Responses to water withdrawal of tobacco plants genetically engineered with the AtTPS1 gene: a special reference to photosynthetic parameters
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We have previously obtained several lines of tobacco transformed with a trehalose-6-phosphate synthase gene of plant origin (Arabidopsis thaliana), involved in the first step of the biosynthesis of trehalose, a known osmoprotectant. Two showed distinct intensity of expression: high (B5H) and low (B1F). Such lines were analyzed for trehalose-6-phosphate content and the obtained results demonstrated to be in accordance with the expression results. In order to study the responses of photosynthesis to water deficit of transgenic lines in comparison to wild type (WT), three experiments were performed under different conditions: (1) Relative water (2) Leaf gas exchange (3) Modulated Chlorophyll a Fluorescence. Different responses in RWC of plant lines to water withdrawal were detected, with transgenic line B5H indicating less water loss after the water withdrawal period. Similar responses to water deficit regarding the leaf gas exchanges were recorded for the three lines. When subjected to water deficit stress situations, higher F v/F m, ΦPSII and qP were detected for the transgenic lines. Under a SWC of 20% where higher values for such parameters were detected with special relevance for the B5H line, indicating a possible higher ability to withstand severe drought stress and to resist to prolonged periods without water than the B1F and WT lines.
KeywordsTrehalose Photosynthesis Water deficit
Financial support from Fundação para a Ciência e a Tecnologia is acknowledged as grant PRAXIS XXI/BD/21270/99 (FCT / FSE, III Quadro Comunitário de Apoio). Authors would also like to thank Josep Matas Jorba of the Faculty of Biology of the University of Barcelona for technical assistance regarding the leaf gas exchange assay and to P. Fontanet, A. Sanz and E. Saavedra (IBMB, Barcelona, Spain) for Greenhouse work.
- Almeida AM, Villalobos E, Araújo SS, Leyman B, van Dijk P, Alfaro-Cardoso L, Fevereiro PS, Torné JM, Santos DM (2005) Transformation of tobacco with an Arabidopsis thaliana gene involved in trehalose biosynthesis increases tolerance to several abiotic stresses. Euphytica 146:165–176CrossRefGoogle Scholar
- Arrabaça MC (1981) The effect of temperature on photosynthetic and photorespiratory metabolism (PhD thesis), University of London, LondonGoogle Scholar
- Jang IC, Oh SJ, Seo JS, Choi WB, Song SY, Kim CH, Kim YS, Seo HS, Choi YD, Nahm BH, Kim JK (2003) Expression of a bifunctional fusion of the Escherichia coli genes for Trehalose-6-phosphate synthase and Trehalose-6-phosphate phosphatase in transgenic rice plants increases trehalose accumulation and abiotic stress tolerance without stunting growth. Plant Physiol 131:516–524PubMedCrossRefGoogle Scholar
- LI-COR (1990) Li-6200 Technical reference. LI-COR, Lincoln, Nebraska, USAGoogle Scholar
- Pilon-Smits E, Terry N, Sears T, Kim H, Zayed A, Hwang S, van Dun K, Voogd E, Verwoerd TC, Krutwagen RH, Goddijn OJ (1998) Trehalose-producing transgenic tobacco plants show improved growth performance under drought stress. J Plant Physiol 152:525–532Google Scholar
- Roe JH (1934) A colorimetric method for the determination of fructose in blood and urine. J Biol Chem 107:809–818Google Scholar
- Schreiber U (1997) Chlorophyll Fluorometer PAM-200 (Teaching PAM) and data acquisition software DA-TEACH, Heinz Walz GmbH, Effeltrich, GermanyGoogle Scholar