Abstract
Regulatory mechanism of flowering is well studied in model plants. However, there is only limited knowledge about flowering regulation in tree plants. In this study, to understand regulatory mechanisms of flowering in tree plants, we isolate and characterize genes controlling flowering in Eucalyptus.
FT and CO are known as floral promoters in Arabidopsis. Ten EgCOs and four EgFTs were found by BLAST search with E. grandis genome database. We succeeded in isolation of 3 CO homologues and 3 FT homologues, including EugCO1 and EugFT1 that are closest related to Arabidopsis CO and FT, respectively from E. urograndis. To study function of the EugCO and EugFT genes, we introduced the Eucalyptus genes into Arabidopsis wild type plants or co and ft;tsf double mutants. We found that EugCO1 and EugFT1 could promote flowering in Arabidopsis. To investigate the periodic expression pattern of EugCO1 and EugFT1, we collected samples from E. urograndis every month and analyzed the expression of these genes by using RT-PCR. In leaves, the expression level of EugFT1 was the highest in April before the flower bud emergence in June ,while it was the lowest in September.
