Regulation of Temperature-Responsive Flowering by MADS-Box Transcription Factor Repressors

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Science  01 Nov 2013:
Vol. 342, Issue 6158, pp. 628-632
DOI: 10.1126/science.1241097

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Chilly Repression Stalls Flowering

In a cool spring, flowering might be delayed compared to a warm spring, even though the change in day length marches on regardless of temperature. Lee et al. (p. 628, published online 12 September; see the Perspective by Nilsson) now show that this delay in flowering is a regulated process, not simply a consequence of sluggish metabolism. In the model plant Arabidopsis, transcription of the gene encoding the regulator SHORT VEGETATIVE PHASE (SVP) is unaffected by temperature, but the stability of the SVP protein is decreased at higher temperatures. Its regulatory partner, FLOWERING LOCUS M (FLM)-β, is the product of alternative splicing of transcripts from the gene encoding FLM that favors the β form at lower temperatures. SVP and FLM-β form a complex that represses flowering. At lower temperatures, more of the repressive complex is present and flowering is delayed. At higher temperatures, SVP tends to degrade and FLM-β tends not to be produced, yielding reduced levels of the repressive complex, which allows flowering to proceed.


Changes in ambient temperature affect flowering time in plants; understanding this phenomenon will be crucial for buffering agricultural systems from the effects of climate change. Here, we show that levels of FLM-β, an alternatively spliced form of the flowering repressor FLOWERING LOCUS M, increase at lower temperatures, repressing flowering. FLM-β interacts with SHORT VEGETATIVE PHASE (SVP); SVP is degraded at high temperatures, reducing the abundance of the SVP–FLM-β repressor complex and, thus, allowing the plant to flower. The svp and flm mutants show temperature-insensitive flowering in different temperature ranges. Control of SVP–FLM-β repressor complex abundance via transcriptional and splicing regulation of FLM and posttranslational regulation of SVP protein stability provides an efficient, rapid mechanism for plants to respond to ambient temperature changes.

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