Plant Non-Coding RNAs: Origin, Biogenesis, Mode of Action and Their Roles in Abiotic Stress

Role of non-coding RNAs in quality improvement of horticultural crops: computational tools, databases, and algorithms for identification and analysis

Horticultural crops, including fruits, vegetables, flowers, and herbs, are essential for food security and economic sustainability. Advances in biotechnology, including genetic modification and omics approaches, have significantly improved these crops'traits. While initial transgenic efforts focused on protein-coding genes, recent research highlights the crucial roles of non-coding RNAs (ncRNAs) in plant growth, development, and gene regulation. ncRNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), influence key biological processes through transcriptional and post-transcriptional regulation. This review explores the classification, functions, and regulatory mechanisms of ncRNAs, emphasizing their potential in enhancing horticultural crop quality. This growing understanding offers promising avenues for enhancing crop performance and developing new horticultural varieties with improved traits. Additionally, we elucidate the role of ncRNA databases and predictive bioinformatics tools into modern horticultural crop improvement strategies.

Long non-coding RNAs and their role in breast cancer pathogenesis and drug resistance: Navigating the non-coding landscape review

Despite the progress made in the development of targeted therapies, breast cancer (BC) continues to pose a significant threat to the health of women. Transcriptomics has emerged due to the advancements in high-throughput sequencing technology. This provides crucial information about the role of non-coding RNAs (ncRNAs) in human cells, particularly long ncRNAs (lncRNAs), in disease development and function. When the control of these ncRNAs is disrupted, various illnesses emerge, including cancer. Numerous studies have produced empirical data on the function of lncRNAs in tumorigenesis and disease development. However, the roles and mechanisms of numerous lncRNAs remain unidentified at the molecular level because their regulatory role and the functional implications of abnormalities in cancer biology have yet to be thoroughly defined. The review gives an itemized summary of the most current developments in the role of lncRNA in BC, focusing on three main pathways, PI3K, MAPK, NF-kB, and hypoxia, and their resistance mechanisms.

PmiR-Select® - a computational approach to plant pre-miRNA identification in genomes

Precursors of microRNAs (pre-miRNAs) are less used in silico to mine miRNAs. This study developed PmiR-Select® based on covariance models (CMs) to identify new pre-miRNAs, detecting conserved secondary structural features across RNA sequences and eliminating the redundancy. The pipeline preceded PmiR-Select® filtered 20% plant pre-miRNAs (from 38589 to 8677) from miRBase. The second filter reduced pre-miRNAs by 7% (from 8677 to 8045) through length limit to pre-miRNAs (70-300 nt) and miRNAs (20-24 nt). The 80% redundancy threshold was statistically the best, eliminating 55% pre-miRNAs (from 8045 to 3608). Angiosperms retained the highest number of pre-miRNAs and their families (2981 and 2202), followed by gymnosperms (362 and 271), bryophytes (183 and 119), and algae (82 and 78). Thirty-seven conserved pre-miRNA families happened among plant land clades, but none with algae. The PmiR-Select® was applied to the rice genome, producing 8536 pre-miRNAs from 36 families. The 80% redundancy threshold retained 3% pre-miRNAs (n = 264) from 36 families, valuable experimental and computational research resources. 14% (n = 1216) of 8536 were new pre-miRNAs from 19 new families in rice. Only 16 new sequences from six families overlapped (39 to 54% identities) with rice pre-miRNAs and five species on miRBase. The validation against mature miRNAs identified 8086 pre-miRNAs from 13 families. Eleven ones have already been recorded, but two new and abundant pre-miRNAs [miR437 (n = 296) and miR1435 (n = 725)] scattered in all 12-rice chromosomes. PmiR-Select® identified pre-miRNAs, decreased the redundancy, and discovered new miRNAs. These findings pave the way to delineating benchtop and computational experiments.

Technologies for Targeted RNA Degradation and Induced RNA Decay

The vast majority of the human genome codes for RNA, but RNA-targeting therapeutics account for a small fraction of approved drugs. As such, there is great incentive to improve old and develop new approaches to RNA targeting. For many RNA targeting modalities, just binding is not sufficient to exert a therapeutic effect; thus, targeted RNA degradation and induced decay emerged as powerful approaches with a pronounced biological effect. This review covers the origins and advanced use cases of targeted RNA degrader technologies grouped by the nature of the targeting modality as well as by the mode of degradation. It covers both well-established methods and clinically successful platforms such as RNA interference, as well as emerging approaches such as recruitment of RNA quality control machinery, CRISPR, and direct targeted RNA degradation. We also share our thoughts on the biggest hurdles in this field, as well as possible ways to overcome them.

Genetic and epigenetic reprogramming in response to internal and external cues by induced transposon mobilization in Moso bamboo

Long terminal repeat retroelements (LTR-REs) have profound effects on DNA methylation and gene regulation. Despite the vast abundance of LTR-REs in the genome of Moso bamboo (Phyllostachys edulis), an industrial crop in underdeveloped countries, their precise implication of the LTR-RE mobility in stress response and development remains unknown. We investigated the RNA and DNA products of LTR-REs in Moso bamboo under various developmental stages and stressful conditions. Surprisingly, our analyses identified thousands of active LTR-REs, particularly those located near genes involved in stress response and developmental regulation. These genes adjacent to active LTR-REs exhibited an increased expression under stress and are associated with reduced DNA methylation that is likely affected by the induced LTR-REs. Moreover, the analyses of simultaneous mapping of insertions and DNA methylation showed that the LTR-REs effectively alter the epigenetic status of the genomic regions where they inserted, and concomitantly their transcriptional competence which might impact the stress resilience and growth of the host. Our work unveils the unusually strong LTR-RE mobility in Moso bamboo and its close association with (epi)genetic changes, which supports the co-evolution of the parasitic DNAs and host genome in attaining stress tolerance and developmental robustness.

An undiscovered circadian clock to regulate phytoplankton photosynthesis

Circadian clocks exist in all types of organisms and coordinate key biological processes, e.g. photosynthesis in phytoplankton (microalgae) and land plants. We asked whether a circadian rhythm sustains in phytoplankton when living under constant illumination without environmental cues. Here, we report the first transcriptomic architecture of persistent oscillatory gene expression in the model marine diatom, Phaeodactylum tricornutum living under constant illumination and temperature without environmental cues. We show that cyclic expression of a considerable number of genes involved in light harvesting and carbon fixation sustained after 24 h of constant illumination (free-running), which could pose additional constraints on cell growth under constant light conditions. Over long-term adaptation to constant illumination, the majority of the rhythmic genes identified under diel light conditions lose their oscillatory expression in the absence of external entrainers, and the genes potentially controlled by persistent circadian clocks are primarily involved in transcriptional regulation and cell division. We find constant illumination leads to an increased average expression of transcription factors and cell division genes, while genes involved in the Calvin-Benson cycle and pigment biosynthesis are kept at low expression levels, which plays a role in the down-regulation of photosynthetic efficiency. By manipulation of the dark rest period, we confirm a fine-tuned light/dark cycle could dramatically improve photosynthetic efficiency in microalgae. Our results unveil a novel persistent circadian rhythm on photosynthetic regulation in marine phytoplankton and provide critical insights into the interaction between environmental signals and inheritable internal circadian clocks in diatoms.

Unraveling the ncRNA landscape that governs colorectal cancer: A roadmap to personalized therapeutics

Colorectal cancer (CRC) being one of the most common malignancies, has a significant death rate, especially when detected at an advanced stage. In most cases, the fundamental aetiology of CRC remains unclear despite the identification of several environmental and intrinsic risk factors. Numerous investigations, particularly in the last ten years, have indicated the involvement of epigenetic variables in this type of cancer. The development, progression, and metastasis of CRC are influenced by long non-coding RNAs (lncRNAs), which are significant players in the epigenetic pathways. LncRNAs are implicated in diverse pathological processes in CRC, such as liver metastasis, epithelial to mesenchymal transition (EMT), inflammation, and chemo-/radioresistance. It has recently been determined that CRC cells and tissues exhibit dysregulation of tens of oncogenic and tumor suppressor lncRNAs. Serum samples from CRC patients exhibit dysregulated expressions of several of these transcripts, offering a non-invasive method of detecting this kind of cancer. In this review, we outlined the typical paradigms of the deregulated lncRNA which exert significant role in the underlying molecular mechanisms of CRC initiation and progression. We comprehensively discuss the role of lncRNAs as innovative targets for CRC prognosis and treatment.

FEAtl: a comprehensive web-based expression atlas for functional genomics in tropical and subtropical fruit crops

BACKGROUND

Fruit crops, including tropical and subtropical fruits like Avocado (Persea americana), Fig (Ficus carica), Date Palm (Phoenix dactylifera), Mango (Mangifera indica), Guava (Psidium guajava), Papaya (Carica papaya), Pineapple (Ananas comosus), and Banana (Musa acuminata) are economically vital, contributing significantly to global agricultural output, as classified by the FAO's World Programme for the Census of Agriculture. Advancements in next-generation sequencing, have transformed fruit crop breeding by providing in-depth genomic and transcriptomic data. RNA sequencing enables high-throughput analysis of gene expression, and functional genomics, crucial for addressing horticultural challenges and enhancing fruit production. The genomic and expression data for key tropical and sub-tropical fruit crops is currently lacking a comprehensive expression atlas, revealing a significant gap in resources for horticulturists who require a unified platform with diverse datasets across various conditions and cultivars.

RESULTS

The Fruit Expression Atlas (FEAtl), available at http://backlin.cabgrid.res.in/FEAtl/ , is a first-ever extensive and unified expression atlas for tropical and subtropical fruit crops developed using 3-tier architecture. The expressivity of coding and non-coding genes, encompassing 2,060 RNA-Seq samples across 91 tissue types and 177 BioProjects, it provides a comprehensive view of gene expression patterns for different tissues under various conditions. FEAtl features multiple tabs that cater to different aspects of the dataset, namely, Home, About, Analyze, Statistics, and Team and contains seven central functional modules: Transcript Information,Sample Information, Expression Profiles in FPKM and TPM, Functional Analysis, Genes Based on Tau Score, and Search for Specific Gene. The expression of a transcript of interest can be easily queried by searching by tissue ID and transcript type. Expression data can be displayed as a heat map, along with functional descriptions as well as Gene Ontology and Kyoto Encyclopedia of Genes and Genomes.

CONCLUSIONS

This atlas represents a groundbreaking compilation of a wide array of information pertaining to eight distinct fruit crops and serves as a fundamental resource for comparative analysis among different fruit species and is a catalyst for functional genomic studies. Database availability: http://backlin.cabgrid.res.in/FEAtl/ .

Tumour-regulatory role of long non-coding RNA HOXA-AS3

Dysregulation of long non-coding RNA (lncRNA) HOXA-AS3 has been shown to contribute to the development of multiple cancer types. Several studies have presented the tumour-modulatory role or prognostic significance of this lncRNA in various kinds of cancer. Overall, HOXA-AS3 can act as a competing endogenous RNA (ceRNA) that inhibits the activity of seven microRNAs (miRNAs), including miR-29a-3p, miR-29 b-3p, miR-29c, miR-218-5p, miR-455-5p, miR-1286, and miR-4319. This relieves the downstream messenger RNA (mRNA) targets of these miRNAs from miRNA-mediated translational repression, allowing them to exert their effect in regulating cellular activities. Examples of the pathways regulated by lncRNA HOXA-AS3 and its associated downstream targets include the WNT/β-catenin and epithelial-to-mesenchymal transition (EMT) activities. Besides, HOXA-AS3 can interact with other cellular proteins like homeobox HOXA3 and HOXA6, influencing the oncogenic signaling pathways associated with these proteins. Generally, HOXA-AS3 is overexpressed in most of the discussed human cancers, making this lncRNA a potential candidate to diagnose cancer or predict the clinical outcomes of cancer patients. Hence, targeting HOXA-AS3 could be a new therapeutic approach to slowing cancer progression or as a potential biomarker and therapeutic target. A drawback of using lncRNA HOXA-AS3 as a biomarker or therapeutic target is that most of the studies that have reported the tumour-regulatory roles of lncRNA HOXA-AS3 are single observational, in vitro, or in vivo studies. More in-depth mechanistic and large-scale clinical trials must be conducted to confirm the tumour-modulatory roles of lncRNA HOXA-AS3 further. Besides, no lncRNA HOXA-AS3 inhibitor has been tested preclinically and clinically, and designing such an inhibitor is crucial as it may potentially slow cancer progression.

Update on functional analysis of long non-coding RNAs in common crops

With the rapid advances in next-generation sequencing technology, numerous non-protein-coding transcripts have been identified, including long noncoding RNAs (lncRNAs), which are functional RNAs comprising more than 200 nucleotides. Although lncRNA-mediated regulatory processes have been extensively investigated in animals, there has been considerably less research on plant lncRNAs. Nevertheless, multiple studies on major crops showed lncRNAs are involved in crucial processes, including growth and development, reproduction, and stress responses. This review summarizes the progress in the research on lncRNA roles in several major crops, presents key strategies for exploring lncRNAs in crops, and discusses current challenges and future prospects. The insights provided in this review will enhance our comprehension of lncRNA functions in crops, with potential implications for improving crop genetics and breeding.

The roles of non-coding RNAs in male reproductive development and abiotic stress responses during this unique process in flowering plants

Successful male reproductive development is the guarantee for sexual reproduction of flowering plants. Male reproductive development is a complicated and multi-stage process that integrates physiological processes and adaptation and tolerance to a myriad of environmental stresses. This well-coordinated process is governed by genetic and epigenetic machineries. Non-coding RNAs (ncRNAs) play pleiotropic roles in the plant growth and development. The identification, characterization and functional analysis of ncRNAs and their target genes have opened a new avenue for comprehensively revealing the regulatory network of male reproductive development and its response to environmental stresses in plants. This review briefly addresses the types, origin, biogenesis and mechanisms of ncRNAs in plants, highlights important updates on the roles of ncRNAs in regulating male reproductive development and emphasizes the contribution of ncRNAs, especially miRNAs and lncRNAs, in responses to abiotic stresses during this unique process in flowering plants.

The Emerging Role of Non-Coding RNAs (ncRNAs) in Plant Growth, Development, and Stress Response Signaling

Plant species utilize a variety of regulatory mechanisms to ensure sustainable productivity. Within this intricate framework, numerous non-coding RNAs (ncRNAs) play a crucial regulatory role in plant biology, surpassing the essential functions of RNA molecules as messengers, ribosomal, and transfer RNAs. ncRNAs represent an emerging class of regulators, operating directly in the form of small interfering RNAs (siRNAs), microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs). These ncRNAs exert control at various levels, including transcription, post-transcription, translation, and epigenetic. Furthermore, they interact with each other, contributing to a variety of biological processes and mechanisms associated with stress resilience. This review primarily concentrates on the recent advancements in plant ncRNAs, delineating their functions in growth and development across various organs such as root, leaf, seed/endosperm, and seed nutrient development. Additionally, this review broadens its scope by examining the role of ncRNAs in response to environmental stresses such as drought, salt, flood, heat, and cold in plants. This compilation offers updated information and insights to guide the characterization of the potential functions of ncRNAs in plant growth, development, and stress resilience in future research.

Unveiling the Roles of LncRNA MOIRAs in Rice Blast Disease Resistance

Rice blast disease, caused by the fungal pathogen Magnaporthe oryzae, is a major threat to rice production worldwide. This study investigates the role of long non-coding RNAs (lncRNAs) in rice's response to this destructive disease, with a focus on their impacts on disease resistance and yield traits. Three specific lncRNAs coded by M. oryzae infection-responsive lncRNAs (MOIRAs), MOIRA1, MOIRA2, and MOIRA3, were identified as key regulators of rice's response to M. oryzae infection. Strikingly, when MOIRA1 and MOIRA2 were overexpressed, they exhibited a dual function: they increased rice's susceptibility to blast fungus, indicating a negative role in disease resistance, while simultaneously enhancing tiller numbers and single-plant yield, with no adverse effects on other yield-related traits. This unexpected improvement in productivity suggests the possibility of overcoming the traditional trade-off between disease resistance and crop yield. These findings provide a novel perspective on crop enhancement, offering a promising solution to global food security challenges by developing rice varieties that effectively balance disease resistance and increased productivity.

Comprehensive non-coding RNA analysis reveals specific lncRNA/circRNA-miRNA-mRNA regulatory networks in the cotton response to drought stress

Root and leaf are essential organs of plants in sensing and responding to drought stress. However, comparative knowledge of non-coding RNAs (ncRNAs) of root and leaf tissues in the regulation of drought response in cotton is limited. Here, we used deep sequencing data of leaf and root tissues of drought-resistant and drought-sensitive cotton varieties for identifying miRNAs, lncRNAs and circRNAs. A total of 1531 differentially expressed (DE) ncRNAs was identified, including 77 DE miRNAs, 1393 DE lncRNAs and 61 DE circRNAs. The tissue-specific and variety-specific competing endogenous RNA (ceRNA) networks of DE lncRNA-miRNA-mRNA response to drought were constructed. Furthermore, the novel drought-responsive lncRNA 1 (DRL1), specifically and differentially expressed in root, was verified to positively affect phenotypes of cotton seedlings under drought stress, competitively binding to miR477b with GhNAC1 and GhSCL3. In addition, we also constructed another ceRNA network consisting of 18 DE circRNAs, 26 DE miRNAs and 368 DE mRNAs. Fourteen circRNA were characterized, and a novel molecular regulatory system of circ125- miR7484b/miR7450b was proposed under drought stress. Our findings revealed the specificity of ncRNA expression in tissue- and variety-specific patterns involved in the response to drought stress, and uncovered novel regulatory pathways and potentially effective molecules in genetic improvement for crop drought resistance.

The applications of CRISPR/Cas-mediated microRNA and lncRNA editing in plant biology: shaping the future of plant non-coding RNA research

MAIN CONCLUSION

CRISPR/Cas technology has greatly facilitated plant non-coding RNA (ncRNA) biology research, establishing itself as a promising tool for ncRNA functional characterization and ncRNA-mediated plant improvement. Throughout the last decade, the promising genome editing tool clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated proteins (Cas; CRISPR/Cas) has allowed unprecedented advances in the field of plant functional genomics and crop improvement. Even though CRISPR/Cas-mediated genome editing system has been widely used to elucidate the biological significance of a number of plant protein-coding genes, this technology has been barely applied in the functional analysis of those non-coding RNAs (ncRNAs) that modulate gene expression, such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Nevertheless, compelling findings indicate that CRISPR/Cas-based ncRNA editing has remarkable potential for deciphering the biological roles of ncRNAs in plants, as well as for plant breeding. For instance, it has been demonstrated that CRISPR/Cas tool could overcome the challenges associated with other approaches employed in functional genomic studies (e.g., incomplete knockdown and off-target activity). Thus, in this review article, we discuss the current status and progress of CRISPR/Cas-mediated ncRNA editing in plant science in order to provide novel prospects for further assessment and validation of the biological activities of plant ncRNAs and to enhance the development of ncRNA-centered protocols for crop improvement.

Changes in epigenetic features in legumes under abiotic stresses

Legume crops are rich in nutritional value for human and livestock consumption. With global climate change, developing stress-resilient crops is crucial for ensuring global food security. Because of their nitrogen-fixing ability, legumes are also important for sustainable agriculture. Various abiotic stresses, such as salt, drought, and elevated temperatures, are known to adversely affect legume production. The responses of plants to abiotic stresses involve complicated cellular processes including stress hormone signaling, metabolic adjustments, and transcriptional regulations. Epigenetic mechanisms play a key role in regulating gene expressions at both transcriptional and posttranscriptional levels. Increasing evidence suggests the importance of epigenetic regulations of abiotic stress responses in legumes, and recent investigations have extended the scope to the epigenomic level using next-generation sequencing technologies. In this review, the current knowledge on the involvement of epigenetic features, including DNA methylation, histone modification, and noncoding RNAs, in abiotic stress responses in legumes is summarized and discussed. Since most of the available information focuses on a single aspect of these epigenetic features, integrative analyses involving omics data in multiple layers are needed for a better understanding of the dynamic chromatin statuses and their roles in transcriptional regulation. The inheritability of epigenetic modifications should also be assessed in future studies for their applications in improving stress tolerance in legumes through the stable epigenetic optimization of gene expressions.

Unveiling the biosynthesis, mechanisms, and impacts of miRNAs in drought stress resilience in plants

Drought stress is one of the most serious threats to sustainable agriculture and is predicted to be further intensified in the coming decades. Therefore, understanding the mechanism of drought stress tolerance and the development of drought-resilient crops are the major goals at present. In recent years, noncoding microRNAs (miRNAs) have emerged as key regulators of gene expressions under drought stress conditions and are turning out to be the potential candidates that can be targeted to develop drought-resilient crops in the future. miRNAs are known to target and decrease the expression of various genes to govern the drought stress response in plants. In addition, emerging evidence also suggests a regulatory role of long non-coding RNAs (lncRNAs) in the regulation of miRNAs and the expression of their target genes by a process referred as miRNA sponging. In this review, we present the regulatory roles of miRNAs in the modulation of drought-responsive genes along with discussing their biosynthesis and action mechanisms. Additionally, the interactive roles of miRNAs with phytohormone signaling components have also been highlighted to present the global view of miRNA functioning under drought-stress conditions.

Research progress of non-coding RNAs in vegetable responses to abiotic stresses

Vegetable crops play a crucial role in agricultural production, providing essential vitamins and minerals necessary for a healthy diet. Recently, there has been growing interest in cultivating vegetable varieties with outstanding agricultural and economic traits. However, vegetable production is often exposed to various abiotic stresses like soil drought, temperature fluctuations, and heavy metal stress, which can negatively impact yield and quality. While previous research has investigated the physiological responses of vegetable crops to such stressors, less attention has been given to genetic networks. Plants respond to environmental stress mainly by adapting first and then reacting, thereby enhancing their resistance to stress. Typically, different abiotic stresses trigger epigenetic changes, which can regulate non-coding RNAs. Therefore, studying the epigenetic mechanisms of vegetable crop responses to abiotic stress can provide insights into the molecular response mechanisms of plants under stress. This knowledge has practical applications in breeding vegetable crops for resistance. This article summarizes the primary research findings on the regulation of non-coding RNAs and their expression levels in vegetable crops exposed to abiotic stresses to guide molecular breeding approaches for vegetable crops.

Role of non-coding RNAs against salinity stress in Oryza species: Strategies and challenges in analyzing miRNAs, tRFs and circRNAs

Salinity is an imbalanced concentration of mineral salts in the soil or water that causes yield loss in salt-sensitive crops. Rice plant is vulnerable to soil salinity stress at seedling and reproductive stages. Different non-coding RNAs (ncRNAs) post-transcriptionally regulate different sets of genes during different developmental stages under varying salinity tolerance levels. While microRNAs (miRNAs) are well known small endogenous ncRNAs, tRNA-derived RNA fragments (tRFs) are an emerging class of small ncRNAs derived from tRNA genes with a demonstrated regulatory role, like miRNAs, in humans but unexplored in plants. Circular RNA (circRNA), another ncRNA produced by back-splicing events, acts as target mimics by preventing miRNAs from binding with their target mRNAs, thereby reducing the miRNA's action upon its target. Same may hold true between circRNAs and tRFs. Hence, the work done on these ncRNAs was reviewed and no reports were found for circRNAs and tRFs under salinity stress in rice, either at seedling or reproductive stages. Even the reports on miRNAs are restricted to seedling stage only, in spite of severe effects on rice crop production due to salt stress during reproductive stage. Moreover, this review sheds light on strategies to predict and analyze these ncRNAs in an effective manner.

CircPCBL: Identification of Plant CircRNAs with a CNN-BiGRU-GLT Model

Circular RNAs (circRNAs), which are produced post-splicing of pre-mRNAs, are strongly linked to the emergence of several tumor types. The initial stage in conducting follow-up studies involves identifying circRNAs. Currently, animals are the primary target of most established circRNA recognition technologies. However, the sequence features of plant circRNAs differ from those of animal circRNAs, making it impossible to detect plant circRNAs. For example, there are non-GT/AG splicing signals at circRNA junction sites and few reverse complementary sequences and repetitive elements in the flanking intron sequences of plant circRNAs. In addition, there have been few studies on circRNAs in plants, and thus it is urgent to create a plant-specific method for identifying circRNAs. In this study, we propose CircPCBL, a deep-learning approach that only uses raw sequences to distinguish between circRNAs found in plants and other lncRNAs. CircPCBL comprises two separate detectors: a CNN-BiGRU detector and a GLT detector. The CNN-BiGRU detector takes in the one-hot encoding of the RNA sequence as the input, while the GLT detector uses k-mer (k = 1 - 4) features. The output matrices of the two submodels are then concatenated and ultimately pass through a fully connected layer to produce the final output. To verify the generalization performance of the model, we evaluated CircPCBL using several datasets, and the results revealed that it had an F1 of 85.40% on the validation dataset composed of six different plants species and 85.88%, 75.87%, and 86.83% on the three cross-species independent test sets composed of Cucumis sativus, Populus trichocarpa, and Gossypium raimondii, respectively. With an accuracy of 90.9% and 90%, respectively, CircPCBL successfully predicted ten of the eleven circRNAs of experimentally reported Poncirus trifoliata and nine of the ten lncRNAs of rice on the real set. CircPCBL could potentially contribute to the identification of circRNAs in plants. In addition, it is remarkable that CircPCBL also achieved an average accuracy of 94.08% on the human datasets, which is also an excellent result, implying its potential application in animal datasets. Ultimately, CircPCBL is available as a web server, from which the data and source code can also be downloaded free of charge.

Role of long non-coding RNAs in pancreatic cancer pathogenesis and treatment resistance- A review

Pancreatic cancer (PC) is one of the deadliest cancers associated with poor prognosis. The lack of reliable means of early cancer detection contributes to this disease's dismal prognosis. Long non-coding RNAs (LncRNAs) are protein-free RNAs produced by genome transcription; they play critical roles in gene expression regulation, epigenetic modification, cell proliferation, differentiation, and reproduction. Recent research has shown that lncRNAs play important regulatory roles in PC behaviors, in addition to their recently found functions. Several in-depth investigations have shown that lncRNAs are strongly linked to PC development and progression. Here, we discuss how lncRNAs, which are often overlooked, play many roles as regulators in the molecular mechanism underlying PC. This review also discusses the involved LncRNAs in PC pathogenesis and treatment resistance.

Regulatory roles of noncoding RNAs in callus induction and plant cell dedifferentiation

Plant regulatory noncoding RNAs (ncRNAs) have emerged as key modulators of gene expression during callus induction. Their further study may promote the design of innovative plant tissue culture protocols. The use of plants by humans has recently taken on a new and expanding insight due to the advent of genetic engineering technologies. In this context, callus cultures have shown remarkable potential for synthesizing valuable biomolecules, crop improvement, plant micropropagation, and biodiversity preservation. A crucial stage in callus production is the conversion of somatic cells into totipotent cells; compelling evidence indicates that stress factors, transcriptional regulators, and plant hormones can trigger this biological event. Besides, posttranscriptional regulators of gene expression might be essential participants in callus induction. However, research related to the analysis of noncoding RNAs (ncRNAs) that modulate callogenesis and plant cell dedifferentiation in vitro is still at an early stage. During the last decade, some relevant studies have enlightened the fact that different classes of ncRNAs, such as microRNAs (miRNAs), small interfering RNAs (siRNAs), and long noncoding RNAs (lncRNAs) are implicated in plant cell dedifferentiation through regulating the expression levels of diverse gene targets. Hence, understanding the molecular relevance of these ncRNAs in the aforesaid biological processes might represent a promising source of new biotechnological approaches for callus culture and plant improvement. In this current work, we review the experimental evidence regarding the prospective roles of ncRNAs in callus induction and plant cell dedifferentiation to promote this field of study.

Circulatory long noncoding RNAs (circulatory-LNC-RNAs) as novel biomarkers and therapeutic targets in cardiovascular diseases: Implications for cardiovascular diseases complications

Cardiovascular diseases (CVDs) are a group of disorders with major global health consequences. The prevalence of CVDs continues to grow due to population-aging and lifestyle modifications. Non-coding RNAs (ncRNAs) as key regulators of cell signaling pathways have gained attention in the occurrence and development of CVDs. Exosomal-lncRNAs (exos-lncRNAs) are emerging biomarkers due to their high sensitivity and specificity, stability, accuracy and accessibility in the biological fluids. Recently, circulatory and exos-based-lncRNAs are emerging and novel bio-tools in various pathogenic conditions. It is worth mentioning that dysregulation of these molecules has been found in different types of CVDs. In this regard, we aimed to discuss the knowledge gaps and suggest research priorities regarding circulatory and exos-lncRNAs as novel bio-tools and therapeutic targets for CVDs.

DNA Methylation in Algae and Its Impact on Abiotic Stress Responses

Epigenetics, referring to heritable gene regulatory information that is independent of changes in DNA sequences, is an important mechanism involved both in organism development and in the response to environmental events. About the epigenetic marks, DNA methylation is one of the most conserved mechanisms, playing a pivotal role in organism response to several biotic and abiotic stressors. Indeed, stress can induce changes in gene expression through hypo- or hyper-methylation of DNA at specific loci and/or in DNA methylation at the genome-wide level, which has an adaptive significance and can direct genome evolution. Exploring DNA methylation in responses to abiotic stress could have important implications for improving stress tolerance in algae. This article summarises the DNA methylation pattern in algae and its impact on abiotic stress, such as heavy metals, nutrients and temperature. Our discussion provides information for further research in algae for a better comprehension of the epigenetic response under abiotic stress, which could favour important implications to sustain algae growth under abiotic stress conditions, often related to high biosynthesis of interesting metabolites.

Comprehensive identification and analysis of circRNAs during hickory (Carya cathayensis Sarg.) flower bud differentiation

Flower bud differentiation represents a crucial transition from vegetative growth to reproductive development. Carya cathayensis (hickory) is an important economic species in China, with a long juvenile period that hinders its commercial development. In recent years, circular RNAs (circRNAs) have been widely studied and identified as sponges for miRNA regulation of mRNA expression. However, little is known regarding the role of circRNAs in flower buds. In this study, we sequenced circRNAs at three developmental stages (undifferentiated, differentiating, and fully differentiated) in both female and male buds. A total of 6,931 circRNAs were identified in the three developmental stages and 4,449 and 2,209 circRNAs were differentially expressed in female and male buds, respectively. Gene ontology demonstrated that many circRNA host genes participated in various processes, for example, cellular and intracellular pH regulation. Function annotation identified 46 differentially expressed circRNAs involved in flowering regulation, with 28 circRNAs found only in female buds, 4 found only in male buds, and 11 found in both female and male buds. A circRNA-miRNA-mRNA network was predicted based on 13 flowering-related circRNAs and their seven putative interacting miRNAs to describe the regulatory mechanism. Our preliminary results demonstrated a potential involvement of circRNA in bud differentiation. They provided a preliminary theoretical basis for how circRNA might participate in flower development in hickory, perhaps in woody plants.

Ten new high-quality genome assemblies for diverse bioenergy sorghum genotypes

Introduction

Sorghum (Sorghum bicolor (L.) Moench) is an agriculturally and economically important staple crop that has immense potential as a bioenergy feedstock due to its relatively high productivity on marginal lands. To capitalize on and further improve sorghum as a potential source of sustainable biofuel, it is essential to understand the genomic mechanisms underlying complex traits related to yield, composition, and environmental adaptations.

Methods

Expanding on a recently developed mapping population, we generated de novo genome assemblies for 10 parental genotypes from this population and identified a comprehensive set of over 24 thousand large structural variants (SVs) and over 10.5 million single nucleotide polymorphisms (SNPs).

Results

We show that SVs and nonsynonymous SNPs are enriched in different gene categories, emphasizing the need for long read sequencing in crop species to identify novel variation. Furthermore, we highlight SVs and SNPs occurring in genes and pathways with known associations to critical bioenergy-related phenotypes and characterize the landscape of genetic differences between sweet and cellulosic genotypes.

Discussion

These resources can be integrated into both ongoing and future mapping and trait discovery for sorghum and its myriad uses including food, feed, bioenergy, and increasingly as a carbon dioxide removal mechanism.

Beyond the Primary Structure of Nucleic Acids: Potential Roles of Epigenetics and Noncanonical Structures in the Regulations of Plant Growth and Stress Responses

Epigenetics deals with changes in gene expression that are not caused by modifications in the primary sequence of nucleic acids. These changes beyond primary structures of nucleic acids not only include DNA/RNA methylation, but also other reversible conversions, together with histone modifications or RNA interference. In addition, under particular conditions (such as specific ion concentrations or protein-induced stabilization), the right-handed double-stranded DNA helix (B-DNA) can form noncanonical structures commonly described as "non-B DNA" structures. These structures comprise, for example, cruciforms, i-motifs, triplexes, and G-quadruplexes. Their formation often leads to significant differences in replication and transcription rates. Noncanonical RNA structures have also been documented to play important roles in translation regulation and the biology of noncoding RNAs. In human and animal studies, the frequency and dynamics of noncanonical DNA and RNA structures are intensively investigated, especially in the field of cancer research and neurodegenerative diseases. In contrast, noncanonical DNA and RNA structures in plants have been on the fringes of interest for a long time and only a few studies deal with their formation, regulation, and physiological importance for plant stress responses. Herein, we present a review focused on the main fields of epigenetics in plants and their possible roles in stress responses and signaling, with special attention dedicated to noncanonical DNA and RNA structures.

milR20 negatively regulates the development of fruit bodies in Pleurotus cornucopiae

The mechanism underlying the development of fruit bodies in edible mushroom is a widely studied topic. In this study, the role of milRNAs in the development of fruit bodies of Pleurotus cornucopiae was studied by comparative analyses of the mRNAs and milRNAs at different stages of development. The genes that play a crucial role in the expression and function of milRNAs were identified and subsequently expressed and silenced at different stages of development. The total number of differentially expressed genes (DEGs) and differentially expressed milRNAs (DEMs) at different stages of development was determined to be 7,934 and 20, respectively. Comparison of the DEGs and DEMs across the different development stages revealed that DEMs and its target DEGs involved in the mitogen-activated protein kinase (MAPK) signaling pathway, protein processing in endoplasmic reticulum, endocytosis, aminoacyl-tRNA biosynthesis, RNA transport, and other metabolism pathways, which may play important roles in the development of the fruit bodies of P. cornucopiae. The function of milR20, which targeted pheromone A receptor g8971 and was involved in the MAPK signaling pathway, was further verified by overexpression and silencing in P. cornucopiae. The results demonstrated that the overexpression of milR20 reduced the growth rate of mycelia and prolonged the development of the fruit bodies, while milR20 silencing had an opposite effect. These findings indicated that milR20 plays a negative role in the development of P. cornucopiae. This study provides novel insights into the molecular mechanism underlying the development of fruit bodies in P. cornucopiae.

Environmental Adaptation of Genetically Uniform Organisms with the Help of Epigenetic Mechanisms-An Insightful Perspective on Ecoepigenetics

Organisms adapt to different environments by selection of the most suitable phenotypes from the standing genetic variation or by phenotypic plasticity, the ability of single genotypes to produce different phenotypes in different environments. Because of near genetic identity, asexually reproducing populations are particularly suitable for the investigation of the potential and molecular underpinning of the latter alternative in depth. Recent analyses on the whole-genome scale of differently adapted clonal animals and plants demonstrated that epigenetic mechanisms such as DNA methylation, histone modifications and non-coding RNAs are among the molecular pathways supporting phenotypic plasticity and that epigenetic variation is used to stably adapt to different environments. Case studies revealed habitat-specific epigenetic fingerprints that were maintained over subsequent years pointing at the existence of epigenetic ecotypes. Environmentally induced epimutations and corresponding gene expression changes provide an ideal means for fast and directional adaptation to changing or new conditions, because they can synchronously alter phenotypes in many population members. Because microorganisms inclusive of human pathogens also exploit epigenetically mediated phenotypic variation for environmental adaptation, this phenomenon is considered a universal biological principle. The production of different phenotypes from the same DNA sequence in response to environmental cues by epigenetic mechanisms also provides a mechanistic explanation for the "general-purpose genotype hypothesis" and the "genetic paradox of invasions".

Transcriptional Regulation of zma-MIR528a by Action of Nitrate and Auxin in Maize

In recent years, miR528, a monocot-specific miRNA, has been assigned multifaceted roles during development and stress response in several plant species. However, the transcription regulation and the molecular mechanisms controlling MIR528 expression in maize are still poorly explored. Here we analyzed the zma-MIR528a promoter region and found conserved transcription factor binding sites related to diverse signaling pathways, including the nitrate (TGA1/4) and auxin (AuxRE) response networks. Accumulation of both pre-miR528a and mature miR528 was up-regulated by exogenous nitrate and auxin treatments during imbibition, germination, and maize seedling establishment. Functional promoter analyses demonstrated that TGA1/4 and AuxRE sites are required for transcriptional induction by both stimuli. Overall, our findings of the nitrogen- and auxin-induced zma-MIR528a expression through cis-regulatory elements in its promoter contribute to the knowledge of miR528 regulome.

Multi-omics revolution to promote plant breeding efficiency

Crop production is the primary goal of agricultural activities, which is always taken into consideration. However, global agricultural systems are coming under increasing pressure from the rising food demand of the rapidly growing world population and changing climate. To address these issues, improving high-yield and climate-resilient related-traits in crop breeding is an effective strategy. In recent years, advances in omics techniques, including genomics, transcriptomics, proteomics, and metabolomics, paved the way for accelerating plant/crop breeding to cope with the changing climate and enhance food production. Optimized omics and phenotypic plasticity platform integration, exploited by evolving machine learning algorithms will aid in the development of biological interpretations for complex crop traits. The precise and progressive assembly of desire alleles using precise genome editing approaches and enhanced breeding strategies would enable future crops to excel in combating the changing climates. Furthermore, plant breeding and genetic engineering ensures an exclusive approach to developing nutrient sufficient and climate-resilient crops, the productivity of which can sustainably and adequately meet the world's food, nutrition, and energy needs. This review provides an overview of how the integration of omics approaches could be exploited to select crop varieties with desired traits.

Plant responses to drought stress: microRNAs in action

Drought is common in most regions of the world, and it has a significant impact on plant growth and development. Plants, on the other hand, have evolved their own defense systems to deal with the extreme weather. The reprogramming of gene expression by microRNAs (miRNAs) is one of these defense mechanisms. miRNAs are short noncoding RNAs that have emerged as key post-transcriptional gene regulators in a variety of species. Drought stress modulates the expression of certain miRNAs that are functionally conserved across plant species. These characteristics imply that miRNA-based genetic changes might improve drought resistance in plants. This study highlights current knowledge of plant miRNA biogenesis, regulatory mechanisms and their role in drought stress responses. miRNAs functions and their adaptations by plants during drought stress has also been explained that can be exploited to promote drought-resistance among economically important crops.

Regulatory non-coding RNAs: Emerging roles during plant cell reprogramming and in vitro regeneration

Plant regeneration is a well-known capacity of plants occurring either in vivo or in vitro. This potential is the basis for plant micropropagation and genetic transformation as well as a useful system to analyse different aspects of plant development. Recent studies have proven that RNA species with no protein-coding capacity are key regulators of cellular function and essential for cell reprogramming. In this review, the current knowledge on the role of several ncRNAs in plant regeneration processes is summarized, with a focus on cell fate reprogramming. Moreover, the involvement/impact of microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and small-interfering RNAs (siRNAs) in the regulatory networks of cell dedifferentiation, proliferation and differentiation is also analysed. A deeper understanding of plant ncRNAs in somatic cell reprogramming will allow a better modulation of in vitro regeneration processes such as organogenesis and somatic embryogenesis.

Cold-inducible promoter-driven knockdown of Brachypodium antifreeze proteins confers freezing and phytopathogen susceptibility

The model forage crop, Brachypodium distachyon, has a cluster of ice recrystallization inhibition (BdIRI) genes, which encode antifreeze proteins that function by adsorbing to ice crystals and inhibiting their growth. The genes were targeted for knockdown using a cold-induced promoter from rice (prOsMYB1R35) to drive miRNA. The transgenic lines showed no apparent pleiotropic developmental defects but had reduced antifreeze activity as assessed by assays for ice-recrystallization inhibition, thermal hysteresis, electrolyte leakage, and leaf infrared thermography. Strikingly, the number of cold-acclimated transgenic plants that survived freezing at -8°C was reduced by half or killed entirely, depending on the line, compared with cold-acclimated wild type plants. In addition, more leaf damage was apparent at subzero temperatures in knockdowns after infection with an ice nucleating pathogen, Pseudomonas syringae. Although antifreeze proteins have been studied for almost 60 years, this is the first unequivocal demonstration of their function by knockdown in any organism, and their dual contribution to freeze protection as well as pathogen susceptibility, independent of obvious developmental defects. These proteins are thus of potential interest in a wide range of biotechnological applications from cryopreservation, to frozen product additives, to the engineering of transgenic crops with enhanced pathogen and freezing tolerance.

Maize Flavonoid Biosynthesis, Regulation, and Human Health Relevance: A Review

Maize is one of the most important crops for human and animal consumption and contains a chemical arsenal essential for survival: flavonoids. Moreover, flavonoids are well known for their beneficial effects on human health. In this review, we decided to organize the information about maize flavonoids into three sections. In the first section, we include updated information about the enzymatic pathway of maize flavonoids. We describe a total of twenty-one genes for the flavonoid pathway of maize. The first three genes participate in the general phenylpropanoid pathway. Four genes are common biosynthetic early genes for flavonoids, and fourteen are specific genes for the flavonoid subgroups, the anthocyanins, and flavone C-glycosides. The second section explains the tissue accumulation and regulation of flavonoids by environmental factors affecting the expression of the MYB-bHLH-WD40 (MBW) transcriptional complex. The study of transcription factors of the MBW complex is fundamental for understanding how the flavonoid profiles generate a palette of colors in the plant tissues. Finally, we also include an update of the biological activities of C3G, the major maize anthocyanin, including anticancer, antidiabetic, and antioxidant effects, among others. This review intends to disclose and integrate the existing knowledge regarding maize flavonoid pigmentation and its relevance in the human health sector.

Effects of Combined Abiotic Stresses Related to Climate Change on Root Growth in Crops

Climate change is a major threat to crop productivity that negatively affects food security worldwide. Increase in global temperatures are usually accompanied by drought, flooding and changes in soil nutrients composition that dramatically reduced crop yields. Against the backdrop of climate change, human population increase and subsequent rise in food demand, finding new solutions for crop adaptation to environmental stresses is essential. The effects of single abiotic stress on crops have been widely studied, but in the field abiotic stresses tend to occur in combination rather than individually. Physiological, metabolic and molecular responses of crops to combined abiotic stresses seem to be significantly different to individual stresses. Although in recent years an increasing number of studies have addressed the effects of abiotic stress combinations, the information related to the root system response is still scarce. Roots are the underground organs that directly contact with the soil and sense many of these abiotic stresses. Understanding the effects of abiotic stress combinations in the root system would help to find new breeding tools to develop more resilient crops. This review will summarize the current knowledge regarding the effects of combined abiotic stress in the root system in crops. First, we will provide a general overview of root responses to particular abiotic stresses. Then, we will describe how these root responses are integrated when crops are challenged to the combination of different abiotic stress. We will focus on the main changes on root system architecture (RSA) and physiology influencing crop productivity and yield and convey the latest information on the key molecular, hormonal and genetic regulatory pathways underlying root responses to these combinatorial stresses. Finally, we will discuss possible directions for future research and the main challenges needed to be tackled to translate this knowledge into useful tools to enhance crop tolerance.

The Intersection of Non-Coding RNAs Contributes to Forest Trees' Response to Abiotic Stress

Non-coding RNAs (ncRNAs) play essential roles in plants by modulating the expression of genes at the transcriptional or post-transcriptional level. In recent years, ncRNAs have been recognized as crucial regulators for growth and development in forest trees, and ncRNAs that respond to various abiotic stresses are now under intense study. In this review, we summarized recent advances in the understanding of abiotic stress-responsive microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) in forest trees. Furthermore, we analyzed the intersection of miRNAs, and epigenetic modified ncRNAs of forest trees in response to abiotic stress. In particular, the abiotic stress-related lncRNA/circRNA-miRNA-mRNA regulatory network of forest trees was explored.

Integrated Analysis of Coding and Non-coding RNAs Reveals the Molecular Mechanism Underlying Salt Stress Response in Medicago truncatula

Salt stress is among the most severe abiotic stresses in plants worldwide. Medicago truncatula is a model plant for legumes and analysis of its response to salt stress is helpful for providing valuable insights into breeding. However, few studies have focused on illustrating the whole-transcriptome molecular mechanism underlying salt stress response in Medicago truncatula. Herein, we sampled the leaves of Medicago truncatula treated with water or NaCl and analyzed the characteristics of its coding and non-coding RNAs. We identified a total of 4,693 differentially expressed mRNAs (DEmRNAs), 505 DElncRNAs, 21 DEcircRNAs, and 55 DEmiRNAs. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses revealed that their functions were mostly associated with metabolic processes. We classified the lncRNAs and circRNAs into different types and analyzed their genomic distributions. Furthermore, we predicted the interactions between different RNAs based on the competing endogenous RNA (ceRNA) theory and identified multiple correlation networks, including 27 DEmiRNAs, 43 DEmRNAs, 19 lncRNAs, and 5 DEcircRNAs. In addition, we comprehensively analyzed the candidate DEmRNAs and ceRNAs and found that they were involved in Ca⁺ signaling, starch and sucrose biosynthesis, phenylpropanoid and lignin metabolism, auxin and jasmonate biosynthesis, and transduction pathways. Our integrated analyses in salt stress response in Medicago truncatula revealed multiple differentially expressed coding and non-coding RNAs, including mRNAs, lncRNAs, circRNAs, and miRNAs, and identified multiple DEmRNA and ceRNA interaction pairs that function in many pathways, providing insights into salt stress response in leguminous plants.

The Characters of Non-Coding RNAs and Their Biological Roles in Plant Development and Abiotic Stress Response

Plant growth and development are greatly affected by the environment. Many genes have been identified to be involved in regulating plant development and adaption of abiotic stress. Apart from protein-coding genes, more and more evidence indicates that non-coding RNAs (ncRNAs), including small RNAs and long ncRNAs (lncRNAs), can target plant developmental and stress-responsive mRNAs, regulatory genes, DNA regulatory regions, and proteins to regulate the transcription of various genes at the transcriptional, posttranscriptional, and epigenetic level. Currently, the molecular regulatory mechanisms of sRNAs and lncRNAs controlling plant development and abiotic response are being deeply explored. In this review, we summarize the recent research progress of small RNAs and lncRNAs in plants, focusing on the signal factors, expression characters, targets functions, and interplay network of ncRNAs and their targets in plant development and abiotic stress responses. The complex molecular regulatory pathways among small RNAs, lncRNAs, and targets in plants are also discussed. Understanding molecular mechanisms and functional implications of ncRNAs in various abiotic stress responses and development will benefit us in regard to the use of ncRNAs as potential character-determining factors in molecular plant breeding.

Biogenesis, Functions, Interactions, and Resources of Non-Coding RNAs in Plants

Plant transcriptomes encompass a large number of functional non-coding RNAs (ncRNAs), only some of which have protein-coding capacity. Since their initial discovery, ncRNAs have been classified into two broad categories based on their biogenesis and mechanisms of action, housekeeping ncRNAs and regulatory ncRNAs. With advances in RNA sequencing technology and computational methods, bioinformatics resources continue to emerge and update rapidly, including workflow for in silico ncRNA analysis, up-to-date platforms, databases, and tools dedicated to ncRNA identification and functional annotation. In this review, we aim to describe the biogenesis, biological functions, and interactions with DNA, RNA, protein, and microorganism of five major regulatory ncRNAs (miRNA, siRNA, tsRNA, circRNA, lncRNA) in plants. Then, we systematically summarize tools for analysis and prediction of plant ncRNAs, as well as databases. Furthermore, we discuss the silico analysis process of these ncRNAs and present a protocol for step-by-step computational analysis of ncRNAs. In general, this review will help researchers better understand the world of ncRNAs at multiple levels.

Significance of miRNA in enhancement of flavonoid biosynthesis

Flavonoid metabolism shows very strong plasticity in plant development and coping with the changing environment. Flavonoid biosynthesis is regulated by many metabolic pathways, including transcriptional regulation, post-transcriptional control, post-translational regulationand epigenetic regulation. miRNA is a form of endogenous noncoding single-strand small molecule RNA that primarily regulates the expression of target genes horizontally after transcription through splicing and translational suppression. It also plays an important role in regulating plant growth and development, secondary metabolism and biotic and abiotic stress. miRNA can regulate the formation of flavonoids by acting on structural genes or indirectly by using an MBW transcription complex comprising MYB-bHLH-WD40. This study summarizes the biosynthesis and mechanisms of miRNA, and provides a summary of the mechanisms of miRNAs involved in production of flavonoids, in order to elucidate the biosynthesis pathway and complex regulatory network of plant flavonoids. We aim to provide new insights into improving the content of flavonoid active ingredients in plants.

Global identification of full-length cassava lncRNAs unveils the role of cold-responsive intergenic lncRNA 1 in cold stress response

Long noncoding RNAs (lncRNAs) have been considered to be important regulators of gene expression in a range of biological processes in plants. A large number of lncRNAs have been identified in plants. However, most of their biological functions still remain to be determined. Here, we identified a total of 3004 lncRNAs in cassava under normal or cold-treated conditions from Iso-seq data. We further characterized a cold-responsive intergenic lncRNA 1 (CRIR1) as a novel positive regulator of the plant response to cold stress. CRIR1 can be significantly induced by cold treatment. Ectopic expression of CRIR1 in cassava enhanced the cold tolerance of transgenic plants. Transcriptome analysis demonstrated that CRIR1 regulated a range of cold stress-related genes in a CBF-independent pathway. We further found that CRIR1 RNA can interact with cassava cold shock protein 5 (MeCSP5), which acts as an RNA chaperone, indicating that CRIR1 may recruit MeCSP5 to improve the translation efficiency of messenger RNA. In summary, our study extends the repertoire of lncRNAs in plants as well as their role in cold stress responses. Moreover, it reveals a mechanism by which CRIR1 affected cold stress response by modulating the expression of stress-responsive genes and increasing their translational yield.

Influence of virus-host interactions on plant response to abiotic stress

Environmental factors play a significant role in controlling growth, development and defense responses of plants. Changes in the abiotic environment not only significantly alter the physiological and molecular pathways in plants, but also result in attracting the insect pests that carry a payload of viruses. Invasion of plants by viruses triggers the RNA silencing based defense mechanism in plants. In counter defense the viruses have gained the ability to suppress the host RNA silencing activities. A new paradigm has emerged, with the recognition that plant viruses also have the intrinsic capacity to modulate host plant response to environmental cues, in an attempt to favour their own survival. Thus, plant-virus interactions provide an excellent system to understand the signals in crosstalk between biotic (virus) and abiotic stresses. In this review, we have summarized the basal plant defense responses to pathogen invasion while emphasizing on the role of RNA silencing as a front line of defense response to virus infection. The emerging knowledge indicates overlap between RNA silencing with the innate immune responses during antiviral defense. The suppressors of RNA silencing serve as Avr proteins, which can be recognized by the host R proteins. The defense signals also function in concert with the phytohormones to influence plant responses to abiotic stresses. The current evidence on the role of virus induced host tolerance to abiotic stresses is also discussed.

The Dynamism of Transposon Methylation for Plant Development and Stress Adaptation

Plant development processes are regulated by epigenetic alterations that shape nuclear structure, gene expression, and phenotypic plasticity; these alterations can provide the plant with protection from environmental stresses. During plant growth and development, these processes play a significant role in regulating gene expression to remodel chromatin structure. These epigenetic alterations are mainly regulated by transposable elements (TEs) whose abundance in plant genomes results in their interaction with genomes. Thus, TEs are the main source of epigenetic changes and form a substantial part of the plant genome. Furthermore, TEs can be activated under stress conditions, and activated elements cause mutagenic effects and substantial genetic variability. This introduces novel gene functions and structural variation in the insertion sites and primarily contributes to epigenetic modifications. Altogether, these modifications indirectly or directly provide the ability to withstand environmental stresses. In recent years, many studies have shown that TE methylation plays a major role in the evolution of the plant genome through epigenetic process that regulate gene imprinting, thereby upholding genome stability. The induced genetic rearrangements and insertions of mobile genetic elements in regions of active euchromatin contribute to genome alteration, leading to genomic stress. These TE-mediated epigenetic modifications lead to phenotypic diversity, genetic variation, and environmental stress tolerance. Thus, TE methylation is essential for plant evolution and stress adaptation, and TEs hold a relevant military position in the plant genome. High-throughput techniques have greatly advanced the understanding of TE-mediated gene expression and its associations with genome methylation and suggest that controlled mobilization of TEs could be used for crop breeding. However, development application in this area has been limited, and an integrated view of TE function and subsequent processes is lacking. In this review, we explore the enormous diversity and likely functions of the TE repertoire in adaptive evolution and discuss some recent examples of how TEs impact gene expression in plant development and stress adaptation.

Circular RNAs Repertoire and Expression Profile during Brassica rapa Pollen Development

Circular RNAs (circRNAs) are covalently closed RNA molecules generated by the back-splicing of exons from linear precursor mRNAs. Though various linear RNAs have been shown to play important regulatory roles in many biological and developmental processes, little is known about the role of their circular counterparts. In this study, we performed high-throughput RNA sequencing to delineate the expression profile and potential function of circRNAs during the five stages of pollen development in Brassica rapa. A total of 1180 circRNAs were detected in pollen development, of which 367 showed stage-specific expression patterns. Functional enrichment and metabolic pathway analysis showed that the parent genes of circRNAs were mainly involved in pollen-related molecular and biological processes such as mitotic and meiotic cell division, DNA processes, protein synthesis, protein modification, and polysaccharide biosynthesis. Moreover, by predicting the circRNA–miRNA network from our differentially expressed circRNAs, we found 88 circRNAs with potential miRNA binding sites, suggesting their role in post-transcriptional regulation of the genes. Finally, we confirmed the back-splicing sites of nine selected circRNAs using divergent primers and Sanger sequencing. Our study presents the systematic analysis of circular RNAs during pollen development and forms the basis of future studies for unlocking complex gene regulatory networks underpinning reproduction in flowering plants.

Pan-Genome miRNomics in Brachypodium

Pan-genomes are efficient tools for the identification of conserved and varying genomic sequences within lineages of a species. Investigating genetic variations might lead to the discovery of genes present in a subset of lineages, which might contribute into beneficial agronomic traits such as stress resistance or yield. The content of varying genomic regions in the pan-genome could include protein-coding genes as well as microRNA(miRNAs), small non-coding RNAs playing key roles in the regulation of gene expression. In this study, we performed in silico miRNA identification from the genomic sequences of 54 lineages of Brachypodium distachyon, aiming to explore varying miRNA contents and their functional interactions. A total of 115 miRNA families were identified in 54 lineages, 56 of which were found to be present in all lineages. The miRNA families were classified based on their conservation among lineages and potential mRNA targets were identified. Obtaining information about regulatory mechanisms stemming from these miRNAs offers strong potential to provide a better insight into the complex traits that were potentially present in some lineages. Future work could lead us to introduce these traits to different lineages or other economically important plant species in order to promote their survival in different environmental conditions.