No abstract

Background: Aureochrome, a blue-light receptor found in photosynthetic stramenopiles, plays an important role in brown algal growth and development. Aureochrome preserves the reversed effector-sensor domain for blue light reception and acts as the candidate optogenetic tool for light induced post-transcriptional regulation, but the inner rapid regulation of aureochrome remains to be studied. MicroRNA (miRNAs) of plant can cleavage the specific base-pairing site of mRNA by RNA interference mechanism, and such post-transcriptional regulation of miRNAs to photoreceptor has received attention due to the flexible regulation pathway. However, the targeting relationship between aureochrome and miRNA is unclear.Results: In this study, the potential regulatory network between miRNAs and aureochrome were explored by transcriptome and sRNA sequencing in Saccharina japonica. Our results found that 18 miRNAs perfectly paired with aureochrome. Among the screened miRNAs, miR8181-x was negatively correlated with aureochrome5 with high credibility and exhibited tissue-specific expression in S. japonica. Degradome sequencing detected the exact cleavage site of miR8181-x on aureochrome5, confirming their targeting regulation relationship. Among the 54 target genes of miR8181-x, nine genes of ABC transporters, E3 ubiquitin-protein protein ligase, Hsp90, Mx1, PetC, EF2, GSA, HAD-superfamily hydrolase and SET2 that exhibited similar expression with aureochrome5 competed with the same binding site, thus constructing the competing endogenous RNA network. Functional analysis of miR8181-x target genes revealed that regulation of cell differentiation and development was enriched, indicating the potential role of miR8181-x in the regulation of growth and development.Conclusion: Our study found that miR8181-x negatively regulated the expression of aureochrome5. The exact cleavage site in aureochrome5 were verified by degradome sequencing, confirming the targeting relationships. Functional enrichment of miR8181-x target genes revealed that miR8181-x involved in the cell growth and development regulation of S. japonica.