Biology subjects

Lorenzo, O.

Publications and source records attributed to Lorenzo, O..

9 recordsLinked to original sources

bioRxiv2026

Fungal volatiles affect lateral root formation and increase plant tolerance to osmotic stress

Symbiotic fungi communicate with plants via volatile organic compounds (VOCs), even before physical contact. While fungal VOCs are known to promote plant development under control conditions, their effects under abiotic stress remain poorly characterized. Here, we exposed Arabidopsis thaliana seedlings to VOCs from the ectomycorrhizal fungi Laccaria bicolor and Hebeloma cylindrosporum, and the endophyte Serendipita indica, under osmotic stress. Time-course transcriptional analysis revealed a rapid, transient induction of auxin transport genes within 3 days of VOC exposure, with minimal early cytokinin modulation. Using auxin- (aux1-7, axr1-3) and cytokinin-resistant (cre1, arr1-4) mutants, we show that this early response bypasses classic auxin/cytokinin antagonism, promoting lateral root proliferation by day 10 under both control and stress conditions. Transcriptomic profiling indicated that fungal VOCs modulate glucosinolate and leucine metabolism and regulate potassium (HAK5) and iron (IRT1) transporters. Genetic and phenotypic analyses of hak5-2 and akt1-2 mutants, together with nitric oxide signaling components, revealed that potassium transport and nitric oxide-dependent IRT1 regulation are essential for translating VOC perception into developmental responses. These findings underscore the multifaceted mechanisms by which fungal VOCs coordinate plant development and abiotic stress tolerance.

plant biology↗

bioRxiv2025

Alirocumab attenuated plaque inflammation and PCSK9-induced proinflammatory signalling in M1 macrophages independently of lipid lowering

BackgroundProprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) may directly promote vascular inflammation beyond its action on LDL-C degradation. We investigated whether PCSK9 may exacerbate proinflammatory signalling of M1 macrophages and if alirocumab could attenuate this effect and plaque progression by LDL-C independent mechanisms. MethodsApoE-/- mice were treated with alirocumab for 13 weeks and aortic arches were isolated for atherosclerotic plaques characterization based on lesion size and lipid and macrophage infiltration. Also, plasma and splenic monocytes/macrophages were assessed by flow cytometry, and PCSK9, the lipid profile, inflammatory cytokines were measured by qPCR or western blot. Cultured THP-1-derived M1 macrophages were stimulated with PCSK9 and evaluated for TLR4-NF{kappa}B-NLRP3 activation and cytokine production. PCSK9 and proinflammatory factors were analysed in 1190 patients with acute coronary syndrome (ACS). ResultsAlirocumab reduced plaque lesion (0.42-fold; p< 0.05) and lipid (0.63-fold; p< 0.01) and macrophage (0.61-fold; p<0.05) infiltration, mainly the M1 subtype (0.37-fold; p<0.01), as well as TLR4, NLRP3 and caspase-1 expression (0.49-fold, 0.51-fold and 0.51-fold, respectively; p<0.05), without altering LDL-C. Also, it decreased proinflammatory cytokines but enhanced anti-inflammatory factors and M2 markers at the descending aorta. Alirocumab enriched circulating Ly6Clow monocytes (1.51-fold; p<0.05) and splenic M2 macrophages (1.32-fold; p<0.01), while reducing M1 (0.62-fold; p<0.05). In cultured M1 macrophages, PCSK9 overexpressed proinflammatory cytokines (i.e., CXCL9, CXCL10, TNF-, IL-1{beta}, IL-6) and downregulated anti-inflammatory mediators (i.e., CCL17, TGM2, TGF-{beta}1, IL-10), promoted NF{kappa}B-p65 nuclear translocation, and NLRP3 and gasdermin-D activation. However, TLR4 inhibition or silencing blunted these effects. In addition, there was a positive association between PCSK9 with hsCRP and FGF-23 plasma levels in ACS patients. ConclusionsPCSK9 may be released in parallel to proinflammatory factors such as hsCRP and FGF-23 in ACS patients. However, alirocumab could exert lipid-independent anti-inflammatory effects through activation of the TLR4-NF{kappa}B-NLRP3 signaling in M1 macrophages, promotion of M2, and reducing plaque inflammation.

biochemistry↗

bioRxiv2025

TGA family of transcription factors are nitric oxide sensors in the root stem cell niche

Plant root development is tightly regulated and depends on the coordination among different cell types located in the root stem cell niche (SCN). A complex network of regulators includes the gasotransmitter nitric oxide (NO) known to inhibit primary root growth, modify root architecture and alter meristem organisation. However, little is known about the molecular targets and the mechanistic insights of this signalling molecule during root SCN homeostasis. Here, genetic, molecular and physiological evidence support that TGA transcription factors of the bZIP family, and specifically PERIANTHIA (PAN), contribute to NO-mediated root stem cell regulation. NO induces reversible S-nitrosylation of PAN, thereby inhibiting its binding to DNA and associated transcriptional activation. In turn, the protein-SNO reductase activity of TRXh5 is able to denitrosylate PAN. This switch on and off mechanism of PAN activation modulates WOX5 expression and quiescent centre activity, which alters columella stem cell maintenance through a NO-dependent mechanism. Different TGA members interact with PAN and are also S-nitrosylated, whose expression in the root SCN together with their accumulated mutations contribute to NO sensing during root apical meristem development. Collectively, these findings reveal a molecular framework where NO controls the ability of PAN to bind to its targets as a master regulator of the root SCN.

plant biology↗

bioRxiv2025

Fungal VOCs regulate the expression of WOX5 at the root meristem of plants under osmotic stress in Arabidopsis and Populus tremuloides seedlings

Communication between plants and fungi occurs even before direct physical contact via various chemical signaling pathways, among them, volatile organic compounds (VOCs). Fungal VOCs, including those emitted by ectomycorrhizal and symbiotic endophytic fungi, significantly influence plant development and root architecture. However, the molecular signaling mechanisms underlying its regulation remain unknown. The quiescent center (QC), located within the primary root meristem, serves as a reservoir of stem cells that generate daughter cells and constituting a key regulatory site for architectural modulation. These daughter cells either divide or differentiate to form the transition zone, maintaining a crucial balance for root meristem homeostasis. WOX5, a homeobox transcription factor expressed predominantly in the QC, regulates surrounding stem cells by repressing their differentiation, thereby preserving the stem cell niche and is essential for root meristem integrity. In this study, we aimed to analyze the effects of fungal VOCs emitted by Laccaria bicolor, Hebeloma cylindrosporum, and Serendipita indica on the root architecture and meristem regulation in Arabidopsis thaliana and Populus tremuloides. Our results demonstrate the impact of these fungal VOCs on the root architecture of both species and underline the importance of WOX5 regulation mediated by fungal VOCs for maintaining root meristem homeostasis.

plant biology↗

bioRxiv2025

Vertical transmission of core endophytes through the seeds

Plant-associated microorganisms, particularly endophytes, are essential for plant health and development. Endophytic microbiota is intimately associated with host plants colonizing various tissues, including seeds. Seed endophytes are particularly noteworthy because of their potential for vertical transmission. This pathway may play a role in the long-term establishment and evolution of stable bacteria-host interactions across plant generations. Hundreds of seed-bacteria associations have been recently uncovered; however, most seem to be transient or unspecific. While it is known that microorganisms can be transmitted from plant tissues to seeds and from seeds to seedlings, the experimental confirmation of bacterial transfer through successive plant generations remains unreported. In this study, we identified Pantoea as the unique core endophytic bacteria inhabiting the endosperms of 24 wheat seed samples originally harvested in different worldwide locations. Remarkably, Pantoea is the genus with the highest relative average abundance in wheat seeds (61%) and also in germinated seedlings grown under gnotobiotic conditions (30%). In the field, it was the only genus dwelling roots, shoots, spikes and seeds of 4 different wheat varieties tested and its abundance progressively increased across these tissues. This genuine pattern of vertical enrichment, which was not found in other common wheat-associated taxa, suggests a role in the transfer of these endophytic bacteria through the seeds. To confirm intergenerational transmission, parental plants were inoculated with labelled Pantoea isolates, which specifically colonized the next generations of Poaceae plants, experimentally demonstrating bacterial vertical inheritance to the offspring generations and suggesting transmission specificity.

microbiology↗

bioRxiv2024

Inkjet-printed graphene multielectrode arrays: an accessible platform for in vitro cardiac electrophysiology

In vitro models have now become a realistic alternative to animal models for cardiotoxicity assessment. However, the cost and expertise required to implement in vitro electrophysiology systems to study cardiac cells poses a strong obstacle to their widespread use. This study presents a novel, cost-effective approach for in vitro cardiac electrophysiology using fully-printed graphene-based microelectrode arrays (pGMEAs) coupled with an open-source signal acquisition system. We characterized the pGMEAs electrical properties and biocompatibility, observing low impedance values and cell viability. We demonstrated the platforms capability to record spontaneous electrophysiological activity from HL-1 cell cultures, and we monitored and quantified their responses to chemical stimulation with noradrenaline. This study demonstrates the feasibility of producing fully-printed, graphene-based devices for in vitro electrophysiology. The accessible and versatile platform we present here represents a step further in the development of alternative methods for cardiac safety screening.

bioengineering↗

bioRxiv2024

Integrated Stress Response Triggered by Excessive Glycosylation Drives Thoracic Aortic aneurysm

Thoracic aortic aneurysms and dissections (TAAD) are marked by degenerative changes in the aortic media. Marfan syndrome is the most common inherited connective tissue disorder associated with TAAD. While vascular smooth muscle cell (VSMC) metabolism is emerging as a targetable driver of aortic aneurysm, surgical interventions remain the primary strategy to prevent aortic dissection. Our research indicates that the hexosamine biosynthetic pathway (HBP), a branch of glycolysis, is upregulated in aortas from the Fbn1C1041G/+ Marfan Syndrome mouse model. Enhancing HBP activity promotes aortic dilation and accumulation glycan-rich extracellular matrix, contributing to aortic medial degeneration in wild-type mice. Mechanistically, fueling HBP activity induces VSMC dysfunction through excessive glycosylation, which activates the Integrated Stress Response (ISR). Pharmacological inhibition of HBP, along with ISR inhibition, successfully reverses aortic dilation and aortic medial degeneration in Fbn1C1041G/+ Marfan Syndrome mouse model. Additionally, Marfan Syndrome patients show elevated levels of HBP metabolites in blood plasma and serum, and heightened HBP-ISR signaling in patients with TAAD. These findings unveil a potential causative role for the HBP-ISR axis in medial degeneration in human TAAD, underscoring the need for evaluating HBP and ISR pathway as novel biomarkers and therapeutic strategies for thoracic aortic aneurysm.

molecular biology↗

bioRxiv2024

The autophagy-related genes AtATG5 and AtATG7 influence reserve mobilisation and responses to ABA during seed germination in Arabidopsis thaliana

Autophagy is an intracellular recycling mechanism that generally degrades cytoplasmic components non-selectively, but it can also target specific substrates under certain conditions. Here, we investigate the impact of autophagy on Arabidopsis seed biology through autophagy-related (ATG) genes AtATG5 and AtATG7, and their role in ABA responses. Seeds of atg5 and atg7 mutants germinate significantly slower than Col-0, especially under ABA, and show transcriptomic differences and histochemical alterations in the organization of lipid droplets and protein storage vacuoles. Notably, immunolocalization of ATG8 is observed in PSV of Col-0, but not in atg mutants. Differentially expressed genes in atg7 compared to Col-0 in response to ABA include reported targets of the transcription factor (TF) ABI5, a master regulator of ABA signalling in the seed. Interestingly, the decrease in ABI5 normally observed in Col-0 seeds after imbibition is delayed in atg mutants, which also show altered accumulation in developing seeds of the bZIP67, an ABI5 homolog that regulates reserve biosynthesis. Yeast two-hybrid and co-immunoprecipitation assays confirmed a direct interaction with the autophagy machinery in vitro and in vivo, mediated through ATG8. Our data highlight the relevance of autophagy in seed reserve mobilization, and seed germination through ABA responses by a TF decay mechanism.

plant biology↗

bioRxiv2017

An Inference Approach Combines Spatial And Temporal Gene Expression Data To Predict Gene Regulatory Networks In Arabidopsis Stem Cells

Identifying the transcription factors (TFs) and associated networks involved in stem cell regulation is key for understanding the initiation and growth of plant tissues and organs. Although many TFs have been shown to have a role in the Arabidopsis root stem cells, a comprehensive view of the transcriptional signature of the stem cells is lacking. In this work, we used spatial and temporal transcriptomic data to predict interactions among the genes involved in stem cell regulation. For this, we transcriptionally profiled several stem cell populations and developed a gene regulatory network (GRN) inference algorithm that combines clustering with Dynamic Bayesian Network (DBN) inference. We leveraged the topology of our networks to infer potential key regulators. The results presented in this work show that our combination of molecular biology approaches, computational biology and mathematical modeling was key to identify candidate factors that function in the stem cells. Specifically, through experimental validation and mathematical modeling, we identified PERIANTHIA (PAN) as an important molecular regulator of quiescent center (QC) function.

plant biology↗