Biology subjects

von Wiren, N.

Publications and source records attributed to von Wiren, N..

11 recordsLinked to original sources

bioRxiv2026

Hypermorphic TaARF4 shapes wheat architecture by repressing SPL-mediated developmental timing

Integrating spatial morphogens with temporal developmental clocks is fundamental to optimizing plant architecture and crop yield, yet their molecular interface remains elusive. Here, we characterize Branched shoot 1 (Bsh1), a semi-dominant wheat mutant exhibiting non-canonical upper-aerial branching and aberrant spike development, caused by a T265I substitution in the DNA-binding domain of the auxin response factor TaARF4-A2. Unlike flanking mutations governing protein stability in basal land plants, this central substitution uniquely converts TaARF4-A2 into an auxin-insensitive hypermorphic repressor. The mutant protein disrupts auxin-cytokinin homeostasis and markedly enhances the native repression of SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors, the core timers of developmental phase transitions. This spatial and temporal uncoupling unleashes upper axillary buds from dormancy, promoting aerial branching and diverting resources from reproductive development. Our findings demonstrate how a conserved spatial morphogen effector was evolutionarily rewired in polyploid wheat to dictate the temporal SPL clock, orchestrating species-specific shoot architectural innovation.

plant biology↗

bioRxiv2025

Ethylene signal-driven plant-multitrophic synergy boosts crop performance

Efficient nutrient use in agriculture depends on the dynamic interplay between plant roots, soil, and microbial communities. The root-rhizosphere interface is central to nutrient uptake and serves as a key hub for interactions with beneficial microbes. Arbuscular mycorrhizal (AM) fungi, positioned at the nexus between plant roots and soil microbiota, play a critical role in enhancing crop performance under nutrient-limited conditions. In this study, we dissected the genetic and molecular basis of AM fungi-induced lateral root development in maize (Zea mays), focusing on the role of ethylene-responsive transcription factors (ERFs). We identified ERF genes as essential regulators of pericycle cell division, acting downstream of ethylene biosynthesis genes (ACS6 and ACS7) and AM fungal signaling. Our findings reveal that AM fungi promote lateral root initiation by activating ERF expression and reprogramming flavonoid metabolism, particularly reducing the accumulation of flavonols such as kaempferol and quercetin, which otherwise inhibit root development when over-accumulated. Furthermore, we demonstrated that Massilia, a beneficial rhizobacterium, synergizes with AM fungi to enhance lateral root formation by colonizing fungal hyphae, degrading flavonoids, and contributing to auxin production. Together, our results uncover a tripartite signaling network linking ethylene signaling, flavonoid-mediated microbial recruitment, and AM symbiosis. This study highlights ERFs as central integrators of plant-microbe interactions and provides a molecular framework for engineering root architecture and microbiome assembly to improve nutrient acquisition and support sustainable crop productivity.

plant biology↗

bioRxiv2024

Elucidation and functional characterization of natural sweetener biosynthesis in hortensia species

Among the various coumarins found in Hydrangea species, the bioactive dihydroisocoumarin known as phyllodulcin (PD) stands out as a non-caloric, high-intensity sweetener, which is up to 800 times sweeter than sucrose. Additionally, PD possesses notable medicinal properties, including antifungal, anti-ulcer, and anti-inflammatory effects. PD also plays several plant-specific roles, such as defending against phytopathogens, responding to abiotic and biotic stresses and regulating hormones. However, the biological function and biosynthetic pathway of PD in Hydrangea remain unexplored. This study employs targeted metabolomic and transcriptomic approaches to uncover the regulatory mechanisms and identify potential candidate genes involved in the biosynthesis of PD. 14 out of 182 different Hydrangea accessions, exhibiting varying levels of PD, were selected for detailed analysis. Accessions of H. macrophylla with high PD levels displayed distinct metabolite profiles compared to those with low PD concentrations. Specifically, pathways involving caffeic acid, ferulic acid, and their derivatives, such as scopolin, scopoletin, esculetin, and fraxetin, were predominant in accessions with low PD concentrations. Conversely, the metabolism of phenylalanine, umbelliferone, p-coumaric acid, naringenin, resveratrol, and Thn C was more active in accessions containing PD. Correlation analysis between PD and these metabolites offered valuable insights into their interrelationships. Transcriptome analysis revealed specific genes involved in phenylpropanoid biosynthesis, flavonoid biosynthesis, and stilbene biosynthesis pathways that are crucial for PD biosynthesis. Moreover, the identification of cyclase and ketoreductase genes, which were up regulated in accessions with high PD, provided further understanding of the biosynthetic pathway leading to PD. Finally, based on metabolite levels and gene expression data, a hypothetical pathway from resveratrol to Thn C was proposed, suggesting its potential involvement in PD biosynthesis. HighlightThe metabolic and transcriptomic analysis led to the identification of specific metabolites and genes that are involved in the biosynthesis of dihydrisocoumarin.

plant biology↗

bioRxiv2024

Enhanced auxin signaling hub triggers root hair growth at moderate low temperature in Arabidopsis thaliana

Root hairs (RH) as a mixed tip- and non-tip growing protrusions that develop from root epidermal cells are important for nutrient and water uptake, root anchoring, and interaction with soil microorganisms. Although nutrient availability and temperature are critical interlinked factors for sustained plant growth, the molecular mechanisms underlying their sensing and downstream signaling pathways remain unclear. Here, we identified a moderate low temperature (10{degrees}C) condition that triggers a strong RH elongation response involving several molecular components of the auxin pathway. Then, we have determined that auxin biosynthesis carried out by YUCCAs/TAA1, the auxin transport conducted by PIN2/PIN4 and AUX1/PGP4, and the auxin signaling controlled by TIR1/AFB2 coupled to four specific ARFs (ARF6/ARF8 and ARF7/ARF19), are all crucial for the RH response at moderate low temperature. These results uncover the auxin pathway as one central hub under moderate low temperature in the roots to trigger RH growth. Our work highlights the importance of moderate low temperature stimulus as a complex nutritional signal from the media soil into the roots that may be fine-tuned for future biotechnological applications to enhance nutrient uptake.

plant biology↗

bioRxiv2024

Natural variation in the Arabidopsis thaliana root and shoot response to boron deficiency reveals sensitive and responsive phenes and phylogenetic and geographic clustering of boron efficiency adaptations

O_LIBoron (B) is an essential plant micronutrient with a crucial role in cell wall stability. To improve plant tolerance to suboptimal B-availability, it is crucial to understand the mechanisms plants have evolved to tolerate B-limited conditions. C_LIO_LIWe assessed temporal physiological, ionomic and molecular responses to B-deficiency across a diversity panel of 185 Arabidopsis thaliana accessions. Plants were characterised in soil-substrate in an automated phenotyping system to track shoot performance, and on agar plates to track root traits. C_LIO_LIAccessions varied widely in their response to B-deficiency. Rosette area decreased by 50% under B-deficiency across all accessions on average but by less than 15% in B-efficient accessions alone. Most root traits suffered under B-deficiency but lateral root length increased in 20% of accessions. The B-uptake and B transporter expression response of B-efficient and B-inefficient accessions was similar, suggesting increased B-use rather than B-uptake efficiency in efficient accessions. Phylogenetic analysis demonstrated enrichment of B-efficient accessions within a clade containing accessions originating from areas characterised as B-deficient. K-means clustering revealed increased lateral root length was associated with efficient shoot growth under B-deficiency. C_LIO_LIThe results demonstrate different response strategies to B-deficiency, indicating target traits to improve the performance of plants grown under B-limiting conditions. C_LI

plant biology↗

bioRxiv2023

Heritable maize microbiomes contribute to local adaptation and host stress resilience

Beneficial interactions with microorganisms are pivotal for crop performance and resilience. However, it remains unclear how heritable the microbiome is with respect to the host plant genotype and to what extent host genetic mechanisms can modulate plant-microbe interactions in the face of environmental stress. Here, we surveyed the root and rhizosphere microbiome of 129 accessions of locally adapted Zea mays, sourced from diverse habitats and grown under control and different stress conditions. We quantified treatment and host genotype effects on the microbiome. Plant genotype and source environment were predictive of microbiome composition. Genome wide association analysis identified host genetic variants linked to both rhizosphere microbiome composition and source environment. We identified transposon insertions in a candidate gene linked to both the abundance of a keystone microbe Massilia and source total soil nitrogen, finding mutant plants to show a reduction in lateral root density. We conclude that locally adapted maize varieties exert patterns of genetic control on their root and rhizosphere microbiomes that follow variation in their home environments, consistent with a role in tolerance to prevailing stress.

genetics↗

bioRxiv2022

Elucidating the systemic response of wheat plants under waterlogging based on transcriptomic and metabolic approaches

Extreme weather conditions lead to significant imbalances in crop productivity, which in turn affect food security. Flooding events cause serious problems to many crop species such as wheat. Although metabolic readjustments under flooding are important for plant regeneration, underlying processes remain poorly understood. Here, we investigated the systemic response of wheat to waterlogging using metabolomics and transcriptomics. A 12-day exposure to excess water triggered nutritional imbalances and disruption of metabolite synthesis and translocation, reflected by reduction of plant biomass and growth performance. Metabolic and transcriptomic profiling in roots, xylem, and leaves indicated anaerobic fermentation processes as a local response occurring in roots. Differentially expressed genes and ontological categories revealed that carbohydrate metabolism plays an important role as a systemic response. Analysis of the translocation rate of specific compounds in the xylem showed how waterlogging alters the composition of xylem exudates and thus the root to shoot communication. Interestingly, among all metabolites determined in our study, alanine was the most abundant transported in the xylem. Our results suggest an important role of this amino acid not only as amino-nitrogen source but also as the major root-to-shoot translocated and systemically acting metabolite crucial for balancing C/N between roots and shoots during waterlogging. The relevance of this study relies on the basis to characterize the important role of alanine as HighlightMetabolic and transcriptomic changes in wheat highlight alanine as the major root-to-shoot translocated and systemically acting metabolite crucial for balancing C/N between roots and shoots.

physiology↗

bioRxiv2020

INTERMEDIUM-C mediates the shade-induced bud growth arrest in barley

Tiller formation is a key agronomic determinant for grain yield in cereal crops. The modulation of this trait is controlled by transcriptional regulators and plant hormones, tightly regulated by external environmental conditions. While endogenous (genetics) and exogenous (environmental factors) triggers for tiller formation have mostly been investigated separately, it has remained elusive how they are integrated into the developmental program of this trait. The transcription factor INTERMEDIUM-C (INT-C), which is the barley ortholog of the maize domestication gene TEOSINTE BRANCHED1 (TB1) has a prominent role in regulating tiller bud outgrowth. Here we show that INT-C is expressed in tiller buds, required for bud growth arrest in response to shade. In contrast to wild type plants, int-c mutant plants are impaired in their shade response and do not stop tiller production after shading. Gene expression levels of INT-C are up-regulated under light-limiting growth conditions, and down-regulated after decapitation. Transcriptome analysis of wild-type and int-c buds under control and shading conditions identified target genes of INT-C that belong to auxin and gibberellin biosynthesis and signaling pathways. Our study identifies INT-C as integrator of the shade response into tiller formation, which is prerequisite for implementing shading responses in the breeding of cereal crops.

plant biology↗

bioRxiv2020

ITPK1-Dependent Inositol Polyphosphates Regulate Auxin Responses in Arabidopsis thaliana

The combinatorial phosphorylation of myo-inositol results in the generation of different inositol phosphates (InsP), of which phytic acid (InsP6) is the most abundant species in eukaryotes. InsP6 is also the precursor of higher phosphorylated forms called inositol pyrophosphates (PP-InsPs), such as InsP7 and InsP8, which are characterized by a diphosphate moiety and are also ubiquitously found in eukaryotic cells. While PP-InsPs regulate various cellular processes in animals and yeast, their biosynthesis and functions in plants has remained largely elusive because plant genomes do not encode canonical InsP6 kinases. Recently, it was shown that Arabidopsis ITPK1 catalyzes the phosphorylation of InsP6 to the natural 5-InsP7 isomer in vitro. Here, we demonstrate that Arabidopsis ITPK1 contributes to the synthesis of InsP7 in planta. We further find a critical role of ITPK1 in auxin-related processes including primary root elongation, leaf venation, thermomorphogenic and gravitropic responses, and sensitivity towards exogenously applied auxin. Notably, 5-InsP7 binds to recombinant auxin receptor complex, consisting of the F-Box protein TIR1, ASK1 and the transcriptional repressor IAA7, with high affinity. Furthermore, a specific increase in 5-InsP7 in a heterologous yeast expression system results in elevated interaction of the TIR1 homologs AFB1 and AFB2 with various AUX/IAA-type transcriptional repressors. We also identified a physical interaction between ITPK1 and TIR1, suggesting a dedicated channeling of an activating factor, such as 5-InsP7, to the auxin receptor complex. Our findings expand the mechanistic understanding of auxin perception and lay the biochemical and genetic basis to uncover physiological processes regulated by 5-InsP7.

plant biology↗

bioRxiv2020

Providing an additional electron sink by the introduction of cyanobacterial flavodiirons enhances the growth of Arabidopsis thaliana in varying light

The ability of plants to maintain photosynthesis in a dynamically changing environment is of central importance for their growth. As their photosynthetic machinery typically cannot adapt rapidly to fluctuations in the intensity of radiation, the level of photosynthetic efficiency is not always optimal. Cyanobacteria, algae, non-vascular plants (mosses and liverworts) and gymnosperms all produce flavodiirons (Flvs), a class of proteins not represented in the angiosperms; these proteins act to mitigate the photoinhibition of photosystem I. Here, genes specifying two cyanobacterial Flvs have been expressed in the chloroplasts of Arabidopsis thaliana in an attempt to improve the robustness of Photosystem I (PSI). The expression of Flv1 and Flv3 together shown to enhance the efficiency of the utilization of light and to boost the plants capacity to accumulate biomass. Based on an assessment of the chlorophyll fluorescence in the transgenic plants, the implication was that photosynthetic activity (including electron transport flow and non-photochemical quenching during a dark-to-light transition) was initiated earlier in the transgenic than in wild type plants. The improved photosynthetic performance of the transgenics was accompanied by an increased production of ATP, an acceleration of carbohydrate metabolism and a more pronounced partitioning of sucrose into starch. The indications are that Flvs are able to establish an efficient electron sink downstream of PSI, thereby ensuring that the photosynthetic electron transport chain remains in a more oxidized state. The expression of Flvs in a plant acts to both protect photosynthesis and to control the ATP/NADPH ratio; together, their presence is beneficial for the plants growth potential.

biochemistry↗

bioRxiv2017

Secretion of redox-active metabolites as a general strategy for iron acquisition in plants

Iron is an essential but often poorly bioavailable nutrient due to its low solubility, especially in alkaline soils. Plants have evolved at least two distinct strategies to extract iron from soil: solubilization of ferric iron by phytosiderophores, and reduction to the ferrous form at the root surface followed by direct import. Here, we describe the discovery of a novel redox-active catecholic metabolite, termed sideretin, which derives from the coumarin fraxetin, and is the primary molecule exuded by Arabidopsis thaliana roots in response to iron deficiency. Using a combination of metabolomics, heterologous expression, and coexpression analysis we have identified two enzymes that complete the biosynthetic pathway of sideretin. Chemical characterization of synthetic sideretin and biological assays with pathway mutants suggest that sideretin is critical for iron nutrition and support a role for small molecule-mediated iron reduction in A. thaliana under iron-limiting growth conditions. Further, we show that sideretin production is evolutionarily ancient and occurs in eudicot species only distantly related to A. thaliana. In addition to sideretin, untargeted metabolomics of the root exudates of various eudicots revealed the production of structurally diverse redox-active molecules in response to iron deficiency. Our results indicate that secretion of small molecule reductants by roots may be a widespread and previously underappreciated component of the reduction-based iron uptake strategy.

plant biology↗