过氧化氢参与了黑暗诱导的盐地碱蓬叶片甜菜红素积累

该文比较研究了黑暗和光照条件下C₃盐生植物盐地碱蓬(Suaeda salsa)叶片甜菜红素积累和H₂O₂含量及其抗氧化酶活性的关系,实验分析了甜菜红素体外抗氧化性能,以期揭示诱导盐地碱蓬甜菜红素积累的可能机制以及甜菜红素积累的生理生态意义。结果表明:暗期处理和营养液中加入一定浓度的H₂O₂都明显促进盐地碱蓬叶片H₂O₂含量、甜菜红素的含量、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的活性,而且叶片中 H₂O₂含量与甜菜红含量、SOD和CAT活性具有正相关性;盐地碱蓬甜菜红素体外清除羟自由基的能力明显强于维生素C,而清除超氧阴离子能力低于维生素C。这些结果表明:黑暗作为一种环境胁迫因子诱导盐地碱蓬叶片甜菜红素的积累可能是由自由基介导的,甜菜红素的积累可能与提高植物的抗氧化能力有关。

INVOLVEMENT OF HYDROGEN PEROXIDE IN BETACYANIN ACCUMULATION INDUCED BY DARK IN LEAVES OF SUAEDA SALSA

Aims Betalains are an important class of water-soluble pigments that comprise the red-violet betacyanins and the yellow betaxanthins and accumulate in most families of the Caryophyllales and some higher fungi. However, little is known about the regulation of betalain bio-synthesis by environmental factors in higher plants. Our objective is to explore the mechanism and the biological role of betacyanin accumulation induced by dark in leaves of the C₃ halophyteSuaeda salsa.  Methods Seeds ofS. salsa were cultured in 24 h dark and 14 h light /10 h dark, and watered with 0, 0.2% and 1.0% H₂O₂ nutrient solution. Seedlings were harvested three days later and assayed for betacyanin content, H₂O₂ content, activity of catalase (CAT) and superoxide dismutase (SOD) in leaves.  Important findings Darkness significantly enhanced H₂O₂ content, betacyanin content, activity of SOD and CAT in S. salsa leaves. Application of different concentrations of H₂O₂ to the culture solution increased H₂O₂ content, betacyanin content, activity of SOD and CAT compared to the dark treatment. Betacyanin content and H₂O₂ content in S. salsa leaves were closely related. Moreover, the scavenging superoxide (O₂^.-) ability of the betacyanins from S. salsa leavesin vitro was lower than that of vitamin C, while the scavenging hydroxyl radical (•OH) ability of the betacyains was much higher than that of vitamin C. These results suggest that betacyanin accumulation in S. salsaleaves grown in dark is possibly induced via reactive oxygen species (ROS) such as H₂O₂ and that betacyanin is involved in alleviating damage caused by oxidative stress due to its high ROS scavenging ability.