Insights into the MicroRNA-regulated response of bermudagrass to cold and salt stress

Cold and salt are common stresses in salinized land, which significantly limit plant growth and development. Harnessing and prevention of land salinization is crucial to agricultural production and economic welfare. Although cold or salt stress response has been widely investigated, the information on combined cold and salt stress is little. MicroRNAs (miRNAs) are involved in multiple biological processes at the post-transcriptional level. To explore the functions of miRNAs and their targets is essential for elucidating the molecular mechanisms under those stresses. Bermudagrass [Cynodon dactylon (L).Pers.] has the potential to improve salinized land owing to its high growth rate and excellent tolerance to salinity and alkalinity. Nevertheless, the information on bermudagrass miRNAs remains largely unknown. In this study, four small RNA libraries (control, cold, salt and combined stresses) were constructed using the high-throughput sequencing technology. Transcriptome data of bermudagrass was also applied to discover some new miRNAs and analysis the targets. Totally, 449 mature miRNAs were found in the four libraries, including 203 novel miRNAs and 246 known miRNAs that are similar or identical to miRNAs known in other species. Also, 52 pairs of novel miRNA/miRNA* were also observed. Moreover, 102 miRNAs were found to be differentially expressed among all the comparisons. In addition, 2200 targets of miRNAs were identified and analyzed. This study has provided some insights into the miRNA-regulated response of bermudagrass to cold and high salinity stresses.