Responses of unicellular alga Chlorella pyrenoidosa to allelochemical linoleic acid

摘要

Linoleic acid (LA), is the product of secondary metabolism secreted fromMicrocystis aeruginosa, and it exhibits allelopathic activity against eukaryotic algae. However, information about on the mechanisms associated with the inhibition of algal activity by LA is limited. In this study,Chlorella pyrenoidosawas treated with LA (20–120 μg L−1) for 4 days, and its growth inhibition and physiological responses were examined for potential toxic mechanisms. The photosynthetic efficiency ofC. pyrenoidosawas inhibited by LA treatments, and the Fv/Fmparameter decreased significantly compared to that of controls; however, the photosynthetic pigment content did not change significantly. Peroxidase activity was enhanced, relieving oxidative damage in algae after LA treatments. However, superoxide dismutase and catalase were suppressed, ultimately leading to the aggravation of lipid peroxidation. Transcriptome-based gene expression analysis revealed that the 120 μg L−1LA treatment significantly inhibited the transcription of genes related to photosynthesis, carbon metabolism, and amino acid metabolism inC. pyrenoidosa, suggesting that these genes might be key LA targets inC. pyrenoidosa. Moreover, the expression of genes involved in vitamin, lipid, nitrogen cycling, terpenoid, and ascorbate metabolism was also affected, suggesting that LA inhibits algal cell growth through multiple pathways. The identification of LA-responsive genes inC. pyrenoidosaprovides new insight into LA stress responses in eukaryotic algae.