Altered physiology in trehalose-producing transgenic tobacco plants: Enhanced tolerance to drought and salinity stresses
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Transgenic tobaccoNicotiana tabacum L. var. SR1) plants that over-express theEscherichia coli trehalose-6-phosphate synthase (TPS) gene(otsA) synthesized small amounts of trehalose (<400 µg g-1 leaf) while non-transformants produced no detectable trehalose. Some transgenic plants expressing a high level ofotsA exhibited stunted growth and morphologically altered leaves. We tested F22 homozygous plants devoid of phenotypic changes to determine their physiological responses to dehydration and salinity stresses. All transgenic plants maintained better leaf turgidity under a limited water supply or after treatment with polyethylene glycol (PEG). Furthermore, fresh weight was maintained at higher levels after either treatment. The initial leaf water potential was higher in transgenic plants than non-transformants, but, in both plant types, was decreased to a comparable degree following dehydration. When grown with 250 mM NaCl, transgenic plants exhibited a significant delay in leaf withering and chlorosis, as well as more efficient seed germination. Our results suggest that either trehalose or trehalose-6-phosphate can act as an osmoprotective molecule without maintaining water potential, in contrast to other osmolytes. Furthermore, both appear to protect young embryos under unfavorable water status to ensure subsequent germination.
Keywordsdehydration salinity stress tolerance transgenic tobacco trehalose
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- Argüelles JC (2000) Physiological roles of trehalose in bacteria and yeasts: A comparative analysis. Arch Microbiol17: 217–224Google Scholar
- Drennan PM, Smith MT, Goldsworthy D, van Staden J (1993) The occurrence of trehalose in the leaves of the desiccation-tolerant angiospermMyrothamnus flabellifolius Wiw. J Plant Physiol142: 493–496Google Scholar
- Jang I-C, Oh S-J, Seo J-S, Choi W-B, Song SI, Kim CH, Kim YS, Seo H-S, Choi YD, Nahm BH, Kim J-K (2003) Expression of a bifunctional fusion of theEscherichia coli genes for trehalose-6-phosphate synthase and tre-halose-6-phosphate phosphatase in transgenic rice plants increases trehalose accumulation and abiotic stress tolerance without stunting growth. Plant Physiol131: 516–524PubMedCrossRefGoogle Scholar
- Jun S-S, Choi HJ, Yang JY, Hong Y-N (2001) Photosynthetic response to dehydration and high temperature in treha-lose-producing transgenic tobacco. 12th International Congress on Photosynthesis. CSIRO Publishing, QueenslandGoogle Scholar
- Lee HY, Jun S-S, Hong Y-N (1998) Photosynthetic responses to dehydration in green pepper (Capsicum annuum L.) leaves. J Photosci5: 169–174Google Scholar
- Pilon-Smits EAH, Terry N, Sears T, Kim H, Zayes A, Hwang SB, van Dun K, Voogd E, Verwoerd TC, Krut-wagen RWHH, Coddijn OJM (1998) Trehalose-producing transgenic tobacco plants show improved growth performance under drought stress. J Plant Physiol152: 525–532Google Scholar
- Renger G, Schreiber U (1986) Practical applications of fluorometric methods to algae and higher plant research,In Govindjee, J Amesz, DC Fork, eds, Light Emission by Plants and Bacteria. Academic Press, Orlando/London, pp 587–619Google Scholar
- Zentella R, Mascorro-Gallardo JO, van Dijck P, Folch-Mallol J, Bonini B, van Vaeck C, Gaxiola R, Covarrubias AA, Nieto-Sotelo J, Thevelein JM, Iturriaga G (1999) ASelaginella lepidophylla trehalose-6-phos-phate synthase complements growth and stress-tolerance defects in a yeasttps1 mutant. Plant Physiol119: 1437–1482CrossRefGoogle Scholar