Identification and Characterization of Salt-Responsive MicroRNAs in Taxodium hybrid ‘Zhongshanshan 405’ by High-Throughput Sequencing

MicroRNAs (miRNAs) are a type of noncoding RNA participating in the post-transcriptional regulation of gene expression that regulates plant responses to salt stress. Small RNA sequencing was performed in this study to discover the miRNAs responding to salt stress in Taxodium hybrid ‘Zhongshanshan 405’, which is tolerant to salinity stress. A total of 52 miRNAs were found to be differentially expressed. The target genes were enriched with gene ontology (GO), including protein phosphorylation, cellular response to stimulus, signal transduction, ATP and ADP binding, showing that miRNAs may play key roles in regulating the tolerance to salt stress in T. hybrid ‘Zhongshanshan 405’. Notably, a G-type lectin S-receptor-like serine/threonine-protein kinase (GsSRK) regulated by novel_77 and novel_2 miRNAs and a mitogen-activated protein kinase kinase kinase (MAPKKK) regulated by novel_41 miRNA were discovered under both short- and long-term salt treatments and can be selected for future research. This result provides new insights into the regulatory functions of miRNAs in the salt response of T. hybrid ‘Zhongshanshan 405’.