拟南芥IQM2参与成花调控的功能解析

Both environmental and genetic factors can regulate flowering time in plants. The flowering regulators constitute at least six closely interlinked but divergent genetic regulation pathways including photoperiod, vernalization, ambient temperature, GA and autonomous pathways. Calcium/calmodulin signaling plays an important role in plants response to changed internal and external factors and participates in regulation of a variety of cell physiology and growth and development processes of plant. Although 62 flowering-regulating genes have been identified in Arabidopsis, it is still not enough to fully reveal the molecular network for flowering regulation. Among these genes, only AtCML23 and AtCML24 have been found to involve in calcium/calmodulin signaling. But the direct binding proteins of AtCML23 and AtCML24 still remain unknown. Our previous study suggests that IQM2 is a calmodulin-binding protein containing an IQ motif and is involved in flowering regulation. To illuminate the mechanisms underlying involvement of IQM2 in plant flowering regulation and set up a molecular connection between calmodulin signaling and plant flowering regulation, the functional complementation for iqm2 mutants, the dependence of flowering on the binding between IQM2 and calmodulin, and the molecular network for IQM2 to regulate flowering will be studied. Our results are helpful to fully understand the function of IQM2 and calmodulin, enrich the molecular network of flowering regulation as well as a comprehensive understanding function of Ca2+/CaM signal in plant development, and can provide reference for plant breeding to regulate flowering time.

植物成花与其生存、繁衍和进化息息相关，由遗传和环境两方面因素决定，受光周期、春化、温度、赤霉素、自主以及年龄等6条遗传途径调控。钙/钙调素信号在植物对体内外因子变化的反应中起着重要作用，参与多种细胞生理和生长发育调控。尽管已鉴定出62个拟南芥成花调控基因，但仍不足以全面揭示相关分子调控网络。在这些基因中，仅AtCML23和AtCML24涉及钙/钙调素信号，但其靶标未知。我们的前期研究表明IQM2是1个含有IQ基序的钙调素结合蛋白，参与成花调控。本研究拟通过IQM2突变体的功能互补、成花对IQM2与钙调素结合的依赖性以及IQM2涉及的成花调控途径的研究，解析IQM2参与成花调控的分子机理，建立Ca2+/CaM信号参与成花调控的分子连接点。研究结果有助于理解IQM2和钙调素的功能、丰富成花调控的分子网络以及全面理解Ca2+/CaM信号在植物发育中的作用，并可为植物花期调控提供参考。

植物开花与其生存、繁衍和进化息息相关，由遗传和环境两方面因素决定，受光周期、春化、温度、赤霉素、自主以及年龄等6 条遗传途径调控。钙/钙调素（CaM）信号在植物对体内外因子变化的反应中起着重要作用，参与多种细胞生理和生长发育调控。尽管已鉴定出76 个拟南芥成花调控基因，但仍不足以全面揭示相关分子调控网络。在这些基因中，仅CML23 和CML24 涉及钙/钙调素信号，但其靶标未知。之前，我们发现IQM2 是1 个含有IQ 基序的钙调素结合蛋白，参与成花调控。本研究通过IQM2 突变体的功能互补、成花对IQM2 与钙调素结合的依赖性以及IQM2 涉及的成花调控途径的研究，初步解析了IQM2 参与成花调控的分子机理。结果表明，IQM2在与未知的钙调素结合后，抑制自主途径关键基因FLC的表达，进而通过未知途径促进AP1的表达，最后促进开花促进基因LFY的表达，从而促进植物开花。项目的完成，建立了Ca2+/CaM 信号参与成花调控的新分子连接点，结果有助于理解IQM2和钙调素的功能，丰富了成花调控的分子网络，有助于全面理解Ca2+/CaM 信号在植物发育中的作用，可为植物花期调控提供参考。