Flavonoid gene expression follows the changes in tissue development of twoPetunia hybrida homeotic flower mutants

Abstract

TwoPetunia hybrida homeotic flower mutants,Blind (Bl) andGreen Petals (Gp), were characterized as a way to study floral morphogenesis. The influence of these homeotic mutations on the expression of the two genes encoding the flavonoid biosynthesis enzyme chalcone flavanone isomerase was investigated. TheBl mutation gives rise to highly modified flowers in which the limbs are transformed into antheroid limbs which develop on top of a normally formed tube. In wild type plants,chiA transcripts are detected in the flower limb. In antheroid limbs, however, expression of the anther-specificchiB gene was observed. This is in line with the homeotic nature of theBl mutation. TheGp mutation gives rise to mutated flowers in which the petals are transformed into sepaloid petals. An absence of CHI activity andchi transcripts in sepaloid petals was observed, which is in line with the homeotic nature of theGp gene.