Overexpression of OsGASR1 promotes Al tolerance in rice

Abstract

Aluminum (Al) toxicity in acid soils poses a significant threat to rice, which exhibits highly complex genetic mechanisms for both external detoxification and internal tolerance among cereal crops. Although several genes involved Al tolerance have been identified, the molecular mechanisms underlying Al tolerance in rice remain to be fully explored. Here, we functionally characterized the gibberellin-stimulated transcription gene OsGASR1, which encodes a small cysteine-rich peptide localized to the nucleus and cytoplasm and plays a significant role in Al tolerance in rice. The expression of OsGASR1 is rapidly up-regulated by Al in rice root tips but not in the shoots. Its expression is not regulated by the central regulator Aluminum Resistance Transcription Factor 1 (ART1), indicating that OsGASR1 functions as a novel gene in rice Al resistance independent of ART1. Knockout of OsGASR1 reduced root length but did not affect Al tolerance in rice, whereas overexpression of OsGASR1 enhanced Al tolerance without affecting Al distribution and accumulation and promoted the accumulation of reactive oxygen species (ROS) in the root tips. RNA-seq analysis revealed that overexpression of OsGASR1 upregulated the expression of genes associated with cell wall modification, oxidative stress, and Al tolerance. Collectively, these findings suggest that OsGASR1 is involved in Al tolerance in rice independently of ART1, and the up-regulation of this gene is necessary for rice Al tolerance.