Wakeel Abdul, Wang Lin, Xu Ming
Henan Key Laboratory of Earth System Observation and Modeling, Henan University, Kaifeng 475004, China.
College of Environment and Planning, Henan University, Kaifeng 475004, China.
Plants (Basel). 2021 Feb 24;10(3):432. doi: 10.3390/plants10030432.
Stomatal density, spacing, and patterning greatly influence the efficiency of gas exchange, photosynthesis, and water economy. They are regulated by a complex of extracellular and intracellular factors through the signaling pathways. After binding the extracellular epidermal patterning factor 1 (EPF1) and 2 (EPF2) as ligands, the receptor-ligand complexes activate by phosphorylation through the MAP-kinase cascades, regulating basic helix-loop-helix (bHLH) transcription factors SPEECHLESS (SPCH), MUTE, and FAMA. In this review, we summarize the molecular mechanisms and signal transduction pathways running within the transition of the protodermal cell into a pair of guard cells with a space (aperture) between them, called a stoma, comprising asymmetric and symmetric cell divisions and draw several functional models. The feedback mechanisms involving the bHLH factors SPCH and MUTE are not fully recognized yet. We show the feedback mechanisms driven by SPCH and MUTE in the regulation of EPF2 and the ERECTA family. Intersections of the molecular mechanisms for fate determination of stomatal lineage cells with the role of core cell cycle-related genes and stabilization of SPCH and MUTE are also reported.
气孔密度、间距和格局极大地影响气体交换、光合作用和水分利用效率。它们通过信号通路由细胞外和细胞内多种因素共同调控。作为配体的细胞外表皮模式因子1（EPF1）和2（EPF2）结合后，受体 - 配体复合物通过丝裂原活化蛋白激酶级联反应磷酸化而激活，进而调控碱性螺旋 - 环 - 螺旋（bHLH）转录因子无沉默（SPCH）、沉默（MUTE）和FAMA。在本综述中，我们总结了原表皮细胞转变为一对保卫细胞（其间有一个称为气孔的间隙）过程中所涉及的分子机制和信号转导途径，这一过程包括不对称和对称细胞分裂，并绘制了几个功能模型。涉及bHLH因子SPCH和MUTE的反馈机制尚未完全明确。我们展示了由SPCH和MUTE驱动的在EPF2和ERECTA家族调控中的反馈机制。还报道了气孔谱系细胞命运决定的分子机制与核心细胞周期相关基因的作用以及SPCH和MUTE稳定性的交叉情况。
