CONSTANS–FKBP12 interaction contributes to modulation of photoperiodic flowering in Arabidopsis

• Published in: The Plant journal : for cell and molecular biology 2020-03, Vol.101 (6), p.1287-1302
• Main Authors: Serrano‐Bueno, Gloria, Said, Fatima E., los Reyes, Pedro, Lucas‐Reina, Eva I., Ortiz‐Marchena, M. Isabel, Romero, José M., Valverde, Federico
• Format: Article
• Language: English
• Subjects: Accumulation; Algae; Arabidopsis; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Carbon monoxide; Chlamydomonas reinhardtii - genetics; Conserved Sequence; CONSTANS; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; DNA-Binding Proteins - physiology; FKBP12; floral transition; Flowering; Flowers - genetics; Flowers - growth & development; Flowers - metabolism; Gene Expression Regulation, Plant; Genetics; Insertion; Mutants; Peptidylprolyl Isomerase - genetics; Peptidylprolyl Isomerase - metabolism; Phenotypes; Photoperiod; photoperiodic flowering; post‐translational modification; Proteasomes; Protein Interaction Domains and Motifs; protein stability; Proteins; Real-Time Polymerase Chain Reaction; Signal processing; Stability; Transcription; Transcription Factors - genetics; Transcription Factors - metabolism; Transcription Factors - physiology; Translation; Two-Hybrid System Techniques
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.14590

Summary Flowering time is a key process in plant development. Photoperiodic signals play a crucial role in the floral transition in Arabidopsis thaliana, and the protein CONSTANS (CO) has a central regulatory function that is tightly regulated at the transcriptional and post‐translational levels. The stability of CO protein depends on a light‐driven proteasome process that optimizes its accumulation in the evening to promote the production of the florigen FLOWERING LOCUS T (FT) and induce seasonal flowering. To further investigate the post‐translational regulation of CO protein we have dissected its interactome network employing in vivo and in vitro assays and molecular genetics approaches. The immunophilin FKBP12 has been identified in Arabidopsis as a CO interactor that regulates its accumulation and activity. FKBP12 and CO interact through the CCT domain, affecting the stability and function of CO. fkbp12 insertion mutants show a delay in flowering time, while FKBP12 overexpression accelerates flowering, and these phenotypes can be directly related to a change in accumulation of FT protein. The interaction is conserved between the Chlamydomonas algal orthologs CrCO–CrFKBP12, revealing an ancient regulatory step in photoperiod regulation of plant development. Significance Statement Post‐transcriptional regulation of CONSTANS (CO) protein is essential to promote photoperiodic flowering in Arabidopsis thaliana, and here we show that interaction with the immunophilin FKBP12 promotes CO stabilization and activity, so that fkbp12 mutants are late flowering, while overexpression promotes early flowering. The conserved interaction between algal and plant CrCO–CrFKBP12 orthologs reflects the evolutionary importance of this interaction.