Phosphorus deficiency inducing volatile organic compounds from <i>Microcystis aeruginosa</i> and their effects on <i>Chlamydomonas reinhadtii</i>

Abstract

为了揭示磷（P）营养缺乏对蓝藻释放挥发性有机化合物（VOCs）的影响及其对其他藻类的化感作用，以形成蓝藻水华的主要种类铜绿微囊藻（Microcystis aeruginosa）为材料，在无P培养条件下对其释放的VOCs进行分析，同时测定VOCs对莱茵衣藻（Chlamydomonas reinhardtii）生长、光合色素含量和光合性能的影响.结果表明，采用无P培养基培养铜绿微囊藻24 h后，其释放的VOCs种类和含量均明显增加，与标准培养基培养相比，VOCs总释放量增加了73.4%，并出现7种新化合物.将铜绿微囊藻释放的VOCs通入莱茵衣藻溶液中，在标准培养基中铜绿微囊藻释放的VOCs对莱茵衣藻生长无显著影响，而无P条件下释放的VOCs则明显抑制莱茵衣藻生长，其响应指数（RI）为-0.25.此外，莱茵衣藻光合色素含量、光系统Ⅱ（PSⅡ）最大光化学量子产量（Fv/Fm）、有效光化学量子产量、光化学淬灭系数（qP）和光合电子传递速率（ETR）也明显降低，而非光化学淬灭系数（NPQ）则明显升高，其RI为0.26.由此可见，蓝藻在富营养化水体中大量繁殖以及P自身沉降特性导致的P缺乏会促进蓝藻释放VOCs，同时这些VOCs在保持蓝藻营养竞争优势和水体藻类多样性减少中具有化感抑制作用.;In order to uncover the effects of phosphorus (P) nutrition deficiency on volatile organic compounds (VOCs) released from cyanobacteria and their allelopathic effects on other algae in freshwater bodies, the VOCs from Microcystis aeruginosa that is the main species of cyanobacterial bloom in non-P medium were analyzed, and their effects on Chlamydomonas reinhardtii cell growth, photosynthetic pigment content and photosynthetic abilities were determined in this study. The VOC types and emission amount increased after M. aeruginosa cells were kept in non-P medium for 24 h, with the increase of 73.4% of the total emission amount in contrast to that in normal medium. Meanwhile, 7 new compounds appeared. There was no significant difference in C. reinhardtii growth after the algal cells were exposed to the VOCs from M. aeruginosa in normal medium. However, C. reinhardtii growth was markedly inhibited by the VOCs from M. aeruginosa in non-P medium, with the response index (RI) of -0.25. Meanwhile, the photosynthetic pigment content, maximum quantum yield of photosystem Ⅱ (PSⅡ) photochemistry (Fv/Fm), effective quantum yield in PSⅡ photochemistry, coefficient of photochemical quenching (qP) and apparent electron transport rate through PSⅡ (ETR) in C. reinhardtii also reduced remarkably, while non-photochemical dissipation of absorbed light energy (NPQ) increased significantly, with the RI of 0.26. Therefore, P deficiency caused by cyanobacteria mass propagation and P sedimentation in eutrophicated water might induce cyanobacteria releasing abundance of VOCs, which might play allelopathic inhibitory roles in cyanobacteria keeping advantages for nutrition competition and the reduction of algal biodiversity in water bodies.