Identification and analysis of microRNAs in Botryococcus braunii using high-throughput sequencing

MicroRNAs (miRNAs) play important regulatory roles in the growth and development of organisms. The colonial green microalga Botryococcus braunii is an oil-rich algae and little is known about its miRNAs and their target genes. Here we constructed and sequenced a small RNA library for B. braunii using the HiSeq 2000 deep sequencing method. In total, we identified 42 known miRNA families and 14 novel miRNAs from B. braunii via sequence alignment and secondary structure prediction. Quantitative real-time PCR analysis indicated that the majority of miRNAs were effective and credible. Gene ontology analysis showed that most of the targets of miRNAs were classified as being involved in metabolic and cellular processes, gene expression regulation and stress/defense functions. Our findings provide the first large-scale identification and characterization of B. braunii miRNAs and their potential target genes. This study could lead to further identification of B. braunii miRNAs and enhance our understanding of their regulatory mechanisms in diverse biological and metabolic processes.