College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China; Beijing Key Laboratory of Biodiversity and Organic Farming, China Agricultural University, Beijing, 100193, China.
College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China; Beijing Key Laboratory of Biodiversity and Organic Farming, China Agricultural University, Beijing, 100193, China.
Environ Pollut. 2022 Oct 15;311:119848. doi: 10.1016/j.envpol.2022.119848. Epub 2022 Aug 7.
Phytogenic allelochemical luteolin has potential to mitigate Microcystis-dominated cyanobacterial blooms (MCBs), but its algicidal effect against toxigenic Microcystis may be impacted by natural factors, especially nitrogen (N) level in waters. This study innovatively explored N-dependent effect of luteolin on Microcystis growth and its microcystins (MCs) production/release, and elucidated underlying mechanisms from proteomics and gene expression views. Generally, at each N level, rising luteolin dose progressively inhibited Microcystis growth by inhibiting proteins syntheses and genes expression involving light-capturing, photosynthetic electron transfer, Calvin cycle and phosphorus (P) acquisition, according to comparative proteomics and gene expression. At higher luteolin dose and lower N level, Microcystis cell tended to increase microcystins (MCs) production and conservation ability, with the highest increase degree observed at 12 mg/L luteolin and 0.5 mg/L N on day 10, reaching 1.96 and 2.68 folds of luteolin-free control, respectively, but decrease MC-release as extracellular MCs content (EMC), with inhibition ratio of 72.86%, 73.57%, 74.45% and 40.58%, 45.28%, 60.00% at rising N level under 12 mg/L luteolin stress on day 10 and 16, respectively. These enabled cellular defensive response of Microcystis to stronger stress and N limitation. Under luteolin stress, higher N level more strongly up-regulated numerous processes (e.g., oxidoreductase activity, ATP binding and transmembrane transport, oxidative phosphorylation, tricarboxylic acid cycle, fatty acid biosynthesis, glycolysis/gluconeogenesis, pyruvate, amino acids metabolism, metal ion-binding, P acquisition) as compensative protective responses to progressively down-regulated photosynthetic and ribosomal processes at higher N level, thus causing faster Microcystis growth than lower N level. This study provided novel insights for N-dependent effect and mechanisms of luteolin on MCBs mitigation and MCs risk control, and guided algicidal application of luteolin in different eutrophic-degree waters.
植物源化感物质木犀草素具有减轻微囊藻为主的蓝藻水华（MCBs）的潜力，但它对产毒微囊藻的杀藻作用可能受到自然因素的影响，特别是水中的氮（N）水平。本研究创新性地探索了木犀草素对微囊藻生长及其微囊藻毒素（MCs）产生/释放的依赖 N 的影响，并从蛋白质组学和基因表达的角度阐明了潜在机制。一般来说，在每个 N 水平下，随着木犀草素剂量的增加，通过抑制涉及光捕获、光合作用电子传递、卡尔文循环和磷（P）获取的蛋白质合成和基因表达，微囊藻的生长逐渐受到抑制。根据比较蛋白质组学和基因表达，在较高的木犀草素剂量和较低的 N 水平下，微囊藻细胞倾向于增加微囊藻毒素（MCs）的产生和保存能力，在 12mg/L 木犀草素和 0.5mg/L N 下，第 10 天观察到最大增加程度，分别达到木犀草素对照的 1.96 倍和 2.68 倍，但随着胞外微囊藻毒素含量（EMC）的减少，MC 释放减少，抑制率分别为 72.86%、73.57%、74.45%和 40.58%、45.28%、60.00%，在第 10 天和第 16 天 12mg/L 木犀草素胁迫下，N 水平升高。这使微囊藻对更强的胁迫和 N 限制产生了细胞防御反应。在木犀草素胁迫下，较高的 N 水平更强烈地上调了许多过程（例如，氧化还原酶活性、ATP 结合和跨膜运输、氧化磷酸化、三羧酸循环、脂肪酸生物合成、糖酵解/糖异生、丙酮酸、氨基酸代谢、金属离子结合、P 获取），作为对较高 N 水平下光合作用和核糖体过程逐渐下调的补偿性保护反应，从而导致较高 N 水平下微囊藻的生长速度快于较低 N 水平。本研究为木犀草素对 MCBs 缓解和 MCs 风险控制的依赖 N 效应和机制提供了新的见解，并指导了木犀草素在不同富营养化程度水域中的杀藻应用。
