Identification and characterization of salt-responsive microRNAs in Populus tomentosa by high-throughput sequencing

► We compared RNA libraries from salt-treated and untreated Populus by Solexa sequencing. ► Sequence analyses identified 141 conserved miRNAs, 29 non-conserved miRNAs, and 17 novel miRNAs. ► Differential expression analysis revealed 28 salt-responsive miRNAs. ► Eight miRNAs were validated by qRT-PCR and their dynamic differential expression analyzed. ► We discuss the functions of some salt-responsive/new miRNAs and their target genes.