Abstract
MicroRNAs (miRNAs) are a class of small noncoding RNAs that regulate gene expression at the post-transcriptional level. Extensive studies have revealed that miRNAs have critical functions in plant growth, development, and stress responses and may provide valuable genetic resources for plant breeding research. We herein reviewed the development, mechanisms, and characteristics of miRNA techniques while highlighting widely used approaches, namely, the short tandem target mimic (STTM) approach. We described STTM-based advances in plant science, especially in the model crop rice, and introduced the CRISPR-based transgene-free crop breeding. Finally, we discussed the challenges and unique opportunities related to combining STTM and CRISPR technology for crop improvement and agriculture.
Highlights
MicroRNAs are a class of short noncoding RNAs (20–24 nt) that mediate gene expression by complementarily binding to their targeted transcripts for mRNA cleavage or protein translation inhibition (Sanei and Chen, 2015)
We reviewed the major approaches used for determining the function of miRNAs, with a focus on the short tandem target mimic (STTM) technique and its applications in the functional characterization of miRNAs involved in various rice agronomic traits, and illustrated transgene-free breeding practices based on transgenic outcomes via CRISPR/Cas9
STTM and related miRNA techniques help to reveal the complex molecular mechanisms involved in the regulation of agronomic traits, and provide potential breeding materials for crop improvement and breeding
Summary
MicroRNAs (miRNAs) are a class of short noncoding RNAs (20–24 nt) that mediate gene expression by complementarily binding to their targeted transcripts for mRNA cleavage or protein translation inhibition (Sanei and Chen, 2015). Functional analyses of miRNAs have been achieved through overexpression for gain-of-function or knockdown/knockout for loss-of-function Among these techniques, RNAi, amiRNA, TALEN, and CRISPR/ Cas, which were initially applied for the functional analysis of protein-encoding genes, have proven to be useful for the subsequent regulation of miRNAs (Fire et al, 1998; Schwab et al, 2006; Morbitzer et al, 2010; Shan et al, 2013). MiRNA decoys/mimics such as target mimic (TMs) and short tandem target mimics (STTMs) were developed based on the discovery of miRNA sequestration by endogenous target mimics in plants (FrancoZorrilla et al, 2007; Todesco et al, 2010; Yan et al, 2012) These techniques have greatly expanded our abilities in plant miRNA research; more importantly, these methods are constantly being improved for broader applications in research and plant breeding. We discussed the challenges and potential future trends of STTM applications in the functional analysis of miRNAs and in crop breeding
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