The RAE1-STOP1-GL2-RHD6 module regulates the ALMT1-dependent aluminum resistance in Arabidopsis
Hongrui Cao, Meng Zhang, Xue Zhu, Zhimin Bai, Yanqi Ma, Chao‐Feng Huang, Zhong‐Bao Yang
Abstract
Aluminum (Al) toxicity is one of the major constraints for crop production in acid soils, Al-ACTIVATED MALATE TRANSPORTER1 (ALMT1)-dependent malate exudation from roots is essential for Al resistance in Arabidopsis, in which the C2H2-type transcription factor SENSITIVE TO PROTONRHIZOTOXICITY1 (STOP1) play a critical role. In this study, we reveal that the RAE1-GL2-STOP1-RHD6 protein module regulated the ALMT1-mediated Al resistance. GL2, STOP1 and RHD6 directly target the promoter of ALMT1 to suppress or activate its transcriptional expression, respectively, and mutually influence their action on the promoter of ALMT1 by forming a protein complex. STOP1 mediates the expression of RHD6 and RHD6-regulated root growth inhibition, while GL2 and STOP1 suppress each other’s expression at the transcriptional and translational level and regulate Al-inhibited root growth. F-box protein RAE1 degrades RHD6 via the 26S proteasome, leading to suppressed activity of the ALMT1 promoter. RHD6 inhibits the transcriptional expression of RAE1 by directly targeting its promoter. Unlike RHD6, RAE1 promotes the GL2 expression at the protein level and GL2 activates the expression of RAE1 at the transcriptional level by directly targeting its promoter. The study provides insights into the transcriptional regulation of ALMT1, revealing its significance in Al resistance and highlighting the crucial role of the STOP1-associated regulatory networks. This study has identified new regulators, such as RHD6 and GL2, involved in the regulation of the RAE1-STOP1-ALMT1 module, contributing to Al resistance. It has also established a complex transcriptional network that controls STOP1-dependent ALMT1 expression, offering new insights into Al resistance and signaling.