) Coordinate transcriptional induction of myo-inositol metabolism during environmental stress. Plant J 9: 537–548

    Article  PubMed  Google Scholar 

  81. Itai C and Vaadia Y (1965) Kinetin-like activity in root exudate of water-stressed sunflower plants. Physiol Plant 118: 941–944

    Google Scholar 

  82. Itai C, Ben-Zioni A and Ordin L (1973) Correlative changes in endogenous hormone levels and shoot growth induced by short heat treatments to the root. Physiol Plant 29: 355–360

    Google Scholar 

  83. Itai C, Benzioni A and Munz S (1978) Heat stress: effects of abscisic acid and kinetin on response and recovery of tobacco leaves. Plant Cell Physiol 19: 453–459

    Google Scholar 

  84. Iwasaki T, Yamaguchi-Shinozaki K and Shinozaki K (1995) Identification of a cis-regulatory region of a gene in Arabidopsis thaliana whose induction by dehydration is mediated by abscisic acid and requires protein synthesis. Mol Gen Genet 247: 391–398

    Article  PubMed  Google Scholar 

  85. Jarillo JA, Capel J, Leyva A, Martinez-Zapater JM and Salinas J (1994) Two related low-temperature-inducible genes of Arabidopsis encode proteins showing high homology to 14-3-3 proteins, a family of putative kinase regulators. Plant Mol Biol 25: 693–704

    PubMed  Google Scholar 

  86. Jonak C, Kiegerl S, Ligterink W, Barker PJ, Huskisson NS and Hirt H (1996) Stress signalling in plants: a mitogen-activated protein kinase pathway is activated by cold and drought. Proc Natl Acad Sci USA 93: 11274–11279

    Article  PubMed  Google Scholar 

  87. Jones DL and Kochian LV (1995) Aluminium inhibition of the inositol 1,4,5-trisphosphate signal transduction pathway in wheat roots: a role in alumminium toxicity? Plant Cell 7: 1913–1922

    Article  PubMed  Google Scholar 

  88. Jones JT and Mullet JE (1995) A salt-and dehydration-inducible pea gene, Cyp15a, encodes a cell-wall protein with sequence similarity of cysteine proteases. Plant Mol Biol 28: 1055–1065

    PubMed  Google Scholar 

  89. Kawalleck P, Plesch G, Hahlbrock K and Somssich IE (1992) Induction by fungal elicitor of S-adenosyl-L-methionine synthetase and S-adenosyl-L-homocysteine hydrolase mRNAs in cultured cells and leaves of Petroselinum crispum. Proc Natl Acad Sci USA 89: 4713–4717

    PubMed  Google Scholar 

  90. Khan AA and Prusinski J (1989) Kinetin enhanced 1-aminocyclopropane-1-carboxylic acid utilisation during alleviation of high temperature stress in lettuce seeds. Plant Physiol 91: 733–737

    Google Scholar 

  91. Khan AA, Thakur R, Akbar M, HilleRisLambers D and Seshu DV (1988) Hormonal regulation of elongation in floating rice during submergence. Crop Sci 28: 121–127

    Google Scholar 

  92. Konings H and De Wolf A (1984) Promotion and inhibition by plant growth regulators of aerenchyma formation in seedling roots of Zea mays. Physiol Plant 60: 309–314

    Google Scholar 

  93. Kieber JJ, Rothenberg M, Roman G, Feldman KA and Ecker JR (1993) CTR1, a negative regulator of the ethylene response pathway in Arabidopsis, encodes a member of the Raf family of protein kinases. Cell 72: 427–441

    Article  PubMed  Google Scholar 

  94. Király Z, El Hammady M and Pozsár BI (1967) Increased cytokinin activity of rust-inffected bean and broad-bean leaves. Phytopathology 57: 93–94

    Google Scholar 

  95. Kirkham MB, Gardner WR and Gerloff GC (1974) Internal water status of kinetin-treated, salt-stressed plants. Plant Physiol. 53: 241–243

    Google Scholar 

  96. Knight H, Trewavas AJ and Knight MR (1996) Cold calcium signalling in Arabidopsis involves two cellular pools and a change in calcium signature after acclimation. Plant Cell 8: 489–503

    Article  PubMed  Google Scholar 

  97. Kuiper D, Kuiper PJC, Lambers H, Schuit J and Staal M (1989) Cytokinin concentration in relation to mineral nutrition and benzyladenine treatment in Plantago major spp. pleiosperma. Physiol Plant 75: 511–517

    Google Scholar 

  98. Kuiper D, Schuit J and Kuiper PJC (1990) Actual cytokinin concentrations in plant tissue as an indicator for salt resistance in cereals. Plant Soil 123: 243–250

    Google Scholar 

  99. Kulaeva ON, Fedina AB, Burkhanova EA, Karavaiko NN, Karpeisky MY, Kaplan IB, Taliansky ME and Atabekov JG (1992) Biological activities of human interferon and 2′–5′ oligoadenylates in plants. Plant Mol Biol 20: 383–393

    PubMed  Google Scholar 

  100. Kuraishi S, Tezuka T, Ushijima T and Tazaki T (1966) Effect of cytokinins on frost hardiness. Plant Cell Physiol 7: 705–706

    Google Scholar 

  101. Kuriger WE and Agrios GN (1977) Cytokinin levels and kinetin-virus interactions in tobacco ringspot virus-infected cowpea plants. Phytopathology 67: 604–609

    Google Scholar 

  102. Kyriakis JM, Banerjee P, Nikolakaki E, Dal T, Rubie EA, Ahmad MF, Avruch J and Woodgett JR (1994) The stress-activated protein kinase subfamily of c-Jun kinases. Nature 369: 156–160

    Article  PubMed  Google Scholar 

  103. Lau O-I and Yang SF (1974) Synergistic effect of calcium and kinetin on ethylene production by the mungbean hypocotyl. Planta 118: 1–6

    Google Scholar 

  104. Legendre L, Yueh YG, Crain R, Haddock N, Heinstein PF and Low PS (1993) Phospholipase C activation during elicitation of the oxidative burst in cultured plant cells. J Biol Chem 268: 24559–24563

    PubMed  Google Scholar 

  105. Letham DS and Palni LMS (1983) The biosynthesis and metabolism of cytokinins. Annu Rev Plant Physiol 34: 163–197

    Article  Google Scholar 

  106. Leung J, Merlot S and Giraudat J (1997) The Arabidopsis ABSCISIC ACID-INSENSITIVE2 (ABI2) and ABI1 genes encode homologous protein phosphatases 2C involved in abscisic acid signal transduction. Plant Cell 9: 759–771

    Article  PubMed  Google Scholar 

  107. Leymarie J, Damerval C, Marcotte L, Combes V and Vartanian N (1996) Two-dimensional protein patterns of Arabidopsis wild-type and auxin insensitive mutants, axr1, axr2, reveal interactions between drought and hormonal responses. Plant Cell Physiol 37: 966–975

    PubMed  Google Scholar 

  108. Li Y, Hagen G and Guilfoyle TJ (1992) Altered morphology in transgenic tobacco plants that overproduce cytokinins in specific tissues and organs. Dev Biol 153: 386–395

    Article  PubMed  Google Scholar 

  109. Liu Z and Bushnell WR (1986) Effects of cytokinins on fungus development and host response in powdery mildew of barley. Physiol Mol Plant Pathol 29: 41–52

    Google Scholar 

  110. Lopez-Carbonell M, Alegre L, Pastor A, Prinsen E and Van Onckelen H (1996) Variations in abscisic acid, indole-3-acetic acid and zeatin riboside concentrations in two Mediterranean shrubs subjected to water stress. Plant Growth Regul 20: 271–277

    Google Scholar 

  111. Ludlow MM, Ng TT and Ford CW (1980) Recovery after water stress of leaf gas excahnge in Panicum maximum var. trichoglume. Aust J Plant Physiol 7: 299–313

    Google Scholar 

  112. MacIsaac SA, Sawhney VK and Pohorecky Y (1989) Regulation of lateral root formation in lettuce (Lactuca sativa) seedling roots: interacting effects of α-naphthalene acetic acid and kinetin. Physiol Plant 77: 287–293

    Google Scholar 

  113. Maeda T, Takehara M and Saito H (1995) Activation of yeast PBS2 MAPKK by MAPKKKs or by binding of an SH3-containing osmosensor. Science 269: 554–558

    PubMed  Google Scholar 

  114. Marguía JR, Bellés JM and Serrano R (1995) A salt-sensitive 3′(2′),5′bisphosphate nucleotidase involved in sulfate activation. Science 267: 232–234

    PubMed  Google Scholar 

  115. Marivet J, Frendo P and Burkard G (1992) Effects of abiotic stresses on cyclophilin gene expression in maize and bean and sequence analysis of bean cyclophilin cDNA. Plant Sci 84: 171–178

    Article  Google Scholar 

  116. Masia A, Pitacco Braggio L and Giulivo C (1994) Hormonal responses to partial drying of the root system of Helianthus anuus. J Exp Bot 45: 69–76

    Google Scholar 

  117. Masuta C, Tanaka H, Uehara K, Kuwata S, Koiwai A and Noma M (1995) Broad resistance to plant viruses in transgenic plants conferred by antisense inhibition of a host gene essential in S-adenosylmethionine-dependent transmethylation reactions. Proc Natl Acad Sci USA 92: 6117–6121

    PubMed  Google Scholar 

  118. Mauk CS and Langille AR (1978) Physiology of tuberization in Solanum tuberosum L. Plant Physiol 62: 438–442

    Google Scholar 

  119. Mayer R, Raventos D and Chua N-H (1996) det1, cop1, and cop9 mutations cause inappropriate expression of several gene sets. Plant Cell 8: 1951–1959

    Article  PubMed  Google Scholar 

  120. McKeon TA, Hoffman NE and Yang SF (1982) The effect of plant hormone pre-treatments on ethylene production and synthesis of 1-aminocyclopropane-1-carboxylic acid in water-stressed wheat leaves. Planta 155: 437–443

    Google Scholar 

  121. Medford JI, Horgan R, El-Sawi Z and Klee HJ (1989) Alterations of endogenous cytokinins in transgenic plants using a chimeric isopentenyl transferase gene. Plant Cell 1: 403–413

    Article  PubMed  Google Scholar 

  122. Meinzer FC, Grantz DG and Smit B (1991) Root signals mediate coordination of stomatal and hydraulic conductance in growing sugarcane. Aust J Plant Physiol 18: 329–338

    Google Scholar 

  123. Memelink J, Hoge JHC and Schilperoort RA (1987) Cytokinin stress changes the developmental regulation of several defence-related genes in tobacco. EMBO J 6: 3579–3583

    Google Scholar 

  124. Menary RC and Van Staden J (1976) Effect of phosphorus nutrition and cytokinins on flowering in the tomato, Lycopersicon esculentum Mill. Aust J Plant Physiol 3: 201–205

    Google Scholar 

  125. Mett VL, Podivinsky E, Tennant AM, Lochhead LP, Jones WT and Reynolds PHS (1996) A system for tissue-specific copper-controllable gene expression in transgenic plants: nodule-specific antisense of aspartate aminotransferase-P2. Transgenic Res 5: 105–113

    PubMed  Google Scholar 

  126. Mills PR, Gussine J and Wood RSK (1986) Induction of resistance in cucumber to Colletotrichum lagenarium by 6-benzylaminopurine. J Phytopathol 116: 11–17

    Google Scholar 

  127. Misaghi I, Devay Je and Kosuge T (1972) Changes in cytokinin activity associated with the development of Verticillium wilt and water stress in cotton plants. Physiol Plant Pathol 2: 187–196

    Google Scholar 

  128. Mitchell JJ and Van Staden J (1983) Cytokinins and the wounding response in potato tissue. Z Pflanzenphysiol 109: 1–5

    Google Scholar 

  129. Mitsui S, Wakasugi T and Sugiura M (1996) A cytokinin-binding protein complex from tobacco leaves: the 57 kDa subunit has high homology to S-adenosyl-L-homocysteine hydrolase. Plant Growth Regul 18: 39–43

    Google Scholar 

  130. Mizoguchi T, Irie K, Hirayama T, Hayashida N, Yamaguchi-Shinozaki K, Matsumoto K and Shinozaki K (1996) A gene encoding a mitogen-activated protein kinase kinase kinase is induuced simultaneously with genes for a mitogen-activated protein kinase and an S6 ribosomal kinase by touch, cold and water stress in Arabidopsis thaliana. Proc Natl Acad Sci USA 93: 765–769

    Article  PubMed  Google Scholar 

  131. Mizrahi Y, Scherings SG, Arad S and Richmmond AE (1973) Aspects of the effect of ABA on the water status of barley and wheat seedlings. Physiol Plant 31: 44–50

    Google Scholar 

  132. Monroy AF and Dhindsa RS (1995) Low-temperature signal transduction: induction of cold acclimation-specific genes of alfalfa by calcium at 25°C. Plant Cell 7: 321–331

    Article  PubMed  Google Scholar 

  133. Naqvi SSM, Ansari R and Kuawada AN (1982) Responses of salt-stressed wheat seedlings to kinetin. Plant Sci Lett 26: 279–283

    Google Scholar 

  134. Neuman DS, Rood SB and Smit BA (1990) Does cytokinin transport from root-to-shoot in the xylem sap regulate leaf responses to root hypoxia? J Exp Bot 41: 1325–1333

    Google Scholar 

  135. Novacky A (1972) Suppression of the bacterially induced hypersensitive reaction by cytokinins. Physiol Plant Pathol 2: 101–104

    Google Scholar 

  136. Orr W, Singh J and Brown DCW (1985) Induction of freeze tolerance in alfalfa cell suspension cultures. Plant Cell Rep 4: 15–18

    Article  Google Scholar 

  137. Patrick TW, Hall R and Fletcher RA (1977) Cytokinin levels in healthy and Verticillium-infected tomato plants. Can J Bot 55: 377–382

    Google Scholar 

  138. Peña-Cortés H and Willmitzer L (1995) The role of hormones in gene activation in response to wounding. In: Davies PJ (ed) Plant Hormones: Physiology, Biochemistry and Molecular Biology, pp 395–414. Dordrecht, The Netherlands: Kluwer Academic Publishers

    Google Scholar 

  139. Peng Z and Verma DPS (1995) A rice HAL2-like gene encodes a Ca2+-sensitive 3′(2′),5′-diphosphonucleoside 3′(2′)-phosphohydrolase and complements yeast met22 and Escherichia coli cysQ mutations. J Biol Chem 270: 29105–29110

    Article  PubMed  Google Scholar 

  140. Pesci P (1996) Is photosynthetic activity responsible for the stimulating effect of light on ABA-induced proline accumulation in barley leaves? J Plant Physiol 147: 729–735

    Google Scholar 

  141. Price AH, Taylor A, Ripley S, Griffiths A, Trewavas AJ and Knight MR (1994) Oxidative signals in tobacco increase cytosolic calcium. Plant Cell 6: 1301–1310

    Article  PubMed  Google Scholar 

  142. Prinsen E, Kaminek M and Van Onckelen HA (1997) Cytokinin biosynthesis: a black box. Plant Growth Regul 23: 3–15

    Article  Google Scholar 

  143. Quintero FJ, Garciadeblás B and Rodríguez-Navarro A (1996) The SAL1 gene of Arabidopsis encoding an enzyme with 3′(2′),5′-bisphosphate nucleotidase and inositol polyphosphate 1-phosphatase activities, increases salt tolerance in yeast. Plant Cell 8: 529–537

    Article  PubMed  Google Scholar 

  144. Rajagopal R (1977) Effect of tobacco mosaic virus infection on the endogenous levels of indoleacetic, phenylacetic and abscisic acids of tobacco leaves in various stages of development. Z. Pflanzenphysiol 83: 403–409

    Google Scholar 

  145. Rammesmayer G, Pichorner H, Adams P, Jensen RG and Bohnert HJ (1995) Characterisation of IMT1, myo-inositol O-methyltransferase, from Mesembryanthemum crystallinum. Arch Biochem Biophys 322: 183–188

    Article  PubMed  Google Scholar 

  146. Raz V and Fluhr R (1992) Calcium requirement for ethylene-dependent responses. Plant Cell 4: 1123–1130

    Article  PubMed  Google Scholar 

  147. Raz V and Fluhr R (1993) Ethylene signal is transduced via protein phosphorylation events in plants. Plant Cell 5: 523–530

    Article  PubMed  Google Scholar 

  148. Rengel Z (1992) The role of calcium in salt toxicity. Plant Cell Environ 15: 625–632

    Google Scholar 

  149. Roman G, Lubarsky B, Kieber JJ, Rothenberg M and Ecker JR (1995) Genetic analysis of ethylene signal transduction in Arabidopsis thaliana: five novel mutant loci integrated into a stress response pathway. Genetics 139: 1393–1409

    PubMed  Google Scholar 

  150. Ross CW, Orr GL and Bowman RN (1983) Growth promotion of excised cucumber cotyledons by rubbing or by cuticular abrasion. Plant Sci Lett 29: 97–105

    Article  Google Scholar 

  151. Ryu SB, Costa A, Xin Z and Li PH (1995) Induction of cold hardiness by salt stress involves synthesis of cold-and abscisic acid-responsive proteins in potato (Solanum commersonii Dun.) Plant Cell Physiol 36: 1245–1251

    Google Scholar 

  152. Salama AMSE-DA and Wareing PF (1979) Effects of mineral nutrition on endogenous cytokinins in plants of sunflower (Helianthus annuus L.) J Exp Bot 30: 971–981

    Google Scholar 

  153. Sanada Y, Ueda H, Kuribayashi K, Andoh T, Hayashi F, Tamai N and Wada K (1995) Novel light-dark change of proline levls in halophyte (mesembryanthemum crystallinum L.) and glycophytes (Hordeum vulgare L. and Triticum aestivum L.) leaves and roots under salt stress. Plant Cell Physiol 36: 965–970

    Google Scholar 

  154. Sano H and Youssefian S (1994) Light and nutritional regulation of transcripts encoding a wheat protein kinase homolog is mediated by cytokinins. Proc Natl Acad Sci USA 91: 2582–2586

    PubMed  Google Scholar 

  155. Sano H and Ohashi Y (1995) Involvement of small GTP-binding proteins in defense signal-transduction pathways of higher plants. Proc Natl Acad Sci USA 92: 41338–4144

    Google Scholar 

  156. Sano H, Seo S, Orudgev E, Youssefian S, Ishizuka K and Ohashi Y (1994) Expression of the gene for a small GTP binding protein in transgenic tobacco elevates endogenous cytokinin levels, abnormally induces salicylic acid in response to wounding, and increases resistance to tobacco mosaic virus infection. Proc Natl Acad Sci USA 91: 10556–10560

    PubMed  Google Scholar 

  157. Sano H, Seo S, Koizumi N, Niki T, Iwamura H and Ohashi Y (1996) Regulation by cytokinins of endogenous levels of jasmonic and salicylic acids in mechanically wounded tobacco plants. Plant Cell Physiol 37: 762–769

    Google Scholar 

  158. Sattelmacher B and Marschner H (1978) Nitrogen nutrition and cytokinin activity in Solanum tuberosum. Physiol Plant 42: 185–189

    Google Scholar 

  159. Savouré A, Hua X-J, Bertauche N, Van Montagu M and Verbruggen N (1997) Abscisic acid-independent and abscisic acid-dependent regulation of proline biosynthesis following cold and osmotic stresses. Mol Gen Genet 254: 104–109

    Article  PubMed  Google Scholar 

  160. Schmitt JM and Piepenbrock M (1992) Regulation of phosophoenolpyruvate carboxylase and crassulacean acid metabolism induction in Mesembryanthemum crystallinum L. by cytokinin. Plant Physiol 99: 1664–1669

    Google Scholar 

  161. Schmülling T, Beinsberger S, De Greef J, Schell J, Van Onckelen H and Spena A (1989) Construction of a heat-inducible chimaeric gene to increase the cytokinin content in transgenic plant tissue. FEBS Lett 249: 401–406

    Article  Google Scholar 

  162. Schröder G, Eichel J, Breinig S and Schröder J (1997) Three differentially exprressed S-adenosylmethionine synthetases from Catharanthus roseus: molecular and functional characterisation. Plant Mol Biol 33: 211–222

    Article  PubMed  Google Scholar 

  163. Schuur U, Gollan T and Schulze E-D (1992) Stomatal response to drying soil in relation to changes in the sap composition of Helianthus annuus. II.Stomatal sensitivity to abscisic acid imported from the xylem sap. Plant Cell Enviro 15: 561–567

    Google Scholar 

  164. Sedbrook JC, Kronebusch PJ, Borisy GG, Trewavas AJ and Masson PH (1996) Transgenic AEQUORIN reveals organ-specific cytosolic Ca2+ responses to anoxia in Arabidopsis thaliana seedlings. Plant Physiol 111: 243–257

    Article  PubMed  Google Scholar 

  165. Seo S, Okamoto M, Seto H, Ishizuka K, Sano H and Ohashi Y (1995) Tobacco MAP kinase: a possible mediator in wound signal transduction pathways. Science 270: 1988–1992

    PubMed  Google Scholar 

  166. Sharma YK, León J, Raskin I and Davis KR (1996) Ozone-induced responses in Arabidopsis thaliana: the role of salicylic acid in the accumulation of defence-related transcripts and induced resistance. Proc Natl Acad Sci USA 93: 5099–5104

    Article  PubMed  Google Scholar 

  167. Shashidhar VR, Prasad TG and Sudharshan L (1996) Hormone signals from roots to shoots of sunflower (Helianthus annuus L.). Moderate soil drying increases delivery of abscisic acid and depresses delivery of cytokinins in xylem sap. Ann Bot 78: 151–155

    Article  Google Scholar 

  168. Shibata W, Banno H, Ito Y, Hirano K, Irie K, Usami S, Machida C and Machida Y (1995) A tobacco protein kinase, NPK2, has a domain homologous to a domain found in activators of mitogen-activated protein kinases (MAPKKs). Mol Gen Genet 246: 401–410

    Article  PubMed  Google Scholar 

  169. Shinozaki K and Yamaguchi-Shinozaki K (1996) Molecular responses to drought and cold stress. Curr Opin Biotech 7: 161–167

    Article  PubMed  Google Scholar 

  170. Skene KGM (1972) Cytokinins in the xylem sap of grape vine canes: changes in activity during cold storage. Planta 104: 89–92

    Google Scholar 

  171. Smart CM, Scofield SR, Bevan MW and Dyer TA (1991) Delayed leaf senescence in tobacco plants transformed with tmr, a gene for cytokinin production in Agrobacterium. Plant Cell 3: 647–656

    Article  PubMed  Google Scholar 

  172. Smigocki AC, Neal JW, McCanna I and Douglass L (1993) Cytokinin-mediated insect resistance in Nicotiana plants transformed with the ipt gene. Plant Mol Biol 23: 325–335

    PubMed  Google Scholar 

  173. Smirnoff N (1993) The role of active oxygen in the response of plants to water deficit and desiccation. New Phytol 125: 27–58

    Google Scholar 

  174. Stewart CR, Voetberg G and Rayapati PJ (1986) The effects of benzyladenine, cycloheximide and cordycepin on wilting-induced abscisic acid and proline accumulations and abscisic acid-and salt-induced proline accumulation in barley leaves. Plant Physiol 82: 703–707

    Google Scholar 

  175. Storti EP, Bogani P, Bettini P, Bittini P, Guardiola ML, Pellegrini MG, Inze D and Buiatti M (1994) Modification of competence for in vitro response to Fusarium oxysporum in tomato cells. II. Effect of the integration of Agrobacterium tumefaciens genes for auxin and cytokinin synthesis. Theor Appl Genet 88: 89–96

    Article  Google Scholar 

  176. Suzuki K and Shinishi H (1995) Transient activation and tyrosine phosphorylation of a protein kinase in tobacco cells treated with a fungal elicitor. Plant Cell 7: 639–647

    Article  PubMed  Google Scholar 

  177. Szekeres M, Németh K, Koncz-Kálmán Z, Mathur J, Kauschmann A, Altman T, Rédei GP, Nagy F, Schell J and Koncz C (1996) Brassinosteroids rescue the deficiency of CYP90, a cytochrome P450, controlling cell elongation and de-etiolation in Arabidopsis. Cell 85: 171–182

    Article  PubMed  Google Scholar 

  178. Sziráki I, Balázs E and Király Z (1980) Role of different stresses in inducing systemic acquired resistance to TMV and increasing cytokinin level in tobacco. Physiol Plant Pathol 16: 277–284

    Google Scholar 

  179. Tavantzis SM, Smith SH and Witham FH (1979) The influence of kinetin on tobacco ringspot virus infectivity and the effect of virus infection on the cytokinin activity in intact leaves of Nicotiana glutinosa L. Physiol Plant Pathol 14: 227–233

    Google Scholar 

  180. Taylor JS, Bhalla MK, Robertson JM and Piening LJ (1990) Cytokinins and abscisic acid in hardening winter wheat. Can J Bot 68: 1597–1601

    Google Scholar 

  181. Thomas JC, McElwain EF and Bohnert HJ (1992) Convergent induction of osmotic stress-responses: abscisic acid, cytokinin, and the effects of NaCl. Plant Physiol 100: 416–423

    Google Scholar 

  182. Thomas JC, Smigocki AC and Bohnert HJ (1995) Light-induced expression of ipt from Agrobacterium tumefaciens results in cytokinin accumulation and osmotic stress symptoms in transgenic tobacco. Plant Mol Biol 27: 225–235

    PubMed  Google Scholar 

  183. Thomas TH (1992) Some reflections on the relationship between endogenous hormones and light-mediated seed dormancy. Plant Growth Regul 11: 239–248

    Google Scholar 

  184. Thomas TH, Hare PD and Van Staden J (1997) Phytochrome and cytokinin responses. Plant Growth Regul 23: 105–122

    Article  Google Scholar 

  185. Thorsteinsson B and Eliasson L (1990) Growth retardation induced by nutritional deficiency or abscisic acid in Lemna gibba: the relationship between growth rate and endogenous cytokinin content. Plant Growth Regul 9: 171–181

    Google Scholar 

  186. Toyama T, Teramoto H, Takeba G and Tsuji H (1995) Cytokinin induces a rapid decrease in the levels of mRNAs for catalase, 3-hydroxy-3-methylglutaryl CoA reductase, lectin and other unidentified proteins in etiolated cotyledons of cucumber. Plant Cell Physiol 36: 1349–1359

    PubMed  Google Scholar 

  187. Trejo CL and Davies WJ (1991) Drought induced closure of Phaseolus vulgaris L. stomata precedes leaf water deficit and any increase in xylem ABA concentration. J Exp Bot 42: 1507–1515

    Google Scholar 

  188. Urao T, Katagiri T, Mizoguchi T, Yamaguchi-Shinozaki K, Hayashida N and Shinozaki K (1994) Two genes that encode Ca2+-dependent protein kinases that are induced by drought and high-salt stresses in Arabidopsis thaliana. Mol Gen Genet 224: 331–340

    Google Scholar 

  189. Usami S, Banno H, Ito Y, Nishimama R and Machida Y (1995) Cutting activates a 46-kilodalton protein kinase in plants. Proc Natl Acad Sci USA 92: 8660–8664

    PubMed  Google Scholar 

  190. Vaadia Y (1976) Plant hormones and water stress. Philos Trans R Soc (Series B) 273: 513–522

    Google Scholar 

  191. Van Loven K, Beinsberger SEI, Valcke RLM, Van Onckelen HA and Clijsters HMM (1993) Morphometric analysis of the growth of Phsp70-ipt transgenic tobacco plants. J Exp Bot 44: 1671–1678

    Google Scholar 

  192. Van Staden J and Crouch NR (1996) Benzyladenine and derivatives —their significance and interconversion in plants. Plant Growth Regul 19: 153–175

    Google Scholar 

  193. Van Staden J and Davey JE (1979) The synthesis, transport and metabolism of endogenous cytokinins. Plant Cell Environ 2: 93–106

    Google Scholar 

  194. Van Staden J and Joughin JI (1988) Cytokinins in cut carnation flowers. IV. Effects of benzyladenine on flower longevity and the role of different longevity treatments on its transport following application to petals. Plant Growth Regul 7: 117–128

    Google Scholar 

  195. Van Staden J, Cook EL and Noodén LD (1988) Cytokinins and senescence. In: Noodén LD and Leopold AC (eds) Senescence and Aging in Plants, pp 281–328. San Diego, USA: Academic Press

    Google Scholar 

  196. Vernon DM, Ostrem JA and Bohnert HJ (1993) Stress perception and response in a facultative halophyte: the regulation of salinity-induced genes in Mesembryanthemum crystallinum. Plant Cell Environ 16: 437–444

    Google Scholar 

  197. Voesenek LACJ and Van der Veen R (1994) The role of phytohormones in plant stress: too much or too little water. Acta Bot Neerl 43: 91–127

    Google Scholar 

  198. Wagner BM and Beck E (1993) Cytokinins in the perennial herb Urtica dioica L. as influenced by itss nitrogen status. Planta 190: 511–518

    Article  Google Scholar 

  199. Walker MA and Dumbroff EB (1981) Effects of salt stress on abscisic acid and cytokinin levels in tomato. Z Pflanzenphysiol 101: 461–470

    Google Scholar 

  200. Wample RL and Bewley JD (1975) Proline accumulation in flooded and wilted sunflower and the effects of benzyladenine and abscisic acid. Can J Bot 53: 2893–2896

    Google Scholar 

  201. Wang YY, Zhou R and Zhou X (1994) Endogenous levels of ABA and cytokinins and their relation to stomatal behaviour in dayflower (Commelina communis L.) J Plant Physiol 144: 45–48

    Google Scholar 

  202. Weiler EW and Ziegler H (1981) Determination of phytohormones in phloem exudate from tree species by radioimmunoassay. Planta 152: 168–170

    Google Scholar 

  203. Whenham RJ (1989) Effect of systemic tobacco mosaic virus infection on endogenous cytokinin concentration in tobacco (Nicotiana tabacum L.) leaves: consequences for the control of resistance and symptom development. Physiol Mol Plant Pathol 35: 85–95

    Google Scholar 

  204. Wightman F, Schneider EA and Thimann KV (1980) Hormonal factors controlling the initiation and development of lateral roots. II. Effects of exogenous growth factors on lateral root formation in pea roots. Physiol Plant 49: 304–314

    Google Scholar 

  205. Wojtaszek P (1997) Oxidative burst: an early plant response to pathogen infection. Biochem J 322: 681–692

    PubMed  Google Scholar 

  206. Wright STC (1980) The effect of plant growth regulator treatments on the level of ethylene emanating from excised turgid and wilted leaves. Planta 148: 381–388

    Google Scholar 

  207. Yalpani N, Enyedi AJ, León J and Raskin I (1994) Ultraviolet light and ozone stimulate accumuulation of salicylic acid, pathogenesis-related proteins and virus resistance in tobacco. Planta 193: 372–376

    Article  Google Scholar 

  208. Yamaguchi-Shinozaki K and Shinozaki K (1994) A novel cis-acting element in an Arabidopsis gene is involved in responsiveness to drought, low-temperature or high-salt stress. Plant Cell 6: 251–264

    Article  PubMed  Google Scholar 

  209. Yang SF and Hoffman NE (1984) Ethylene biosynthesis and its regulation in higher plants. Annu Rev Plant Physiol 35: 155–189

    Google Scholar 

  210. Zhou J, Loh Y-T, Bressan RA and Martin GB (1995) The tomato gene Ptil encodes a serine/threonine kinase that is phosphorylated by Pto and is involved in the hypersensitive response. Cell 83: 925–935

    Article  PubMed  Google Scholar 

  211. Zimmermann S, Nürnberger T, Frachisse J-M, Wirtz W, Guern J, Hedrich R and Scheel D (1997) Receptor-mediated activation of a plant Ca2+-permeable ion channel involved in pathogen defence. Proc Natl Acad Sci USA 94: 2751–2755

    Article  PubMed  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Natal University Research Unit for Plant Growth and Development, Department of Botany, University of Natal Pietermaritzburg, Private Bag X01, Scottsville, 3209, South Africa

    P.D. Hare, W.A. Cress & J. van Staden

Authors
  1. P.D. Hare
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. W.A. Cress
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. J. van Staden
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Hare, P., Cress, W. & van Staden, J. The involvement of cytokinins in plant responses to environmental stress. Plant Growth Regulation 23, 79–103 (1997). https://doi.org/10.1023/A:1005954525087

Download citation

  • Issue Date:

  • DOI: https://doi.org/10.1023/A:1005954525087

Search

Navigation