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<p>Air quality plays a pivotal role in regulating plant productivity and ecological stability. However, rapid urbanization and escalating vehicular emissions have severely altered atmospheric composition, exposing plants to intense oxidative, metabolic, and physiological stresses. Using the moss <i>Semibarbula orientalis</i> as a sensitive bioindicator, this study examines the mechanistic progression of plant responses along an air pollution gradient through chlorophyll <i>a</i> fluorescence, biochemical measurements, and multivariate statistical analyses. Under control conditions (S1), photosynthetic and metabolic attributes remained stable, reflecting optimal redox balance. Moderate pollution (S2) induced a compensatory phase marked by increased antioxidant enzyme activity and starch accumulation, indicating activation of redox defence pathways, while declining total soluble protein levels and early suppression of fluorescence parameters signalled initial photochemical stress. At S3 (Poor pollution), PSII performance indices and quantum yields declined sharply, coupled with intensified non-photochemical quenching and progressive reaction-centre closure (↓RC/CSm). Simultaneous reductions in antioxidant activity and carbohydrate reserves indicated a shift from acclimation to metabolic fatigue. At S4 (very Poor pollution), caused marked pigment degradation and depletion of starch and total soluble protein pools, revealing profound metabolic impairment. Inhibition of electron transport beyond QA⁻ [↓PSI₀, ↓PHI(Eo)], reduced primary photochemistry [↓PHI(Po)], and elevated energy dissipation [↑DIo/RC, ↑PHI(Do), ↑Kn] confirmed severe disruption of photosynthetic electron flow. Together, the pollution-gradient responsive biochemical and physiological alterations, including total chlorophyll, Fm, RC/CSm, PSI₀, PHI(P₀), PIabs, and PIcsm, establish these parameters as key diagnostic indicators of air-pollution stress, collectively demonstrating <i>Semibarbula orientalis</i> to be a highly sensitive and reliable bioindicator species for urban air-quality monitoring and ecological risk assessment.</p>

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Air pollution drives photosynthetic breakdown and metabolic stress in Semibarbula orientalis

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月15日

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  • Vineet Soni,
  • Upma Bhatt,
  • Dipti Agarwal,
  • Yashwant Sompura

摘要

Air quality plays a pivotal role in regulating plant productivity and ecological stability. However, rapid urbanization and escalating vehicular emissions have severely altered atmospheric composition, exposing plants to intense oxidative, metabolic, and physiological stresses. Using the moss Semibarbula orientalis as a sensitive bioindicator, this study examines the mechanistic progression of plant responses along an air pollution gradient through chlorophyll a fluorescence, biochemical measurements, and multivariate statistical analyses. Under control conditions (S1), photosynthetic and metabolic attributes remained stable, reflecting optimal redox balance. Moderate pollution (S2) induced a compensatory phase marked by increased antioxidant enzyme activity and starch accumulation, indicating activation of redox defence pathways, while declining total soluble protein levels and early suppression of fluorescence parameters signalled initial photochemical stress. At S3 (Poor pollution), PSII performance indices and quantum yields declined sharply, coupled with intensified non-photochemical quenching and progressive reaction-centre closure (↓RC/CSm). Simultaneous reductions in antioxidant activity and carbohydrate reserves indicated a shift from acclimation to metabolic fatigue. At S4 (very Poor pollution), caused marked pigment degradation and depletion of starch and total soluble protein pools, revealing profound metabolic impairment. Inhibition of electron transport beyond QA⁻ [↓PSI₀, ↓PHI(Eo)], reduced primary photochemistry [↓PHI(Po)], and elevated energy dissipation [↑DIo/RC, ↑PHI(Do), ↑Kn] confirmed severe disruption of photosynthetic electron flow. Together, the pollution-gradient responsive biochemical and physiological alterations, including total chlorophyll, Fm, RC/CSm, PSI₀, PHI(P₀), PIabs, and PIcsm, establish these parameters as key diagnostic indicators of air-pollution stress, collectively demonstrating Semibarbula orientalis to be a highly sensitive and reliable bioindicator species for urban air-quality monitoring and ecological risk assessment.