JXB Advance Access originally published online on February 13, 2008
Journal of Experimental Botany 2008 59(4):839-848; doi:10.1093/jxb/erm364
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© 2008 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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RESEARCH PAPER |
Water deficits and heat shock effects on photosynthesis of a transgenic Arabidopsis thaliana constitutively expressing ABP9, a bZIP transcription factor
1Biotechnology Research Institute, National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing100081, China
2Department of Genetics and Biotechnology, Faculty of Agricultural Sciences, University of Aarhus, Forsøgsvej 1, DK-4200 Slagelse, Denmark
3Key Laboratory of Crop Growth Regulation of Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
4Department of Agricultural Sciences, Faculty of Life Sciences, University of Copenhagen, DK-2630 Taastrup, Denmark
* To whom correspondence should be addressed. E-mail: Bernd.Wollenweber{at}agrsci.dk; E-mail: junzhao{at}caas.net.cn
The effects of water deficits (WD), heat shock (HS), and both (HSWD) on photosynthetic carbon- and light-use efficiencies together with leaf ABA content, pigment composition and expressions of stress- and light harvesting-responsive genes were investigated in ABP9 [ABA-responsive-element (ABRE) binding protein 9] transgenic Arabidopsis (5P2). WD, HS, and HSWD significantly decreased photosynthetic rate (A) and stomatal conductance (gs) in wild-type plants (WT). A and gs of 5P2 transgenic plants were slightly reduced by a single stress and were hardly modified by HSWD. Although A and electron transport rate (ETR) in 5P2 plants were depressed under optimal growth conditions (control) in relation to WT, they were enhanced under HS and HSWD. These results indicate that ABP9 transgenic plants are less susceptible to stress than the WT. In addition, the increased ABA contents in both WT and 5P2 plants in response to WD and/or HS stresses suggest that declines in A and gs might have been due to ABA-induced stomatal closure. Moreover, compared with WT, 5P2 plants exhibited higher ABA content, instantaneous water use efficiency (IWUE), Chl a/b, NPQ, and lower Chl/carotenoid ratios. Finally, altered expression of stress-regulated or light harvesting-responsive genes was observed. Collectively, our results indicate that constitutive expression of ABP9 improves the photosynthetic capacity of plants under stress by adjusting photosynthetic pigment composition, dissipating excess light energy, and elevating carbon-use efficiency as well as increasing ABA content, IWUE, and expression of stress-defensive genes, suggesting an important role of ABP9 in the regulation of plant photosynthesis under stress.
Key words: ABP9, ABA, heat shock, photosynthesis, stress tolerance, water deficits
Received 1 September 2007; Revised 19 December 2007 Accepted 21 December 2007
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