Overexpression of A RING finger ubiquitin ligase gene AtATRF1 enhances aluminium tolerance in Arabidopsis thaliana

Aluminium (Al) toxicity is a primary limitation of crop production in acid soils, which take over 40% of arable soil worldwide. In previous studies, a series of genes have been identified to regulate the plant Al resistance or tolerance. However, none of E3 ubiquitin ligase, the key factor of ubiquitination that plays an important role in plant growth and development, has been characterized for Al response in Arabidopsis. In this study, an E3 ubiquition ligase gene AtATRF1 (Al Tolerance RING Finger 1), a homolog of RAD18 interacting RAD6 to repair the damaged DNA in human and yeast, is isolated from Arabidopsis. It encodes a predicted protein of 296 amino acids with a C3HC4 type RING finger domain. The expression of AtATRF1 is induced by Al, and the transgenic plant overexpressing AtATRF1 enhances the Al tolerance. Similar as RAD18, the AtATRF1 locates in nucleus and regulates the expression of AtATR, which involves in DNA repair and Al response in Arabidopsis. Our results indicate that nuclearlocated AtATRF1 may interact and ubiquitinate the transcriptional regulator of AtATR to mediate the Al tolerance of Arabidopsis.