FLOWER COLOUR PATTERNS FOR ORNAMENTAL PURPOSES

There is a wide range of colour patterns in the flowers of various plant species.
Flower patterns have an immense importance in horticulture due to their ornamental value.
Similar patterns may arise as a result of different causes.
In addition to genetically inherited patterns, instable alleles of floral genes, patterns caused by infections and anatomically or environmental caused modifications, chimeric determined patterns of flowers may result in bicoloured flowers.
Bicoloured cultivars of Angelonia, Saintpaulia and Pelargonium were investigated and proved as plants with chimeric determined pattern of flower.
There were differences of in vitro callus regeneration of the bicoloured cultivars: Angelonia and Pelargonium mainly regenerated from subepidermal tissues, seldom from epidermal tissue, however the investigated Saintpaulia cultivars regenerated from both, epidermal and subepidermal tissues.
Very rarely it is possible that more than one cell form the new apex and bicolour flowering plants are regenerated (Pelargonium, Angelonia). Chimeric determined bicolourness of flowers is due to different genotypes of the apex layers in respect to flower colour.
Generally, angiosperms consist of three different apex layers (L1, L2, L3). Petal tissues usually originate from the two outer apex layers (L1, L2). In Angelonia and Saintpaulia it was possible to show, that very seldom the third apex layer takes part in the formation of petals and thus plays an insignificant role in the formation of bicoloured chimeric determined patterns of flowers.