Transcriptomic and proteomic choreography in response to light quality variation reveals key adaption mechanisms in marine Nannochloropsis oceanica

Photosynthetic organisms need to respond frequently to the fluctuation of light quality and light quantity in their habitat. In response to the fluctuation of different single wavelength lights, these organisms have to adjust and optimize the employment of light energy by redistributing excitation energy and remodeling photosystem stoichiometry or light complex structure. However, the response of whole cellular processes to fluctuations in single wavelength light is mostly unknown. Here, we report the transcriptomic and proteomic dynamics and metabolic adaptation mechanisms of Nannochloropsis oceanica to blue and red light. Preferential exposure to different light spectra induces massive reprogramming of the Nannochloropsis transcriptome and proteome. Combined with physiological and biochemical investigation, the rewiring of many cellular processes was observed, including carbon/nitrogen assimilation, photosynthesis, chlorophyll and cartenoid biosynthesis, reactive oxygen species (ROS) scavenging systems, and chromatin state regulation. A strong and rapid regulation of genes or proteins related to nitrogen metabolism, photosynthesis, chlorophyll synthesis, ROS scavenging system, and carotenoid metabolism were observed during 12 h and 24 h of exposure under red light. Additionally, two light harvesting complex proteins induced by blue light and one by red light were observed. The differential responses of N. oceanica to red and blue irradiation reveal how marine microalgae adapt to change in light quality and can be exploited for biofuel feedstock development.