Biology subjects

von Roepenack-Lahaye, E.

Publications and source records attributed to von Roepenack-Lahaye, E..

8 recordsLinked to original sources

bioRxiv2026

Pre-chlorotic Mg2+ deficiency impairs guard-cell PSII and leaf gas exchange in Vicia faba

Magnesium deficiency impairs photosynthesis and transpiration before visible chlorosis, but whether guard cells themselves are affected at this early stage remains unresolved. We combined whole-leaf gas exchange and chlorophyll fluorescence with cell-specific fluorescence measurements of individual guard cell pairs, together with elemental analysis, metabolite profiling, adenosine triphosphate quantification, and proteome profiling of guard cell-enriched material in hydroponically grown Vicia faba. Magnesium deficiency reduced magnesium concentrations in both whole leaves and guard cell-enriched fractions. Under red light, magnesium-deficient leaves showed reduced effective quantum yield of photosystem II, CO2 assimilation, transpiration, and stomatal conductance, whereas intercellular CO2 concentration remained unchanged. Individual guard cell pairs likewise showed reduced effective quantum yield of photosystem II, demonstrating that the early deficiency response extended to guard cells. Electron transport rate and non-photochemical quenching in guard cells were not significantly altered. Only a small set of metabolites in guard cell-enriched material, mainly fatty acids and citrate, responded to magnesium deficiency, whereas ATP abundance and light-induced proton extrusion remained unchanged. In contrast, the guard cell-enriched proteome showed higher abundance of photosynthesis- and translation-related proteins despite reduced guard-cell PSII efficiency. Together, these findings identify guard cells as an early responsive cell type under magnesium deficiency and show that guard-cell photochemistry is impaired before visible chlorosis, alongside reduced whole-leaf carbon gain and water loss.

physiology↗

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

Intrinsic disorder in elicitin-like effectors: Molecular shields in the arms race of biotrophic pathogens

Plant pathogens establish colonization through effector secretion to modulate host immune responses. Within bacterial effectors intrinsically disordered regions (IDRs) contribute to diverse functions and pathogenicity, but their role in effectors of phytopathogenic oomycetes remains poorly understood. Here, analysis of oomycete secretomes across lifestyles reveal widespread intrinsic disorder in secreted proteins, particularly in apoplastic elicitin and elicitin-like effectors (ELLs). Combining in vitro and in planta experiments, we show that IDRs in ELLs from the biotrophic pathogen Albugo candida reduce immune recognition, consistent with an IDR-mediated shielding mechanism. This function is transferable, as fusion of an ELL-derived IDR to the immunogenic elicitin INF1 from Phytophthora infestans abolishes its recognition. These findings identify intrinsic disorder as a functional feature of apoplastic effectors that modulates host detection and promotes pathogen fitness. Graphical summary O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/717489v1_ufig1.gif" ALT="Figure 1"> View larger version (59K): org.highwire.dtl.DTLVardef@1363e05org.highwire.dtl.DTLVardef@21f34dorg.highwire.dtl.DTLVardef@ec6e5borg.highwire.dtl.DTLVardef@41327b_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2025

Small Molecule Binding to EDS1/PAD4 in LRR-RP-Mediated Pattern-Triggered Immunity

Pattern-triggered immunity (PTI) is a key defense mechanism initiated when pathogen-associated molecular patterns are recognized by receptors, including leucine-rich repeat receptor proteins (LRR-RPs)1,2. EDS1 and PAD4 are crucial for LRR-RP-mediated PTI activation3. Small molecule (SM) phosphoribosyl-AMP/ADP, generated by TIR-domain NADase activity, promote the recruitment of helper NLRs into EDS1-PAD4 complex4,5. Here, we show that BAK1 recruitment to LRR-RP complexes is unaffected in eds1-2 or pad4-1 mutants, but is abolished in the sobir1-12 mutant, highlighting the essential role of SOBIR1 in surface immune receptor complex formation. Furthermore, SM-binding to EDS1 and PAD4 is critical for LRR-RP-mediated PTI, as SM-binding-deficient mutants fail to restore immune responses. De novo SM synthesis is required for late PTI responses, including PR1 expression and bacterial resistance, but not for early responses such as ROS and ethylene production. The TNL SADR1 functions only in late PTI responses, suggesting distinct roles of multiple TIR-domain proteins in PTI signaling.

plant biology↗

bioRxiv2023

A Tyrosine Phospho-switch within the Longin Domain of VAMP721 modulates SNARE functionality

The final step in secretion is membrane fusion facilitated by SNARE proteins that reside in opposite membranes. The formation of a trans-SNARE complex between one R and three Q coiled-coiled SNARE domains drives the final approach of the membranes providing the mechanical energy for fusion. Biological control of this mechanism is exerted by additional domains within some SNAREs. For example, the N-terminal Longin domain (LD) of R-SNAREs (also called Vesicle-associated membrane proteins, VAMPs) can fold back onto the SNARE domain blocking interaction with other cognate SNAREs. The LD may also determine the subcellular localization via interaction with other trafficking related proteins. Here, we provide cell-biological and genetic evidence that phosphorylation of the Tyrosine57 residue regulates the functionality of VAMP721. We found that an aspartate mutation mimics phosphorylation, leading to protein instability and subsequent degradation in lytic vacuoles. The mutant SNARE also fails to rescue the defects of vamp721vamp722 loss-of-function lines in spite of its wildtype-like localization within the secretory pathway and the ability to interact with cognate SNARE partners. Most importantly, it imposes a dominant negative phenotype interfering with root growth, normal secretion and cytokinesis in wildtype plants generating large aggregates that mainly contain secretory vesicles. Non-phosphorylatable VAMP721Y57F needs higher gene dosage to rescue double mutants in comparison to native VAMP721 underpinning that phosphorylation modulates SNARE function. We propose a model where a short-lived phosphorylation of Y57 serves as a regulatory step to control VAMP721 activity, favouring its open state and interaction with cognate partners to ultimately drive membrane fusion.

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

The genetic interaction of REVOLUTA and WRKY53 links plant development, senescence, and immune responses

In annual plants, tight coordination of successive developmental events is of primary importance to optimize performance under fluctuating environmental conditions. The recent finding of the genetic interaction of WRKY53, a key senescence-related gene with REVOLUTA, a master regulator of early leaf patterning, raises the question of how early and late developmental events are connected. Here, we investigated the developmental and metabolic consequences of an alteration of the REVOLUTA and WRKY53 gene expression, from seedling to fruiting. Our results show that REVOLUTA critically controls late developmental phases and reproduction while inversely WRKY53 determines vegetative growth at early developmental stages. We further show that these regulators of distinct developmental phases frequently, but not continuously, interact throughout ontogeny and demonstrated that their genetic interaction is mediated by the salicylic acid (SA). Moreover, we showed that REVOLUTA and WRKY53 are keys regulatory nodes of development and plant immunity thought their role in SA metabolic pathways, which also highlights the role of REV in pathogen defence. Together, our findings demonstrate how late and early developmental events are tightly intertwined by molecular hubs. These hubs interact with each other throughout ontogeny, and participate to the interplay between plant development and immunity.

plant biology↗

bioRxiv2017

Lipid transfer from plants to arbuscular mycorrhiza fungi

Arbuscular mycorrhiza (AM) symbioses contribute to global carbon cycles as plant hosts divert up to 20% of photosynthate to the obligate biotrophic fungi. Previous studies suggested carbohydrates as the only form of carbon transferred to the fungi. However, de novo fatty acid (FA) synthesis has not been observed in AM fungi in absence of the plant. In a forward genetic approach, we identified two Lotus japonicus mutants defective in AM-specific paralogs of lipid biosynthesis genes (KASI and GPAT6). These mutants perturb fungal development and accumulation of emblematic fungal 16:1{omega}5 FAs. Using isotopolog profiling we demonstrate that 13C patterns of fungal FAs recapitulate those of wild-type hosts, indicating cross-kingdom lipid transfer from plants to fungi. This transfer of labelled FAs was not observed for the AM-specific lipid biosynthesis mutants. Thus, growth and development of beneficial AM fungi is not only fueled by sugars but depends on lipid transfer from plant hosts.

plant biology↗