Morphological variation and agamous-like gene expression in double flowers of Cyclamen persicum Mill.

Several kinds of double-flowered cultivars have been produced from spontaneous mutants in Cyclamen persicum Mill. The morphology and number of organs in double flowers were investigated, and were categorized into three types: “petaloid-stamen type”, “petaloid-sepal type”, and “extra petals in whorl 2 type”. Morphological observations showed that petaloid mutations of stamen and sepal did not appear together within an individual. In addition, three types of AG-like gene were isolated from single and petaloid-stamen-type double-flower buds, and expressions in each whorl were compared. All AG-like genes were expressed in whorl 3 of single flowers, but not in that of petaloid-stamen-type double flowers. In whorl 4, although expressions of the three types of AG-like gene were observed in both single and double flowers, the expression of double flowers was lower than that of single flowers. These results suggest that naturally occurring double flowers of cyclamen can be explained by the ABC-model, and it is suspected that petaloidy of the stamen is caused by the repression of AG-like gene expression in whorl 3.