Methods and resultsWestern blot was used to detect the modification abundance of H3K4me3 in A. pacificum cultured under different conditions, including high light (HL), high nitrogen (HN), and f/2 medium (control, CT), in the rapid growth exponential phase. The results showed that the modification abundance of H3K4me3 under HL or HN was greater than that under CT. Chromatin immunoprecipitation-sequencing was used to explore the acting genes of H3K4me3 under different conditions for the first time. Nitrogen metabolism and endocytosis were significantly associated with H3K4me3 regulation under HL. Furthermore, H3K4me3 was also significantly associated with the vitamin metabolism pathway under HN.