Hexaploid wheat (Triticum aestivum) root miRNome analysis in response to salt stress

Hexaploid bread wheat (Triticum aestivum) is one of the major crops grown and consumed all over the world. Elevated soil salinity causes reduction in crop yield and quality; therefore, several strategies were developed to improve salt-tolerant cultivars. MicroRNAs (miRNAs), small and non-coding RNAs, regulate gene expression at post-transcriptional level and play important roles in stress tolerance. Here, we used a broad-range miRNA-microarray analysis to investigate the root-miRNA profiles of two cultivars, Bezostaja (sensitive) and Seri-82 (tolerant). A total of 44 differentially regulated miRNAs were identified in the 8 x 15K array containing 11 862 plant miRNAs available in the database. Sixteen novel salt-responsive miRNAs were determined in wheat for the first time. The expression of three miRNAs (hvu-miR5049a, ppt-miR1074 and osa-miR444b.2) was up-regulated more than 260-fold in cv. Bezostaja upon salt stress. The target-gene analyses showed that several salt-stress-responsive miRNAs regulate mainly transcription factors such as bHLH135-like, AP2/ERBP, MADS-box and transporters. Gene ontology searches for 565 putative salt-stress-responsive miRNA target-genes revealed 623 processes in 10 different main topics such as metabolic process and response to stimuli. The genome-wide root miRNome study indicates salt-stress-responsive wheat miRNAs and the possible mechanisms behind the tolerance.