Suppression of zeaxanthin formation does not reduce photosynthesis and growth of transgenic tobacco under field conditions |
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Authors: | Sun Wen-Hao Verhoeven Amy S Bugos Robert C Yamamoto Harry Y |
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Institution: | (1) Department of Molecular Biosciences and Biosystems Engineering, University of Hawaii at Manoa, 1955 East West Road, Ag Sci 218, Honolulu, HI 96822, USA;(2) Department of Biology, University of St. Thomas, 2115 Summit Avenue, St. Paul, Minnesota 55105-1096, USA |
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Abstract: | Tobacco (Nicotiana tabacum cv. Xanthi) transformed with an antisense cDNA construct of violaxanthin de-epoxidase (VDE) was examined for the effects of suppressed xanthophyll-cycle activity on photoinhibition, photosynthesis and growth under field conditions. De-epoxidation of violaxanthin and non-photochemical quenching were highly inhibited in antisense plants relative to vector-control and wild-type plants. However, no differences were observed between antisense and control plants in photosynthetic CO2 uptake and maximum photochemical yield (Fm–Fo)/Fm] measured at predawn or in actual photochemical yield (Fm –Fs)/Fm ] measured at midday. Moreover, growth rates of the plants were the same, as were the leaf area ratio, plant height and leaf number. Similarly, antisense plants did not exhibit greater susceptibility to photoinhibition than controls under field conditions. In contrast, when chloroplast protein (D1) synthesis was inhibited by lincomycin, antisense plants were more vulnerable to photoinhibition than wild-type plants. These results indicate that photoprotection under field conditions is not strictly dependent on the levels of the de-epoxidized xanthophylls, antheraxanthin and zeaxanthin.This revised version was published online in October 2005 with corrections to the Cover Date. |
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Keywords: | antheraxanthin D1 turnover de-epoxidase non-photochemical quenching photoinhibition photosynthesis violaxanthin xanthophyll cycle zeaxanthin |
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