Authors have study and agreed for the published version on the manuscript. Funding: NAS Agenda System (No. PJ01501201 and PJ01501202) with the Rural Development Administration, Jeonju, Korea. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Requests for further details about sources, reagents and information availability needs to be directed to the corresponding author. Acknowledgments: This study was financially supported by the NAS Agenda Program in the Rural Development Administration, Jeonju, Korea. Conflicts of Interest: The authors declare no conflict of interest.AbbreviationsHz dB PI GUS QC TZ EZ qRT-PCR NPA Yucasin CK IAA ABA GA JA SA GFP Hertz Decibel Propidium iodide -glucuronidase Quiescent center Transition zone Elongation zone Quantitative real-time polymerase chain reaction N-1-naphthylphthalamic acid 5-(4-chlorophenyl)-4H-1,2,COX-3 Inhibitor Species 4-triazole-3-thiol Cytokinin Indole acetic acid Abscisic acid JAK2 Inhibitor Molecular Weight Gibberellin Jasmonic acid Salicylic acid Green fluorescent protein
Circular RNAs (circRNAs) are endogenous non-coding RNAs (ncRNAs) that have gained growing consideration in recent years. circRNAs are formed by exon or intron cyclization that ligates the five terminal cap and three terminal poly(A) tail to form a circular structure. They’re primarily located within the cytoplasm or stored in exosomes, are unaffected by RNA exonucleases, are much more stably expressed and much less susceptible to degradation, and have already been shown to exist inside a wide wide variety of eukaryotic organisms (Li Y. et al., 2015; Pradeep et al., 2020). The widespread existence of circRNAs suggests that they have certain biological functions as lncRNAs and microRNAs (miRNAs) play (Jiang et al., 2009, 2014, 2015; Wang et al., 2014; Cheng L. et al., 2019; Liang et al., 2019; Wei and Liu, 2020; Yang et al., 2020). In recent years, studies have shown a diversity of formation mechanismsFrontiers in Genetics | www.frontiersin.orgMarch 2021 | Volume 12 | ArticleJiao et al.Circular RNAs and Human Diseasesand biological functions of circRNAs. circRNAs are formed by a variety of mechanisms; for instance, spliceosomes (intracellular protein NA complexes) catalyze splicing as follows (Salgia et al., 2003): very first, the spliceosome recognizes introns, that are flanked by the splice donor (or 5 splice web-site) and the splice acceptor (or 3 splice web site) with certain sequences in the 5 and 3 ends; then, the two hydroxyl group on the downstream sequence attacks the splice donor, resulting in a circular intron lariat structure; lastly, the three hydroxyl group of your upstream exon splice donor attacks the splice acceptor, the upstream and downstream exons are sequentially spliced to kind a linear structure, and also the intron lariat structure is usually degraded rapidly by debranching enzyme. Variable splicing will be the procedure by which a precursor mRNA (pre-mRNA) can be transcribed from different RNA splicing techniques; that is certainly, different combinations of splice sites, to create mutually exclusive mRNA splice isoforms, which in turn are translated to produce various protein products (Pan et al., 2008). This can be the main function of RNA cyclization. Cyclization of circRNAs is often divided into intron and exon cyclization (Sanger et al., 1976), along with the present mainstream cyclization mechanisms are categorized as follows: (1) exon skipping, (2) direct back-splicing of intron, (three) circRNA formation by RNAbinding proteins (RBPs; Chen, 2016; Zhang et al., 2018), and (4).