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TitleVariation in the ability of the maize Lc regulatory gene to upregulate flavonoid biosynthesis in heterologous systems
Publication TypeJournal Article
Year of Publication1999
AuthorsBradley, J.M., Deroles S.C., Boase M.R., Bloor S.J., Swinny E., and Davies K.M.
JournalPlant Science
Pagination31 - 39
Date Published1999
ISSN01689452 (ISSN)
Keywordsarticle, biosynthesis, cultivar, Eustoma grandiflorum, flavonoid, gene overexpression, genetic variability, maize, nonhuman, Pelargonium domesticum, phenotype, pigmentation, regulator gene, regulatory mechanism, transcription regulation, transgene
AbstractWe have previously shown that overexpression of the maize basic helix- loop-helix (bHLH) regulatory gene, Leaf colour (Lc) in petunia enhanced pigmentation through the upregulation of the flavonoid biosynthetic pathway (Bradley et al. Plant J. (13) (1998) 381-392) [1]. Here we report on the effect of Lc expression in two popular ornamental species, lisianthus (Eustoma grandiflorum) and a regal pelargonium cultivar (Pelargonium X domesticum Dubonnet). A number of transformants expressing the Lc cDNA under the control of the cauliflower mosaic virus (CaMV) 35S promoter were generated in three different lisianthus cultivars, including purple, pink and cream flowered lines, and the pelargonium cultivar Dubonnet. Unlike transgenic Lc petunia, which had enhanced pigmentation in foliage and flowers, no visible phenotypic alteration in vegetative or floral pigmentation was observed in either the pelargonium or lisianthus lines expressing Lc. A detailed analysis of flavonoid content and expression of a number of flavonoid biosynthetic genes in the leaves of these lines indicated that, unlike in petunia, Lc alone was unable to transcriptionally upregulate the flavonoid biosynthetic genes of lisianthus or pelargonium. This suggests there may be a divergence of the regulatory mechanisms in different dicots and that a combination of introduced bHLH and MYB factors may be required to increase pigmentation in some plant species. This report extends the study of bHLH regulatory gene action in several Solanaceae and a single Brassiceae species to include members of the Gentianaceae and Geraniaceae.

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