The WRKY76-miR528-SOD2 module: regulating submergence tolerance through ROS scavenging in sorghum

Area of Science:

• Plant Molecular Biology
• Crop Science
• Environmental Stress Response

Background:

• Flooding poses a significant threat to global agriculture, exacerbated by climate change.
• Developing flood-tolerant crops is crucial, but molecular mechanisms remain poorly understood.
• Sorghum (Sorghum bicolor) is a vital crop susceptible to flooding stress.

Purpose of the Study:

• To investigate the molecular basis of submergence tolerance in sorghum.
• To identify key genetic regulators involved in the plant's response to flooding.
• To uncover novel targets for engineering climate-resilient sorghum varieties.

Main Methods:

• Comparative transcriptomic analysis of submergence-tolerant and sensitive sorghum accessions.
• Quantitative analysis of microRNA (SbmiR528) and Superoxide Dismutase 2 (SOD2) gene expression.
• Investigation of transcription factor (SbWRKY76) binding to the SbMIR528 promoter.
• Functional validation through overexpression of key genes in sorghum.

Main Results:

• Natural variation in submergence tolerance was observed in sorghum populations.
• The tolerant accession SC473 showed lower SbmiR528 levels, correlating with higher SOD2 transcript accumulation.
• SbWRKY76 directly activates SbMIR528 transcription, and its expression is higher in sensitive varieties.
• Overexpression of SbWRKY76 or SbMIR528 reduced submergence tolerance in sorghum.

Conclusions:

• The SbWRKY76-SbmiR528-SbSOD2 module is a novel regulatory axis controlling sorghum submergence response.
• This pathway fine-tunes reactive oxygen species (ROS) scavenging to mediate flooding tolerance.
• Findings provide critical targets for breeding and engineering flood-resilient sorghum for climate change adaptation.