Biology subjects

Medina-Puche, L.

Publications and source records attributed to Medina-Puche, L..

11 recordsLinked to original sources

bioRxiv2026

NO VEIN is an ancestral immunity protein involved in plant-virus interaction

The conservation of immune systems from prokaryotes to eukaryotes can guide discovery of immunity genes across the tree of life. Most studies to date have focused on metazoan systems, while the extent of ancestral immunity conservation in plants remains underexplored. Here we show that NO VEIN (NOV), a plant protein previously characterized for its essential developmental roles in Arabidopsis thaliana, shares domain composition and structural similarity with Tiamat, a bacterial antiphage protein. In light of the antiviral function of the bacterial protein, we asked whether NOV is involved in plant-virus interactions. We found that NOV knockdown in the model plant Nicotiana benthamiana resulted in an impaired transcriptional response to tobacco rattle virus, including reduced induction of defense genes, and observed increased potato virus x accumulation in a secondary infection. We also reveal that NOV, previously considered plant-specific, has homologs in animals - pointing to a shared origin. Together, these findings uncover a deeply conserved protein involved in plant-virus interaction, and demonstrate the power of prokaryote-eukaryote homology to reveal new aspects of plant biology.

plant biology↗

bioRxiv2026

Selective repurposing of the eukaryotic DNA replication machinery by a plant virus

Eukaryotic DNA viruses that replicate in the nucleus often exploit components of the host DNA replication machinery for genome replication. Geminiviruses, causal agents of devastating crop diseases worldwide, strictly depend on host factors to replicate their circular single-stranded (ss) DNA genomes, with only a single virus-encoded protein, Rep, required for this process. Rep recruits host replication proteins to the viral genome and catalyzes nicking and ligation at the initiation and termination sites of rolling-circle replication. Despite the reliance of geminiviral replication on plant proteins, the composition of the viral replisome remains largely unknown. Here, we use TurboID-based proximity labeling to identify plant proteins in the vicinity of the Rep proteins from the geminiviruses tomato yellow leaf curl virus (TYLCV) and abutilon mosaic virus (AbMV) during infection. Combining virus-induced gene silencing, infection assays, and chromatin immunoprecipitation, we identify host DNA replication-related factors required for viral genome replication and likely components of the viral replisome. Our results indicate that geminiviruses and related eukaryotic ssDNA viruses selectively repurpose components of the eukaryotic replication fork to support rolling-circle replication, and suggest that they follow a leading-strand replication mode while utilizing the lagging-strand DNA polymerase {delta}. These findings shed light on the molecular mechanism of geminiviral DNA replication and identify potential targets for engineering antiviral resistance in crops.

plant biology↗

bioRxiv2026

An ancient cis-element regulates translation of arginine decarboxylase to control downstream polyamine biosynthesis and stress responses

Polyamines (PAs) are ubiquitous metabolites that, despite their simple structure, profoundly influence plant growth, development, and stress adaptation. Their cellular levels are largely determined by arginine decarboxylase (ADC), a key rate-limiting enzyme in their biosynthesis. We previously identified a [~]50 bp GC-rich sequence in the 5' untranslated region (UTR) of plant ADC genes, termed the ADC-box, that is conserved across land plants. Transient reporter assays in tomato, in which ADC upstream regions were decoupled from their native coding sequences and fused to reporter genes, suggested that this element represses translation. However, its function in the native genomic context and its impact on PA homeostasis remain unclear. Here, we combined CRISPR-Cas9 genome editing, metabolite profiling, enzymatic assays, and RNA structure probing to define ADC-box function in tomato and in the seedless land plant Marchantia polymorpha, which retains a conserved [~]20 bp core region. Mutation of the M. polymorpha ADC-box increased ADC activity and altered PA levels, indicating that the ADC-box functions as a conserved translational repressor. In tomato, disruption of the ADC-boxes in SlADC1 and SlADC2 increased ADC activity, demonstrating that the ADC-box acts as a translational repressor in its native context. These ehects were most pronounced under cold stress, when ADC transcript levels increase, suggesting that the ADC-box buhers stress-induced translation. Metabolically, ADC-box disruption led to agmatine accumulation and alterations in upstream intermediates, while downstream PA pools remained largely unchanged. SHAPE analysis revealed that the tomato ADC-box folds into a three-stem RNA structure, with a central stem representing the major inhibitory module. ADC-box mutants displayed altered plant-microbe interactions, with enhanced resistance to Pseudomonas syringae and Tobacco rattle virus, but increased susceptibility to Ralstonia solanacearum and Tomato yellow leaf curl virus. Together, these findings establish the ADC-box as an evolutionarily conserved cis-regulatory element that stabilizes PA homeostasis and modulates plant-microbe interactions.

plant biology↗

bioRxiv2026

Alternative splicing expands the functional portfolio of a plant virus to control the viral cycle

Viruses frequently have limited coding space, yet efficiently manipulate complex hosts by deploying intricate, often poorly understood strategies. Geminiviruses, devastating plant pathogens with small single-stranded (ss) DNA genomes, replicate in the nucleus aided by the viral replication-associated protein (Rep), the most conserved protein within this family and related ssDNA viruses. Rep initiates viral DNA replication and represses its own promoter to regulate the infection cycle. The molecular mechanisms enabling this dual functionality are so far unknown. Here, we show that the geminivirus tomato yellow leaf curl virus (TYLCV) exploits the host spliceosome to produce novel Rep splice variants. Splicing generates Rep isoforms lacking the central oligomerization domain that cannot initiate replication but strongly repress the Rep promoter. Conversely, Rep mutants deficient in splicing promote replication but fail to repress transcription. Reduced Rep splicing interferes with the viral gene expression hierarchy and decreases infectivity. Our findings therefore reveal a previously unrecognized viral strategy in which alternative splicing produces functionally specialized viral protein isoforms, providing a mechanistic explanation for the dual role of Rep in viral replication and gene regulation. Splicing events with potentially similar functional consequences in related viruses suggest that this strategy may have convergently evolved across diverse viral lineages infecting different domains of life.

plant biology↗

bioRxiv2026

Characterization of the C4 proteins encoded by okra-infecting geminiviruses in India

Okra (bhendi) is a widely cultivated food crop in warm regions of the world, with India contributing approximately 60% of global production. However, okra cultivation in India is severely constrained by viral diseases, among which infections caused by the geminiviruses bhendi yellow vein mosaic virus (BYVMV) and okra enation leaf curl virus (OELCuV), in association with their satellites, represent major limitations to crop productivity. In recent years, the geminivirus-encoded C4 protein has emerged as a key pathogenicity determinant in this viral family, with functions that include suppression of multiple layers of plant antiviral defence and induction of disease symptoms. Here, we comparatively characterize the C4 proteins of BYVMV and OELCuV by determining their targeting signals and subcellular localization, and by assessing their ability to induce developmental abnormalities and suppress the cell-to-cell spread of RNA silencing. Our results reveal that the two C4 proteins display distinct subcellular localization patterns, yet both are capable of inducing developmental alterations, likely through different mechanisms, and of suppressing the intercellular spread of RNA silencing, possibly via interaction with a common host factor. Together, these findings suggest that C4 might be a critical virulence factor in okra-infecting geminiviruses and act as a symptom determinant. The C4 proteins encoded by BYVMV and OELCuV therefore emerge as promising targets for the development of antiviral management strategies in okra.

plant biology↗

bioRxiv2025

Pervasive splicing in a plant DNA virus

RNA splicing is considered an oddity in plant viruses; here, unexpectedly, we find it to be prevalent in the geminivirus tomato yellow leaf curl virus. Transcriptome analysis revealed eight splicing events generating novel protein isoforms, six of which were validated and two shown to depend on the plant spliceosome. Splicing impairment reduced viral accumulation and symptom severity, demonstrating that splicing contributes to infectivity, potentially by expanding the viral proteome, and suggesting that plant virus transcriptomes need to be reassessed.

plant biology↗

bioRxiv2022

A plant virus causes symptoms through the deployment of a host-mimicking protein domain to attract the insect vector

Viruses are obligate intracellular parasites with limited proteomes that heavily rely on the cell molecular machinery for their multiplication and spread. Plant viruses frequently cause symptoms through interference with host developmental programs. Despite the agricultural relevance of symptom development in virus-infected crops, the molecular mechanisms underlying these viral effects remain elusive. Here, we show that the symptoms triggered by tomato yellow leaf curl virus (TYLCV) depend on the physical interaction between the host-mimicking domain of a virus-encoded protein, C4, and a plant-specific family of RCC1-like domain-containing (RLD) proteins. C4 outcompetes endogenous interactors of RLDs, disrupting RLD function in the regulation of endomembrane trafficking and polar auxin transport, ultimately leading to the developmental alterations recognized as symptoms of the viral infection. Importantly, symptoms do not have a detectable effect on the performance of the virus in the plant host, but they serve as attractants for the viral insect vector, the whitefly Bemisia tabaci, hence promoting pathogen spread. Our work uncovers the molecular underpinnings of the viral manipulation that leads to symptom development in the TYLCV-tomato pathosystem, and suggests that symptoms have evolved as a strategy to promote viral transmission by the insect vector. Given that most plant viruses are insect-transmitted, the principles described here might have broad applicability to crop-virus interactions.

plant biology↗

bioRxiv2021

Combinatorial interactions between viral proteins expand the functional landscape of the viral proteome

As intracellular parasites, viruses need to manipulate the molecular machinery of their host cells in order to enable their own replication and spread. This manipulation is based on the activity of virus-encoded proteins. The reduced size of viral genomes imposes restrictions in coding capacity; how the action of the limited number of viral proteins results in the massive cell reprogramming observed during the viral infection is a long-standing conundrum in virology. In this work, we explore the hypothesis that combinatorial interactions expand the multifunctionality of viral proteins, which may exert different activities individually and when in combination, physical or functional. We show that the proteins encoded by a plant-infecting DNA virus physically associate with one another in an intricate network. Our results further demonstrate that these interactions can modify the subcellular localization of the viral proteins involved, and that co-expressed interacting viral proteins can exert novel biological functions in planta that go beyond the sum of their individual functions. Based on this, we propose a model in which combinatorial physical and functional interactions between viral proteins enlarge the functional landscape of the viral proteome, which underscores the importance of studying the role of viral proteins in the context of the infection.

plant biology↗

bioRxiv2019

A novel pathway linking plasma membrane and chloroplasts is co-opted by pathogens to suppress salicylic acid-dependent defences

Chloroplasts are crucial players in the activation of defensive hormonal responses during plant-pathogen interactions. Here, we show that a plant virus-encoded protein re-localizes from the plasma membrane to chloroplasts upon triggering plant defence, interfering with the chloroplast-dependent activation of anti-viral salicylic acid (SA) biosynthesis. Strikingly, we have found that plant pathogens from different kingdoms seem to have convergently evolved to target chloroplasts and impair SA-dependent defences following an association with membranes, which is based on the co-existence of two subcellular targeting signals, an N-myristoylation site and a chloroplast transit peptide. This pattern is also present in plant proteins, at least one of which conversely activates SA defences from the chloroplast. Taken together, our results suggest that a pathway linking plasma membrane to chloroplasts and activating defence exists in plants, and that such pathway has been co-opted by plant pathogens during host-pathogen co-evolution to promote virulence through suppression of SA responses.

plant biology↗

bioRxiv2019

PLANT NATRIURETIC PEPTIDE A antagonizes salicylic acid-primed cell death

Peptide hormones perceived in the cell surface via receptor proteins enable cell-to-cell communication and act in multiple biological processes through the activation of intracellular signaling. Even though Arabidopsis is predicted to have more than 1,000 secreted peptides, the biological relevance of the majority of these is yet to be established. Here, we demonstrate that PLANT NATRIURETIC PEPTIDE A (PNP-A), a functional analog to vertebrate atrial natriuretic peptides, antagonizes the salicylic acid (SA)-mediated cell death in the Arabidopsis lesion-stimulating disease 1 (lsd1) mutant. While loss of PNP-A potentiates SA signaling, exogenous application of the PNP-A synthetic peptide or overexpression of PNP-A significantly compromises the SA-mediated cell death. Moreover, we identified a plasma membrane-localized receptor-like protein, which we name PNPAR (for PNP-A receptor), that binds PNP-A and is required to counteract SA responses. Our work identifies a novel peptide-receptor pair which modulates SA responses in Arabidopsis.

plant biology↗

bioRxiv2017

A plant receptor-like kinase promotes cell-to-cell spread of RNAi and is targeted by a virus

RNA interference (RNAi) in plants can move from cell to cell, allowing for systemic spread of an anti-viral immune response. How this cell-to-cell spread of silencing is regulated is currently unknown. Here, we describe that the C4 protein from Tomato yellow leaf curl virus has the ability to inhibit the intercellular spread of RNAi. Using this viral protein as a probe, we have identified the receptor-like kinase (RLK) BARELY ANY MERISTEM 1 (BAM1) as a positive regulator of the cell-to-cell movement of RNAi, and determined that BAM1 and its closest homologue, BAM2, play a redundant role in this process. C4 interacts with the intracellular domain of BAM1 and BAM2 at the plasma membrane and plasmodesmata, the cytoplasmic connections between plant cells, interfering with the function of these RLKs in the cell-to-cell spread of RNAi. Our results identify BAM1 as an element required for the cell-to-cell spread of RNAi and highlight that signalling components have been co-opted to play multiple functions in plants.

plant biology↗