Analysis of the Arabidopsis MADS AFFECTING FLOWERING gene family:: MAF2 prevents vernalization by short periods of cold
Analysis of the Arabidopsis MADS AFFECTING FLOWERING gene family:: MAF2 prevents vernalization by short periods of cold
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DOI：
10.1105/tpc.009506
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发表时间：
2003-05-01
期刊：
影响因子：
11.6
通讯作者：
Riechmann, JL
中科院分区：
文献类型：
--
作者：
Ratcliffe, OJ;Kumimoto, RW;Riechmann, JL
拟南芥开花基因座 C (FLC) 基因是维持春化反应的关键花抑制因子。在春化敏感的遗传背景中，FLC 水平很高，并且在暴露于长时间寒冷后会下降。四个 FLC 旁系同源物（MAF2 [MADS AFFECTING FLOWERING2] 至 MAF5）以串联阵列排列在拟南芥 V 号染色体的底部。我们使用反向遗传学方法来分析它们的功能。功能丧失和功能获得研究表明 MAF2 充当花抑制因子。特别是，maf2突变体植物在经历相对较短的寒冷期时表现出明显的春化反应，尽管FLC水平大幅降低，但不足以在野生型中引发强烈的开花反应。 MAF2 表达对春化作用的敏感性低于 FLC，并且其阻遏活性独立发挥或在 FLC 转录下游发挥。因此，MAF2 可以防止因短暂寒冷而导致的过早春化。 MAF3 或 MAF4 的过度表达会导致开花时间的改变，这表明这些基因也充当花抑制因子，并可能有助于维持春化要求。然而，簇中的最后一个基因 MAF5 通过春化作用上调。因此，MAF5在春化反应中可以发挥与FLC相反的作用。
The Arabidopsis FLOWERING LOCUS C (FLC) gene is a key floral repressor in the maintenance of a vernalization response. In vernalization-sensitive genetic backgrounds, FLC levels are high, and they decline after exposure to long cold periods. Four FLC paralogs (MAF2 [MADS AFFECTING FLOWERING2] to MAF5) are arranged in a tandem array on the bottom of Arabidopsis chromosome V. We used a reverse genetics approach to analyze their functions. Loss-of-function and gain-of-function studies indicate that MAF2 acts as a floral repressor. In particular, maf2 mutant plants display a pronounced vernalization response when subjected to relatively short cold periods, which are insufficient to elicit a strong flowering response in the wild type, despite producing a large reduction in FLC levels. MAF2 expression is less sensitive to vernalization than that of FLC, and its repressor activity is exerted independently or downstream of FLC transcription. Thus, MAF2 can prevent premature vernalization in response to brief cold spells. Overexpression of MAF3 or MAF4 produces alterations in flowering time that suggest that these genes also act as floral repressors and might contribute to the maintenance of a vernalization requirement. However, the final gene in the cluster, MAF5, is upregulated by vernalization. Therefore, MAF5 could play an opposite role to FLC in the vernalization response.