Abstract
Petals are formed between sepals and stamens. Processes of petal maturation were described precisely (Smyth et al., 1990), which contain three phases. 1) Petal primordia appear between sepal primordia and bases of stamen primordia. 2) Petals elongate along the sepals through narrow space between sepals and the anthers. 3) Petals elongate rapidly to mature when flower opens.
To investigate the mechanism underlying the processes, we screened mutants with defects in petal morphology. We isolated a mutant, folded petals (fop). Histological analysis showed that folding of the petals was observed at the second phase shown above. The petals in fop showed no difference in size and shape from those in wild type. FOP encodes a putative transmembrane protein with unknown function. Analysis of pFOP:GUS transgenic plants revealed that FOP was expressed in petals. We will discuss about the function of FOP in the context of the petal maturation.
