Transgenic Torenia Research Articles

A Transgene Locus is Required for Wavy-patterned Flowers of Transgenic Torenia Plants

Modification of flower colour in torenia (Torenia fournieri Lind.) by reintroduction of the chalcone synthase (CHS) or dihydroflavonol-4-reductase genes has been reported (Aida et al., 2000.Plant Science153: 33–42). The typical modified phenotype among plants with an introduced antisense gene is a uniformly lighter-coloured corolla. Of the 67 plants in which an antisense CHS gene was introduced, only a single line (411-7) showed a wavy pattern on the flower lip. In flowers of this plant, the inner part of the corolla lip was pigmented more deeply than the outer part in a wave-like pattern—a pattern that does not exist in normal cultivars. The segregation ratio of the flower colour patterns of the offspring and Southern blot analysis demonstrated that one of the two transgene loci detected may cause the wavy phenotype; the other locus is never associated with the wavy phenotype but alone it could produce the typical antisense type pattern.

Copigmentation gives bluer flowers on transgenic torenia plants with the antisense dihydroflavonol-4-reductase gene

When anthocyanins in plants make complexes with copigments such as flavones or flavonols (copigmentation), the visible absorption maximum of the flowers is shifted so that it becomes longer: that is, the flowers look bluer. In an earlier study, our group reported the modification of flower color in torenia ( Torenia fournieri Lind.) by re-introduction of the dihydroflavonol-4-reductase ( DFR) gene or the chalcone synthase ( CHS) gene. Our initial observation of torenia transformants was that plants with the antisense DFR gene produced bluer flowers than plants with the antisense CHS gene. In the present study we found that inactivation of the DFR gene by genetic transformation caused the accumulation of flavones — possible copigments — and that the resulting copigmentation likely to make the torenia flowers bluer. This method could be applied to other plant species to produce bluer flowers.

Analysis of transgenic Torenia plants introduced gibberellin 20-oxidase gene from pumpkin

Analysis of transgenic Torenia plants introduced gibberellin 20-oxidase gene from pumpkin

Analysis of transgenic Torenia plants introduced gibberellin 20-oxidase gene from pumpkin

Analysis of transgenic Torenia plants introduced gibberellin 20-oxidase gene from pumpkin

Extension of flower longevity in transgenic torenia plants incorporating ACC oxidase transgene

We demonstrated extension of flower longevity in torenia ( Torenia fournieri Lind.) by introducing a fragment of the 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase gene in sense or antisense orientation. Torenia was transformed by Agrobacterium-mediated gene transfer. Among primary transformants, 8 sense-gene-introduced plants (average flower longevity 2.7–7.1 days) and 3 antisense-gene-introduced plants (from 2.5–2.7 days) showed significantly greater longevity than did wild-type plants (2.0 days). Analysis of offspring suggested that the introduced gene had been inherited, and that the extended flower longevity was linked to the existence of the gene. Northern blot analysis and measurement of ethylene production demonstrated a reduction in mRNA level and endogenous ethylene production in plants with improved flower longevity.

Gene Silencing in Transgenic Torenia and Its Applications for Breeding.

The gene silencing by sense and antisense transgenes in plants is an effective method to breed new cultivars. Torenia fournieri Lind. is an ornamental plant in the family Scrophulariaceae. We have established a transformation system for Torenia and modified flower longevity and color by transformation-mediated gene silencing. The introduction of a fragment of the ACC oxidase gene, in sense or antisense orientation, allowed the production of transgenic Torenia plants with extended flower longevity. The extended flower longevity was linked to the existence of the transgene. The introduction of a chalcone synthase (CHS) or dihydroflavonol-4-reductase (DFR) gene, in sense or antisense orientation, allowed the production of transgenic Torenia plants whose flower color had been changed. Some transformants showed a pastel flower color, and one showed a wavy pattern on the flower lip. These characters do not exist in normal cultivars.