Open AccessUp‐regulation of sucrose synthase and UDP‐glucose pyrophosphorylase impacts plant growth and metabolism
Author(s) -
Coleman Heather D.,
Ellis Dave D.,
Gilbert Margarita,
Mansfield Shawn D.
Publication year - 2006
Publication title -
plant biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.525
H-Index - 115
eISSN - 1467-7652
pISSN - 1467-7644
DOI - 10.1111/j.1467-7652.2005.00160.x
Subject(s) - biology , sucrose synthase , transgene , nicotiana tabacum , cauliflower mosaic virus , sucrose , sugar , genetically modified crops , carbohydrate metabolism , gene , biochemistry , sucrose phosphate synthase , enzyme , tobacco etch virus , starch , gene expression , genetics , invertase , virus , plant virus , potyvirus
Summary The effects of the overexpression of sucrose synthase (SuSy) and UDP‐glucose pyrophosphorylase (UGPase) on plant growth and metabolism were evaluated in tobacco ( Nicotiana tabacum cv. Xanthi). T 1 transgenic plants expressing either gene under the control of a tandem repeat cauliflower mosaic virus 35S promoter (2×35S) or a xylem‐localized 4CL promoter (4‐coumarate:CoA ligase; 4CL) were generated, and reciprocally crossed to generate plants expressing both genes. Transcript levels, enzyme activity, growth parameters, fibre properties and carbohydrate content of stem tissue were quantified. The expression profiles of both genes confirmed the expression pattern of the promoters: 2×35S expressed more strongly in leaves, while 4CL expression was highest in stem tissue. In‐depth plant characterization revealed that the single‐transgene lines showed significant increases in the height growth compared with corresponding control lines. The double‐transgene plants demonstrated an additive effect, proving to be even taller than the single‐transgene parents. Several of these lines had associated increases in soluble sugar content. Although partitioning of storage carbohydrates into starch or cellulose was not observed, the increased height growth and increases in soluble carbohydrates suggest a role for SuSy as a marker in sink strength and lend credit to the function of UGPase in a similar role. The up‐regulation of these two genes, although not increasing the percentage cellulose content, was effective in increasing the total biomass, and thus the overall cellulose yield, from a given plant.