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Two FLX family members are non-redundantly required to establish the vernalization requirement in Arabidopsis.

Lee J, Amasino RM - Nat Commun (2013)

Bottom Line: In this study, we show that FLOWERING LOCUS C EXPRESSOR-LIKE 4 (FLL4) is essential for upregulation of FLC in winter-annual Arabidopsis accessions and establishment of a vernalization requirement.Epistasis analysis among FRIGIDA, FLL4, FLOWERING LOCUS C EXPRESSOR and autonomous-pathway genes reveals that FRIGIDA fve exhibits an extreme delay of flowering compared with fri fve, but mutants in other autonomous-pathway genes do not, indicating that FVE acts most antagonistically to FRIGIDA.FLL4 may represent a new member of a FRI-containing complex that activates FLC.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, Wisconsin 53706, USA.

ABSTRACT
Studies of natural genetic variation for the vernalization requirement in Arabidopsis have revealed two genes, FRIGIDA and FLOWERING LOCUS C (FLC), that are determinants of the vernalization-requiring, winter-annual habit. In this study, we show that FLOWERING LOCUS C EXPRESSOR-LIKE 4 (FLL4) is essential for upregulation of FLC in winter-annual Arabidopsis accessions and establishment of a vernalization requirement. FLL4 is part of the FLOWERING LOCUS C EXPRESSOR gene family and both are non-redundantly involved in flowering time control. Epistasis analysis among FRIGIDA, FLL4, FLOWERING LOCUS C EXPRESSOR and autonomous-pathway genes reveals that FRIGIDA fve exhibits an extreme delay of flowering compared with fri fve, but mutants in other autonomous-pathway genes do not, indicating that FVE acts most antagonistically to FRIGIDA. FLL4 may represent a new member of a FRI-containing complex that activates FLC.

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flx-3 and fll4-1 alter VIN3 and FLC expression without coldflx-3 and fll4-1 exhibit VIN3 up-regulation (a) and FLC down-regulation (b) without vernalization. FRI 3–9 and FRI 38-11 were selected as negative controls for VIN3 expression from among the FRI-suppressor mutants we identified. FLC and VIN3 expression were also monitored in fri elf7-2, FRI elf7-2, fri elf8-1, FRI elf8-1, fri efs-3 and FRI efs-3 as additional controls. (c) Flowering phenotype of flx-3 and fll4-1. All of the expression data are presented as mean values of three biological replicates. Error bars indicate standard deviation.
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Figure 1: flx-3 and fll4-1 alter VIN3 and FLC expression without coldflx-3 and fll4-1 exhibit VIN3 up-regulation (a) and FLC down-regulation (b) without vernalization. FRI 3–9 and FRI 38-11 were selected as negative controls for VIN3 expression from among the FRI-suppressor mutants we identified. FLC and VIN3 expression were also monitored in fri elf7-2, FRI elf7-2, fri elf8-1, FRI elf8-1, fri efs-3 and FRI efs-3 as additional controls. (c) Flowering phenotype of flx-3 and fll4-1. All of the expression data are presented as mean values of three biological replicates. Error bars indicate standard deviation.

Mentions: Previous studies have reported the identification of mutants that suppress the delayed flowering that occurs in the absence of vernalization in the line Col FRI, which was generated by introgression of functional Sf-2 FRIGIDA allele4, 29. We screened additional ethyl methane sulfonate (EMS)-generated mutants in Col FRI for rapid-flowering lines that exhibited two properties of vernalized Arabidopsis plants in the absence of cold exposure: reduced FLC expression and increased VIN3 expression. In wild-type, VIN3 is expressed only after a relatively long period of cold exposure24. From 98 lines initially identified as rapid-flowering, we found two independent mutants that exhibited both reduced FLC expression and increased VIN3 expression. These mutants, which we now refer to as flx-3 and flx like 4-1 (fll4-1) (Fig. 1a, b) were chosen for further study because they appeared identical to Col and to vernalized Col FRI (Fig. 1c)—i.e., there were no apparent pleiotropic phenotypes and they exhibited features of vernalized plants in the absence of cold exposure.


Two FLX family members are non-redundantly required to establish the vernalization requirement in Arabidopsis.

Lee J, Amasino RM - Nat Commun (2013)

flx-3 and fll4-1 alter VIN3 and FLC expression without coldflx-3 and fll4-1 exhibit VIN3 up-regulation (a) and FLC down-regulation (b) without vernalization. FRI 3–9 and FRI 38-11 were selected as negative controls for VIN3 expression from among the FRI-suppressor mutants we identified. FLC and VIN3 expression were also monitored in fri elf7-2, FRI elf7-2, fri elf8-1, FRI elf8-1, fri efs-3 and FRI efs-3 as additional controls. (c) Flowering phenotype of flx-3 and fll4-1. All of the expression data are presented as mean values of three biological replicates. Error bars indicate standard deviation.
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Related In: Results  -  Collection

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Figure 1: flx-3 and fll4-1 alter VIN3 and FLC expression without coldflx-3 and fll4-1 exhibit VIN3 up-regulation (a) and FLC down-regulation (b) without vernalization. FRI 3–9 and FRI 38-11 were selected as negative controls for VIN3 expression from among the FRI-suppressor mutants we identified. FLC and VIN3 expression were also monitored in fri elf7-2, FRI elf7-2, fri elf8-1, FRI elf8-1, fri efs-3 and FRI efs-3 as additional controls. (c) Flowering phenotype of flx-3 and fll4-1. All of the expression data are presented as mean values of three biological replicates. Error bars indicate standard deviation.
Mentions: Previous studies have reported the identification of mutants that suppress the delayed flowering that occurs in the absence of vernalization in the line Col FRI, which was generated by introgression of functional Sf-2 FRIGIDA allele4, 29. We screened additional ethyl methane sulfonate (EMS)-generated mutants in Col FRI for rapid-flowering lines that exhibited two properties of vernalized Arabidopsis plants in the absence of cold exposure: reduced FLC expression and increased VIN3 expression. In wild-type, VIN3 is expressed only after a relatively long period of cold exposure24. From 98 lines initially identified as rapid-flowering, we found two independent mutants that exhibited both reduced FLC expression and increased VIN3 expression. These mutants, which we now refer to as flx-3 and flx like 4-1 (fll4-1) (Fig. 1a, b) were chosen for further study because they appeared identical to Col and to vernalized Col FRI (Fig. 1c)—i.e., there were no apparent pleiotropic phenotypes and they exhibited features of vernalized plants in the absence of cold exposure.

Bottom Line: In this study, we show that FLOWERING LOCUS C EXPRESSOR-LIKE 4 (FLL4) is essential for upregulation of FLC in winter-annual Arabidopsis accessions and establishment of a vernalization requirement.Epistasis analysis among FRIGIDA, FLL4, FLOWERING LOCUS C EXPRESSOR and autonomous-pathway genes reveals that FRIGIDA fve exhibits an extreme delay of flowering compared with fri fve, but mutants in other autonomous-pathway genes do not, indicating that FVE acts most antagonistically to FRIGIDA.FLL4 may represent a new member of a FRI-containing complex that activates FLC.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, Wisconsin 53706, USA.

ABSTRACT
Studies of natural genetic variation for the vernalization requirement in Arabidopsis have revealed two genes, FRIGIDA and FLOWERING LOCUS C (FLC), that are determinants of the vernalization-requiring, winter-annual habit. In this study, we show that FLOWERING LOCUS C EXPRESSOR-LIKE 4 (FLL4) is essential for upregulation of FLC in winter-annual Arabidopsis accessions and establishment of a vernalization requirement. FLL4 is part of the FLOWERING LOCUS C EXPRESSOR gene family and both are non-redundantly involved in flowering time control. Epistasis analysis among FRIGIDA, FLL4, FLOWERING LOCUS C EXPRESSOR and autonomous-pathway genes reveals that FRIGIDA fve exhibits an extreme delay of flowering compared with fri fve, but mutants in other autonomous-pathway genes do not, indicating that FVE acts most antagonistically to FRIGIDA. FLL4 may represent a new member of a FRI-containing complex that activates FLC.

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