Effects of Two Potential Allelochemicals on the Photosystem II of Nitzschia closterium and Monostroma nitidum
  • Bowen Huang, Enyi Xie*, Yu Ran, Xinyi Chen, Yongjian Huang, Jianjun Cui*
Fishery College, Guangdong Ocean University, Zhanjiang, 524088, China
* Corresponding Authors: Jianjun Cui. Email: cuijianjun29@163.com; Enyi Xie. Email: xieenyi@163.com
(This article belongs to this Special Issue:Role of Biostimulants in the Alleviation of Biotic and Abiotic Stress)
Received 20 March 2022; Accepted 20 May 2022 ; Published online 09 June 2022
In aquaculture, high-density seaweed farming brings higher economic benefits but also increases outbreaks of diatom felt. The effective control of diatom felt in high-density seaweed farming has always been a research hotspot. This study selected two potential allelochemicals 2-hydroxycinnamic acid and quinic acid to explore their effects on a diatom Nitzschia closterium and an economic seaweed Monostroma nitidum. The results showed that 2-hydroxycinnamic acid had better inhibitory effects than quinic acid on the growth, pigment content and photosynthetic efficiency of N. closterium. Their half-maximal inhibitory concentrations at 120 h (IC50–120 h) were 0.9000 and 1.278 mM, respectively. Additionally, these allelochemicals had limited inhibitory effects on the growth, pigment content and photosynthetic efficiency of M. nitidum before 24 h. To further explore the allelopathic effect of these chemicals, this study focused on the photosystem II energy fluxes of N. closterium. It was found that 3 mM 2-hydroxycinnamic acid could destroy the whole photosynthetic system by devastating the PSII reaction centre (RC) before 24 h; however, the same concentration of quinic acid could only down-regulate the electron transport efficiency by changing the effective antenna size of an active RC and downregulating the PSII reaction centre density. These experimental results are expected to provide a new strategy to control diatom felt blooms on the high-density seaweed farming areas.
Allelochemicals; 2-hydroxycinnamic acid; quinic acid; Nitzschia closterium; Monostroma nitidum; photosynthetic system