Identification and expression analysis of genome-wide long noncoding RNA responsive CO fluctuated environment in marine microalga Nannochloropsis oceanica.

Long non-coding RNAs (lncRNAs) have been demonstrated to participate in plant growth and development as well as response to different biotic and abiotic stresses. However, the knowledge of lncRNA was limited in microalgae. In this study, by RNA deep sequencing, 134 lncRNAs were identified in marine Nannochloropsis oceanica in response to carbon dioxide fluctuation. Among them, there were 51 lncRNAs displayed differentially expressed between low and high CO treatments, including 33 upregulation and 18 downregulation lncRNAs. Cellulose metabolic process, glucan metabolic process, polysaccharide metabolic process, and transmembrane transporter activity were functionally enriched. Multiple potential target genes of lncRNA and lncRNA-mRNA co-located gene network were analyzed. Subsequent analysis had demonstrated that lncRNAs would participate in many biological molecular processes, including gene expression, transcriptional regulation, protein expression and epigenetic regulation. In addition, alternative splicing events were firstly analyzed in response to CO fluctuation. There were 2051 alternative splicing (AS events) identified, which might be associated with lncRNA. These observations will provide a novel insight into lncRNA function in Nannochloropsis and provide a series of targets for lncRNA-based gene editing in future.