The B3-Domain Transcription Factor VAL1 Regulates the Floral Transition by Repressing FLOWERING LOCUS T
The B3-Domain Transcription Factor VAL1 Regulates the Floral Transition by Repressing FLOWERING LOCUS T
复制标题
B3 结构域转录因子 VAL1 通过抑制 FLOWERING LOCUS T 调节花的转变
DOI：
10.1104/pp.19.00642
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发表时间：
2019-09-01
期刊：
影响因子：
7.4
通讯作者：
Lin, Rongcheng
中科院分区：
文献类型：
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作者：
Jing, Yanjun;Guo, Qiang;Lin, Rongcheng
许多植物监测日长（或光周期）的变化，并相应地调整开花过渡的时间，以确保繁殖成功。在长日照植物中，长日照光周期触发成花素的产生，促进成花转变。拟南芥（Arabidopsis thaliana）中的FLOWerk LOCUS T（FT）编码成花素的主要组分，并且FT表达通过光周期途径在叶片中被激活，特别是在黄昏时。由Polycomb group（PcG）蛋白介导的FT抑制可以防止早熟开花，并为FT调节增加了另一层。在这里，我们确定了组蛋白H3的高水平三甲基化的Lys 27（H3 K27 me 3）在高三甲基化区域（HTR）的FT基因座从第二内含子3'非翻译区。HTR含有H3 K27 me 3富集所需的顺式调节DNA元件，其被转录抑制子VIVIPAROUS 1/脱落酸不敏感3样1（VAL 1）识别。VAL 1直接抑制黄昏前和夜间的FT表达，与VAL 1 mRNA和VAL 1同源二聚体的高丰度相一致。此外，VAL 1像异染色质蛋白1和IRA 1的多拷贝替代物一样招募到FT染色质，导致FT的HTR处的H3 K27 me 3峰。这些研究结果揭示了一种机制，PcG抑制FT介导的内含子顺式沉默元件，并建议可能的作用VAL 1在调节PcG抑制FT开花反应。
Many plants monitor changes in day length (or photoperiod) and adjust the timing of the floral transition accordingly to ensure reproductive success. In long-day plants, a long-day photoperiod triggers the production of florigen, which promotes the floral transition. FLOWERING LOCUS T (FT) in Arabidopsis (Arabidopsis thaliana) encodes a major component of florigen, and FT expression is activated in leaf veins specifically at dusk through the photoperiod pathway. Repression of FT mediated by Polycomb group (PcG) proteins prevents precocious flowering and adds another layer to FT regulation. Here, we identified high-level trimethylation of histone H3 at Lys 27 (H3K27me3) in the high trimethylation region (HTR) of the FT locus from the second intron to the 3' untranslated region. The HTR contains a cis-regulatory DNA element required for H3K27me3 enrichment that is recognized by the transcriptional repressor VIVIPAROUS1/ABSCISIC ACID INSENSITIVE3-LIKE1 (VAL1). VAL1 directly represses FT expression before dusk and at night, coinciding with the high abundance of both VAL1 mRNA and VAL1 homodimer. Furthermore, VAL1 recruits LIKE HETEROCHROMATIN PROTEIN1 and MULTICOPY SUPRESSOR OF IRA1 to FT chromatin, leading to an H3K27me3 peak at the HTR of FT. These findings reveal a mechanism for PcG repression of FT mediated by an intronic cis-silencing element and suggest a possible role for VAL1 in modulating PcG repression of FT during the flowering response.