Genome-wide investigation of microRNAs and expression profiles during rhizome development in ginger (Zingiber officinale Roscoe)

Abstract

Background: MicroRNAs (miRNAs) are endogenous, non-coding small functional RNAs that govern the post-transcriptional regulatory system of gene expression and control the growth and development of plants. Ginger is an herb that is well-known for its flavor and medicinal properties. The genes involved in ginger rhizome development and secondary metabolism have been discovered, but the genome-wide identification of miRNAs and their overall expression profiles and targets during ginger rhizome development are largely unknown. In this study, we used BGISEQ-500 technology to perform genome-wide identification of miRNAs from the leaf, stem, root, flower, and rhizome of ginger during three development stages. Results: In total, 104 novel miRNAs and 160 conserved miRNAs in 28 miRNA families were identified. A total of 181 putative target genes for novel miRNAs and 2772 putative target genes for conserved miRNAs were predicted. Transcriptional factors were the most abundant target genes of miRNAs, and 17, 9, 8, 4, 13, 8, 3 conserved miRNAs and 5, 7, 4, 5, 5, 15, 9 novel miRNAs showed significant tissue-specific expression patterns in leaf, stem, root, flower, and rhizome. Additionally, 53 miRNAs were regarded as rhizome development-associated miRNAs, which mostly participate in metabolism, signal transduction, transport, and catabolism, suggesting that these miRNAs and their target genes play important roles in the rhizome development of ginger. Twelve candidate miRNA target genes were selected, and then, their credibility was confirmed using qRT-PCR. As the result of qRT-PCR analysis, the expression of 12 candidate target genes showed an opposite pattern after comparison with their miRNAs. The rhizome development system of ginger was observed to be governed by miR156, miR319, miR171a_2, miR164, and miR529, which modulated the expression of the SPL, MYB, GRF, SCL, and NAC genes, respectively. Conclusion: This is a deep genome-wide investigation of miRNA and identification of miRNAs involved in rhizome development in ginger. We identified 52 rhizome-related miRNAs and 392 target genes, and this provides an important basis for understanding the molecular mechanisms of the miRNA target genes that mediate rhizome development in ginger.