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Longitudinal whole-genome analysis of bluetongue virus identifies conserved serotype-specific genomes and distinct genomic constellations within a Colorado sheep flock (2021-2023).

Bluetongue virus (BTV) is a segmented double-stranded RNA virus of ruminants transmitted by Culicoides spp. biting midges. Although the genome consists of ten segments, classification into serotypes is primarily based on genome segment 2. However, reassortment among genomic segments is a major driver of BTV evolution and diversity. This study used longitudinal whole-genome sequencing to characterize BTV genomes collected from 2021 to 2023 within a single sheep flock in Colorado, where multiple serotypes co-circulate. Whole-genome sequences were generated from fourteen blood samples representing four serotypes: BTV-6, -11, -13, and -17. Longitudinal sampling identified multiple BTV serotypes within individual sheep across consecutive years. Tanglegram analysis comparing segment phylogenies to the segment 2 tree demonstrated incongruent topologies across all genomic segments, suggestive of reassortment or the circulation of distinct genomic constellations. Nucleotide-level comparisons revealed high sequence homology among same-serotype samples from the same year, while the greatest genetic divergence was observed among BTV-17 genomes collected in different years. Additionally, all BTV-13 genomes contained a previously undescribed nonsynonymous substitution in segment 10 predicted to extend the encoded protein by three amino acids. Together, these findings demonstrate that highly conserved BTV genomes and distinct genomic constellations can be detected at the flock level across multiple years. This longitudinal whole-genome approach reveals the genetic complexity of endemic BTV populations, including novel variants and genomic patterns consistent with reassortment that are lost with conventional serotyped-based approaches, highlighting the need to integrate whole-genome characterization into endemic BTV monitoring programs.

Animals

Upscaling Genotyping by Amplicon Sequencing With GBAS-GUI.

Genotyping by amplicon sequencing (GBAS) is a relatively low-cost approach for generating genotypic data compared with established genomic methods, making it highly scalable and particularly suitable for large-scale genetic monitoring projects. However, most existing analytical pipelines are either marker-specific, insufficiently scalable, or lacking efficient data management systems for the long-term integration of genotypic information, limiting the full potential of GBAS. Here, we address this gap by introducing GBAS-GUI (https://github.com/sonnenbe-dot/GBAS-GUI), a pipeline capable of generating GBAS-based genotypic data for a wide variety of loci at scale. GBAS-GUI integrates a graphical user interface with multiple checkpoints to improve accessibility and robustness. It implements multiprocessing architecture and a relational database that links genotypic data with associated sample metadata to enhance scalability and data management. The pipeline further enables marker screening through automated calculation of polymorphism information content (PIC) and implements a strategy to recover homologous genotypic information from paralogous loci with non-overlapping amplicon length ranges. Using multiple empirical datasets, we demonstrate substantial improvements in processing speed, database management and handling artefacts related to co-amplification of unspecific regions and duplicates of the same genomic region. We further show that incorporating the full sequence information captured by an amplicon increases marker information content beyond what is achievable with length-based genotyping alone and expands the analytical versatility of GBAS. Overall, GBAS-GUI provides a robust, scalable and versatile framework that unlocks the potential of GBAS for large-scale population genetic and phylogeographic studies.

Genotyping Techniques

Mendelian randomisation for rheumatology: beyond hype-what it's good for, what it can't do, and how to read it critically.

Mendelian randomisation (MR) has become abundant in the literature, with variation in quality and frequent overinterpretation of causality. This creates a problem for clinical readers, reviewers, and editors: some MR studies can sharpen causal thinking, prioritise drug targets, and challenge misleading observational claims, whereas others are little more than automated exposure-outcome scans with causal claims disproportionate to the evidence. MR can strengthen causal inference when randomised trials are impractical and conventional observational studies are vulnerable to confounding, reverse causation, or selection bias. In rheumatology, credible MR can contribute to questions about disease aetiology, modifiable risk factors, therapeutic target validation, adverse-effect anticipation, and phenotype validation. However, its interpretation depends on whether the exposure is plausibly instrumentable, whether the genetic instruments are biologically defensible, whether assumptions are interrogated in ways appropriate to the design, and whether findings are triangulated with clinical, observational, experimental, and mechanistic evidence. Instead of recapitulating all methodological issues of MR, this review aims to help rheumatologists distinguish robust MR from weak or overinterpreted analyses quickly. We provide an accessible framework for reading and triaging MR studies in rheumatology. Papers that use poorly justified instruments, treat medication use as drug-target evidence, interpret genetic liability as diagnosis, rely on mechanical sensitivity analyses, ignore prior evidence or ask no clinically meaningful question can often be passed over by readers. The goal is not to discourage MR in rheumatology, but to raise the standard; useful MR should clarify causal reasoning rather than simply generate another statistically significant association.

Journal Article

The Childhood Cancer and Leukemia International Consortium (CLIC): Expanding global collaboration in pediatric cancer etiology research.

Childhood cancers are rare, but incidence has risen modestly in countries with robust registration, partly reflecting improved diagnosis. In high-income countries, cancer is the leading cause of disease-related death in children. Marked inequities in incidence, survival, and research capacity underscore the need for large-scale collaboration to identify environmental, genetic, and contextual determinants of risk. The Childhood Cancer and Leukemia International Consortium (CLIC) was established in 2007 to study the etiology of childhood leukemia and later expanded in 2019 to include other childhood cancers, principally solid tumors. CLIC pools harmonized, individual-level data from case-control and cohort studies, obtained through interviews, record linkage (insurance claims, registries), or geographic information systems, and integrates germline genomic data where available. Membership has grown from 13 studies in 9 countries to 57 studies in 21 countries; recruitment spans the early 1960s to the present and encompasses approximately 150,000 cases across all tumor types and 300,000 controls with clinical, demographic, and exposure data, centralized via harmonized data dictionaries at the Data Coordination Center, established in 2014 at the International Agency for Research on Cancer, and supported by a secure analysis platform. Pooled analyses across diverse populations have implicated parental age, prenatal vitamin or folic acid use, mode of delivery, fetal growth, selected congenital anomalies, occupational or household exposures (e.g., pesticides), paternal smoking, and markers of early-life immune modulation (e.g., breastfeeding, daycare attendance) in leukemia risk, informing carcinogen evaluation and prevention. The integration of genetic ancestry and germline susceptibility data is clarifying ancestry-related differences in leukemia biology and outcomes, while confirming risk loci with population-specific effects. CLIC is now adding polygenic risk scores and exposomic data to refine etiologic subtyping and identify modifiable pathways, while broadening representation from underserved regions through partnership-building and capacity-strengthening.

Humans

Cross-tissue multi-omics integration highlights BPHL and mitochondrial targets in Alzheimer's disease.

BACKGROUND: Mitochondrial dysfunction is a hallmark of Alzheimer's disease (AD), yet specific molecular targets remain to be fully characterized. METHODS: A summary-data-based Mendelian randomization (SMR) framework integrated AD genome-wide association study (GWAS) statistics (39,918 cases) with blood DNA methylation quantitative trait loci (mQTL), gene expression (eQTL), and protein (pQTL) data for 1136 mitochondria-related genes. Associations were assessed using Bayesian colocalization and HEIDI testing. Tissue relevance was evaluated in four brain regions (hippocampus, amygdala, cortex, frontal cortex) using GTEx and external transcriptomic datasets. RESULTS: Screening identified eight candidates supported across blood mQTL and eQTL layers. Stepwise central nervous system (CNS) evaluation singled out biphenyl hydrolase-like (BPHL) as the consistent candidate. Higher genetically predicted BPHL expression was associated with reduced AD risk across the hippocampus (OR=0.920, 95% CI 0.873-0.970), amygdala (OR=0.925, 95%CI 0.880-0.973), cortex (OR=0.943, 95% CI 0.908-0.978), and frontal cortex (OR=0.938, 95%CI 0.901-0.976). These findings aligned with protein-protein interactions connecting BPHL to respiratory complexes and lower BPHL expression in independent AD brains. Functional enrichment converged on oxidative phosphorylation pathways. CONCLUSIONS: By integrating multi-omics data with tissue-specific validation, this study nominates BPHL as a consistent protective candidate in the brain. These findings provide genetic support for mitochondrial molecular perturbations in AD, offering insights for future validation.

Alzheimer Disease

Adeno-Associated Virus Gene Therapy Translation: Lessons from Early Regulatory Meetings.

The Platform Vector-Gene Therapy (PaVe-GT) program is a National Institutes of Health (NIH) initiative that aims to develop adeno-associated virus (AAV) gene therapies for four monogenic rare diseases, two organic acidemias and two congenital myasthenic syndromes. PaVe-GT's platform-based approach identifies and diminishes redundancies and applies efficiencies in preclinical, clinical, and regulatory activities. The program's hypothesis is that implementing these efficiencies can accelerate clinical trial initiation. Based on its platform-centric experience and public-serving mission, the PaVe-GT program actively shares its scientific and regulatory learnings with the public to benefit the development of similar gene therapy products for rare diseases. PaVe-GT's first investigational AAV gene therapy candidate is AAV serotype 9 human propionyl-CoA carboxylase alpha subunit (AAV9-hPCCA) for propionic acidemia caused by PCCA deficiency, which received initial feedback from the Food and Drug Administration (FDA) in an INitial Targeted Engagement for Regulatory Advice on CBER/Center for Drug Evaluation and Research (CDER) ProducTs (INTERACT) meeting. Upon further product development that took into consideration the FDA's initial advice, the program obtained the Agency's feedback in pre-investigational new drug (IND) (Type B) and Type C meetings. Here, we share our experience from these meetings, including strategy, preparation, pre- and post-meeting feedback from the FDA, and lessons learned during the AAV9-hPCCA regulatory process, which the program plans to apply across the PaVe-GT platform. Topics discussed in the regulatory meetings included animal model and efficacy studies, toxicology study plans, manufacturing of the investigational AAV product, and clinical trial design. The main lessons learned from the pre-IND and Type C meetings for AAV9-hPCCA are: (1) Pharmacology/Toxicology studies in a single rodent species are sufficient for filing an initial IND; (2) FDA feedback guides product quality improvements and early development of a quantitative potency assay; (3) use of biomarkers as potential surrogate endpoints in a future efficacy trial benefits from collection of data in the natural history study and the first-in-human Phase 1/2 study; and (4) evidence from the Phase 1/2 clinical trial could be leveraged to support a license application. Lightly redacted regulatory documents and comprehensive templates developed by the PaVe-GT team are available on the PaVe-GT website.

Dependovirus

[A case of bilateral open-lip schizencephaly with West syndrome due to variant of PAFAH1B1 gene and literature review].

OBJECTIVE: To report the clinical manifestations, genetic features, diagnosis, treatment, and prognosis of a child with bilateral open-lip schizencephaly complicated by West syndrome due to a variant of PAFAH1B1 gene, and review the relevant literature. METHODS: Clinical data of a 4-month-old boy were retrospectively analyzed, and 35 previously reported cases were systematically reviewed. This study was approved by the Medical Ethics Committee of Gansu Provincial People's Hospital (Ethics No.: 2025-871). RESULTS: The 4-month-old boy presented with clustered flexor spasms, hypsarrhythmia on electroencephalography, and developmental regression. Brain magnetic resonance imaging revealed bilateral pachygyria, schizencephaly, and dysgenesis of the corpus callosum. Trio whole-exome sequencing identified a de novo heterozygous NM_000430.4: c.703_704delAG (p.Glu235Metfs*20) frameshift variant in the PAFAH1B1 gene. Sanger sequencing confirmed that neither parent carried this variant. Based on the guidelines from American College of Medical Genetics and Genomics (ACMG), the variant has met the criteria for PVS1+PS2_Moderate+PM2_Supporting, and was classified as pathogenic. After treatment with adrenocorticotropic hormone combined with vigabatrin and other antiseizure medications, the epileptic spasms were controlled and the electroencephalographic abnormalities had improved. However, global developmental delay persisted at the 12-month follow-up. Analysis of the present case and 35 previously reported cases showed that PAFAH1B1-related phenotypes were highly consistent, mainly including infantile spasms (28/36), developmental delay/intellectual disability (29/36), and abnormal brain MRI findings (30/36), predominantly cortical malformations. The reported variant types included deletions, frameshift variants, nonsense variants, missense variants, and splice-site variants. CONCLUSION: PAFAH1B1 gene variants are an important cause for cortical malformations, including schizencephaly, and may lead to secondary West syndrome. This study has systematically summarized the genotypic and phenotypic features of bilateral open-lip schizencephaly complicated by West syndrome associated with a frameshift variant of the PAFAH1B1 gene. For infants with epileptic spasms or early-onset epilepsy accompanied by structural brain abnormalities, early genetic evaluation should be performed, and antiseizure treatment should be integrated with neurodevelopmental rehabilitation to facilitate long-term management.

Humans

Functional characterization of the MdFLZ2 gene in drought and salt stress tolerance in apple.

Drought and salt stress are significant environmental limitations that severely constrain plant growth and productivity, therefore, enhancing stress tolerance is a key goal in crop improvement. The plant-specific FCS-like zinc finger (FLZ) proteins have been identified as important regulators of stress adaptation. In this study, we conducted a genome-wide characterization of the FLZ gene family in apple and functionally characterized MdFLZ2. qRT-PCR analysis revealed that MdFLZ2 was differentially expressed across various tissues and transcriptionally induced by both drought and salt stress. Subcellular localization assays demonstrated that the MdFLZ2 protein is localized to both the nucleus and the cytoplasm. The overexpression of MdFLZ2 in apple calli, Arabidopsis and tomato conferred increased resistance to drought and salt stress. In addition, yeast two-hybrid (Y2H) assays confirmed that MdFLZ2 interacted with MdSnRK1.1, and similar interactions were also detected between other MdFLZ family members and MdSnRK1.1. Collectively, our findings suggest MdFLZ2 as a positive regulator of drought and salt tolerance and highlight its potential to serve as a genetic resource for abiotic stress improvement.

Malus

Epithelial regeneration in the gastrointestinal tract.

The gastrointestinal tract possesses a remarkable regenerative capacity to maintain tissue homeostasis against various injuries. However, the intestine and stomach exhibit distinct regenerative strategies. In the intestine, damage to Lgr5-positive (Lgr5+) stem cells induces cellular plasticity and the emergence of transient Revival stem cells (RevSCs), a process critically dependent on YAP/TAZ signaling. Conversely, the stomach utilizes paligenosis, where quiescent p57-positive (p57+) mature chief cells act as reserve stem cells, dedifferentiating to restore damaged tissue. Although the cellular origins differ, both organs appear to share some common regenerative features, including transient activation of pro-proliferative programs such as YAP/TAZ signaling. In contrast, whether Retinoic Acid (RA) signaling also serves as a conserved mechanism for regenerative resolution in the stomach remains to be determined. In this review, we discuss the cellular and molecular mechanisms governing regeneration in these two organs. This comparative analysis provides a framework for future research.

Regeneration

Wildlife forensic DNA evidence links a suspected vehicle to a fatal lowland tapir (Tapirus terrestris) collision in Misiones, Argentina.

Vehicle collisions are recognized as a major driver of biodiversity loss, particularly in road-dense landscapes, exceeding the impact of invasive species and wildlife trafficking. For large-bodied, slow-reproducing, and low-abundance species, such as the lowland tapir (Tapirus terrestris), this threat can have major impacts. Here, we present a wildlife forensic investigation in Misiones, Argentina, involving a tapir, a species afforded the highest level of legal protection as a Provincial Natural Monument. The fatal hit-by-vehicle (HBV) incident occurred in northern Misiones on 31 March 2019 along Provincial Route 19, in a portion that bisects Parque Provincial Urugua-í, with the driver involved in the collision leaving the scene. The suspect was later located and claimed that the damage to the vehicle resulted from a collision with a horse (Equus caballus) rather than a tapir. To legally resolve the incident, DNA (hair and blood) recovered from the suspected vehicle's bumper (evidence) was compared with tissue samples from the tapir carcass (reference). Genetic confirmation of species identity used a 110-bp region of the mitochondrial cytochrome b gene, and individual identity was assessed using 12 species-specific microsatellite loci. These analyses confirmed that all evidence matched the tapir carcass at both species and individual levels, strongly supporting the association between the suspected vehicle and the HBV tapir, and refuting the alternative explanation proposed by the driver. This case demonstrates the value of using wildlife forensic genetics to reconstruct wildlife-vehicle collisions, supporting environmental law enforcement, and strengthening conservation efforts in the Atlantic Forest of Misiones, Argentina.

Animals

A therapeutic atlas of monogenic inflammatory bowel disease.

BACKGROUND AND AIMS: Evidence-based, mechanism-guided therapies are urgently needed for treating monogenic inflammatory bowel disease (mIBD). For such rare diseases, mechanistic insight is essential to guide treatment when conventional clinical trials are often not feasible. We aimed to summarize literature-based evidence and to identify knowledge gaps. METHODS: We conducted a systematic review of published manuscripts evaluating the therapeutic efficacy in mIBD. We quantified and compared the global therapeutic response score across treatments and conditions. In a subset of conditions, biomarkers of longitudinal therapeutic response were evaluated in comparison to non-monogenic pediatric IBD cohorts. RESULTS: Responses to 35 therapeutics across the 102 known genetic causes of mIBD were evaluated in 241 articles and 669 patients, summarizing 302 gene-drug responses. The efficacy of at least one pharmacological intervention was identified in 61% (n = 62/102) of the mIBD conditions, highlighting a major unmet need for effective medications in many others. Gene- and pathway-specific responses were demonstrated for several therapies, including allogeneic hematopoietic stem cell transplantation, gene therapy, and advanced therapies such as anti-TNF agents, IL-1 inhibitors, mTOR inhibitors, as well as eculizumab in CD55 deficiency, abatacept in CTLA4 deficiency, and the immunometabolic agent empagliflozin in glycogen storage disease type 1b. CONCLUSIONS: This study highlights the potential of precision medicine approaches tailored to genetic and pathway-specific mechanisms, while underscoring the urgent need for effective therapies in many monogenic conditions that remain without established treatment options.

Humans

The cold case of state transition 7 (stt7) mutants of Chlamydomonas reinhardtii, solved by whole-genome sequencing.

The process of State Transitions (ST) corresponds to an STT7 kinase-driven redistribution of the transmembrane LHCII antenna proteins between Photosystem II (PSII) and Photosystem I (PSI), which results from changes in their phosphorylation state. For the past two decades, two LHCII-kinase mutants, stt7-1 and stt7-9, have been instrumental in the study of STs in Chlamydomonas reinhardtii, the former being a null mutant for the kinase but quasi-sterile in crosses, while the latter, although fertile, has a leaky phenotype. Using long-read sequencing, this study further characterized the genetic lesions of the stt7 mutant strains through whole-genome reconstruction and de novo chromosome assembly. In addition, two new stt7 null mutants were generated, one derived by crosses from the original stt7-1 and one obtained by Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-associated protein 9 (Cas9) technology. This work provides a comprehensive genomic characterization of the original stt7-1 null mutant, revealing extensive chromosomal rearrangements and high levels of aneuploidy, associated with increased cell size and meiotic dysfunction. Reassessment of their physiology and genetic backgrounds highlights the need for caution in interpreting genetic information. We thus produced more reliable null mutants for the LHCII-kinase, amenable to genetic crosses for the study of STs in a variety of genetic backgrounds.

Chlamydomonas reinhardtii

A case report of Xp21 contiguous gene deletion syndrome with adrenal crisis and sensorineural hearing loss: clinical highlights and management pitfalls.

OBJECTIVES: To report a rare association of Xp21 contiguous gene deletion syndrome (CGDS) featuring sensorineural hearing loss (SNHL), and to discuss the diagnostic and therapeutic challenges. CASE PRESENTATION: A male infant presented with a salt-wasting adrenal crisis consistent with X-linked adrenal hypoplasia congenita. His follow-up clinical course during childhood revealed global developmental delay and SNHL, the latter of which has been under-reported in the literature for this condition. At five years of age, the development of progressive proximal muscle weakness and markedly elevated creatine phosphokinase levels led to a diagnosis of Duchenne muscular dystrophy (DMD). The patient also exhibited pseudohypertriglyceridemia and elevated urinary glycerol, consistent with glycerol kinase deficiency. While initial exome sequencing failed to detect the genetic abnormality, subsequent chromosomal microarray analysis identified an Xp21 CGDS involving NR0B1, IL1RAPL1, DMD, and GK. Treatment of adrenal insufficiency with fludrocortisone and hydrocortisone was complicated by the higher steroid doses required for the management of DMD, resulting in exogenous Cushing syndrome and associated complications. CONCLUSIONS: This case highlights the necessity of evaluating for Xp21 CGDS in patients presenting with adrenal crisis and emphasizes the importance of multidisciplinary management to optimize outcomes in this complex pediatric endocrine disorder.

Humans

3D epigenomic remodelling mediated by Foxa1 drives gemcitabine resistance in pancreatic cancer.

Gemcitabine remains a cornerstone treatment for pancreatic ductal adenocarcinoma (PDAC), yet the emergence of resistance constitutes a major clinical challenge with poorly understood epigenomic mechanisms. Here, we identified the pioneer transcription factor Foxa1 as a master regulator of gemcitabine resistance through multi-omics analysis. Mechanistically, Foxa1 drives widespread super-enhancer (SE) reprogramming and 3D genome remodelling in resistant cells, which coordinately activates the expression of key resistance genes, notably Rrm1 and Cdadc1. This is accompanied by increased chromatin accessibility, elevated H3K27ac enrichment at SEs, and enhanced Foxa1 binding at regulatory elements. Moreover, post-translational stabilization of Foxa1 via USP7-mediated deubiquitination sustains this epigenomic program. Genetic ablation of Foxa1 or specific SE regions near Rrm1 resensitizes resistant cells to gemcitabine. Building upon this mechanism, we demonstrate that bromodomain and extraterminal (BET) inhibitors, which disrupt SE function, potently reverse resistance. Notably, the clinical-stage BET inhibitor AZD5153, in combination with gemcitabine, achieves robust tumor suppression and overcomes resistance in cell-derived xenograft (CDX) models by dismantling the Foxa1-mediated resistant transcriptome and reinvigorating drug sensitivity. Our findings establish Foxa1-orchestrated enhancer reprogramming as a fundamental mechanism of gemcitabine resistance and unveil a promising epigenetic therapy to restore treatment efficacy in PDAC.

Hepatocyte Nuclear Factor 3-alpha

Decoding bipotency: a transient regulatory state bridging totipotency and lineage commitment.

Early mammalian embryogenesis entails a coordinated transition from totipotency to the first lineage bifurcation, giving rise to embryonic lineages and the extra-embryonic trophectoderm. The mechanisms by which totipotency is resolved into lineage-primed states remain incompletely understood. Emerging evidence supports a non-binary model in which cells traverse a continuum of potency states, passing through a transient bipotent intermediate that retains both embryonic and extra-embryonic potential while exiting totipotency. Here, we synthesize recent advances in the mechanisms that establish, maintain, and resolve bipotency. We emphasize the coordinated roles of transposable elements, transcription factors, and signaling pathways in regulating this transition. We also highlight newly developed bipotent stem cell models and their implications in generating advanced embryo models in vitro. Notably, current insights are largely derived from mouse systems; given key differences between mouse and human early embryogenesis, extending these findings to human models remains a critical next step.

Animals

De Novo 2.2 Mb 19q13.42-q13.43 Microdeletion Encompassing U2AF2: Support for a Haploinsufficiency Model.

U2 small nuclear RNA auxiliary factor 2 (U2AF2) is an essential pre-mRNA splicing factor involved in the early stages of pre-mRNA splicing. To date, multiple individuals have been reported with predominantly heterozygous missense variants presenting intellectual disability, speech and motor delays, seizures, hypotonia, and thin or hypoplastic corpus callosum. Here, we describe a patient with a de novo 2.2 Mb interstitial deletion involving chromosome 19q13.42-q13.43, encompassing U2AF2, presenting with intellectual disability, epilepsy, corpus callosum hypoplasia, dysmorphic features, and congenital heart disease. The patient's clinical features overlap substantially with those reported in individuals harboring heterozygous U2AF2 variants, supporting haploinsufficiency as a plausible disease mechanism. To our knowledge, this represents the first postnatal report of complete U2AF2 gene deletion. In addition, this is the first detailed phenotypic characterization of a distal 19q chromosomal interstitial deletion, further delineating the clinical spectrum associated with this genomic region.

Humans

Modelling the effects of biological intervention in a dynamical gene network.

Cellular response to environmental and internal signals can be modeled by dynamical gene regulatory networks (GRN). In the literature, three main classes of gene network models can be distinguished: (1) non-quantitative (or data-based) models which do not describe the probability distribution of gene expressions; (2) quantitative models which fully describe the probability distribution of all genes co-expression; and (3) mechanistic models which allow for a causal interpretation of gene interactions. We propose two rigorous frameworks to model gene alteration in a dynamical GRN, depending on whether the network model is quantitative or mechanistic. We explain how these models can be used for design of experiment, or, if additional alteration data are available, for validation purposes or to improve the parameter estimation of the original model. We apply these methods to the Gaussian graphical model, which is quantitative but non-mechanistic, and to mechanistic models of Bayesian networks and penalized linear regression.

Gene Regulatory Networks

The RrWRKY75-mediated activation of ascorbate synthesis in Rosa roxburghii Tratt contributes to salt stress tolerance.

L-Ascorbic acid (AsA) is a key antioxidant that alleviates oxidative stress in plants. Previous yeast one-hybrid (Y1H) screening identified RrWRKY75 as a transcription factor capable of binding to the promoter of RrGGP2 (GDP-L-galactose pyrophosphatase 2), a key structural gene responsible for massive AsA accumulation in Rosa roxburghii fruit. The function of RrWRKY75 in plant stress responses remains unclear. Here, RrWRKY75 is verified to specifically bind to the RrGGP2 promoter and activate its transcription. This positive regulatory effect on RrGGP2 transcript levels and AsA accumulation is further confirmed through overexpression or silencing of RrWRKY75 in R. roxburghii fruit or callus. Among various abiotic stress conditions, RrWRKY75 expression is significantly induced by salt stress. Upon its overexpression in callus or Arabidopsis thaliana, elevated AsA levels and antioxidant capacity are observed, thereby enhancing salt tolerance. Interestingly, RrWRKY75 also binds to the promoter of RrUNE12, a salt-responsive factor in R. roxburghii, and activates its expression. Moreover, yeast two-hybrid and bimolecular fluorescence complementation (BiFC) assays confirm the physical interaction between RrWRKY75 and RrUNE12, which jointly upregulates RrGGP2 expression and AsA production. Collectively, RrWRKY75 boosts AsA biosynthesis and salt tolerance both by directly trans-activating RrGGP2 and by synergizing with RrUNE12 through transcriptional activation and protein complex formation. These findings provide insights into the regulatory role of RrWRKY75 in abiotic stress tolerance and offer valuable genetic resources for R. roxburghii germplasm improvement.

Rosa