Abstract
AtC401 was isolated as an Arabidopsis homologue of the Pharbitis nil C401 (PnC401) that is a gene which encodes a leaf protein closely related to the photoperiodic induction of flowering. C401 expression shows a dark-inducible circadian rhythm at the transcriptional level. AtC401 consists of a kinase domain in the N-terminal half and 12 times of pentatricopeptide repeat (PPR) in the C-terminal half. Although C401 has no intracellular localization signals, transgenic lines expressing the green fluorescent protein (GFP) fused to C401 demonstrated that C401:GFP localized in the nucleus. AtC401 protein physically interacts with CONSTANS, through PPR motif, in yeast. Although AtC401-overexpressor (35S::AtC401) showed almost no difference compared to wild type Columbia, and CO-overexpressor (35S::CO) showed early flowering, 35S::CO/atc401-1 and 35S::CO/35S::AtC401 showed late flowering phenotype. These results suggest that AtC401 functions as a floral regulator, by associating with CONSTANS.
