Li Jieming, Chen Yanran, Wan Qianruo, Zhang Mingxia
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.
Ecotoxicol Environ Saf. 2023 Apr 15;255:114794. doi: 10.1016/j.ecoenv.2023.114794. Epub 2023 Mar 20.
Luteolin as a phytogenic algicide can inhibit the growth and microcystins (MCs) release of Microcystis, a dominant genus during cyanobacterial blooms, but how phosphorus (P) level impacts luteolin effect on its growth and MC-pollution risk is unclear. By employing Microcystis aeruginosa as test alga, this study addressed this concern and explored response mechanisms from novel insights of relationship between extracellular polysaccharide (ex-poly) and protein (ex-pro) contents and MC-production/release. At each P level (0.05-5 mg/L), rising luteolin dose more greatly inhibited Microcystis growth and MC-pollution risk, with growth inhibition ratio of around 10%-30%, 20%-50% and 40%-90% for 3, 6 and 12 mg/L luteolin, respectively, but almost increasingly enhanced cellular ability of MC-production/conservation and total and bound ex-poly/ex-pro production. Rising P level promoted Microcystis growth and intracellular/extracellular MCs content (IMC, EMC) in test system at each luteolin dose, thus higher P level weakened algicidal and MC-removal effects of luteolin, indicating that P-decrease was required for stronger application outcome of luteolin. Total and bound ex-poly/ex-pro amount were positively correlated with cellular MC-production/conservation ability, IMC and EMC, which constituted cooperative stress-defense of Microcystis at each P level. Besides, rising luteolin dose posed stronger algicidal effect by inactivating gene expression involving peroxidase synthesis (especially at P-limitation), photosynthesis and P acquisition, while rising P level alleviated algicidal and MC-pollution inhibition effects of luteolin by enhancing gene expression involving N acquisition and peroxidase synthesis. This study shed novel insights for P-dependent effect and mechanisms of luteolin on toxigenic Microcystis growth and MC-pollution control, which guided to mitigating toxigenic Microcystis-dominated cyanobacterial blooms in different P-level water areas.
木犀草素作为一种植物源杀藻剂，可以抑制蓝藻水华期间的优势属——微囊藻的生长和微囊藻毒素（MCs）释放，但磷（P）水平如何影响木犀草素对其生长和MC污染风险的作用尚不清楚。本研究以铜绿微囊藻为受试藻，解决了这一问题，并从细胞外多糖（ex-poly）和蛋白质（ex-pro）含量与MC产生/释放之间关系的新视角探索了响应机制。在每个P水平（0.05 - 5 mg/L）下，增加木犀草素剂量对微囊藻生长和MC污染风险的抑制作用更大，3、6和12 mg/L木犀草素的生长抑制率分别约为10% - 30%、20% - 50%和40% - 90%，但几乎会逐渐增强细胞产生/储存MC的能力以及总的和结合的ex-poly/ex-pro产量。在每个木犀草素剂量下，升高P水平均促进了受试体系中微囊藻的生长以及细胞内/外MCs含量（IMC、EMC），因此较高的P水平削弱了木犀草素的杀藻和MC去除效果，这表明为了使木犀草素的应用效果更强需要降低P含量。总的和结合的ex-poly/ex-pro量与细胞产生/储存MC的能力、IMC和EMC呈正相关，它们在每个P水平下构成了微囊藻的协同应激防御。此外，增加木犀草素剂量通过使涉及过氧化物酶合成（特别是在P限制条件下）、光合作用和P获取的基因表达失活，从而产生更强的杀藻效果，而升高P水平则通过增强涉及N获取和过氧化物酶合成的基因表达来减轻木犀草素的杀藻和MC污染抑制作用。本研究为木犀草素对产毒微囊藻生长和MC污染控制的P依赖性作用及机制提供了新见解，为减轻不同P水平水域中以产毒微囊藻为主的蓝藻水华提供了指导。
