Research progress about microRNAs involved in plant secondary metabolism

MicroRNA (miRNA) is an endogenous single-stranded noncoding small RNA with a base length of 18-30, which widely exists in eukaryotic cells. It plays an important role in plant growth and development, metabolic biosynthesis and stress response. Mature miRNAs are evolutionarily conserved and have both sequential and tissue-specific expression. This paper summarizes the production, action mechanisms, main technologies, research progress and biological functions of miRNAs. miRNA research includes miRNA discovery (genetic screening, direct cloning, bioinformatics prediction and high-throughput sequencing) and biological function analysis (overexpression, the expression or inhibition of target gene mutants). It was found that most miRNAs are involved in plant secondary metabolism biosynthesis and have great potential as molecular breeding tools. The same biological process can be regulated by different miRNAs. Interestingly, the role of the same miRNA in different plants may behave in completely opposite manner, and the mode of action of each miRNA is also unique. Moreover, miRNA interaction and miRNA self-regulation will also be the developmental direction in the future. However, miRNA target recognition and functional verification are still major challenges for the future. This study will provide a reference for further exploration and verification the specific biological functions and related applications of miRNAs in plants.