This document discusses ornamental plant breeding through both traditional and genetic engineering methods. It covers topics such as the economic importance of ornamentals, hybridization techniques, effects of ploidy levels, and genetic modification of traits like flower color, plant size, architecture, and post-harvest life. The document notes both the limitations of traditional breeding as well as the new potentials and challenges of genetic engineering for modifying commercial ornamental plant traits.

1. Breeding ornamentals

2. Ornamental breeding
Overview
• Plant grown for pleasure
• Seed or vegetative propagation
• Economical importance
• Aesthetic instead of Yield criteria
– conservative old ideas
– special new types
• Hybrids: uniformity instead of heterosis
• Auto- and alloploidy widespread

3. Seed propagated ornamentals
• Economically large
– hybrid cultivars
– manual hybridisation for seed production
• Economically small
– population cultivars
– maintained through mass selection

4. Vegetative ornamentals
• Gardens, parks, pot plants, cut (green, flower)
• Extensive interspecific hybridisation ( no species)
• Odd ploidies
– aneuploid, triploidy, pentaploidy
• Cross and select cloned seed offspring (Breeders
rights protection)
• producers selection of mutants (sports) (No
Breeders rights protection)

5. Floriculture: Genetic engineering
of commercial traits
• Limitations of traditional breeding:
– genera limited gene pools
– ”limited organized financing (breeders rights)”
• New potentials with genetic engineering:
– gene transfer unrestricted
– transformation systems available
• ”Ornamentals not generally eaten and most
of them do not have wild relatives where
grown (gene spreading)”

6. Flower color modification
• Brick red Pelargonidin pigment in Petunias
– express DFR from maize (Dihydrokaempferol
as substrate)
– mutate F3’H and F3’5’H to accumulate
dihydrokaempferol)
• Most inserts gene silenced
• Hybridisation creates new color types

7. Flower color modification
• In future blue flowers (rose, tulip, carnation)
– synthesis of delphinidins (enzymes known)
– existence of flavonol co-pigments (enzymes known)
– high vacuolar pH (regulation poorly understood)
• Reduce color intensity
– sense or antisense constructs to reduce chalcone
synthetase (chs) activity

8. Plant size (dwarfing)
• Cytokinin-glucosidase from A. rhizogenes
– releases cytokinin from glucoside conjugates
(multiple shooting and compact plants)
• Sense or antisense inactivation of genes in
GA synthesis pathway to reduce cell
stretching
• Dwarfing is quite often obtained through
traditional mutation treatments.

9. Architecture of flowers and
inflorescences
• Homeotic genes controlling flower
formation and morphology
– many isolated from Arabidopsis and Petunia
– seems to work in other species
– may be used instead of mutations (not well
understood)

10. Post-harvest life
Methionine
S-Adenosyl methionine SAM
1-Aminocyclopropane-
1-carboxylic acid (ACC)
Ethylene
ACS
ACO
Reduce ethylene reactivity:
• inactivate acs
• inactivate aco

11. Major problems for success
• Gene silencing (pre- or post transcriptional)
• Test many inserts of a construct
• Pleiotropic effects (necessitates intensive
breeding )