IMPORTIN β4 Facilitates CONSTANS Nuclear Accumulation and FT Activation in Arabidopsis.

IMPORTIN β4 enhances CONSTANS nuclear accumulation, promoting FT activation and accelerating flowering in Arabidopsis, with a delay observed when IMB4 is lost.

• Why it matters: Understanding how CO accumulates in the nucleus is crucial because it directly influences flowering time, a key factor for plant reproductive success, yet this process is poorly understood.
• What they did: The study used interaction assays and expression analysis to show that IMPORTIN β4 binds to CO’s CCT domain, facilitating its nuclear import, especially during dusk when both are expressed.
• The result: Loss of IMB4 delays flowering and reduces FT expression without changing CO transcript levels, highlighting IMB4’s role in nucleocytoplasmic transport and flowering regulation.