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<p>Light quality is a critical abiotic environmental factor that affects growth and β-carotene accumulation in <i>Dunaliella salina</i>. However, the influence of light quality on the primary photochemical reactions in <i>D. salina</i> and the physiological mechanisms regulating β-carotene metabolism remain unclear. This study involved batch culturing of <i>D. salina</i> under low light (40 ± 5 μmol photons m<sup>-2</sup> s<sup>-1</sup>, without inhibiting photosynthetic electron transfer) provided by different colored LEDs. Our results showed that the growth rate and contents of chlorophyll <i>a</i>, chlorophyll <i>b</i>, and β-carotene in <i>D. salina</i> cells were higher under blue light (BL) and red light (RL) than under white light (WL) and green light (GL). The maximum specific growth rate (μ) (0.066 ± 0.005 day<sup>-1</sup>) was higher under BL than under other light qualities, and the chlorophyll content was also higher under BL. The light absorption rates of chloroplasts in algal cells were higher under BL (22.8%) and RL (18.6%) than under WL (14.0%) and GL (10.2%), which can be attributed to reduced light energy dissipation and increased photochemical efficiency under BL and RL. BL and RL enhanced photosynthetic efficiency and β-carotene synthesis in <i>D. salina</i> cells. Under low-light conditions, light quality had little effect on β-carotene synthesis. However, two key genes involved in the β-carotene degradation pathway (<i>LUT5</i> and <i>ABA2</i>) were significantly downregulated under both BL and RL. The higher content of all-<i>trans</i> β-carotene under BL compared to RL was attributed to a more pronounced inhibition of the conversion pathway from all-<i>trans</i> β-carotene to the ABA biosynthesis precursor (9-<i>cis</i>-β-carotene) under BL. This explains why <i>D. salina</i> accumulated more all-<i>trans</i> β-carotene under BL and more 9-<i>cis</i>-β-carotene under RL.</p>

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Effects of monochromatic LED light quality on photosynthetic capacity and pigment content in Dunaliella salina under low light intensity

  • 期刊论文

  • 发表日期：

    2025年3月27日

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  • Tianze Zhao,
  • Yongfu Li,
  • Xingkai Che,
  • Haixing Wu,
  • Yuchen Ye,
  • Dingning Fan,
  • Zhendong Li,
  • Yingjie Zhao,
  • Wei Ye

摘要

Light quality is a critical abiotic environmental factor that affects growth and β-carotene accumulation in Dunaliella salina. However, the influence of light quality on the primary photochemical reactions in D. salina and the physiological mechanisms regulating β-carotene metabolism remain unclear. This study involved batch culturing of D. salina under low light (40 ± 5 μmol photons m-2 s-1, without inhibiting photosynthetic electron transfer) provided by different colored LEDs. Our results showed that the growth rate and contents of chlorophyll a, chlorophyll b, and β-carotene in D. salina cells were higher under blue light (BL) and red light (RL) than under white light (WL) and green light (GL). The maximum specific growth rate (μ) (0.066 ± 0.005 day-1) was higher under BL than under other light qualities, and the chlorophyll content was also higher under BL. The light absorption rates of chloroplasts in algal cells were higher under BL (22.8%) and RL (18.6%) than under WL (14.0%) and GL (10.2%), which can be attributed to reduced light energy dissipation and increased photochemical efficiency under BL and RL. BL and RL enhanced photosynthetic efficiency and β-carotene synthesis in D. salina cells. Under low-light conditions, light quality had little effect on β-carotene synthesis. However, two key genes involved in the β-carotene degradation pathway (LUT5 and ABA2) were significantly downregulated under both BL and RL. The higher content of all-trans β-carotene under BL compared to RL was attributed to a more pronounced inhibition of the conversion pathway from all-trans β-carotene to the ABA biosynthesis precursor (9-cis-β-carotene) under BL. This explains why D. salina accumulated more all-trans β-carotene under BL and more 9-cis-β-carotene under RL.