Several pathways conferring environmental flowering responses in Arabidopsis converge on developmental processes that mediate floral transition in the shoot apical meristem. Many characterized mutations disrupt these environmental responses, but downstream developmental processes have been more refractory to mutagenesis. We constructed a quintuple mutant impaired in several environmental pathways and showed that it possesses severely reduced flowering responses to changes in photoperiod and ambient temperature. RNA-seq analysis of the quintuple mutant showed that the expression of genes encoding gibberellin biosynthesis enzymes and transcription factors involved in the age pathway correlates with flowering. Mutagenesis of the quintuple mutant generated two late-flowering mutants, quintuple ems 1 (qem1) and qem2. The mutated genes were identified by isogenic mapping and transgenic complementation. The qem1 mutant was an allele of ga20ox2, confirming the importance of gibberellin for flowering in the absence of environmental responses. By contrast, qem2 is in CHROMATIN REMODELING 4 (CHR4), which has not been genetically implicated in floral induction. Using co-immunoprecipitation, RNA-seq and ChIP-seq, we show that CHR4 interacts with transcription factors involved in floral meristem identity and affects expression of key floral regulators. We conclude that CHR4 mediates the response to endogenous flowering pathways in the inflorescence meristem to promote floral identity.

拟南芥中赋予环境开花应答的几种途径汇聚在介导茎尖分生组织中花期过渡的发育过程中。许多特征性的突变破坏了这些环境反应，但是下游的发育过程对诱变更难。我们构建了一个在几个环境途径中受损的五倍体突变体，表明该突变体对光周期和环境温度的变化具有严重降低的开花反应。对五重突变体的RNA-seq分析表明，编码赤霉素生物合成酶的基因表达和与年龄相关的转录因子与开花相关。五元突变体的诱变产生了两个晚开花的突变体，五元组ems 1（qem1）和qem2。通过等基因作图和转基因互补鉴定突变的基因。qem1突变体是ga20ox2的等位基因，证实了在没有环境反应的情况下赤霉素对开花的重要性。相比之下，qem2位于染色质重塑4（CHR4）中，该基因尚未与花诱导有关。使用共免疫沉淀，RNA序列和ChIP序列，我们显示CHR4与参与花分生组织同一性的转录因子相互作用，并影响关键花卉调控因子的表达。我们得出的结论是，CHR4介导了花序分生组织中对内源性开花途径的应答，从而促进了花的同一性。证实了在没有环境反应的情况下赤霉素对开花的重要性。相比之下，qem2位于染色质重塑4（CHR4）中，该基因尚未与花诱导有关。使用共免疫沉淀，RNA序列和ChIP序列，我们显示CHR4与参与花分生组织同一性的转录因子相互作用，并影响关键花卉调控因子的表达。我们得出的结论是，CHR4介导了花序分生组织中对内源性开花途径的应答，从而促进了花的同一性。证实了在没有环境反应的情况下赤霉素对开花的重要性。相比之下，qem2位于染色质重塑4（CHR4）中，该基因尚未与花诱导有关。使用共免疫沉淀，RNA序列和ChIP序列，我们显示CHR4与参与花分生组织同一性的转录因子相互作用，并影响关键花卉调控因子的表达。我们得出的结论是，CHR4介导了花序分生组织中对内源性开花途径的应答，从而促进了花的同一性。