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Background and aims <p>Chromium (Cr) toxicity is a significant threat to horticultural crop productivity. This study investigates the mechanisms of exogenous γ-Aminobutyric acid (GABA) in alleviating Cr-induced phytotoxicity in pepper seedlings.</p> Methods <p>Pepper seedlings (<i>Capsicum chinense</i> Jacq. cv. Cc268) were divided into four groups: CK (control), GABA, Cr, and GABA + Cr. The GABA and GABA + Cr groups were pretreated with 20 mM GABA for seven days, while the CK and Cr groups were treated with water. After which the Cr and GABA + Cr groups were exposed to 100 mg kg⁻<sup>1</sup> Cr (sourced from K₂Cr₂O₇) for two weeks.</p> Results <p>Cr stress significantly impedes plant growth. Conversely, GABA pretreatment markedly alleviated these toxic effects, increasing plant height, fresh weight, and dry weight by 33.08%, 33.71%, and 47.98%. GABA supplementation significantly reduced Cr accumulation in roots (by 29.59%) and leaves (by 19.36%), while improving nitrogen, phosphorus, and potassium content in roots. Photosynthetic efficiency was enhanced, evidenced by higher chlorophyll content and improved gas exchange. GABA activated ROS-scavenging enzymes (SOD, POD, CAT, APX), maintained the ascorbate–glutathione cycle by increasing AsA and GSH levels, and elevated osmolytes like proline and soluble sugars. Gene expression analysis revealed that GABA upregulated genes related to antioxidant defense, detoxification, and secondary metabolism, contributing to enhanced stress tolerance.</p> Conclusion <p>GABA alleviates Cr-induced toxicity in pepper seedlings by enhancing photosynthesis, reducing Cr accumulation, stimulating antioxidant defense system, and regulating osmotic balance, offering an effective strategy to improve crop tolerance in Cr-contaminated environments.</p>

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Exogenous γ-Aminobutyric acid alleviates chromium phytotoxicity by activating the antioxidant defense mechanism and oxidative stress tolerance in pepper seedlings

  • 期刊论文

  • 发表日期：

    2026年2月16日

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  • Liping Zhang,
  • Xiaoyue Wang,
  • Yanhui Yang,
  • Xiangrui Li,
  • Muhammad Ahsan Altaf,
  • Zhiwei Wang

摘要

Background and aims

Chromium (Cr) toxicity is a significant threat to horticultural crop productivity. This study investigates the mechanisms of exogenous γ-Aminobutyric acid (GABA) in alleviating Cr-induced phytotoxicity in pepper seedlings.

Methods

Pepper seedlings (Capsicum chinense Jacq. cv. Cc268) were divided into four groups: CK (control), GABA, Cr, and GABA + Cr. The GABA and GABA + Cr groups were pretreated with 20 mM GABA for seven days, while the CK and Cr groups were treated with water. After which the Cr and GABA + Cr groups were exposed to 100 mg kg⁻1 Cr (sourced from K₂Cr₂O₇) for two weeks.

Results

Cr stress significantly impedes plant growth. Conversely, GABA pretreatment markedly alleviated these toxic effects, increasing plant height, fresh weight, and dry weight by 33.08%, 33.71%, and 47.98%. GABA supplementation significantly reduced Cr accumulation in roots (by 29.59%) and leaves (by 19.36%), while improving nitrogen, phosphorus, and potassium content in roots. Photosynthetic efficiency was enhanced, evidenced by higher chlorophyll content and improved gas exchange. GABA activated ROS-scavenging enzymes (SOD, POD, CAT, APX), maintained the ascorbate–glutathione cycle by increasing AsA and GSH levels, and elevated osmolytes like proline and soluble sugars. Gene expression analysis revealed that GABA upregulated genes related to antioxidant defense, detoxification, and secondary metabolism, contributing to enhanced stress tolerance.

Conclusion

GABA alleviates Cr-induced toxicity in pepper seedlings by enhancing photosynthesis, reducing Cr accumulation, stimulating antioxidant defense system, and regulating osmotic balance, offering an effective strategy to improve crop tolerance in Cr-contaminated environments.