A large number of noncoding circular RNAs (circRNAs) with regulatory potency have been identified in animals, but little attention has been given to plant circRNAs.
We performed genome-wide ...identification of circRNAs in Oryza sativa and Arabidopsis thaliana using publically available RNA-Seq data, analyzed and compared features of plant and animal circRNAs.
circRNAs (12037 and 6012) were identified in Oryza sativa and Arabidopsis thaliana, respectively, with 56% (10/18) of the sampled rice exonic circRNAs validated experimentally. Parent genes of over 700 exonic circRNAs were orthologues between rice and Arabidopsis, suggesting conservation of circRNAs in plants. The introns flanking plant circRNAs were much longer than introns from linear genes, and possessed less repetitive elements and reverse complementary sequences than the flanking introns of animal circRNAs. Plant circRNAs showed diverse expression patterns, and 27 rice exonic circRNAs were found to be differentially expressed under phosphate-sufficient and -starvation conditions. A significantly positive correlation was observed for the expression profiles of some circRNAs and their parent genes.
Our results demonstrated that circRNAs are widespread in plants, revealed the common and distinct features of circRNAs between plants and animals, and suggested that circRNAs could be a critical class of noncoding regulators in plants.
Main conclusion
Long non-coding RNAs modulate gene activity in plant development and stress responses by various molecular mechanisms.
Long non-coding RNAs (lncRNAs) are transcripts larger than 200 ...nucleotides without protein coding potential. Computational approaches have identified numerous lncRNAs in different plant species. Research in the past decade has unveiled that plant lncRNAs participate in a wide range of biological processes, including regulation of flowering time and morphogenesis of reproductive organs, as well as abiotic and biotic stress responses. LncRNAs execute their functions by interacting with DNA, RNA and protein molecules, and by modulating the expression level of their targets through epigenetic, transcriptional, post-transcriptional or translational regulation. In this review, we summarize characteristics of plant lncRNAs, discuss recent progress on understanding of lncRNA functions, and propose an experimental framework for functional characterization.
Short noncoding RNAs have been demonstrated to play important roles in regulation of gene expression and stress responses, but the repertoire and functions of long noncoding RNAs (lncRNAs) remain ...largely unexplored, particularly in plants.
To explore the role of lncRNAs in disease resistance, we used a strand-specific RNAsequencing approach to identify lncRNAs responsive to Fusarium oxysporum infection in Arabidopsis thaliana.
Antisense transcription was found in c. 20% of the annotated A. thaliana genes. Several noncoding natural antisense transcripts responsive to F. oxysporum infection were found in genes implicated in disease defense. While the majority of the novel transcriptionally active regions (TARs) were adjacent to annotated genes and could be an extension of the annotated transcripts, 159 novel intergenic TARs, including 20 F. oxysporum-responsive lncTARs, were identified. Ten F. oxysporum-induced lncTARs were functionally characterized using T-DNA insertion or RNA-interference knockdown lines, and five were demonstrated to be related to disease development. Promoter analysis suggests that some of the F. oxysporum-induced lncTARs are direct targets of transcription factor(s) responsive to pathogen attack.
Our results demonstrated that strand-specific RNA sequencing is a powerful tool for uncovering hidden levels of transcriptome and that IncRNAs are important components of the antifungal networks in A. thaliana.
Summary
Securing agricultural supplies for the increasing population without negative impacts on environment demands new crop varieties with higher yields, better quality, and stronger stress ...resilience. But breeding such super crop varieties is restrained by growth–defense (G–D) trade‐off. MicroRNAs (miRNAs) are versatile regulators of plant growth and immune responses, with several being demonstrated to simultaneously regulate crop growth and defense against biotic stresses and to balance G–D trade‐off. Increasing evidence also links miRNAs to the metabolism and signaling of phytohormones, another type of master regulator of plant growth and defense. Here, we synthesize the reported functions of miRNAs in crop growth, development, and responses to bio‐stressors, summarize the regulatory scenarios of miRNAs based on their relationship with target(s), and discuss how miRNAs, particularly those involved in crosstalk with phytohormones, can be applied in balancing G–D trade‐off in crops. We also propose several open questions to be addressed for adopting miRNAs in balancing crop G–D trade‐off.
The genetic diversity and phenotypic variability of crop agronomic traits is valued by breeders for their benefits in crop breeding but are limited for most target traits. The rice Waxy (Wx) gene ...(LOC_Os06g04200) encodes granule‐bound starch synthase I (GBSSI), which determines the amylose content (AC) of endosperm by controlling amylose synthesis. The number of altered bases in each line (coloured in red) is indicated by the letter S followed by a number. (c) A structural model of Wxb constructed using the PROTEIN DATA BANK server; mutated residues contributing to the changes of AC are shown as spheres and are coloured (P124 in apricot, R125 in blue, R158 in red violet, G159 in white, V160 in green, D161 in red, T178 in orange and Y191 in purple). (d) Analysis of potential off‐target sites in the seven T1 edited lines. To determine the effect of these mutations on AC, we measured the apparent amylose contents (AACs) of grains from the seven mutant lines (Wxm5‐Wxm11), NIP (Wxb) and a 'soft rice' control Nangeng9108 (NG9108) (Wxmp) (Figure 1e).
Since the discovery of miRNAs in plants it has become clear that they are central to the regulation of many aspects of plant development and responses to the environment. miR172 regulates expression ...of a small group of AP2-like transcription factors in an evolutionarily ancient interaction. miR172 functions in regulating the transitions between developmental stages and in specifying floral organ identity. These two roles are conserved across monocotyledons and dicotyledons. Investigations into the roles of miR172 and its targets in phase changes in the model plant Arabidopsis have illustrated that this process is governed by complex regulatory systems. In addition to its conserved roles, miR172 has also acquired specialized species-specific functions in other aspects of plant development such as cleistogamy and tuberization.
In this study, we characterized the miR482 family in cotton using existing small RNA datasets and the recently released draft genome sequence of Gossypium raimondii, a diploid cotton species whose ...progenitor is the putative contributor of the Dt (representing the D genome of tetraploid) genome of the cultivated tetraploid cotton species G. hirsutum and G. barbadense. Of the three ghr-miR482 members reported in G. hirsutum, ghr-miR482a has no homolog in G. raimondii, ghr-miR482b and ghr-miR482c each has a single homolog in G. raimondii. Gra-miR482d has five homologous loci (gra-miR482d, f-i) in G. raimondii and also exists in G. hirsutum (ghr-miR482d). A variant, miR482.2 that is a homolog of miR2118 in other species, is produced from several GHR-MIR482 loci in G. hirsutum. Approximately 12% of the G. raimondii NBS-LRR genes were predicted targets of various members of the gra-miR482 family. Based on the rationale that the regulatory relationship between miR482 and NBS-LRR genes will be conserved in G. raimondii and G. hirsutum, we investigated this relationship using G. hirsutum miR482 and G. raimondii NBS-LRR genes, which are not currently available in G. hirsutum. Ghr-miR482/miR482.2-mediated cleavage was confirmed for three of the four NBS-LRR genes analysed. As in tomato, miR482-mediated cleavage of NBS-LRR genes triggered production of phased secondary small RNAs in cotton. In seedlings of the susceptible cultivar Sicot71 (G. hirsutum) infected with the fungal pathogen Verticillium dahliae, the expression levels of ghr-miR482b/miR482b.2, ghr-miR482c and ghr-miR482d.2 were down-regulated, and several NBS-LRR targets of ghr-miR482c and ghr-miR482d were up-regulated. These results imply that, like tomato plants infected with viruses or bacteria, cotton plants are able to induce expression of NBS-LRR defence genes by suppression of the miRNA-mediated gene silencing pathway upon fungal pathogen attack.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Dear Editor Circular RNAs （circRNAs） are a kind of non-coding RNAs; they were first found over 35 years ago but have only become a research hotspot in recent years. CircRNAs are covalently closed ...loops derived from precursor mRNAs by non-sequential back-splicing. Based on their genomic location, circRNAs can be classified into exonic, intronic, intergenic, and exon-intronic circRNAs （Chen, 2016）. By taking advantages of recent advances in bioinformatics algorithms, a large number of circRNAs have been detected among diverse organisms,
Summary
Heterosis is a fundamental biological phenomenon characterized by the superior performance of a hybrid compared with its parents. The underlying molecular basis for heterosis, particularly ...for allopolyploids, remains elusive. In this study we analyzed the transcriptomes of Brassica napus parental lines and their F1 hybrids at three stages of early flower development. Phenotypically, the F1 hybrids show remarkable heterosis in silique number and grain yield. Transcriptome analysis revealed that various phytohormone (auxin and salicylic acid) response genes are significantly altered in the F1 hybrids relative to the parental lines. We also found evidence for decreased expression divergence of the homoeologous gene pairs in the allopolyploid F1 hybrids and suggest that high‐parental expression‐level dominance plays an important role in heterosis. Small RNA and methylation studies aimed at examining the epigenetic effect of the changes in gene expression level in the F1 hybrids showed that the majority of the small interfering RNA (siRNA) clusters had a higher expression level in the F1 hybrids than in the parents, and that there was an increase in genome‐wide DNA methylation in the F1 hybrid. Transposable elements associated with siRNA clusters had a higher level of methylation and a lower expression level in the F1 hybrid, implying that the non‐additively expressed siRNA clusters resulted in lower activity of the transposable elements through DNA methylation in the hybrid. Our data provide insights into the role that changes in gene expression pattern and epigenetic mechanisms contribute to heterosis during early flower development in allopolyploid B. napus.
Significance Statement
We found that the majority of small interfering RNA clusters had a higher expression level in F1 hybrids than in the parents, and there was an increase in the genome‐wide DNA methylation of F1 hybrids. Our data provide insights into the role that changes in gene expression pattern and epigenetic mechanisms play in heterosis during early flower development in allopolyploid B. napus.
SUMMARY
Protein lysine acetylation is an important post‐translational modification mechanism involved in cellular regulation in eukaryotes. Calmodulin (CaM) is a ubiquitous Ca2+ sensor in eukaryotes ...and is crucial for plant immunity, but it is so far unclear whether acetylation is involved in CaM‐mediated plant immunity. Here, we found that GhCaM7 is acetylated upon Verticillium dahliae (V. dahliae) infection and a positive regulator of V. dahliae resistance. Overexpressing GhCaM7 in cotton and Arabidopsis enhances V. dahliae resistance and knocking‐down GhCaM7 makes cotton more susceptible to V. dahliae. Transgenic Arabidopsis plants overexpressing GhCaM7 with mutation at the acetylation site are more susceptible to V. dahliae than transgenics overexpressing the wild‐type GhCaM7, implying the importance of the acetylated GhCaM7 in response to V. dahliae infection. Yeast two‐hybrid, bimolecular fluorescent complementation, luciferase complementation imaging, and coimmunoprecipitation assays demonstrated interaction between GhCaM7 and an osmotin protein GhOSM34 that was shown to have a positive role in V. dahliae resistance. GhCaM7 and GhOSM34 are co‐localized in the cell membrane. Upon V. dahliae infection, the Ca2+ content reduces almost instantly in plants with downregulated GhCaM7 or GhOSM34. Down regulating GhOSM34 enhances accumulation of Na+ and increases cell osmotic pressure. Comparative transcriptomic analyses between cotton plants with an increased or reduced expression level of GhCaM7 and wild‐type plants indicate the involvement of jasmonic acid signaling pathways and reactive oxygen species in GhCaM7‐enabled disease resistance. Together, these results demonstrate the involvement of CaM protein in the interaction between cotton and V. dahliae, and more importantly, the involvement of the acetylated CaM in the interaction.
Significance Statement
GhCaM7 positively regulator cotton defense responses to Verticillium dahliae by acetylation and interacting with osmotin protein GhOSM34, leading to activation of Ca2+, jasmonic acid, and reactive oxygen species signaling pathways.
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