Analysis of Effects of Berberine on the Photosynthesis of Microcystis aeruginosa at Gene Transcriptional Level

Microcystis aeruginosa has great competition advantages to survive, grow, and dominate phytoplankton communities for its high photosynthetic activity in unsuitable conditions. Berberine was the allelochemical capable of inhibiting M. aeruginosa growth. To better understand the allelopathic mechanism involved, RNA-sequencing technology was used to investigate the berberine-induced changes in photosynthesis gene expression of M. aeruginosa. Using the next-generation sequencing platform Illumina/Solexa, a total of 13 099 868 and 13 870 448 90-bp pair-end reads for no berberine and berberine libraries were obtained, respectively. Among these genes, 10 324 794 (no berberine) and 8 944 254 (berberine) reads mapped multiply in the genome, while 9 988 318 (no berberine) and 8 316 668 (berberine) mapped to unique targets, respectively. It was indicated that berberine significantly repressed the expression of 869 genes and induced the expression of 1419 genes. Those berberine-affected genes belonged to different functional categories, especially enriched in various photosynthesis-relevant metabolic pathways based on the analysis of gene ontology, clusters of orthologous group terms, and Kyoto Encyclopedia of Genes and Genomes. The results suggested that berberine-induced disturbance in the algal photosynthesis process via repressing the expression of key photosynthesis genes, such as psbD, psaA, psaB, might be one of the main mechanisms involved in inhibitory allelopathic activity of berberine.