Abstract Nina Vik

Institutt for plante- og miljøvitenskap

Poinsettia, Euphorbia pulcherrima, is the economically most important pot plant in Norway. Poinsettia breeders in Norway approached us at the Agricultural University with the wish to explore modern methods of introducing genetic variation to poinsettia, because they felt the natural variation in the centre of origin (Mexico) had been exploited as far as it could go.

First we had to establish transformation protocols for poinsettia, since there were no prior reports of poinsettia genetic transformation we could base our work on. The gusA reporter gene was used in all transformations where we compared methods. We chose to use the transformation methods of Agrobacterium, particle bombardment and in vivo DNA transfer electrophoresis. The first two methods have been used extensively, while the last is relatively unknown. All methods gave transient GUS expression with the highest transformation frequencies (24%) found when using in vivo electrophoresis. Southern analysis of putatively transformed plants by the analysis of stable integration of novel genes through electrophoresis has been performed.

Secondly, we went on to transform poinsettia with the rolC gene of the soil bacteria Agrobacterium rhizogenes. Effects of rolC transformation in other species are reduced apical dominance, dwarf growth, enhanced rooting, enhanced branching and others. Our aim was to control plant height and branching in poinsettia. Stable transformation was confirmed by Southern analysis. Compared to control plants we observed a strong development in rolC transformants of adventitious shoots from cut surfaces after decapitation. In addition a large number of the adventitious shoots were fused together in a fasciation-like growth. Histological studies of stem sections revealed that the cortex cells showed increased cell division in the transgenic plants. There are some indications of thicker leaves in the rolC transgenic plants.

We also transformed poinsettia with a flavonoid 3’,5’-hydroxylase (F3’5’H) cDNA clone from petunia. The F3’5’H is an enzyme in the flavonoid pathway that shifts the synthesis of anthocyanins towards blue delphinidin, creating purple or blue colours. Stable transformation was confirmed using TaqMan real-time PCR and variation in relative copy-numbers was also confirmed. Furthermore we observed pigment change in a number of plants, some with even colour change in the bracts and others with bluer sectors.

Key words: Euphorbia pulcherrima, genetic transformation methods, DNA transfer electrophoresis, rolC, adventitious shoots, fasciation, branching, F3’5’H, plant pigments
Vik, N.I. (2003). Genetic transformation of poinsettia (Euphorbia pulcherrima). Doctor Scientiarum Theses, 2003: 21. Agricultural University of Norway. ISSN: 0802-3220 ISBN: 82-575-0560-9


Oppdatert: 04.10.04
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