图1. 生长素信号转导途径
低浓度生长素主要通过受体TIR1泛素化并降解经典的Aux/IAAs蛋白, 解除对生长素响应因子ARFs的抑制, 启动对下游基因的调控及生长素信号响应。高浓度生长素主要通过TMK1蛋白激酶磷酸化并稳定非经典Aux/IAA32/34, 抑制ARFs的活性。TMK1-IAA32/34-ARFs模型解释了植物发育过程中生长素积累调控顶端弯钩内外侧的差异性生长。

Figure 1. Pathway of auxin signal transduction
The perception of low levels of auxin is mainly mediated through the TIR1 receptor, which ubiquitinates and degrades Aux/IAAs proteins, and thus de-represses ARFs to activate downstream gene transcription and trigger auxin responses. Higher levels of auxin activate TMK1, which phosphorylates and stabilizes non-canonical IAA32/34, and repress ARFs activities. The TMK1-IAA32/34-ARFs module interprets how the local auxin accumulation modulates asymmetric growth during apical hook development.