microRNAs (miRNAs) are key post-transcriptional regulators of gene expression in animals and plants. They guide RNA-induced silencing complexes (RISCs) to complementary target mRNA, thereby mediating mRNA degradation or translational repression.
Highlights • The destructive plant pathogens in the genus Phytophthora produce effectors that promote infection by interfering with host RNA silencing. • PSR1 targets a DEAH box-RNA helicase in plants to suppress small RNA biogenesis. •...
This is a very exciting piece of work that suggests that the food we eat may directly regulate gene expression in our bodies,” said Clay Marsh, Director of the Center for Personalized Health Care at the Ohio State University College of Medicine who...
Satellite RNAs and viriods are sub-viral pathogens of plants.
Satellite RNAs are dependent on their HVs for replication and encapsidation.
Viroids do not encode any proteins and are replicated by cellular enzymes.
Some commonly shared replication features exist between satellite RNAs and viroids.
Since the discovery of non-coding, small, highly structured, satellite RNAs (satRNAs) and viroids as subviral pathogens of plants , have been of great interest to molecular biologists as possible living fossils of pre-cellular evolution in an RNA world. Despite extensive studies performed in the last four decades, there is still mystery surrounding the origin and evolutionary relationship between these subviral pathogens. Recent technical advances revealed some commonly shared replication features between these two subviral pathogens. In this review, we discuss our current perception of replication and evolutionary origin of these petite RNA pathogens.
The use of next-generation sequencing has become an established method for virus detection. Efficient study design for accurate detection relies on the optimal amount of data representing a significant portion...
Summary 1 I. Introduction 1 II. The roles of miRNAs in the specification of embryonic roots 3 III. The roles of miRNAs at the post-embryonic root meristem (Fig. ) 4 IV. The roles of miRNAs during lateral and adventitious root formation (Fig.
Replication and intercellular spread of viruses depend on host mechanisms supporting the formation, transport and turnover of functional complexes between viral genomes, virus-encoded products and cellular factors. To enhance these processes, viruses assemble and replicate in membrane-associated complexes that may develop into “virus factories” or “viroplasms” in which viral components and host factors required for replication are concentrated. Many plant viruses replicate in association with the cortical ER-actin network that is continuous between cells through plasmodesmata. The replication complexes can be highly organized and supported by network interactions between the viral genome and the virus-encoded proteins. Intracellular PD targeting of replication complexes links the process of movement to replication and provides specificity for transport of the viral genome by the virus-encoded movement proteins. The formation and trafficking of replication complexes and also the development and anchorage of replication factories involves important roles of the cortical cytoskeleton and associated motor proteins.
KeywordsPlant virus;TMV;TuMV;RCNMV;PVX;Membranes;Cytoskeleton;Plasmodesmata;Viral replication complex;Movement protein
Plus-strand RNA viruses utilize cis-acting RNA elements to control viral processes.
Cis-acting RNA elements can be linear sequences or various higher-order structures.
Long-range inter-genomic RNA–RNA interactions also play important regulatory roles.
In the future, it will be important to understand global RNA genome structure.
Positive-strand RNA viruses are the most common type of plant virus. Many aspects of the reproductive cycle of this group of viruses have been studied over the years and this has led to the accumulation of a significant amount of insightful information. In particular, the identification and characterization of cis-acting RNA elements within these viral genomes have revealed important roles in many fundamental viral processes such as virus disassembly, translation, genome replication, subgenomic mRNA transcription, and packaging. These functional cis-acting RNA elements include primary sequences, secondary and tertiary structures, as well as long-range RNA–RNA interactions, and they typically function by interacting with viral or host proteins. This review provides a general overview and update on some of the many roles played by cis-acting RNA elements in positive-strand RNA plant viruses.
We discuss the antiviral function of RNA silencing and the host factors implicated.
We summarize the status of knowledge about the viral suppressors’ strategies.
We consider the multi-functionality of VSR proteins.
We present connections between RNA-based and other types of antiviral defense.
Finally, we will present the current applications of VSRs.
RNA silencing is a homology-dependent gene inactivation mechanism that regulates a wide range of biological processes including antiviral defense. To deal with host antiviral responses viruses evolved mechanisms to avoid or counteract this, most notably through expression of viral suppressors of RNA silencing. Besides working as silencing suppressors, these proteins may also fulfill other functions during infection. In many cases the interplay between the suppressor function and other “unrelated” functions remains elusive. We will present host factors implicated in antiviral pathways and summarize the current status of knowledge about the diverse viral suppressors’ strategies acting at various steps of antiviral silencing in plants. Besides, we will consider the multi-functionality of these versatile proteins and related biochemical processes in which they may be involved in fine-tuning the plant-virus interaction. Finally, we will present the current applications and discuss perspectives of the use of these proteins in molecular biology and biotechnology.
KeywordsPlants;Viruses;Antiviral RNA interference;Viral suppressors of silencing;Defense;Pathogenesis
The discovery of peptides encoded by what were thought to be non-coding – or 'junk' – regions of precursors to microRNA sequences reveals a new layer of gene regulation. These sequences may not be junk, after all.
In plants and animals, microRNAs regulate the expression of many different genes1. Such regulation is crucial in a variety of processes, including transitions through developmental stages and responses to environmental stresses. MicroRNAs (miRNAs) are short in sequence and are generated by enzymatic excision from precursor transcripts called primary miRNAs (pri-miRs), which until now had been assumed not to encode any proteins. But on Nature's website today, Lauressergues et al.2 provide convincing evidence to the contrary. They find that some pri-miRs encode peptides that enhance production of their miRNAs. This is the first report of a functional peptide being encoded by a pri-miR and provides a fresh perspective on the significance of pri-miR regions beyond those that directly give rise to miRNAs.
MicroRNAs (miRNAs) are small regulatory RNA molecules that inhibit the expression of specific target genes by binding to and cleaving their messenger RNAs or otherwise inhibiting their translation into proteins1. miRNAs are transcribed as much larger primary transcripts (pri-miRNAs), the function of which is not fully understood. Here we show that plant pri-miRNAs contain short open reading frame sequences that encode regulatory peptides. The pri-miR171b of Medicago truncatula and the pri-miR165a of Arabidopsis thaliana produce peptides, which we term miPEP171b and miPEP165a, respectively, that enhance the accumulation of their corresponding mature miRNAs, resulting in downregulation of target genes involved in root development. The mechanism of miRNA-encoded peptide (miPEP) action involves increasing transcription of the pri-miRNA. Five other pri-miRNAs of A. thaliana and M. truncatula encode active miPEPs, suggesting that miPEPs are widespread throughout the plant kingdom. Synthetic miPEP171b and miPEP165a peptides applied to plants specifically trigger the accumulation of miR171b and miR165a, leading to reduction of lateral root development and stimulation of main root growth, respectively, suggesting that miPEPs might have agronomical applications.
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