Biology subjects

Crespi, M.

Publications and source records attributed to Crespi, M..

At least 19 recordsLinked to original sources

bioRxiv2026

The root knot nematode effector MiEFF186 interacts with a splicing factor to reshape plant transcriptome

The root-knot nematode Meloidogyne incognita secretes specific effectors to manipulate root cells and induce their redifferentiation into multinucleate feeding giant cells, which are essential for its development. A dedicated screen identified the M. incognita MiEFF186a effector as a regulator of alternative splicing, a crucial mechanism of transcriptional gene regulation whereby a single gene can produce multiple mature mRNA variants, in plants. EFF186 is expressed in the esophageal glands of nematode juveniles, and in planta, it localizes to the nucleus and accumulates in the nucleolus. A yeast two-hybrid approach identified the nucleolar G-patch protein GDP1/CIS2 as a MiEFF186a target in tomato and Arabidopsis. Transcriptomic analyses of Arabidopsis roots ectopically expressing MiEFF186a or impaired in GDP1/CIS2 function revealed changes in both gene expression and alternative splicing, with partially overlapping responses. Finally, alteration of GDP1/CIS2 expression by virus-induced gene silencing in Solanaceae or in Arabidopsis gdp1 mutants affects susceptibility to M. incognita. Together, these results identify GDP1/CIS2 as a host target of MiEFF186a and support a role for these proteins in the modulation of host RNA metabolism during nematode parasitism.

plant biology↗

bioRxiv2026

Bioinf-Farma: supervised integration of epitope prediction and recombinant protein developability for automated vaccine candidate prioritization

Vaccine antigen discovery requires prioritizing protein candidates according to both immunogenic potential and recombinant expression feasibility. These properties are typically evaluated using separate computational tools, requiring researchers to integrate heterogeneous outputs through ad hoc workflows. Here, we present BIOINF-farma, a modular platform integrating epitope prediction and developability assessment for rational antigen selection within a unified environment. Candidates can be submitted as amino acid sequences or three-dimensional structures. When experimental structures are unavailable, BIOINF-farma automatically searches for models in AlphaFold DB or performs structure prediction using Boltz-2, ensuring a standardized structural representation for downstream analyses. Antigenicity is quantified by combining structure-based conformational epitope signals (MLCE/REBELOT-BEPPE) and sequence-based linear epitope propensity scores (BepiPred 3.0) into a protein-level Antigenicity Score, with a classification threshold optimized on a manually curated validation dataset. Developability is evaluated through two supervised Random Forest meta-learners that integrate three solubility predictors (DeepSoluE, SoluProt, Protein-Sol) and three thermal stability predictors (TemStaPro, ProLaTherm, BertThermo), whose outputs are combined into an Expression Efficiency Score (EES). By integrating complementary predictive signals, the meta-learning framework achieves greater accuracy and robustness than individual predictors while maintaining performance across a broad range of sequence identities. The Antigenicity Score effectively discriminates antigenic from non-antigenic proteins with a large effect size, whereas EES successfully distinguishes soluble from insoluble outcomes on an independent panel of recombinant proteins expressed in Escherichia coli. BIOINF-farma jointly assesses antigenicity and expression feasibility within a single framework. Its modular architecture facilitates the incorporation of future predictive methods, while its web-based interface makes the full pipeline accessible to users without programming expertise, supporting rapid candidate triage in vaccine research and emerging pathogen responses. Author SummaryVaccine development begins with a critical step: identifying, among the many proteins encoded in a pathogen genome, those most suitable as candidate antigens. A promising candidate must satisfy two requirements that are rarely evaluated together. It must be recognized by the immune system, so that vaccination elicits a protective response; and it must be amenable to recombinant production, since antigens that cannot be obtained in sufficient quantity and quality are of limited practical use. Current computational tools typically address only one of these aspects, and researchers must integrate their outputs manually, through procedures that are time-consuming and prone to inconsistency. We developed BIOINF-farma, an automated platform that brings these two assessments into a single analytical framework. Starting from a protein sequence or an experimental structure, the platform retrieves or predicts a three-dimensional model, evaluates the proteins antigenic potential by combining complementary epitope predictors, and estimates its expression feasibility by integrating multiple solubility and stability predictors through supervised machine learning. A web-based interface makes the full workflow available to experimental immunologists and vaccine developers without requiring computational expertise, supporting rational candidate prioritization in routine vaccine research and during emerging pathogen responses.

bioinformatics↗

bioRxiv2026

ALTERNATIVE SPLICING OF A CODING GENE PRODUCES A NUCLEAR REGULATORY LONG NON-CODING RNA

Alternative splicing (AS) is traditionally understood to increase transcript and protein diversity by generating multiple coding isoforms from a single gene. In addition, many alternative isoforms are degraded through non-sense mediated decay (NMD). Furthermore, we show here that AS also produces nuclear long non-coding RNAs (lncRNAs) from protein-coding genes, which can serve regulatory functions rather than expanding proteomic complexity. Focusing on the Arabidopsis thaliana SR protein gene At-RS31, we found that a non-coding isoform (mRNA3) accumulates in the nucleus under dark conditions. This transcript binds the protein product of its own transcriptional unit, modulating splicing decisions and balancing gene activity in response to environmental cues. Overexpression of mRNA3 down-regulates the action of At-RS31 on its target genes in trans and restores the phenotype induced by intron-less At-RS31 accumulation. Further sub-cellular fractionation and RT-PCR analyses show that many SR genes generate nuclear-retained non-coding isoforms, especially under dark conditions, suggesting a widespread mechanism. These findings redefine the role of AS in plants, highlighting its capacity to generate regulatory lncRNAs to fine-tune gene expression beyond protein diversification. Highlights- Alternative splicing generates regulatory lncRNAs from protein-coding genes - A nuclear-retained isoform forms an autoregulatory RNA-protein feedback loop - Non-coding isoforms of SR genes accumulate in the nucleus under dark conditions - Co-expression of the non-coding isoform rescues splicing factor overexpression phenotypes

molecular biology↗

bioRxiv2026

The long non-coding RNA ACHLYS modulates biomolecular condensates to regulate alternative splicing in root development

Alternative splicing (AS) enables eukaryotes to dynamically adjust RNA and protein isoforms encoded in one gene. Long non-coding RNAs (lncRNA) have emerged as novel regulators of AS through multiple modes of action, including interactions with splicing factor (SF) proteins. Here, we used Arabidopsis thaliana lateral root development to dissect the specificity of lncRNAs in AS regulation. Data mining and a transient expression screen allowed us to identify novel lncRNAs interacting in vivo with the well-characterized SFs Nuclear speckle RNA binding protein A (NSRa) and glycine-rich RNA-binding protein 7 (GRP7), that are differentially expressed during lateral root organogenesis. We identified 4 lncRNAs affecting more than 250 AS events in plant cells, whereby most AS events are unique for each lncRNA. Notably, 19% of the AS events linked to two NSRa-recognized lncRNAs are identical and positively correlated. One lncRNA was named ACHLYS and is highly conserved in several Brassicaceae whereas another was the recently characterized FLAIL lncRNA. ACHLYS knockdown (KD-ACHLYS) and overexpressing lines (OE-ACHLYS) modulate AS regulation in plants and affect root architecture. In parallel, we performed NSRa-iCLIP to determine in vivo genome-wide NSRa binding sites. Interestingly, NSRa binding sites are locally enriched in ACHLYS-dependent AS introns and ACHLYS itself. A specific ACHLYS-induced AS event requires NSRa function showing that ACHLYS defines AS targets through NSRa interaction on specific transcripts. In vitro assays indicate that direct interaction of NSRa with ACHLYS promotes NSRa phase separation. Furthermore, overexpression of ACHLYS in NSRa-GFP plants results in increased accumulation of NSRa in Nuclear speckles. Our data revealed that ACHLYS can modulate NSRa condensates in vivo and binds to NSRa for modifying AS patterns, suggesting a new mechanism where lncRNAs can fine tune SFs regulation and the transcriptome output in eukaryotic organogenesis.

molecular biology↗

bioRxiv2025

The subunit 3 of the SUPERKILLER (SKI) complex mediates miR172-directed cleavage of Nodule Number Control 1 (NNC1) to modulate nodulation in Medicago truncatula

Legumes and rhizobia establish a nitrogen-fixing symbiosis that involves the formation of a lateral root organ, the nodule, and the infection process that allows intracellular accommodation of rhizobia within nodule cells. This process involves significant gene expression changes regulated at the transcriptional and post-transcriptional levels. We have previously shown that a transcript encoding the subunit 3 of the Superkiller Complex (SKI), which guides mRNAs to the exosome for 3'-to-5' degradation, is required for nodule formation and bacterial persistence within the nodule, as well as the induction of early nodulation genes (e.g., MtENOD40) during the Medicago truncatula-Sinorhizobium meliloti symbiosis. Here, we reveal through transcript degradome and small RNA sequencing analysis that knockdown of MtSKI3 impairs the miR172-directed endonucleolytic cleavage of the mRNA encoding Nodule Number Control 1 (MtNNC1), an APETALA2 transcription factor that negatively modulates nodulation. Knockdown of MtNNC1 enhances nodule number, bacterial infection, and the induction of MtENOD40 upon inoculation with S. meliloti whereas overexpression of a miR172-resistant form of MtNNC1 significantly reduces nodule formation. This work identifies miR172 cleavage of MtNNC1 and its control by MtSKI3, a component of the 3'-to-5'mRNA degradation pathway, as a new regulatory hub controlling indeterminate nodulation.

plant biology↗

bioRxiv2024

The Arabidopsis RNA-binding protein SGS3 is recruited to the chromatin remodeler CHR11 to promote siRNA production from protein-coding genes

In plants, aberrant RNAs produced by endogenous genes or transgenes are normally degraded by the nuclear and cytosolic RNA quality control (RQC) pathways. Under certain biotic or abiotic stresses, RQC is impaired, and aberrant RNAs are converted into siRNAs that initiate post-transcriptional gene silencing (PTGS) in the cytosol. How aberrant RNAs are selected and brought to the cytoplasm is not known. Here we show that the RNA-binding protein SUPPRESSOR OF GENE SILENCING (SGS)3 shuttles between the cytosol and the nucleus where it associates with the ISWI-like CHROMATIN REMODELER (CHR)11. CHR11 binds to transgenes prone to trigger PTGS. Knocking down CHR11 and its paralog CHR17 strongly reduces transgene PTGS, suggesting that SGS3 recruitment by CHR11/17 facilitates PTGS initiation. CHR11 is also enriched at endogenous protein-coding genes (PCGs) producing nat-siRNAs and va-siRNAs under biotic or abiotic stresses, and this production is reduced in chr11 chr17 double mutants at genome-wide level. Moreover, impairing CHR11 and CHR17 rescues the lethal phenotype caused by the massive production of siRNAs from PCGs in RQC-deficient mutants. We propose that SGS3 recruitment by CHR11/17 allows exporting RNAs to the cytosol to initiate the production of siRNAs. One Sentence SummaryThe plant PTGS component SGS3 is recruited by the chromatin remodeler CHR11 to select nuclear RNAs for export to the cytosol and siRNA production.

cell biology↗

bioRxiv2024

A plant-specific clade of serine/arginine-rich proteins regulates RNA splicing homeostasis and thermotolerance in tomato

High temperatures cause heat stress (HS), which has negative effects on plant growth and development and affects many cellular processes including pre-mRNA splicing. In tomato plants the splicing profile of many of genes is altered under HS, including that of HSFA2, a central transcriptional regulator of thermotolerance. To identify the core splicing regulators of HS-sensitive alternative splicing, we used HSFA2 as bait and identified two plant-specific members of the serine/arginine-rich family of splicing factors, namely RS2Z35 and RS2Z36, that inhibit HSFA2 intron splicing. Single and double CRISPR mutants of these proteins show dysregulated splicing of many genes and exhibit lower basal and acquired thermotolerance. Individual-nucleotide resolution UV cross-linking and immunoprecipitation (iCLIP) of tomato leaves revealed that the majority of HS-sensitive alternatively spliced RNAs are bound by RS2Z35 and RS2Z36 and this interaction occurs at purine-rich RNA motifs. Phenotypic and transcriptome analyses revealed that RS2Z35 and RS2Z36 are important players in the stress response and thermotolerance in plants that mitigate the negative effects of HS on RNA splicing homeostasis.

plant biology↗

bioRxiv2023

The transcription factor NF-YA10 determines the area explored by Arabidopsis thaliana roots through direct regulation of LAZY and TAC genes

Root developmental plasticity relies on transcriptional reprogramming, which largely depends on the activity of transcription factors (TFs). NF-YA2 and NF-YA10 (Nuclear Factor A2 and A10) are down-regulated by the specific miRNA isoform miR169defg, in contrast to miR169a. Here, we analyzed the role of the Arabidopsis thaliana TF NF-YA10 in the regulation of lateral root development. Plants expressing a version of NF-YA10 resistant to miR169 cleavage showed a perturbation in the lateral root gravitropic response. By extracting novel features of root architecture using the ChronoRoot deep-learning-based phenotyping system, we uncovered a differential emergence angle of lateral roots over time when compared to Col-0. Detailed phenotyping of root growth dynamics revealed that NF-YA10 activity modulates the area explored by Arabidopsis roots. Furthermore, we found that NF-YA10 directly regulates TAC1 and LAZY genes by targeting their promoter regions, genes previously linked to gravitropism. Hence, the TF NF-YA10 is a new element in the control of LR gravitropism and root system architecture.

plant biology↗

bioRxiv2023

Long noncoding RNA-mediated epigenetic regulation of auxin-related genes controlling shade avoidance syndrome in Arabidopsis thaliana

The long noncoding RNA (lncRNA) AUXIN-REGULATED PROMOTER LOOP (APOLO) recognizes a subset of target loci across the Arabidopsis thaliana genome by forming RNA-DNA hybrids (R-loop) and modulating local three-dimensional chromatin conformation. Here we show that APOLO is involved in regulating the shade avoidance syndrome (SAS) by dynamically modulating the expression of key factors. In response to far-red (FR) light, the expression of APOLO anticorrelates with its target BRANCHED1 (BRC1), a master regulator of shoot branching in Arabidopsis thaliana. APOLO deregulation results in BRC1 transcriptional repression and an increase in the number of branches. APOLO transcriptional accumulation fine-tunes the formation of a repressive chromatin loop encompassing the BRC1 promoter, which normally occurs only in leaves as well as in a late response to FR treatment in axillary buds. In addition, our data reveal that APOLO participates in leaf hyponasty, in agreement with its previously reported role in the control of auxin homeostasis through direct modulation of YUCCA2 (auxin synthesis), PID and WAG2 (auxin efflux). We found that direct application of APOLO RNA to leaves results in a rapid increase in auxin accumulation that is associated with changes in the response of the plants to FR light. Collectively, our data support the view that lncRNAs coordinate the shade avoidance syndrome in Arabidopsis thaliana and shed light on the potential of lncRNAs as bioactive exogenous molecules. Deploying exogenous RNAs that modulate plant-environment interactions are important new tools for sustainable agriculture.

plant biology↗

bioRxiv2022

Regulatory and evolutionary annotation identifies KAN1, MYB44 and PIF4 as regulators of Arabidopsis lincRNAs expressed in root

Thousands of long intergenic noncoding RNAs (lincRNAs) have been identified in plant genomes. While some lincRNAs have been characterized as important regulators in different biological processes, little is known about the transcriptional regulation for most plant lincRNAs. Through the integration of eight annotation resources, we defined 6,599 high-confidence lincRNA loci in Arabidopsis thaliana. For lincRNAs belonging to different evolutionary age categories, we identified major differences in sequence and chromatin features, as well as in the level of conservation and purifying selection acting during evolution. Spatiotemporal gene expression profiles combined with transcription factor (TF) chromatin immunoprecipitation data were used to construct a TF- lincRNA regulatory network containing 2,659 lincRNAs and 15,686 interactions. We found that properties characterizing lincRNA expression, conservation and regulation differ between plants and animals. Experimental validation confirmed the role of three TFs, KAN1, MYB44, and PIF4, as key regulators controlling root- specific lincRNA expression, demonstrating the predictive power of our network. Furthermore, we identified 58 lincRNAs, regulated by these TFs, showing strong root cell-type specific expression or chromatin accessibility, which are linked with GWAS genetic associations related to root system development and growth. The multi-level genome-wide characterization covering chromatin state information, promoter conservation, and ChIP-based TF binding, for all detectable lincRNAs across 769 expression samples, permits to rapidly define the biological context and relevance of lincRNAs in Arabidopsis regulatory networks. One-line sentenceA multi-level Arabidopsis gene regulatory network identifies novel regulators controlling root-specific lincRNA expression, offering a promising strategy to identify lincRNAs involved in plant biology.

plant biology↗

bioRxiv2022

Synergistic action of the Arabidopsis spliceosome components PRP39a and SmD1 in promoting post-transcriptional transgene silencing

Besides regulating splicing, the conserved spliceosome component SmD1 was shown to promote posttranscriptional silencing of sense transgenes (S-PTGS). Here, we show that the conserved spliceosome component PRP39a also plays a role in S-PTGS. However, PRP39a and SmD1 actions appear distinct in both splicing and S-PTGS. Indeed, RNA-seq analysis of prp39a and smd1 mutants identified different sets of deregulated mRNAs and non-coding RNAs, both at expression level and alternative splicing genome-wide. Moreover, double mutant analyses involving prp39a or smd1 and RNA quality control (RQC) mutants revealed genetic interactions of SmD1 and PRP39a with distinct nuclear RQC machineries, suggesting synergistic rather than redundant roles in the RQC/PTGS interplay. Supporting this hypothesis, a prp39a smd1 double mutant exhibited enhanced suppression of S-PTGS compared with single mutants. Because no major changes in the expression of PTGS or RQC components or in small RNA production were identified in prp39a and smd1 mutants, and because prp39a and smd1 mutations do not alter PTGS triggered by inverted-repeat transgenes directly producing dsRNA (IR-PTGS), PRP39a and SmD1 seem to synergistically promote a step specific to S-PTGS. We propose that, independent of their specific roles in splicing, PRP39a and SmD1 limit 3-to-5 and 5-to-3 degradation of transgene aberrant RNAs, respectively, thus favoring the export of aberrant RNAs to the cytoplasm where their transformation into dsRNA initiates S-PTGS.

plant biology↗

bioRxiv2021

A high resolution single molecule sequencing-based Arabidopsis transcriptome using novel methods of Iso-seq analysis

BackgroundAccurate and comprehensive annotation of transcript sequences is essential for transcript quantification and differential gene and transcript expression analysis. Single molecule long read sequencing technologies provide improved integrity of transcript structures including alternative splicing, and transcription start and polyadenylation sites. However, accuracy is significantly affected by sequencing errors, mRNA degradation or incomplete cDNA synthesis. ResultsWe present a new and comprehensive Arabidopsis thaliana Reference Transcript Dataset 3 (AtRTD3). AtRTD3 contains over 160k transcripts - twice that of the best current Arabidopsis transcriptome and including over 1,500 novel genes. 79% of transcripts are from Iso-seq with accurately defined splice junctions and transcription start and end sites. We developed novel methods to determine splice junctions and transcription start and end sites accurately. Mis- match profiles around splice junctions provided a powerful feature to distinguish correct splice junctions and remove false splice junctions. Stratified approaches identified high confidence transcription start/end sites and removed fragmentary transcripts due to degradation. AtRTD3 is a major improvement over existing transcriptomes as demonstrated by analysis of an Arabidopsis cold response RNA-seq time-series. AtRTD3 provided higher resolution of transcript expression profiling and identified cold- and light-induced differential transcription start and polyadenylation site usage. ConclusionsAtRTD3 is the most comprehensive Arabidopsis transcriptome currently available. It improves the precision of differential gene and transcript expression, differential alternative splicing, and transcription start/end site usage from RNA-seq data. The novel methods for identifying accurate splice junctions and transcription start/end sites are widely applicable and will improve single molecule sequencing analysis from any species.

plant biology↗

bioRxiv2021

Sequence-unrelated long noncoding RNAs converged to modulate the activity of conserved epigenetic machineries across kingdoms

RNA-DNA hybrid (R-loop)-associated long noncoding RNAs (lncRNAs), including the Arabidopsis lncRNA AUXIN-REGULATED PROMOTER LOOP (APOLO), are emerging as important regulators of three-dimensional chromatin conformation and gene transcriptional activity. Here, we showed that in addition to the PRC1-component LIKE-HETEROCHROMATIN PROTEIN 1 (LHP1), APOLO interacts with the methylcytosine-binding protein VARIANT IN METHYLATION 1 (VIM1), a conserved homolog of the mammalian DNA methylation regulator UBIQUITIN-LIKE CONTAINING PHD AND RING FINGER DOMAINS 1 (UHRF1). The APOLO-VIM1-LHP1 complex directly regulates the transcription of the auxin biosynthesis gene YUCCA2 by dynamically determining DNA methylation and H3K27me3 deposition over its promoter during the plant thermomorphogenic response. Strikingly, we demonstrated that the lncRNA UHRF1 Protein Associated Transcript (UPAT), a direct interactor of UHRF1 in humans, can be recognized by VIM1 and LHP1 in plant cells, despite the lack of sequence homology between UPAT and APOLO. In addition, we showed that increased levels of APOLO or UPAT hamper VIM1 and LHP1 binding to YUCCA2 promoter. Collectively, our results uncover a new mechanism in which a plant lncRNA coordinates Polycomb action and DNA methylation, and reveal that evolutionary unrelated lncRNAs may exert similar functions across kingdoms.

plant biology↗

bioRxiv2021

A conserved HSF:miR169:NF-YA loop involved in tomato and Arabidopsis heat stress tolerance

Regulatory feedbacks are at the basis of different stress and developmental networks in plants. Here, we report that tomato and Arabidopsis plants improve their heat stress tolerance through Heat stress transcription factor (HSF)-mediated transcriptional regulation of MIR169 and post-transcriptional regulation of NF-YA transcription factors. We show that HSFs recognize tomato and Arabidopsis MIR169 promoters using yeast-one-hybrid/ChIP-qPCR. Silencing tomato HSFs using virus-induced-gene-silencing (VIGS) reduce Sly-MIR169 levels and enhance Sly-NF-YA9/A10 target expression. Further, tomato transgenic plants overexpressing Sly-MIR169 and Sly-NF-YA9/A10-VIGS knock-down tomato plants as well as Arabidopsis plants overexpressing At-MIR169d and At-nf-ya2 mutants showed a link with increased heat tolerance. In contrast, Arabidopsis plants overexpressing At-NF-YA2, or those expressing a non-cleavable At-NF-YA2 form (miR169-resistant At-NF-YA2) as well as plants inhibited for At-miRNA169d regulation (miR169d mimic plants) were more sensitive to heat stress, highlighting NF-YA as negative regulator of heat tolerance. Furthermore, post-transcriptional cleavage of NF-YA by elevated miR169 levels result in alleviating the repression of heat stress effectors HSFA7a/b in tomato and Arabidopsis revealing a retroactive control of HSFs by the miR169:NF-YA node. Hence, a regulatory feedback loop involving HSFs, miR169s and NF-YAs plays a critical role in the regulation of heat stress response in tomato and Arabidopsis plants.

genomics↗

bioRxiv2020

ChronoRoot: High-throughput phenotyping by deep segmentation networks reveals novel temporal parameters of plant root system architecture

BackgroundDeep learning methods have outperformed previous techniques in most computer vision tasks, including image-based plant phenotyping. However, massive data collection of root traits and the development of associated artificial intelligence approaches have been hampered by the inaccessibility of the rhizosphere. Here we present ChronoRoot, a system which combines 3D printed open-hardware with deep segmentation networks for high temporal resolution phenotyping of plant roots in agarized medium. ResultsWe developed a novel deep learning based root extraction method which leverages the latest advances in convolutional neural networks for image segmentation, and incorporates temporal consistency into the root system architecture reconstruction process. Automatic extraction of phenotypic parameters from sequences of images allowed a comprehensive characterization of the root system growth dynamics. Furthermore, novel time-associated parameters emerged from the analysis of spectral features derived from temporal signals. ConclusionsAltogether, our work shows that the combination of machine intelligence methods and a 3D-printed device expands the possibilities of root high-throughput phenotyping for genetics and natural variation studies as well as the screening of clock-related mutants, revealing novel root traits.

plant biology↗

bioRxiv2020

Identification and functional prediction of anthocyanin biosynthesis regulatory long non-coding RNAs (lncRNAs) in carrot

Carrot (Daucus carota L.) is one of the most cultivated vegetable in the world and of great importance in the human diet. Its storage organs can accumulate large quantities of anthocyanins, metabolites that confer the purple pigmentation to carrot tissues and whose biosynthesis is well characterized. Long non-coding RNAs (lncRNAs) play critical roles in regulating gene expression of various biological processes in plants. In this study, we used a high throughput stranded RNA-seq to identify and analyze the expression profiles of lncRNAs in phloem and xylem root samples using two genotypes with a strong difference in anthocyanin production. We discovered and annotated 8484 new genes, including 2095 new protein-coding and 6373 non-coding transcripts. Moreover, we identified 639 differentially expressed lncRNAs between the phenotypically contrasted genotypes, including certain only detected in a particular tissue. We then established correlations between lncRNAs and anthocyanin biosynthesis genes in order to identify a molecular framework for the differential expression of the pathway between genotypes. A specific natural antisense transcript (NAT) linked to the DcMYB7 key anthocyanin biosynthetic transcription factor suggested how the regulation of this pathway may have evolved between genotypes.

genomics↗

bioRxiv2020

The lncRNA MARS modulates the epigenetic reprogramming of the marneral cluster in response to ABA

Clustered organization of biosynthetic non-homologous genes is emerging as a characteristic feature of plant genomes. The co-regulation of clustered genes seems to largely depend on epigenetic reprogramming and three-dimensional chromatin conformation. Here we identified the long noncoding RNA (lncRNA) MARneral Silencing (MARS), localized inside the Arabidopsis marneral cluster, which controls the local epigenetic activation of its surrounding region in response to ABA. MARS modulates the POLYCOMB REPRESSIVE COMPLEX 1 (PRC1) component LIKE-HETEROCHROMATIN PROTEIN 1 (LHP1) binding throughout the cluster in a dose-dependent manner, determining H3K27me3 deposition and chromatin condensation. In response to ABA, MARS decoys LHP1 away from the cluster and promotes the formation of a chromatin loop bringing together the MARNERAL SYNTHASE 1 (MRN1) locus and a distal ABA-responsive enhancer. The enrichment of co-regulated lncRNAs in clustered metabolic genes in Arabidopsis suggests that the acquisition of novel noncoding transcriptional units may constitute an additional regulatory layer driving the evolution of biosynthetic pathways.

genetics↗

bioRxiv2020

The lncRNA APOLO interacts with the transcription factor WRKY42 to trigger root hair cell expansion in response to cold

Plant long noncoding RNAs (lncRNAs) have emerged as important regulators of chromatin dynamics, impacting on transcriptional programs leading to different developmental outputs. The lncRNA AUXIN REGULATED PROMOTER LOOP (APOLO) directly recognizes multiple independent loci across the Arabidopsis genome and modulates their three-dimensional chromatin conformation, leading to transcriptional shifts. Here, we show that APOLO recognizes the locus encoding the root hair (RH) master regulator ROOT HAIR DEFECTIVE 6 (RHD6) and controls RHD6 transcriptional activity leading to cold-enhanced RH elongation through the consequent activation of the transcription factor gene RHD6-like RSL4. Furthermore, we demonstrate that APOLO interacts with the transcription factor WRKY42 and modulates its binding to the RHD6 promoter. WRKY42 is required for the activation of RHD6 by low temperatures and WRKY42 deregulation impairs cold-induced RH expansion. Collectively, our results indicate that a novel ribonucleoprotein complex involving APOLO and WRKY42 forms a regulatory hub which activates RHD6 by shaping its epigenetic environment and integrates signals governing RH growth and development. SUMMARYThe lncRNA APOLO directly regulates the transcription of the root hair-master gene RHD6. In response to cold, APOLO is induced and it decoys the H3K27me3-binding protein LHP1 away from RHD6. In addition, APOLO modulates the binding of the transcription factor WRKY42 to the RHD6 promoter at low temperatures.

plant biology↗