Fig. 3

Strategies of Neoporphyra haitanensis photosynthetic system responding to cold stress. A Photochemical efficiency of N. haitanensis during low temperature treatment. Thalli were cultured at − 4, 4, 10 and 20 °C (T-4, T4, T10 and T20) for 1, 2 or 7 days (D1, D2, or D7). ^**P < 0.01, compared to 20 °C group; ^##P < 0.01, compared to 0 day group. B Changes of photosynthetic pigments contents under cold stress. ^*P < 0.05, ^**P < 0.01, compared to 20 °C group; ^#P < 0.05, ^##P < 0.01, compared to day-0 group. C Transcriptome expression profiles of the N. haitanensis photosynthetic system in cold conditions are shown near the pathways as heatmaps. D Overview of the Calvin cycle of N. haitanensis in response to cold stress. The data shows the transcriptomic profiles from the T20D1, T10D1, T4D1 and T-4D1 groups (from left to right). FPKM values of genes in different groups were used to construct the heatmaps after a z-score normalization (n = 3)