Effects of overnight radiation with monochromatic far-red and blue light on flower budding and expression of flowering-related and light quality-responsive genes in Eustoma grandiflorum

The effects of overnight radiation with monochromatic light on flower budding using far-red- and blue light-emitting diodes (FR and B, respectively) were investigated in Eustoma grandiflorum under controlled temperature and 8-h sunlight. Flower budding was promoted by FR and B, while it was not observed under short-day conditions with an 8-h photoperiod during the treatment period. The flower budding with FR was earlier than with B. Expression analysis of flowering-related genes and potential light quality-responsive genes was performed to find genes involved in light quality-dependent regulation of flowering. The levels of EgFTL and EgSOC1L mRNA increased preceding flower budding with FR and B, suggesting that both genes could be involved in the effects on flowering brought about by far-red and blue lights. Later and lower expression of these genes induced by B compared to FR could be associated with the weak promotion of flowering by blue light in E. grandiflorum. In potential light quality-responsive genes, the level of EgBTB-POZI mRNA peaked with EgFTL with FR. Collectively, EgFTL and EgSOC1 likely promote flowering with FR and B, and EgBTB-POZI might be possibly involved in the promotion of flowering with FR.