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<p>The phytohormone abscisic acid (ABA) is present in microalgae, but its roles in microalgae remain largely unclear. We examined exogenous ABA effects on <i>Dunaliella salina</i> TG under nitrogen deprivation. Endogenous ABA rose 2.8-fold to 81.3&#xa0;ng&#xa0;g⁻<sup>1</sup> DCW within 12&#xa0;days. Exogenous ABA (0.2&#xa0;μM) further increased total-colored carotenoids from 6.9 to 8.42&#xa0;pg cell⁻<sup>1</sup> and β-carotene from 5.9 to 7.3&#xa0;pg cell⁻<sup>1</sup>; ABA was not taken up, indicating that ABA acts via extracellular signaling. Chlorophyll <i>a</i> declined more slowly, yet F<sub>v</sub>/F<sub>m</sub> and photosynthetic rate were stable; respiration increased. GC–MS metabolomics revealed 58 of 82 profiled metabolites (71%) significantly altered, with sucrose, trehalose and glycerol up 1.2–1.5-fold, whereas glutamate fell 40%. Total fatty acids increased 5.5% to 1031&#xa0;μg&#xa0;g⁻<sup>1</sup> DCW, driven by a 15% rise in α-linolenic acid and a 13% increase in unsaturated species. Thus, exogenous ABA reprograms carbon flux toward carotenoid and lipid synthesis while maintaining photosynthetic efficiency under nitrogen stress.</p>

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Exogenous ABA enhances β-carotene and reprograms metabolism in nitrogen-starved Dunaliella salina

  • 期刊论文

  • 发表日期：

    2025年11月26日

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  • Bao Zhang,
  • Kexin Han,
  • Bingbing Qi,
  • Cuihua Liu,
  • Hexin Lv

摘要

The phytohormone abscisic acid (ABA) is present in microalgae, but its roles in microalgae remain largely unclear. We examined exogenous ABA effects on Dunaliella salina TG under nitrogen deprivation. Endogenous ABA rose 2.8-fold to 81.3 ng g⁻1 DCW within 12 days. Exogenous ABA (0.2 μM) further increased total-colored carotenoids from 6.9 to 8.42 pg cell⁻1 and β-carotene from 5.9 to 7.3 pg cell⁻1; ABA was not taken up, indicating that ABA acts via extracellular signaling. Chlorophyll a declined more slowly, yet Fv/Fm and photosynthetic rate were stable; respiration increased. GC–MS metabolomics revealed 58 of 82 profiled metabolites (71%) significantly altered, with sucrose, trehalose and glycerol up 1.2–1.5-fold, whereas glutamate fell 40%. Total fatty acids increased 5.5% to 1031 μg g⁻1 DCW, driven by a 15% rise in α-linolenic acid and a 13% increase in unsaturated species. Thus, exogenous ABA reprograms carbon flux toward carotenoid and lipid synthesis while maintaining photosynthetic efficiency under nitrogen stress.