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<p>Arsenic (As) contamination in paddy soils severely constrained rice crop (<i>Oryza sativa</i> L.) growth by disturbing water relations and thereby redox homeostasis. The present study investigated water balance, subcellular As distribution, and antioxidant dynamics in rice seedlings (cv. HUR-105) exposed to graded As concentrations (0–200 µM) under controlled hydroponic conditions. As stress significantly reduced root absorption rate and transpiration, indicating impaired water uptake. Leaf relative water content declined rapidly within two days but partially recovered after four to six days due to stomatal regulation, osmolyte accumulation, and increased dry matter allocation. Proline and total soluble sugars accumulated up to 2.3-fold, contributing to osmotic adjustment and stabilization of leaf water potential. Subcellular fractionation revealed preferential sequestration of As in the cell vacuoles and cell walls, restricting its cytoplasmic toxicity. Elevated As concentrations enhanced reactive oxygen species (ROS) (O₂˙⁻, H₂O₂, OH˙) generation leading to peroxidation of lipids, while moderate As exposure stimulated the antioxidant enzymatic activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione peroxidase (GPX) (1.8–2.4-fold), thereby reducing oxidative injury. The results indicated that coordinated regulation of water status, osmoprotectant metabolism, and As compartmentation contributed to partial tolerance in the rice seedlings. These biochemical and physiological adjustments provide mechanistic insight and potential selection markers for breeding As-resilient rice cultivars.</p>

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Arsenic stress-induced biochemical, physiological and morphological responses in rice (Oryza sativa L.) seedlings: symptom characterization and plant metabolic adaptation

  • 期刊论文

  • 发表日期：

    2026年6月19日

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  • Jyotsna Setty,
  • Pavan Singh,
  • Vijai Pandurangam

摘要

Arsenic (As) contamination in paddy soils severely constrained rice crop (Oryza sativa L.) growth by disturbing water relations and thereby redox homeostasis. The present study investigated water balance, subcellular As distribution, and antioxidant dynamics in rice seedlings (cv. HUR-105) exposed to graded As concentrations (0–200 µM) under controlled hydroponic conditions. As stress significantly reduced root absorption rate and transpiration, indicating impaired water uptake. Leaf relative water content declined rapidly within two days but partially recovered after four to six days due to stomatal regulation, osmolyte accumulation, and increased dry matter allocation. Proline and total soluble sugars accumulated up to 2.3-fold, contributing to osmotic adjustment and stabilization of leaf water potential. Subcellular fractionation revealed preferential sequestration of As in the cell vacuoles and cell walls, restricting its cytoplasmic toxicity. Elevated As concentrations enhanced reactive oxygen species (ROS) (O₂˙⁻, H₂O₂, OH˙) generation leading to peroxidation of lipids, while moderate As exposure stimulated the antioxidant enzymatic activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione peroxidase (GPX) (1.8–2.4-fold), thereby reducing oxidative injury. The results indicated that coordinated regulation of water status, osmoprotectant metabolism, and As compartmentation contributed to partial tolerance in the rice seedlings. These biochemical and physiological adjustments provide mechanistic insight and potential selection markers for breeding As-resilient rice cultivars.