Identification and Characterization of Heat-Responsive miRNAs and their Regulatory Network in Maize

Abstract

Background: MicroRNAs (miRNAs) are a class of small non-coding RNAs, which have been demonstrated to play essential roles in plant growth and development, and in responses to abiotic stress. Heat stress is one of the most serious stresses that affecting crop yield and quality, however, the related regulatory mechanisms of miRNAs remains poorly understanding in maize. Results: In this study, a total of 340 miRNAs, including 215 known and 125 novel members, were identified from maize seedlings under heat stress (MH) and control conditions (MC) using high-throughput sequencing approach. The 215 known miRNAs can be further divided into 40 different families, and 21-nt miRNAs were found to be most abundant among the known miRNAs. Thirty-five miRNAs, including 26 known and 9 novel members, were significantly different expressed between MC and MH libraries. Furthermore, 174 target genes were predicted to be cleaved by 115 miRNAs using degradome sequencing. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed for these targets to explore the biological function and pathways involved. Based on the relationships of miRNAs, target genes and the enriched results, a regulatory network was constructed for the miRNAs and their respective target genes, and 16 significantly differently expressed miRNAs (DEMs) were involved in the network. Conclusions: The results revealed novel insights into the roles of miRNAs in heat stress response and provided a useful foundation for understanding the regulatory mechanisms of heat-responsive miRNAs in maize.