Overexpression of sucrose phosphate synthase increases sucrose unloading in transformed tomato fruit

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  2. Mimi Nguyen
  3. Professor Christine Foyer
Author(s)Nguyen-Quoc B, N'Tchobo H, Foyer CH, Yelle S
Publication type Article
JournalJournal of Experimental Botany
Year1999
Volume50
Issue335
Pages785-791
ISSN (print)0022-0957
ISSN (electronic)1460-2431
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Sucrose unloading and sink activity were examined in tomato plants (Lycopersicon esculentum) overexpressing sucrose phosphate synthase (SPS; EC 2.3.1.14). Like the leaves, the fruit of the transformed tomato plants had elevated (2.4-fold) SPS activity. SPS over-expression in tomato fruit did not significantly change acid invertase, and only slightly reduced ADPglc ppase activity, but enhanced sucrose synthase activity by 27%. More importantly, the amount of sucrose unloaded into the fruit was considerably increased. Using [3H]- (fructosyl)-sucrose in in vitro unloading experiments with harvested 20-d-old fruit, 70% more sucrose was unloaded into the transformed fruits compared to the untransformed controls. Furthermore, the turnover of the sucrose unloaded into the fruit of transformed plants was 60% higher than that observed in the untransformed controls. Taken together, these results demonstrate that SPS overexpression increases the sink strength of transformed tomato fruit.
PublisherOxford University Press
URLhttp://dx.doi.org/10.1093/jxb/50.335.785
DOI10.1093/jxb/50.335.785
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