Allelopathically inhibitory effects of 5,4′-dihydroxyflavone on the growth, antioxidant system and photosynthesis of the bloom-forming cyanobacterium Microcystis aeruginosa

The allelochemical 5,4′-dihydroxyflavone (DHF) exerts a strong inhibitory effect against Microcystis aeruginosa TY001. In this study, the effects of DHF on growth, full photosynthetic performance, gene expression, and the antioxidant system of M. aeruginosa were examined to explore the possible damage mechanism. Quantitative real-time polymerase chain reaction analysis revealed downregulated expression of prx and fabZ, two photosynthesis-related genes (psaB and psbA), and a DNA repair gene (recA) on days 3 and 5. The levels of antioxidant enzymes also decreased, including superoxide dismutase, catalase, and peroxidase. Additionally, DHF significantly increased malondialdehyde and reactive oxygen species levels in cells. In conclusion, inhibited photosynthesis and oxidative damage were the main mechanisms by which DHF inhibited M. aeruginosa TY001. This study provides evidence that polyphenolic compounds, such as DHF, may be effective components of aquatic management strategies.