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FRIGIDA establishes a local chromosomal environment for FLOWERING LOCUS C mRNA production


FRIGIDA (FRI) upregulates the expression of the potent floral repressor FLOWERING LOCUS C (FLC) to confer the winter-annual growth habit in Arabidopsis thaliana: accelerated transition to flowering after prolonged cold exposure (vernalization). Here, we show that FRI, histone acetyltransferases, the histone methyltransferase COMPASS-like and other chromatin modifiers are part of a FRI-containing supercomplex enriched in a region around the FLC transcription start site (TSS) to promote its expression. Several FRI partners are also enriched in a 3’ region flanking FLC and, together with FRI, they function to increase the frequency of physical association of the region around TSS with the 3’ region and promote the expression of both sense FLC and antisense non-coding RNAs. Our results show that the FRI supercomplex establishes a local chromosomal environment at FLC with active chromatin modifications and topology to promote transcriptional activation, fast elongation and efficient pre-messenger RNA splicing, leading to a high-level production of FLC mRNAs.

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We are very grateful to R. M. Amasino for graciously providing the FRI-Col, FRI flc-2 and FRI efs seeds. We thank A. Jarmolowski for supplying the cbp20 seeds and Y. Ou and F. Huang for assistance. This work was supported in part by the National Natural Science Foundation of China (grant no. 31721001), the National Key Research and Development Program of China (grant no. 2017YFA0503803) and the Chinese Academy of Sciences (grant no. XDPB0404).

Author information

Y.H. conceived and supervised the research. Z.L. and D.J. conducted the experiments. Z.L., D.J. and Y.H. analysed the data. Y.H. and Z.L. wrote the paper.

Competing interests

The authors declare no competing interests.

Correspondence to Yuehui He.

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Further reading

Fig. 1: COMPASS-like forms a complex with FRIc and mediates its binding to FLC chromatin.
Fig. 2: Functional association of COMPASS-like with SWR1c at the FLC locus.
Fig. 3: HAM1 and HAM2 mediates FRI-dependent FLC upregulation.
Fig. 4: FRI interacts with UBC1 and functions to promote its enrichment across the FLC locus.
Fig. 5: Analysis of the roles of FRI and WDR5a in transcription initiation and elongation at FLC.
Fig. 6: Analysis of the binding of FRI partners to the region downstream of FLC TTS and 5’ to 3’ gene looping.