Molecular Strategies of Cadmium Detoxification in the Marine Diatom Phaeodactylum tricornutum: A Transcriptomic Perspective
Keywords:
Cadmium, Phaeodactylum Tricornutum, Transcriptomics, Oxidative Stress, Heavy Metal Detoxification, Bioindicator, Marine MicroalgaeAbstract
Cadmium (Cd) is a hazardous heavy metal increasingly contaminating marine ecosystems, posing risks to primary producers such as microalgae. This study investigates the physiological and transcriptomic responses of the marine diatom Phaeodactylum tricornutum to cadmium stress, with the goal of elucidating detoxification mechanisms and assessing its bioindicator potential. Cultures of P. tricornutum were exposed to 123 µg/L and 1230 µg/L Cd for 96 hours. Physiological assessments included growth rate, chlorophyll content, ROS levels, and cell viability. Concurrently, RNA-seq was performed to identify differentially expressed genes (DEGs) and enriched gene ontology (GO) terms associated with Cd stress. Results revealed that exposure to 1230 µg/L Cd caused substantial physiological impairments: decreased growth and chlorophyll content, elevated ROS accumulation, and reduced cell viability. Transcriptomic profiling showed marked upregulation of genes associated with metal efflux (ATPase5-1B), vacuolar sequestration (VIT1, CCC1), and oxidative stress mitigation (SOD, GSH1, HSP70). Enriched GO terms included “oxidative stress response” and “metal ion transport,” indicating activation of detoxification and stress adaptation pathways. The findings demonstrate that P. tricornutum employs a coordinated molecular defense strategy involving metal transport and antioxidant pathways, conferring resilience under high cadmium exposure. These adaptive responses support its use as a sensitive bioindicator species for marine cadmium pollution. This integrative approach enhances understanding of diatom detoxification strategies and offers practical applications in ecotoxicological monitoring.
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