Abstract
Small RNAs (sRNAs) are 20–30-nucleotide-long, regulatory, noncoding RNAs that induce silencing of target genes at the transcriptional and posttranscriptional levels. They are key components for cellular functions during plant development, hormone signaling, and stress responses. Generated from the cleavage of double-stranded RNAs (dsRNAs) or RNAs with hairpin structures by Dicer-like proteins (DCLs), they are loaded onto Argonaute (AGO) protein complexes to induce gene silencing of their complementary targets by promoting messenger RNA (mRNA) cleavage or degradation, translation inhibition, DNA methylation, and/or histone modifications. This mechanism of regulating RNA activity, collectively referred to as RNA interference (RNAi), which is an evolutionarily conserved process in eukaryotes. Plant RNAi pathways play a fundamental role in plant immunity against viruses and have been exploited via genetic engineering to control disease. Plant viruses of RNA origin that contain double-stranded RNA are targeted by the RNA-silencing machinery to produce virus-derived small RNAs (vsRNAs). Some vsRNAs serve as an effector to repress host immunity by capturing host RNAi pathways. High-throughput sequencing (HTS) strategies have been used to identify endogenous sRNA profiles, the “sRNAome”, and analyze expression in various perennial plants. Therefore, the review examines the current knowledge of sRNAs in perennial plants and fruits, describes the development and implementation of RNA interference (RNAi) in providing resistance against economically important viruses, and explores sRNA targets that are important in regulating a variety of biological processes.
Highlights
Small RNAs are single-stranded, noncoding RNA molecules 20–30 nucleotides long.They are conserved in most eukaryotes and regulate gene expression in a sequence-specific manner either transcriptionally or post-transcriptionally [1,2]
The miRNAs are encoded by genes that produce hairpin-like RNA structures that are cleaved by Dicer-like proteins (DCLs), while small interfering RNA (siRNA) are produced by DCLs from host RDR-dependent RNA polymerase (RDR) [24]
The progression of perennial species by conventional plant breeding approaches has several limitations mainly caused by their considerable degree of heterozygosity, auto-incompatibility and the length of their juvenile phase
Summary
Small RNAs (sRNAs) are single-stranded, noncoding RNA molecules 20–30 nucleotides (nt) long. Plants 2019, 8, 359 associated with virus disease outbreaks, such as evolution of virus at high pace, vector migration dynamics, and unpredictable virus host-range expansions, it is difficult to develop an efficient disease dynamics, andstrategies unpredictable virus host-rangeofexpansions, is difficult to develop anproven efficienttodisease management [6]. The deployment of genotypes with virus resistance has proven to be the most effective strategy [7,8,9]. Viral-encoded proteins interact with host transcription machinery, DNA factories”. These host–virus interactions trigger antiviral responses from the host. These interactions alsovirus trigger antiviralincluding responses from systemic the host.acquired. Plants use several severalhost–virus mechanisms to challenge infection, RNAi, resistance, mechanisms to challenge virus infection, including.
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