A Maize ZmAT6 Gene Confers Aluminum Tolerance via Reactive Oxygen Species Scavenging

Aluminum (Al) toxicity is the primary limiting factor that affects crop yields in acid soil. However, the genes that contribute to the Al tolerance process in maize are still poorly understood. Previous studies have predicted that ZmAT6 is a novel protein which could be upregulated under Al stress condition. Here, we found thatZmAT6is expressed in many tissues and organs and can be dramatically induced by Al in both the roots and shoots but particularly in the shoots. The overexpression ofZmAT6in maize andArabidopsisplants increased their root growth and reduced the accumulation of Al, suggesting the contribution ofZmAT6to Al tolerance. Moreover, theZmAT6transgenic maize plants had lower contents of malondialdehyde and reactive oxygen species (ROS), but much higher proline content and even lower Evans blue absorption in the roots compared with the wild type. Furthermore, the activity of several enzymes of the antioxidant system, such as peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX), increased inZmAT6transgenic maize plants, particularly SOD. Consistently, the expression ofZmSODin transgenic maize was predominant upregulated by Al stress. Taken together, these findings revealed thatZmAT6could at least partially confer enhanced tolerance to Al toxicity by scavenging ROS in maize.