Identification of differentially expressed genes during flower development in carnation (Dianthus caryophyllus)

Flower development is a complex process mediated by a cascade of transcriptional regulation and signal transduction. Differentially expressed genes in two different developmental stages of carnation flowers were isolated. For this purpose, the suppression subtractive hybridization (SSH) technique followed by the differential hybridization screening was employed to identify rarely transcribed flower maturation-inducible genes. Using the reverse Northern blot analysis we screened 85 positive clones from a total 274 clones obtained by SSH. Among these 85 cDNAs, 60 genes showed obvious distinction of signal intensity. Thirty-five out of 60 clones were analyzed by Northern blot, and 60% (21 of 35) of the clones revealed the true positives of flower maturation-related genes, but others were not certain. Thirteen clones (CFMI-3, 5, 6, 8, 9, 10, 11, 16, 38, 61, 230, 237, 263) were only expressed in mature flowers. None of 13 clones exhibited any visible expression in the driver populations, but were distinctly induced during flower maturation (tester populations). However, the other eight clones (CFMI-7, 14, 49, 66, 203, 205, 243, 388) showed a basal level of expression in the flower bud and increased expression in the mature flower.