Abstract
SBP-box genes encode plant-specific transcription factors originally isolated from Antirrhinum as factors binding to promoter of SQUAMOSA, a floral meristem identity gene. In Arabidopsis, 16 SBP-box genes (SPL1-SPL16) were identified, and some of them were shown to have binding ability to the promoter of APETALA1, the Arabidopsis homolog of SQUAMOSA. There are few reports regarding the function of SBP-box genes, probably because of existence of functionally redundant genes. Therefore, we analyzed function of SBP-box genes using CRES-T system in Arabidopsis, in which a chimeric repressor acts dominantly both to endogenous and functionally redundant transcription factors. SPL2, SPL10 and SPL11 sharing high sequence homology were highly expressed in flowers. While loss-of-function mutant of SPL2 showed no visible phenotype, transgenic plants that express the chimeric SPL2 repressor had short petals and pedicels as well as reduced apical dominance. This suggests that SPL2, SPL10 and SPL11 are functionally redundant.
