The MdZAT5-MdAGL42 transcriptional regulatory module enhances aluminum tolerance via enhancing ROS scavenging in apple

Abstract

Aluminum (Al) toxicity induced by soil acidification is a global environmental concern that threatens agricultural production and ecosystem health in acid-soil regions. To advance the breeding of Al-tolerant crops and support ecological restoration, this study aimed to elucidate the molecular mechanism underlying Al tolerance in apple (Malus domestica). Through molecular cloning, genetic transformation, and protein-DNA interaction assays, we identified an Al-responsive MADS-box gene, MdAGL42, and its upstream regulator, the C2H2-type zinc finger transcription factor MdZAT5. Overexpression of MdAGL42 significantly enhanced Al tolerance, while reducing the accumulation of reactive oxygen species (ROS), malondialdehyde (MDA), and Al3+ under Al stress. Furthermore, we demonstrated that MdZAT5 transcriptionally activates both MdAGL42 and MdCSD1 (Cu/Zn superoxide dismutase 1), thereby forming a synergistic regulatory network. Our findings reveal, for the first time, the molecular basis of the MdZAT5-MdAGL42 transcriptional regulatory module in conferring Al tolerance. This study provides crucial genetic resources for molecular breeding of Al-tolerant Rosaceae crops and contributes to strategies for ecological restoration and sustainable agriculture in acidified regions.