Optimizing culture conditions for micropropagation of Codium tomentosum
摘要
Codium tomentosum is currently cultivated through vegetative propagation (cuttings) in tumble culture systems targeting niche markets. To scale up and expand its aquaculture production, optimization of propagation and culture methods is key. In Asia, artificial seed production via regeneration of isolated utricles and medullary filaments has already been established for the commercial production of Codium fragile. Our preliminary findings indicate that this approach also holds strong potential for C. tomentosum. In this context, the present study aimed to identify optimized culture conditions for the micropropagation of this species. The effects of temperature (12 °C, 16 °C, and 20 °C), light intensity (20, 40, 60 and 100 µmol photons m−2 s−1), and light spectra (white, blue, red and green) on the development of filamentous thalli from isolated utricles and medullary filaments were investigated. Our findings show that productivity was primarily influenced by light intensity and spectral composition, with optimal growth observed under intermediate irradiance (60 µmol photons m⁻2 s⁻1) and either blue or white light. Red or white light, low irradiance (20 µmol photons m⁻2 s⁻1) and higher temperatures (20 °C), promoted elongation of filamentous thalli. On the other hand, cooler temperatures (12 °C), low irradiance, and exposure to blue or white light enhanced photosynthetic efficiency. Pigment content (Chl a, Chl b, and total Chl) decreased with increasing irradiance suggesting a light-induced downregulation of pigment synthesis under high-light conditions, while carotenoid levels were only mildly affected by temperature and irradiance. Blue light induced higher pigment accumulation. This study provides important insights into the growth, productivity, and physiological responses of filamentous thalli of C. tomentosum under varying abiotic conditions, thereby supporting the development of future nursery protocols based on micropropagation.