木犀草素化感调控微囊藻生长生理及其种属内竞争机制研究

Microcystis-dominated algal blooms (MDABs), coupled with microcystins (MCs)-production, severely threaten ecosystem-safety. It reached a consensus that MC-producing (MC+) Microcystis and MC-free (MC-) Microcystis always co-exist to form competitive interaction with each other in aquatic habitats, greatly affects MDABs toxicity and toxicity-dynamics. Our study found that plant-originated allelochemical—luteolin could inhibit the growth of MC+ Microcystis and its MC-production, and showed the potential implications for MDABs-remediation. However, how luteolin affects the growth and physiological characteristics of MC+ and MC- Microicystis, respectively, at different nitrogen and phosphorus levels was still unclear. Also, the signaling compounds mediating the competitive interaction between MC+ and MC- Microcystis deserved further elucidation. From proteomic—metabolomic views, this proposal aimed to provide novel understanding into growth, cellular and physiological responsive mechanisms for MC+ and MC- Microcystis exposing to luteolin at various nitrogen and phosphorus levels, through monoculture, co-culture and field samples studies. Based on omics data, this proposal applied chromatography-mass spectrometry technique to further identify Microcystis-originated signaling compound(s) mediating the competitive interaction between MC+ and MC- Microcystis. The findings would shed a deep interpretation on the influence mechanisms of luteolin on growth and physiological characteristics of MC+ and MC- Microcystis and on their competitive interaction (including luteolin-stress on the synthesis of Microcystis-originated signaling compounds), and provide further theory evidences and technical supports for luteolin-involved MDABs-management and -control.

微囊藻水华及所产微囊藻毒素（MCs）危及生态安全，已证实产MCs（MC+）与非产MCs（MC-）微囊藻多形成共存竞争互作，关系着水华毒性。前期研究发现木犀草素可抑制MC+微囊藻生长及其MCs合成，表明其修复水华污染的潜质。然而在不同氮磷水平下木犀草素如何调控MC+、MC-微囊藻生长生理和两者竞争互作并不清楚，而介导MC+与MC-微囊藻竞争互作的信号物质也待深究。通过培养基模拟—自然水体实验相互印证研究，本项目从蛋白质组、代谢组学的全新角度揭示不同氮磷水平下MC+、MC-藻细胞（单培、混培）应对木犀草素胁迫的响应机制，基于组学数据并运用色—质谱联用等技术进一步鉴定介导MC+、MC-微囊藻竞争互作的藻源信号物质，以全面深入阐释木犀草素对MC+、MC-微囊藻生长生理及两者竞争互作的调控效应和机理（包括是否影响了介导互作的信号物质的合成），为加强木犀草素控制微囊藻水华提供深层次理论依据和技术支撑。

产藻毒素的（microcystins，MCs）微囊藻（MC+）和非产毒（MC—）微囊藻通常共存于水体并相互作用，其中MC+微囊藻的相对丰度和胞外藻毒素含量（EMC）决定了水华毒性。木犀草素作为典型黄酮类化感物可以抑制MC+微囊藻生长和藻毒素合成，有着修复水华污染的潜质。然而不同氮（N）磷（P）水平下木犀草素如何调控MC+和MC—微囊藻生长生理和两者竞争互作并不清楚。对此，本项目通过培养基模拟—自然水体实验相互印证，开展如下研究：1）在不同N、P水平下，木犀草素分别对两微囊藻生长及MC+微囊藻的MCs合成/释放能力的影响及机制；2）有无木犀草素胁迫下，N、P介导的MC+与MC—微囊藻的竞争互作效应、生理及蛋白-代谢组学机制；3）木犀草素对不同营养化的自然水体中蓝藻群落多样性和微囊藻生长影响。.取得以下结论：.i）单培的MC+微囊藻可在低中N水平和每一P水平下获得生长优势。木犀草素对各N、P水平下两微囊藻的生长和EMC抑制效应具有剂量依赖关系，其中MC—比MC+微囊藻对木犀草素抗性更强，因为其胞外聚合物较多；.ii）在低N、P水平下，混培的两藻生长、光合作用等受到相互抑制，导致细胞损伤，随N、P水平升高，相互抑制作用减轻，但MC+微囊藻始终占据竞争优势，混培的MC—微囊藻的下调的蛋白和代谢物相对更多，涉及氧化磷酸化、光合作用等过程；.iii）木犀草素扩大了MC+微囊藻的混培优势，但仍抑制两微囊藻生长及EMC，导致MC+微囊藻核糖体、碳代谢和抗生素生物合成等蛋白下调、MC—微囊藻光合作用、脂肪酸生物合成和氧化磷酸化等蛋白下调。另外，木犀草素的抑藻抑毒效应在低N水平被加强（混培的两微囊藻受到严重损伤），而在中高N水平下被削弱；.iv）以木犀草素为原料的抑藻剂可抑制各营养化水体蓝藻丰度，揭示了其在调控微囊藻水华生态风险中的作用。.本项目全面深入阐释了木犀草素对MC+和MC—微囊藻生长生理及两者竞争互作的调控效应和机理，为加强木犀草素控制微囊藻水华提供深层次理论依据和技术支撑。