**6. Conclusions**

It can be summarized that the marker system based on microRNA molecules represents (a) flexible marker system based on sequences of regulatory molecules, (b) species-transfer system due to the conserved nature of mature sequences of miRNAs, (c) functionally potential markers, where observed polymorphism points to changes in miRNA loci sequences evoking changes in the target gene regulatory model, (d) tissue-specific and development-specific characters of markers, and (e) screening tool of genome adaptation changes to induced abiotic stress referred to as stress-sensitive biomarkers. It should be noted that in selecting suitable type(s) of miRNA markers for a particular type of study, it is necessary to know the regulatory background, regulation mechanism, and target sequences of particular type of miRNA molecules.
