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FKF1 and GIGANTEA complex formation is required for day-length measurement in Arabidopsis.

ABSTRACT: Precise timing of CONSTANS (CO) gene expression is necessary for day-length discrimination for photoperiodic flowering. The FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 (FKF1), and GIGANTEA (GI) proteins regulate CO transcription in Arabidopsis. We demonstrate that FKF1 and GI proteins form a complex in a blue-light-dependent manner. The timing of this interaction regulates the timing of daytime CO expression. FKF1 function is dependent on GI, which interacts with a CO repressor, CYCLING DOF FACTOR 1 (CDF1), and controls CDF1 stability. GI, FKF1, and CDF1 proteins associate with CO chromatin. Thus, the FKF1-GI complex forms on the CO promoter in late afternoon to regulate CO expression, providing a mechanistic view of how the coincidence of light with circadian timing regulates photoperiodic flowering.

SUBMITTER: Sawa M

PROVIDER: S-EPMC3709017 | biostudies-literature | 2007 Oct

REPOSITORIES: biostudies-literature

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FKF1 and GIGANTEA complex formation is required for day-length measurement in Arabidopsis.

Sawa Mariko M Nusinow Dmitri A DA Kay Steve A SA Imaizumi Takato T

Science (New York, N.Y.) 20070913 5848

Precise timing of CONSTANS (CO) gene expression is necessary for day-length discrimination for photoperiodic flowering. The FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 (FKF1), and GIGANTEA (GI) proteins regulate CO transcription in Arabidopsis. We demonstrate that FKF1 and GI proteins form a complex in a blue-light-dependent manner. The timing of this interaction regulates the timing of daytime CO expression. FKF1 function is dependent on GI, which interacts with a CO repressor, CYCLING DOF FACTOR 1 ( ...[more]

PMID: 17872410

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Project description:Lateral root (LR) formation is a vital organogenetic process that determines the root architecture in plants. The number of root branches governs the degree of anchorage, efficiency of nutrients acquisition, and water uptake. The molecular pathways involved in LR formation have been extensively studied in Arabidopsis thaliana (At). A plant hormone, Auxin, is a key regulator of root development and promotes LR formation in plants. A plethora of Arabidopsis genes have been identified to regulate LR initiation, patterning, and emergence processes. Recently, the involvement of flowering time control pathways and circadian clock pathways in LR development has come to light, but the connecting link between these processes is still missing. We have established that GIGANTEA (GI), a key component of photoperiodic flowering, can regulate the formation of LRs in Arabidopsis. GI is known to be involved in red light signaling and circadian clock signaling pathways. Here, we report that over-expression of GI enhances LR formation in red light in At. Real-time PCR analysis shows that GI positively regulates the transcription of TRANSPORT INHIBITOR RESPONSE 1 (TIR1) which is an upstream component of auxin signaling. Furthermore, gi-100 mutant downregulates the LR initiation signaling gene, AUXIN RESPONSE FACTOR 7 (ARF7), and its downstream target gene, LATERAL ORGAN BOUNDARIES-DOMAIN 16 (LBD16). Hence, GI acts as a positive regulator of IAA14-ARF7-LBD16 modules during LR initiation. We have also checked the effect of GI on the expression of NAC1 and AIR3 genes which are controlled by TIR1 during LR formation. Our results show that GI induces the NAC1 transcription and its downstream gene, AIR3 expression, which leads to the enhancement of LR initiation. Taken together, our results suggest that GI controls the expression of TIR1 to govern auxin signaling during LR formation in presence of red light and GI can act as a link between circadian clock signaling, flowering time control pathways, light signaling, and lateral root development pathways.

Dataset Information

FKF1 and GIGANTEA complex formation is required for day-length measurement in Arabidopsis.

Publications

FKF1 and GIGANTEA complex formation is required for day-length measurement in Arabidopsis.

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