ABSTRACT Polycomb-group (PcG) proteins are evolutionarily conserved in higher organisms and play essential roles in many developmental processes by catalyzing the trimethylation of histone H3 lysine 27 (H3K27me3), a key repressive histone mark. In Arabidopsis (Arabidopsis thaliana), histone methyltransferase CURLY LEAF (CLF) is one of the major PcG catalytic components, playing critical roles in plant growth and development, especially the floral transition. We have recently profiled the genome-wide occupancy of CLF by chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq). Interestingly, AGAMOUS-LIKE 17 (AGL17) that encodes a known flowering activator was found to be a CLF direct target. Based on this observation, we set out to examine to what extent this genetic module regulates the flowering. First, we validated the ChIP-seq results by ChIP-qPCR and show that CLF indeed targets AGL17, and the level of H3K27me3 is decreased when CLF is lost. Further, we show that the expression of AGL17 is significantly up-regulated in the clf-29 mutant compared to wild-type (WT). Finally, our clf agl17 double mutant analysis suggests that AGL17 is a significant downstream target of CLF in floral transition control.

中文翻译：

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有证据表明 AGL17 是 CLF 在花转化控制中的重要下游靶点

摘要 Polycomb-group (PcG) 蛋白在高等生物中进化上是保守的，并且通过催化组蛋白 H3 赖氨酸 27 (H3K27me3) 的三甲基化（一种关键的抑制性组蛋白标记）在许多发育过程中发挥重要作用。在拟南芥 (Arabidopsis thaliana) 中，组蛋白甲基转移酶 CURLY LEAF (CLF) 是主要的 PcG 催化成分之一，在植物生长发育，尤其是花的过渡中起着关键作用。我们最近通过染色质免疫沉淀和高通量测序 (ChIP-seq) 分析了 CLF 的全基因组占用情况。有趣的是，发现编码已知开花激活剂的 AGAMOUS-LIKE 17 (AGL17) 是 CLF 的直接目标。基于这一观察，我们着手研究该遗传模块在多大程度上调节开花。第一的，我们通过 ChIP-qPCR 验证了 ChIP-seq 结果并表明 CLF 确实针对 AGL17，并且当 CLF 丢失时 H3K27me3 的水平会降低。此外，我们表明与野生型 (WT) 相比，clf-29 突变体中 AGL17 的表达显着上调。最后，我们的 clf agl17 双突变体分析表明 AGL17 是 CLF 在花转化控制中的重要下游靶标。