Poster: Regulation of gene expression

Abs # 764: Analysis of CONSTANS-Interacting Proteins of Arabidopsis Identified by Yeast Two-Hybrid Screen

Presenter:	Song, Younghun , s_bonggu@gshp.gsnu.ac.kr
Authors	Song, Younghun  (A)   Kang, Juhwoan  (A)   Shin, Suyoung  (A)   Kim, Hyejin  (A)   Choi, Jinsoo  (A)   Hong, Jongchan  (A)
Affiliations:	(A): Gyeongsang National Univeristy
Web Site:	http://pgec.gsnu.ac.kr

The transition from vegetative to reproductive growth is a critical transition in the life cycle of flowering plants. The timing of flowering is one of the most important processes for the reproductive success of plants. CONSTANS (CO) was identified as a gene controlling the photoperiodic regulation of flowering in Arabidopsis. CO induce flowering via at least four early target genes such as FT and SOC. However, the molecular mechanisms involved in CO-mediated photoperiodic control were largely unknown. In this study we screened and isolated 23 CO-interacting proteins from Arabidopsis using yeast two-hybrid screen (Y2H). The CIP1 and CIP2, which contain a variant type of B-box zinc-finger motif (C2C2 type), were most abundant in initial screening and studied in more detail. GFP fusion protein study showed that CIP2 and CO were nuclear localized. The abundance of CIP1 and CIP2 messenger RNA cycles with a 24-hr rhythm and is controlled by the circadian clock. We show that the circadian clock regulates expression of CIP1 and CIP2 with a peak in transcript levels around dawn. Unlike CO, altered expression of CIP1 and CIP2 had little effect on flowering time. We also isolated six CO-interacting proteins that have DNA binding activity to a promoter region of FT. In view of the results so far achieved, we suggest that CO forms multimeric-complex with other proteins and then controls the flowering processes (Supported by BK21 program and the grant from Crop Functional Genomic Center of 21C Frontier Research Program).