Pérez-Torres Eduardo, García Andrea, Dinamarca Jorge, Alberdi Miren, Gutiérrez Ana, Gidekel Manuel, Ivanov Alexander G, Hüner Norman P A, Corcuera Luis J, Bravo LeónA
Departamento de Botánica, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
Instituto de Botánica, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile.
Funct Plant Biol. 2004 Aug;31(7):731-741. doi: 10.1071/FP03082.
Deschampsia antarctica Desv. (Poaceae) is the only grass that grows in the maritime Antarctic. Constant low temperatures and episodes of high light are typical conditions during the growing season at this latitude. These factors enhance the formation of active oxygen species and may cause photoinhibition. Therefore, an efficient mechanism of energy dissipation and / or scavenging of reactive oxygen species (ROS) would contribute to survival in this harsh environment. In this paper, non-acclimated and cold-acclimated D. antarctica were subjected to high light and / or low temperature for 24 h. The contribution of non-photochemical dissipation of excitation light energy and the activities of detoxifying enzymes in the development of resistance to chilling induced photoinhibition were studied by monitoring PSII fluorescence, total soluble antioxidants, and pigments contents and measuring variations in activity of superoxide dismutase (SOD; EC 1.15.1.1), ascorbate peroxidase (APX; EC 1.11.1.11), and glutathione reductase (GR; EC 1.6.4.2). The photochemical efficiency of PSII, measured as F / F , and the yield of PSII electron transport (ΦPSII) both decreased under high light and low temperatures. In contrast, photochemical quenching (qP) in both non-acclimated and cold-acclimated plants remained relatively constant (approximately 0.8) in high-light-treated plants. Unexpectedly, qP was lower (0.55) in cold-acclimated plants exposed to 4°C and low light intensity. Activity of SOD in cold-acclimated plants treated with high light at low temperature showed a sharp peak 2-4 h after the beginning of the experiment. In cold-acclimated plants APX remained high with all treatments. Activity of GR decreased in cold-acclimated plants. Compared with other plants, D. antarctica exhibited high levels of SOD and APX activity. Pigment analyses show that the xanthophyll cycle is operative in this plant. We propose that photochemical quenching and particularly the high level of antioxidants help D. antarctica to resist photoinhibitory conditions. The relatively high antioxidant capacity of D. antarctica may be a determinant for its survival in the harsh Antarctic environment.
南极发草（Deschampsia antarctica Desv.，禾本科）是唯一生长在南极海洋地区的禾本科植物。持续的低温和高光照射是该纬度生长季节的典型条件。这些因素会增强活性氧的形成，并可能导致光抑制。因此，一种有效的能量耗散和/或活性氧清除机制将有助于其在这种恶劣环境中生存。在本文中，将未驯化和冷驯化的南极发草置于高光和/或低温条件下24小时。通过监测PSII荧光、总可溶性抗氧化剂和色素含量，并测量超氧化物歧化酶（SOD；EC 1.15.1.1）、抗坏血酸过氧化物酶（APX；EC 1.11.1.11）和谷胱甘肽还原酶（GR；EC 1.6.4.2）活性的变化，研究了激发光能的非光化学耗散以及解毒酶活性在抗冷诱导光抑制过程中的作用。以F/F 测量的PSII光化学效率和PSII电子传递效率（ΦPSII）在高光和低温条件下均下降。相反，在高光处理的未驯化和冷驯化植物中，光化学猝灭（qP）保持相对恒定（约为0.8）。出乎意料的是，在4°C和低光照强度下的冷驯化植物中，qP较低（0.55）。在低温高光处理的冷驯化植物中，SOD活性在实验开始后2 - 4小时出现急剧峰值。在所有处理下，冷驯化植物中的APX活性都保持较高。冷驯化植物中的GR活性下降。与其他植物相比，南极发草表现出较高水平的SOD和APX活性。色素分析表明，叶黄素循环在这种植物中起作用。我们认为，光化学猝灭，特别是高水平的抗氧化剂有助于南极发草抵抗光抑制条件。南极发草相对较高的抗氧化能力可能是其在恶劣南极环境中生存的一个决定因素。
