Expression Pattern of Several Flowering-related Genes during Flower Bud Formation in Rhododendron × pulchrum ‘Oomurasaki’

To investigate the relationship between the development of floral buds and the expression pattern of floweringrelated genes, observation of floral organ development and expression analysis of RpFT, RpSOC1, RpLFY, RpTFL1, RpCEN, and RpAP3 were carried out from July to August 2011 of the evergreen azalea ‘Oomurasaki’. After floral meristem development, floral organs, such as sepals, petals, stamens, and carpels, were observed subsequently on the floral meristems. The expression level of RpTFL1 gradually decreased with floral meristem development; however, the expression level of RpFT and RpLFY increased continuously until carpel development and that of RpAP3 began to increase with stamen development. RpSOC1 and RpCEN showed an irregular expression pattern during floral bud development. These results suggest that the period of floral organ development can be determined by the expression pattern of RpTFL1, RpFT, RpLFY, and RpAP3 in evergreen azalea ‘Oomurasaki’.