Growth, pigment content, antioxidant activity, and phytoene desaturase gene expression in Caulerpa lentillifera grown under different combinations of blue and red light-emitting diodes

Abstract

Light-emitting diodes (LEDs) have been developed as light sources for indoor algae cultivation. In this study, we determined the effects of blue and red light ratios on weight gain, pigment content, antioxidant activity, and phytoene desaturase (PDS) gene expression in Caulerpa lentillifera. Caulerpa lentillifera was grown under six LED light treatments: white (W), red (R, 660 nm, 100%), blue (B, 447 nm, 100%), 1B1R (50% blue + 50% red), 1B2R (33.3% blue + 66.7% red), and 1B5R (16.7% blue + 83.3% red). Our results showed that red light improved the weight gain percentage of C. lentillifera, whereas red light with a low proportion of blue light (1B5R, 16.7%; blue + 83.3% red) led to a significantly higher weight gain percentage and photosynthetic pigment (Chl a + Chl b) content than the other LED light treatments. Increasing the proportion of blue light negatively affected weight gain and the photosynthetic pigment contents. However, blue LED light induced significantly higher transcription of the PDS gene, which coincided with increased β-carotene accumulation and antioxidant activity in C. lentillifera. These results indicated that the ratio of blue to red light is important for the indoor cultivation of C. lentillifera, and 100 μmol photons m−2 s−1 of 1B5R LED light with a 12/12 h light-dark photoperiod resulted in good growth and development.