Altered physiology in trehalose-producing transgenic tobacco plants: Enhanced tolerance to drought and salinity stresses |
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Authors: | Sung-Soo Jun Jin Young Yang Hye Jin Choi Na-Ryung Kim Min Chul Park Young-Nam Hong |
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Institution: | (1) School of Biological Sciences, Seoul National University, 151-742 Seoul, Korea;(2) School of General Education, Institute for Scientifically Able Youth, Kyungwon University, 461-701 Seoungnam, Korea;(3) Department of Life Science, The Catholic University of Korea, 420-743 Puchon, Korea |
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Abstract: | 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. |
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Keywords: | dehydration salinity stress tolerance transgenic tobacco trehalose |
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