Fig. 7: A summary model showing PSKR1/ALR1-dependent Al perception and signaling.
From: The LRR receptor-like kinase ALR1 is a plant aluminum ion sensor
①Al ions entering root cells are perceived by the cytoplasmic domain of the PSKR1/ALR1 receptor. ②The binding of Al ions enables PSKR1/ALR1 to recruit BAK1, the representative of SERKs, as a co-receptor for inter-phosphorylation and activation, and thus ③promotes ALR1-mediated phosphorylation of the NADPH oxidase RbohD at Ser39, hence increasing ROS generation. ④The resultant accumulated ROS in turn inhibits the function of the RAE1 F-box protein via oxidative modification of Cys364 residue, thus suppressing RAE1-mediated degradation of STOP1, the master transcriptional regulator of Al-resistance genes. The consequent accumulation of STOP1 hence activates the expression of downstream genes, including the malate channel-encoding ALMT1 gene, finally promoting organic acid anions secretion to chelate extracellular Al ions, thus conferring Al resistance. OA represents organic acid anions.
