Application of forchlorfenuron (CPPU) to flower buds induces morphologically different paracorollas, i.e., wide and narrow type, in torenia (Torenia fournieri L.). We investigated the morphological properties and the role of floral homeotic genes in the formation of these two types of paracorolla. The morphology of epidermal cells and distribution pattern of vascular bundles in the wide paracorolla was the same as in the petal; however, in the narrow paracorolla, the morphology of epidermal cells was either petal-like or stamen-like, and the distribution pattern of vascular bundles was stamen-like. In situ hybridization analysis of the floral homeotic genes showed that a class A gene, T. fournieri SQUAMOSA (TfSQUA), and class B genes, TfDEFICIENS (TfDEF) and TfGLOBOSA (TfGLO), were expressed in the broad part of the primordia of the wide paracorolla, as in the petal. Class C genes, TfPLENA1 (TfPLE1) and TfFARINELLI (TfFAR), were only expressed at the margin of the primordia. However, in the primordia of the narrow paracorolla, TfSQUA was only expressed at the margin, but the class B genes and one of the class C genes (TfPLE1) were expressed in a broad section, as in the primordia of the wide paracorolla. This expression pattern in the narrow paracorolla was intermediate between that of the petal and the stamen. In later developmental stages, quantitative real-time PCR analyses showed that, in the wide paracorolla, TfSQUA and class B genes were highly expressed but the expression of class C genes, as in the petal, was low. In the narrow paracorolla, class B genes were also highly expressed as in the petal; however, the expression of both TfSQUA and the class C genes was low, as in the stamen and the petal, respectively. This expression pattern probably reflects the unstable floral organ identity of the narrow paracorolla, and the expression pattern in paracorollas is determined by the site where the paracorolla is formed.
|Number of pages||9|
|Journal||Journal of the Japanese Society for Horticultural Science|
|Publication status||Published - 2012|
- Floral organ identity
- Intermediate floral organ
- MADS-box genes
ASJC Scopus subject areas