Ectopic expression of the BoTFL1-like gene of Bambusa oldhamii delays blossoming in Arabidopsis thaliana and rescues the tfl1 mutant phenotype

TERMINAL FLOWER1 (TFL1) homologous genes play major roles in maintaining vegetative growth and inflorescence meristem characteristics in various plant species; however, to date, the function of the bamboo TFL1 homologous gene has not been described. In this study, a TFL1 homologous gene was isolated from Bambusa oldhamii and designated as BoTFL1-like. Phylogenetic analysis of TFL1 homologous genes revealed that BoTFL1-like shared more than 90% identity with the TFL1 genes of other Gramineae. RT-PCR analysis showed that the expression level of BoTFL1-like in floral buds was almost 3.5 times higher than in vegetative buds. In 35S:: BoTFL1-like transgenic Arabidopsis thaliana plants, the time of flowering was significantly delayed by 5 to 9 days, and development of floral buds and sepals was severely affected compared to wild type Arabidopsis plants. This suggests that the BoTFL1-like gene may play roles in flowering time and flower morphological structure in B. oldhamii. The BoTFL1-like gene driven by the 35S promoter almost fully rescued the phenotype of the tfl1 mutant apart from the number of rosette inflorescences, indicating that the function of BoTFL1-like was similar to TFL1 in Arabidopsis. We conclude the TFL1 gene function has been conserved between B. oldhamii and A. thaliana.