Characterization of flowering-related genes and flowering response in relation to blue light in Gypsophila paniculata

The flowering response to monochromatic light and flowering-related genes underlying this response need to be characterized to efficiently use light-emitting diodes for lighting culture. The flowering response to far-red light has been well studied in long-day cut flowers, but there have been few studies investigating the response to blue light. Flowering and the expression of the G. paniculata homologs of the FLOWERING LOCUS T and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 genes (GpFT, GpSOC1) were not previously promoted in Gypsophila paniculata, an important long-day cut flower, ‘Bristol Fairy’ under long-day conditions with blue light. In the present study, we found that flowering was promoted in another G. paniculata ‘Million Star’, under long-day conditions with blue light, suggesting that there is variation in G. paniculata’s flowering response to blue light. Therefore, we analyzed the expression of GpFT and GpSOC1 in the ‘Million Star’. The expression of GpFT and GpSOC1 was promoted with flowering in ‘Million Star’ under long-day conditions with blue light in contrast to ‘Bristol Fairy’. We next analyzed the G. paniculata homologs (GpFKF1, GpGI) of FLAVIN-BINDING KELCH REPEAT F-BOX 1 and GIGANTEA genes, which participate in the flowering response to blue light. GpFKF1 and GpGI amino acid sequences were well conserved; gene expression showed a diurnal rhythm with different peaks under short-day and long-day conditions, as previously observed in Arabidopsis thaliana. GpFKF1 interacted with GpGI. There were no important differences in GpFKF1 or GpGI amino acid sequences between the two cultivars. Our results suggest that variation in the flowering response to blue light is associated with GpFT and GpSOC1, rather than GpFKF1 and GpGI.