Technologies to Address Plant microRNA Functions

Abstract

microRNAs (miRNAs) are small non-coding RNAs which play critical roles in growth, development and responses to abiotic and biotic stresses in plants and animals. Functional characterization of these miRNAs is important in understanding their roles and applications of the gained knowledge in crop improvement programs. Various approaches have been adopted to study functions of miRNAs in plants. These approaches involve overexpressing miRNAs for gain-of-function studies or their decoys/mimics in the form of target mimics (TMs), short tandem target mimics (STTMs) and sponges (SPs), for loss-of-function analyses. These decoys sequester and/or degrade mature target miRNAs, preventing the accumulation of miRNAs in sufficient amount to suppress their respective target genes. To suppress the expression of MIRNA genes or target genes, controlling agronomic traits, RNA knockdown techniques, such as RNAi or CRISPR/Cas13a can be used. Furthermore, gene-editing tools, such as CRISPR/Cas-based systems, can complement RNAi-based approaches to edit and/or alter expression of genes encoding miRNA or their targets. All constructs, targeting miRNAs or their target genes, can be expressed using constitutive, ubiquitous, tissue-specific or inducible promoters to achieve silencing in a desired manner, spatially or temporally. Altogether, modulating the expression of a miRNA, or of its target gene(s), can help manipulating their functions to engineer desirable traits in plants for crop improvement.