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Key message <p><i>OsACX4</i> knockout reduces peroxisomal oxidative stress, enhancing rice drought and salt tolerance through metabolic-redox rebalancing for climate-resilient breeding.</p> Abstract <p>Climate change is intensifying the frequency and severity of abiotic stress, such as salt and drought stresses, which severely limit rice productivity worldwide, necessitating the identification of molecular targets for crop improvement. This study provides the first comprehensive functional characterization of the peroxisomal acyl-CoA oxidase <i>OsACX4</i> in rice (<i>Oryza sativa</i> L.) drought and salinity tolerance, revealing its unexpected role as a negative regulator of stress tolerance through modulation of cellular redox homeostasis. Through genome editing using CRISPR/Cas9-mediated knockout and overexpression approaches, we generated transgenic lines to investigate the function of <i>OsACX4</i> under salt and drought stress. Knockout lines exhibited superior stress tolerance compared to the wild-type (WT) and overexpression lines, demonstrating significantly higher survival rates under severe stress conditions. Enhanced tolerance correlated with coordinated upregulation of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities. Knockout lines accumulated substantially higher proline (Pro) levels while maintaining markedly reduced reactive oxygen species (ROS) compared to overexpression lines. Transcriptional analysis revealed that <i>OsACX4</i> disruption triggered upregulation of stress-responsive genes, including <i>OsSOD1</i>, <i>OsDREB2A</i>, <i>OsDREB1B</i>, and <i>OsAPX1</i> under severe stress. Subcellular localization confirmed peroxisomal targeting of <i>OsACX4</i>, where its β-oxidation activity generates hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) as a metabolic by-product. Our results reveal a metabolic trade-off whereby stress-induced <i>OsACX4</i> expression mobilizes energy reserves but compromises cellular redox homeostasis. The superior performance of knockout lines under both stresses demonstrates that strategic <i>OsACX4</i> disruption enhances plant resilience, identifying this gene as a promising breeding target for developing climate-resilient rice varieties through precision genome editing.</p>

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Peroxisomal acyl-CoA oxidase OsACX4 negatively regulates salt and drought stress tolerance by modulating cellular redox homeostasis in rice

  • 期刊论文

  • 发表日期：

    2026年3月5日

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  • Mohamed Ali Eweda,
  • Jinying Li,
  • Umair Hassan,
  • Sanaullah Jalil,
  • Xiaoli Jin

摘要

Key message

OsACX4 knockout reduces peroxisomal oxidative stress, enhancing rice drought and salt tolerance through metabolic-redox rebalancing for climate-resilient breeding.

Abstract

Climate change is intensifying the frequency and severity of abiotic stress, such as salt and drought stresses, which severely limit rice productivity worldwide, necessitating the identification of molecular targets for crop improvement. This study provides the first comprehensive functional characterization of the peroxisomal acyl-CoA oxidase OsACX4 in rice (Oryza sativa L.) drought and salinity tolerance, revealing its unexpected role as a negative regulator of stress tolerance through modulation of cellular redox homeostasis. Through genome editing using CRISPR/Cas9-mediated knockout and overexpression approaches, we generated transgenic lines to investigate the function of OsACX4 under salt and drought stress. Knockout lines exhibited superior stress tolerance compared to the wild-type (WT) and overexpression lines, demonstrating significantly higher survival rates under severe stress conditions. Enhanced tolerance correlated with coordinated upregulation of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities. Knockout lines accumulated substantially higher proline (Pro) levels while maintaining markedly reduced reactive oxygen species (ROS) compared to overexpression lines. Transcriptional analysis revealed that OsACX4 disruption triggered upregulation of stress-responsive genes, including OsSOD1, OsDREB2A, OsDREB1B, and OsAPX1 under severe stress. Subcellular localization confirmed peroxisomal targeting of OsACX4, where its β-oxidation activity generates hydrogen peroxide (H2O2) as a metabolic by-product. Our results reveal a metabolic trade-off whereby stress-induced OsACX4 expression mobilizes energy reserves but compromises cellular redox homeostasis. The superior performance of knockout lines under both stresses demonstrates that strategic OsACX4 disruption enhances plant resilience, identifying this gene as a promising breeding target for developing climate-resilient rice varieties through precision genome editing.