基于典型化感物质行为动态的沉水植物与铜绿微囊藻相互作用研究

Cyanobacteria, are more sensitive to allelopathic inhibition of submerged macrophytes than eukaryotic algae, which is quite valuable for biological management in eutrophic water bodies. However, the inhibition modes of submerged macrophytes on cyanobacteria through allelochemicals are still unclear. Our previous study provided preliminary evidence that allelochemicals at environmental concentration levels could inhibit cyanobacteria Microcystis aeruginosa significantly by continual exposure, whereas it is an urgent need for research on dynamic behaviors of allelochemicals and impacts of coexisted cyanobacteria. Hence, submerged macrophyte Myriophyllum spicatum and its two typical allelochemicals i.e. pyrogallol and nonanoic acid are selected to conduct the following studies: (1) Analyze release and attenuation dynamics of pyrogallol and nonanoic acid in monoculture system of M. spicatum; (2) Compare their dynamic behaviors during coculture of M. spicatum and three M. aeruginosa strains separately, i.e. toxigenic strain, non-toxigenic strain and colonies of a wild strain; (3) Analyze physiological responses of M. aeruginosa strains to pyrogallol and nonanoic acid in exposure experiments simulating their dynamic rules. The results will firstly reveal difference in influence and response of M. aeruginosa strains with different toxigenicity and phenotype towards dynamic behaviors of pyrogallol and nonanoic acid, and accordingly test whether the allelochemicals at environmental concentration levels could inhibit M. aeruginosa effectively through continual release and action. The present study will provide scientific basis for further research on interaction mechanism of submerged macrophytes and cyanobacteria at ecological levels, and biological management in eutrophic water bodies.

相对于真核藻类，蓝藻更易受到沉水植物的化感抑制，这对富营养水体生物管理具有重要价值，但沉水植物通过化感物质抑制蓝藻的作用模式尚不清楚。申请人前期研究初步证明化感物质能通过持续暴露在环境浓度水平显著抑制铜绿微囊藻，但亟需结合其行为动态规律及共存蓝藻的影响深入研究。为此，本项目选取沉水植物穗花狐尾藻及其典型化感物质焦酚和壬酸，开展以下工作：（1）分析穗花狐尾藻单独培养时焦酚和壬酸的释放和衰减行为动态；（2）比较铜绿微囊藻产毒株、不产毒株和野生群体分别与穗花狐尾藻共培养时焦酚和壬酸的行为动态；（3）通过模拟暴露实验，分析各株铜绿微囊藻对焦酚和壬酸行为动态的生理代谢响应。研究结果将首次揭示产毒、不产毒和野生群体铜绿微囊藻对焦酚和壬酸行为动态的影响和响应差异，验证焦酚和壬酸能否在环境浓度水平通过持续释放和作用抑制蓝藻，为后续从生态水平阐明沉水植物与蓝藻的相互作用机制和富营养水体生物管理提供参考。

相对于真核藻类，蓝藻更易受到沉水植物的化感抑制，这对富营养水体生物管理具有重要价值，但沉水植物通过化感物质抑制蓝藻的作用模式尚不清楚。因此，本项目选取沉水植物穗花狐尾藻及其典型化感物质焦酚，通过室内控制实验较为系统研究沉水植物穗花狐尾藻与产毒非产毒微囊藻之间的相互作用。研究结果显示：1）微囊藻产毒株和非产毒株浸提物均能显著抑制穗花狐尾藻生长、蛋白、多糖、总酚含量，导致穗花狐尾藻膜脂过氧化，改变附植微生物组成，产毒株浸提物抑制作用更强；2）随水环境中碱度上升，焦酚对碱度适应驯化和未适应驯化铜绿微囊藻抑制作用增强，焦酚本身自氧化过程加快，说明高碱度水平下穗花狐尾藻化感物质焦酚及其自氧化产物能有效抑制铜绿微囊藻生长和光合活性；3）单培和共培养系统中，微囊藻产毒株比非产毒株对焦酚更敏感，焦酚对产毒微囊藻生长和光合活性的抑制作用更强。焦酚缓释微囊比焦酚本身对共培和单培系统中的微囊藻抑制作用更强，而相当于非产毒株，焦酚及其缓释微囊对产毒微囊藻抑制作用更强。研究发现除产毒微囊藻外，非产毒微囊藻也能显著影响穗花狐尾藻生长生理代谢过程，随碱度水平增强，穗花狐尾藻典型化感物质焦酚对产毒微囊藻抑制作用更强，模拟沉水植物持续释放化感物质研发的焦酚缓释微囊，比焦酚本身对产毒和非产毒微囊藻的抑制作用更强，进一步验证沉水植物可能通过持续释放化感物质有效抑制微囊藻生长繁殖。而生物非生物环境对沉水植物与微囊藻相互作用的影响有待室内与室外实验结合深入研究。