Anthocyanins are water-soluble pigments in plants known for their photoprotective role against photoinhibitory and photooxidative damage under high light (HL). However, it remains unclear whether light-shielding or antioxidant activity plays a major role in the photoprotection exerted by anthocyanins under HL stress. To shed light on this question, we analyzed the physiological and biochemical responses to HL of three Arabidopsis thaliana lines (Col, chi, ans) with different light absorption and antioxidant characteristics. Under HL, ans had the highest antioxidant capacity, followed by Col, and finally chi; Col had the strongest light attenuation capacity, followed by chi, and finally ans. The line ans had weaker physiological activity of chloroplasts and more severe oxidative damage than chi after HL treatment. Col with highest photoprotection of light absorption capacity had highest resistance to HL among the three lines. The line ans with high antioxidant capacity could not compensate for its disadvantages in HL caused by the absence of the light-shielding function of anthocyanins. In addition, the expression level of the Anthocyanin Synthase (ANS) gene was most upregulated after HL treatment, suggesting that the conversion of colorless into colored anthocyanin precursors was necessary under HL. The contribution of anthocyanins to flavonoids, phenols, and antioxidant capacity increased in the late period of HL, suggesting that plants prefer to synthesize red anthocyanins (a group of colored antioxidants) over other colorless antioxidants to cope with HL. These experimental observations indicate that the light attenuation role of anthocyanins is more important than their antioxidant role in photoprotection.

花青素是植物中的水溶性色素，因其在高光 (HL) 下对光抑制和光氧化损伤具有光保护作用而闻名。然而，目前尚不清楚遮光或抗氧化活性是否在花青素在 HL 胁迫下发挥的光保护作用中起主要作用。为了阐明这个问题，我们分析了三种具有不同光吸收和抗氧化特性的拟南芥品系（Col、chi、ans）对 HL 的生理和生化反应。在HL下，ans的抗氧化能力最高，其次是Col，最后是chi；上校光衰减能力最强，其次是chi，最后是ans。HL处理后，ans系叶绿体生理活性较chi系弱，氧化损伤较chi系严重。具有最高光吸收能力光保护的Col在三个品系中对HL的抗性最高。行ANS具有高的抗氧化能力不能补偿其在HL缺点由于缺少花色苷的遮光功能的。此外，花青素合成酶( ANS)的表达水平) 基因在 HL 处理后上调最多，表明在 HL 下需要将无色转化为有色花青素前体。花青素对黄酮类、酚类和抗氧化能力的贡献在HL后期增加，表明植物比其他无色抗氧化剂更喜欢合成红色花青素（一组有色抗氧化剂）来应对HL。这些实验观察表明，花青素的光衰减作用比它们在光保护中的抗氧化作用更重要。