Title : COP9 SIGNALOSOME 5A protein interacts with FLOWERING LOCUS T (FT) and mediates cell cycle and flowering
CSN5A is a subunit of the COP9 signalosome and is well known for its proteolytic mechanism by ubiquitination as a photomorphogenesis inhibitor. However, it is not well known that the CSN complex is involved in the cell cycle. The csn5a-1 mutants, completely devoid of CSN5A expression, were identified as a cell cycle arrest in the G2 phase. Since csn5a-1 exhibits post-embryonic growth arrest, this phenotype seems to be associated with the cell cycle. As CSN5A interacts with FLOWERING LOCUS T (FT) in our previous results, we analyzed the flowering phenotype of csn5a mutants in order to investigate the role of CSN5A in ambient temperature responsive flowering. The csn5a-1 flowered early at 16°C under long-day conditions, but they showed a normal flowering time phenotype at 23°C under the same conditions. In this study we will show the relationship between temperature-dependent flowering insensitive phenotype and cell cycle.