Linalool- and α-terpineol-induced programmed cell death in Chlamydomonas reinhardtii

• Published in: Ecotoxicology and environmental safety 2019-01, Vol.167, p.435-440
• Main Authors: Chen, Yueting, Weng, Yuanyuan, Zhou, Min, Meng, Yiyu, Liu, Jialu, Yang, Lin, Zuo, Zhaojiang
• Format: Article
• Language: English
• Subjects: Algaecide; Apoptosis - drug effects; Caspase 3 - metabolism; Caspase 9 - metabolism; Chlamydomonas reinhardtii; Chlamydomonas reinhardtii - cytology; Cyclohexenes - toxicity; Herbicides - toxicity; Hydrogen Peroxide - metabolism; Linalool; Monoterpenes - toxicity; Pheromones - toxicity; Photosynthesis - drug effects; Programmed cell death; Reactive Oxygen Species - metabolism; α-Terpineol
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2018.10.062

Plant allelochemicals effectively inhibit and/ or control algal growth, and have potential to use as algaecide. To uncover the lethal mechanism of 2 anti-algal compounds linalool and α-terpineol identified from Cinnamomum camphora extracts, and promote their development as algaecide, the H2O2 production, photosynthetic abilities, caspase-like activities, nuclear changes and DNA degradation were investigated in Chlamydomonas reinhardtii treated with the 2 compounds. H2O2 content burst in linalool treatment at 0.5 h and in α-terpineol treatment at 1 h, with increases of 2.7 folds and 1.3 folds, respectively, compared to that at 0 h. The photosynthetic pigments gradually degraded, and Fv/Fm gradually declined to zero, indicating that the cell death was not a necrosis due to the gradual disappearance of physiological process. In C. reinhardtii cells, the caspase-9-like and caspase-3-like were activated in the treatments with the 2 compounds for 1 h. With prolonging the treatment time, the fluorescent intensity of the cell nucleuses stained by DAPI gradually enhanced and then faded, and the genomic DNA isolated from the cells gradually degraded. These hallmarks indicated that the death of C. reinhardtii cells in linalool and α-terpineol treatments was a programmed cell death (PCD) triggered by the increased reactive oxygen species (ROS). Compared to α-terpineol treatment, linalool treatment showed stronger promoting effects on PCD at the same time point, which may be caused by the higher ROS content inducing higher caspase-9-like and caspase-3-like activities in a short time. •H2O2 burst in C. reinhardtii treated with linalool at 0.5 h and α-terpineol at 1 h.•Cell death caused by the 2 agents was not necrosis, as the Fv/Fm gradually declined.•Caspase-9-like and caspase-3-like were activated by linalool and α-terpineol.•Nucleuses condensed firstly and then broke, and DNA gradually degraded.•The 2 compounds killed the alga by inducing PCD, and linalool showed stronger effect.