The dual role of a bHLH protein: Is SCRM1 / ICE1 an integrator of cold-stress and stomatal fate signaling?

多细胞生物中功能细胞模式的形成需要特定的细胞命运决定因子。这种形成的结果受到环境的影响。拟南芥的气孔发育为研究环境信号在发育过程中的整合提供了一个简单易行的模型。气孔是植物表皮上的阀门，调节空气与细胞间隙之间的气体交换。每叶面积的气孔数受CO2和光照强度的影响，系统信号被认为参与控制气孔发育，以响应这些线索。两个基本的螺旋-环-螺旋（bHLH）转录因子（TF），SCRM 1和2，在调节原胚层细胞进入气孔谱系和通过气孔谱系的进展，最终形成成熟气孔中发挥关键作用。SCRM 1与三种已知的bHLH TF（SPCH，MUTE和法马）相互作用，这些TF在气孔细胞状态进展过程中积极调节顺序步骤，但气孔谱系中SCRM-activity的调节因子尚不清楚。表皮显性突变体的D-D发展只有气孔，所以D-D提供了一个基础SCRM监管机构的遗传筛选。SCRM 1是ICE 1，一种抗冻性调节因子，这一发现表明SCRM 1具有双重作用，它可能是非生物胁迫信号和气孔发育的整合者。该项目旨在揭示调控SCRM 1两种功能的分子机制，并了解冷信号对气孔发育的影响。它将深入了解环境线索如何融入发展过程。具体目标有三：1：确定系统性冷信号在气孔发育中的作用。2：揭示在翻译后水平上调节SCRM 1或ICE 1作用的机制。3：确定调节SCRM 1双重功能的新因子。

The formation of functional cell patterns in multicellular organisms requires specific cell-fate determinants. The outcome of this formation is influenced by the environment. Stomatal development in the plant Arabidopsis thaliana provides an easily accessible model to study the integration of environmental cues into developmental processes. Stomata are valves in the plant epidermis that regulate the gas exchange between the air and the intercellular spaces. The number of stomata per leaf area is influenced by CO2 and light intensity, and systemic signaling is thought to be involved in controlling stomatal development in response to these cues. Two basic helix-loop-helix (bHLH) transcription factors (TFs), SCRM1 and 2, play a key role in regulating the entry of protodermal cells into the stomatal lineage and in the progression through the stomatal lineage that ultimately forms mature stomata. SCRM1 interacts with three known bHLH TFs (SPCH, MUTE and FAMA) that positively regulate sequential steps during stomatal cell-state progression, but regulators of SCRM-activity in the stomatal lineage are unknown. The epidermis of dominant scrm-D mutants develops only stomata, so scrm-D provides a basis for a genetic screen for SCRM regulators. The finding that SCRM1 is ICE1, a regulator of freezing tolerance, suggests a dual role of SCRM1, which may act as an integrator of abiotic stress signaling and stomatal development. This project aims at unraveling the molecular mechanisms that regulate both functions of SCRM1 and at understanding the impact of cold signaling on stomatal development. It will give insight into how environmental cues are integrated into developmental processes. Three specific aims are: 1: Determine the role of systemic cold signaling in stomatal development. 2: Unravel mechanisms that regulate SCRM1 or ICE1 action on the post-translational level. 3: Identify novel factors that regulate the dual function of SCRM1.