RESUMO
Genetic association studies have demonstrated the critical involvement of the microglial immune response in Alzheimer's disease (AD) pathogenesis. Phospholipase C-gamma-2 (PLCG2) is selectively expressed by microglia and functions in many immune receptor signaling pathways. In AD, PLCG2 is induced uniquely in plaque-associated microglia. A genetic variant of PLCG2, PLCG2P522R, is a mild hypermorph that attenuates AD risk. Here, we identified a loss-of-function PLCG2 variant, PLCG2M28L, that confers an increased AD risk. PLCG2P522R attenuated disease in an amyloidogenic murine AD model, whereas PLCG2M28L exacerbated the plaque burden associated with altered phagocytosis and Aß clearance. The variants bidirectionally modulated disease pathology by inducing distinct transcriptional programs that identified microglial subpopulations associated with protective or detrimental phenotypes. These findings identify PLCG2M28L as a potential AD risk variant and demonstrate that PLCG2 variants can differentially orchestrate microglial responses in AD pathogenesis that can be therapeutically targeted.
Assuntos
Doença de Alzheimer , Animais , Camundongos , Doença de Alzheimer/genética , Estudos de Associação Genética , Microglia , Fagocitose/genética , Fenótipo , Placa Amiloide , Fosfolipase C gama/metabolismoRESUMO
Flowering plants have evolved numerous intraspecific and interspecific prezygotic reproductive barriers to prevent production of unfavourable offspring1. Within a species, self-incompatibility (SI) is a widely utilized mechanism that rejects self-pollen2,3 to avoid inbreeding depression. Interspecific barriers restrain breeding between species and often follow the SI × self-compatible (SC) rule, that is, interspecific pollen is unilaterally incompatible (UI) on SI pistils but unilaterally compatible (UC) on SC pistils1,4-6. The molecular mechanisms underlying SI, UI, SC and UC and their interconnections in the Brassicaceae remain unclear. Here we demonstrate that the SI pollen determinant S-locus cysteine-rich protein/S-locus protein 11 (SCR/SP11)2,3 or a signal from UI pollen binds to the SI female determinant S-locus receptor kinase (SRK)2,3, recruits FERONIA (FER)7-9 and activates FER-mediated reactive oxygen species production in SI stigmas10,11 to reject incompatible pollen. For compatible responses, diverged pollen coat protein B-class12-14 from SC and UC pollen differentially trigger nitric oxide, nitrosate FER to suppress reactive oxygen species in SC stigmas to facilitate pollen growth in an intraspecies-preferential manner, maintaining species integrity. Our results show that SRK and FER integrate mechanisms underlying intraspecific and interspecific barriers and offer paths to achieve distant breeding in Brassicaceae crops.
Assuntos
Brassicaceae , Flores , Hibridização Genética , Proteínas de Plantas , Polinização , Brassicaceae/genética , Brassicaceae/metabolismo , Depressão por Endogamia , Óxido Nítrico/metabolismo , Fosfotransferases/metabolismo , Melhoramento Vegetal , Proteínas de Plantas/metabolismo , Pólen/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Especificidade da Espécie , Flores/metabolismo , AutofertilizaçãoRESUMO
Citrus huanglongbing (HLB), which is caused by the phloem-colonizing bacteria Candidatus Liberibacter asiaticus (CLas), poses a significant threat to citrus production worldwide. The pathogenicity mechanism of HLB remains poorly understood. SEC-dependent effectors (SDEs) have been suggested to play critical roles in the interaction between citrus and CLas. Here, we explored the function of CLIBASIA_05320 (SDE19), a core SDE from CLas, and its interaction with its host target. Our data revealed that SDE19 is expressed at higher level during infection of citrus than that during infection of the Asian citrus psyllid. Subcellular localization assays showed that SDE19 is localized in the nucleus and cytoplasm and is capable of moving from cell to cell in Nicotiana benthamiana. To investigate whether SDE19 facilitates pathogen infection, we generated transgenic Arabidopsis thaliana and citrus plants overexpressing SDE19. Transgenic A. thaliana and citrus plants were more susceptible to Pseudomonas syringae pv. tomato (Pst) and Xanthomonas citri subsp. citri (Xcc), respectively. In addition, RNA-seq analysis demonstrated that overexpression of SDE19 resulted in a reprogramming of expression of genes related to biotic stimulus responses. SDE19 interacts with Citrus sinensis Sec12, a guanine nucleotide exchange factor responsible for the assembly of plant COPII (coat protein II)-coated vesicles, which mediate vesicle trafficking from the ER to the Golgi. SDE19 colocalizes with Sec12 in the ER by binding to its N-terminal catalytic region, affecting the stability of Sec12 through the 26S proteasome. This interaction hinders the secretion of apoplastic defense-related proteins such as PR1, P69B, GmGIP1, and RCR3. Furthermore, the secretion of PR1 and callose deposition is decreased in SDE19-transgenic A. thaliana. Taken together, SDE19 is a novel virulent SDE secreted by CLas that interacts with Sec12 to disrupt vesicle trafficking, inhibit defense-related proteins secretion, and promote bacterial infection. This study sheds light on how CLas manipulates the host vesicle trafficking pathway to suppress the secretion of defense-related proteins and interfere with plant immunity.
Assuntos
Citrus sinensis , Doenças das Plantas , Imunidade Vegetal , Doenças das Plantas/microbiologia , Doenças das Plantas/imunologia , Citrus sinensis/microbiologia , Citrus sinensis/imunologia , Citrus sinensis/metabolismo , Arabidopsis/microbiologia , Arabidopsis/imunologia , Arabidopsis/metabolismo , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Plantas Geneticamente Modificadas , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Liberibacter/metabolismo , Rhizobiaceae/metabolismo , Nicotiana/microbiologia , Nicotiana/imunologia , Nicotiana/metabolismo , Transporte ProteicoRESUMO
The aboveground parts of terrestrial plants, collectively called the phyllosphere, have a key role in the global balance of atmospheric carbon dioxide and oxygen. The phyllosphere represents one of the most abundant habitats for microbiota colonization. Whether and how plants control phyllosphere microbiota to ensure plant health is not well understood. Here we show that the Arabidopsis quadruple mutant (min7 fls2 efr cerk1; hereafter, mfec)1, simultaneously defective in pattern-triggered immunity and the MIN7 vesicle-trafficking pathway, or a constitutively activated cell death1 (cad1) mutant, carrying a S205F mutation in a membrane-attack-complex/perforin (MACPF)-domain protein, harbour altered endophytic phyllosphere microbiota and display leaf-tissue damage associated with dysbiosis. The Shannon diversity index and the relative abundance of Firmicutes were markedly reduced, whereas Proteobacteria were enriched in the mfec and cad1S205F mutants, bearing cross-kingdom resemblance to some aspects of the dysbiosis that occurs in human inflammatory bowel disease. Bacterial community transplantation experiments demonstrated a causal role of a properly assembled leaf bacterial community in phyllosphere health. Pattern-triggered immune signalling, MIN7 and CAD1 are found in major land plant lineages and are probably key components of a genetic network through which terrestrial plants control the level and nurture the diversity of endophytic phyllosphere microbiota for survival and health in a microorganism-rich environment.
Assuntos
Arabidopsis/genética , Arabidopsis/microbiologia , Redes Reguladoras de Genes/genética , Componentes Aéreos da Planta/genética , Componentes Aéreos da Planta/microbiologia , Doenças das Plantas/genética , Doenças das Plantas/prevenção & controle , Arabidopsis/imunologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Morte Celular , Meio Ambiente , Firmicutes/genética , Firmicutes/isolamento & purificação , Genes de Plantas/genética , Genótipo , Fatores de Troca do Nucleotídeo Guanina/genética , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Homeostase , Microbiota/genética , Microbiota/fisiologia , Mutação , Fenótipo , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Imunidade Vegetal/genética , Folhas de Planta/genética , Folhas de Planta/microbiologia , Proteobactérias/genética , Proteobactérias/isolamento & purificaçãoRESUMO
We have developed workflows to align 3D magnetic resonance histology (MRH) of the mouse brain with light sheet microscopy (LSM) and 3D delineations of the same specimen. We start with MRH of the brain in the skull with gradient echo and diffusion tensor imaging (DTI) at 15 µm isotropic resolution which is ~ 1,000 times higher than that of most preclinical MRI. Connectomes are generated with superresolution tract density images of ~5 µm. Brains are cleared, stained for selected proteins, and imaged by LSM at 1.8 µm/pixel. LSM data are registered into the reference MRH space with labels derived from the ABA common coordinate framework. The result is a high-dimensional integrated volume with registration (HiDiver) with alignment precision better than 50 µm. Throughput is sufficiently high that HiDiver is being used in quantitative studies of the impact of gene variants and aging on mouse brain cytoarchitecture and connectomics.
Assuntos
Imagem de Tensor de Difusão , Microscopia , Camundongos , Animais , Imagem de Tensor de Difusão/métodos , Imageamento por Ressonância Magnética/métodos , Encéfalo/diagnóstico por imagem , Espectroscopia de Ressonância Magnética , Imagem de Difusão por Ressonância Magnética/métodosRESUMO
Lactylation was initially discovered on human histones. Given its nascence, its occurrence on nonhistone proteins and downstream functional consequences remain elusive. Here we report a cyclic immonium ion of lactyllysine formed during tandem mass spectrometry that enables confident protein lactylation assignment. We validated the sensitivity and specificity of this ion for lactylation through affinity-enriched lactylproteome analysis and large-scale informatic assessment of nonlactylated spectral libraries. With this diagnostic ion-based strategy, we confidently determined new lactylation, unveiling a wide landscape beyond histones from not only the enriched lactylproteome but also existing unenriched human proteome resources. Specifically, by mining the public human Meltome Atlas, we found that lactylation is common on glycolytic enzymes and conserved on ALDOA. We also discovered prevalent lactylation on DHRS7 in the draft of the human tissue proteome. We partially demonstrated the functional importance of lactylation: site-specific engineering of lactylation into ALDOA caused enzyme inhibition, suggesting a lactylation-dependent feedback loop in glycolysis.
Assuntos
Histonas , Proteoma , Glicólise , Histonas/metabolismo , Humanos , Oxirredutases/metabolismo , Proteoma/metabolismo , Espectrometria de Massas em Tandem/métodosRESUMO
Xanthomonas citri pv. citri (Xcc) causes the devastating citrus canker disease. Xcc is known to have been introduced into Florida, USA in at least three different events in 1915, 1986 and 1995 with the first two claimed to be eradicated. It was questioned whether the Xcc introduction in 1986 has been successfully eradicated. Furthermore, it is unknown how Xcc has spread throughout the citrus groves in Florida. In this study, we investigated the population structure of Xcc to address these questions. We sequenced the whole genome of 343 Xcc strains collected from Florida groves between 1997 and 2016. Our analysis revealed two distinct clusters of Xcc. Our data strongly indicate that the claimed eradication of the 1986 Xcc introduction was not successful and Xcc strains from 1986 introduction were present in samples from at least 8 counties collected after 1994. Importantly, our data revealed that the Cluster 2 strains, which are present in all 20 citrus-producing counties sampled in Florida, originated from the Xcc introduction event in the Miami area in 1995. Our data suggest that Polk County is the epicenter of the dispersal of Cluster 2 Xcc strains, which is consistent with the fact that three major hurricanes passed through Polk County in 2004. As copper-based products have been extensively used to control citrus canker, we also investigated whether Xcc strains have developed resistance to copper. Notably, none of the 343 strains contained known copper resistance genes. Twenty randomly selected Xcc strains displayed sensitivity to copper. Overall, this study provides valuable insights into the introduction, eradication, spread, and copper resistance of Xcc in Florida.
Assuntos
Citrus , Xanthomonas , Cobre , Filogenia , Xanthomonas/genética , Doenças das Plantas/genéticaRESUMO
Naturally colored cotton (NCC; Gossypium spp.) does not require additional chemical dyeing and is an environmentally friendly textile material with great research potential and applications. Our previous study using linkage and association mapping identified TRANSPARENT TESTA 2 (Gh_TT2) as acting on the proanthocyanin synthesis pathway. However, limited information is available about the genetic regulatory network of NCC. Here, we verified the effectiveness of Gh_TT2 and the roles of Gh_TT2 and red foliated mutant gene (Re) in pigment formation and deposition of brown fiber cotton (BFC). Variations in Gh_TT2 derived from interspecific hybridization between Gossypium barbadense acc. Pima 90-53 and Gossypium hirsutum acc. Handan208 resulted in gene expression differences, thereby causing phenotypic variation. Additionally, the MYB-bHLH-WD complex was found to be negatively modulated by TRANSPARENT TESTA 16/ARABIDOPSIS BSISTER (TT16/ABS). RNA-seq suggested that differential expression of homologous genes of key enzymes in the proanthocyanin synthesis pathway strongly contributes to the color rendering of natural dark brown and light brown cotton. Our study proposes a regulatory model in BFC, which will provide theoretical guidance for the genetic improvement of NCC.
RESUMO
Structural variations (SVs) are critical factors affecting genome evolution and important traits. However, identification results and functional analyses of SVs in upland cotton are rare. Here, based on the genetic relationships, breeding history and cumulative planting area of upland cotton in China, nine predominant cultivars from the past 60 years (1950s-2010s) were selected for long read sequencing to uncover genic variations and breeding improvement targets for this crop. Based on the ZM24 reference genome, 0.88-1.47 × 104 SVs per cultivar were identified, and an SV set was constructed. SVs affected the expression of a large number of genes during fiber elongation, and a transposable element insertion resulted in the glandless phenotype in upland cotton. Six widespread inversions were identified based on nine draft genomes and high-throughput chromosome conformation capture data. Multiple haplotype blocks that were always associated with aggregated SVs were demonstrated to play a pivotal role in the agronomic traits of upland cotton and drove its adaptation to the northern planting region. Exotic introgression was the source of these haplotype blocks and increased the genetic diversity of upland cotton. Our results enrich the genome resources of upland cotton, and the identified SVs will promote genetic and breeding research in cotton.
Assuntos
Melhoramento Vegetal , Locos de Características Quantitativas , Fenótipo , Haplótipos , Alelos , Gossypium/genética , Fibra de AlgodãoRESUMO
Flowering cherry is a very popular species around the world. High-quality genome resources for different elite cultivars are needed, and the understanding of their origins and the regulation of key ornamental traits are limited for this tree. Here, a high-quality chromosome-scale genome of Prunus campanulata 'Plena' (PCP), which is a native and elite flowering cherry cultivar in China, was generated. The contig N50 of the genome was 18.31 Mb, and 99.98% of its contigs were anchored to eight chromosomes. Furthermore, a total of 306 accessions of flowering cherry germplasm and six lines of outgroups were collected. Resequencing of these 312 lines was performed, and 761â 267 high-quality genomic variants were obtained. The origins of flowering cherry were predicted, and these 306 accessions could be classified into three clades, A, B and C. According to phylogenetic analysis, we predicted two origins of flowering cherry. Flowering cherry in clade A originated in southern China, such as in the Himalayan Mountains, while clades B and C originated in northeastern China. Finally, a genome-wide association study of flower colour was performed for all 312 accessions of flowering cherry germplasm. A total of seven quantitative trait loci (QTLs) were identified. One gene encoding glycosylate transferase was predicted as the candidate gene for one QTL. Taken together, our results provide a valuable genomic resource and novel insights into the origin, evolution and flower colour variations of flowering cherry.
Assuntos
Estudo de Associação Genômica Ampla , Prunus avium , Filogenia , Cor , Prunus avium/genética , Flores/genéticaRESUMO
BACKGROUND: Citrus is a major fruit crop, and RNA-sequencing (RNA-seq) data can be utilized to investigate its gene functions, heredity, evolution, development, and the detection of genes linked to essential traits or resistance to pathogens. However, it is challenging to use the public RNA-seq datasets for researchers without bioinformatics training, and expertise. RESULTS: OrangeExpDB is a web-based database that integrates transcriptome data of various Citrus spp., including C. limon (L.) Burm., C. maxima (Burm.) Merr., C. reticulata Blanco, C. sinensis (L.) Osbeck, and Poncirus trifoliata (L.) Raf., downloaded from the NCBI SRA database. It features a blast tool for browsing and searching, enabling quick download of expression matrices for different transcriptome samples. Expression of genes of interest can be easily generated by searching gene IDs or sequence similarity. Expression data in text format can be downloaded and presented as a heatmap, with additional sample information provided at the bottom of the webpage. CONCLUSIONS: Researchers can utilize OrangeExpDB to facilitate functional genomic analysis and identify key candidate genes, leveraging publicly available citrus RNA-seq datasets. OrangeExpDB can be accessed at http://www.orangeexpdb.com/ .
Assuntos
Citrus , Bases de Dados Genéticas , Citrus/genética , Transcriptoma , Perfilação da Expressão Gênica/métodos , Biologia Computacional/métodos , Regulação da Expressão Gênica de PlantasRESUMO
Brain development is a highly complex process regulated by numerous genes at the molecular and cellular levels. Brain tissue exhibits serial microstructural changes during the development process. High-resolution diffusion magnetic resonance imaging (dMRI) affords a unique opportunity to probe these changes in the developing brain non-destructively. In this study, we acquired multi-shell dMRI datasets at 32 µm isotropic resolution to investigate the tissue microstructure alterations, which we believe to be the highest spatial resolution dMRI datasets obtained for postnatal mouse brains. We adapted the Allen Developing Mouse Brain Atlas (ADMBA) to integrate quantitative MRI metrics and spatial transcriptomics. Diffusion tensor imaging (DTI), diffusion kurtosis imaging (DKI), and neurite orientation dispersion and density imaging (NODDI) metrics were used to quantify brain development at different postnatal days. We demonstrated that the differential evolutions of fiber orientation distributions contribute to the distinct development patterns in white matter (WM) and gray matter (GM). Furthermore, the genes enriched in the nervous system that regulate brain structure and function were expressed in spatial correlation with age-matched dMRI. This study is the first one providing high-resolution dMRI, including DTI, DKI, and NODDI models, to trace mouse brain microstructural changes in WM and GM during postnatal development. This study also highlighted the genotype-phenotype correlation of spatial transcriptomics and dMRI, which may improve our understanding of brain microstructure changes at the molecular level.
Assuntos
Encéfalo , Imagem de Difusão por Ressonância Magnética , Transcriptoma , Animais , Camundongos , Encéfalo/crescimento & desenvolvimento , Encéfalo/diagnóstico por imagem , Encéfalo/anatomia & histologia , Imagem de Difusão por Ressonância Magnética/métodos , Imagem de Tensor de Difusão/métodos , Substância Branca/crescimento & desenvolvimento , Substância Branca/diagnóstico por imagem , Substância Cinzenta/crescimento & desenvolvimento , Substância Cinzenta/diagnóstico por imagem , Substância Cinzenta/anatomia & histologia , Camundongos Endogâmicos C57BL , Masculino , FemininoRESUMO
Attention is one of the basic cognitive functions sensitive to high altitude, and most studies have focussed on exposure times of approximately 3 years; however, it is unclear how attention changes in migrants who have lived and worked at high altitude for nearly 20 years. We explored the dynamics of attentional networks and neurophysiological mechanisms in migrants over 3-20 years using the Attentional Network Test combined with Electrocardiograph and Electroencephalography and found a consistent quadratic correlation between exposure and executive control efficiency, P3 amplitude and heart rate variability (HRV), with a decrease followed by an increase/relative stability, with approximately 10 years being the breakpoint. However, neither linear nor quadratic trajectories were observed for the alerting and orienting network. Mediation analysis revealed that the P3 amplitude mediated the decrease and increase in executive control efficiency with exposure time depends on the breakpoint. Correlations between HRV and executive control efficiency and P3 amplitude suggest that U-shaped changes in executive control in migrants may be related to body homeostasis maintained by the autonomic nervous system, and that P3 amplitude may serve as a neurophysiological marker of migrants' adaptation/recovery from high-altitude exposure.
RESUMO
Z-DNA binding protein 1 (ZBP1), a cytosolic nucleic acid sensor for Z-form nucleic acids (Z-NA), can detect both exogenous and endogenous nucleic acids. Upon sensing of self Z-NA or exposure to diverse noxious stimuli, ZBP1 regulates inflammation by activating nuclear factor kappa B and interferon regulating factor 3 signaling pathways. In addition, ZBP1 promotes the assembly of ZBP1 PANoptosome, which initiates caspase 3-mediated apoptosis, mixed lineage kinase domain like pseudokinase (MLKL)-mediated necroptosis, and gasdermin D (GSDMD)-mediated pyroptosis (PANoptosis), leading to the release of various damage-associated molecular patterns. Thereby, ZBP1 is implicated in the development and progression of diverse sterile inflammatory diseases. This review outlines the expression, structure, and function of ZBP1, along with its dual roles in controlling inflammation and cell death to orchestrate innate immunity in sterile inflammation, especially autoimmune diseases, and cancers. ZBP1 has emerged as an attractive therapeutic target for various sterile inflammatory diseases.
Assuntos
Ácidos Nucleicos , Humanos , Apoptose , Morte Celular , Piroptose , Inflamação/genéticaRESUMO
Callus formation is important for numerous biological processes in plants. Previously, we revealed that the PdeWRKY75-PdeRBOHB module positively regulates hydrogen peroxide (H2 O2 ) accumulation, thereby affecting callus formation in poplar. In this study, we identified and confirmed a transcription factor, PdeERF114, that interacts with PdeWRKY75 both in vitro and in vivo. Gene expression analysis identified both PdeRBOHB and PdeEXPB2 as downstream genes of PdeERF114 and PdeWRKY75. Overexpression (OE) and reduced-expression (RE) transgenic poplar lines for these four genes were generated, and the observation of callus formation was also performed in all plant materials. We demonstrated that PdeERF114 and PdeWRKY75 formed a protein complex and that this complex could bind W-Box motifs in the promoters of PdeRBOHB and PdeEXPB2, thereby positively regulating the expression of PdeRBOHB and PdeEXPB2. The OE/RE transgenic lines for these four genes also showed enhanced/reduced callus formation. Overall, we revealed a novel gene regulatory network for the regulation of callus formation in plants that involves four genes and regulates callus formation through two pathways: the accumulation of H2 O2 in explants and the relaxation of cell walls. In the future, the four genes could be used to enhance transformation effectiveness in genetic engineering.
Assuntos
Populus , Fatores de Transcrição , Regiões Promotoras Genéticas/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Perfilação da Expressão Gênica , Parede Celular/metabolismo , Regulação da Expressão Gênica de Plantas , Populus/genética , Populus/metabolismo , Plantas Geneticamente Modificadas/metabolismoRESUMO
Diffusion-weighted imaging (DWI) is an established MRI technique that can investigate tissue microstructure at the scale of a few micrometers. Musculoskeletal tissues typically have a highly ordered structure to fulfill their functions and therefore represent an optimal application of DWI. Even more since disruption of tissue organization affects its biomechanical properties and may indicate irreversible damage. The application of DWI to the musculoskeletal system faces application-specific challenges on data acquisition including susceptibility effects, the low T2 relaxation time of most musculoskeletal tissues (2-70 msec) and the need for sub-millimetric resolution. Thus, musculoskeletal applications have been an area of development of new DWI methods. In this review, we provide an overview of the technical aspects of DWI acquisition including diffusion-weighting, MRI pulse sequences and different diffusion regimes to study tissue microstructure. For each tissue type (growth plate, articular cartilage, muscle, bone marrow, intervertebral discs, ligaments, tendons, menisci, and synovium), the rationale for the use of DWI and clinical studies in support of its use as a biomarker are presented. The review describes studies showing that DTI of the growth plate has predictive value for child growth and that DTI of articular cartilage has potential to predict the radiographic progression of joint damage in early stages of osteoarthritis. DTI has been used extensively in skeletal muscle where it has shown potential to detect microstructural and functional changes in a wide range of muscle pathologies. DWI of bone marrow showed to be a valuable tool for the diagnosis of benign and malignant acute vertebral fractures and bone metastases. DTI and diffusion kurtosis have been investigated as markers of early intervertebral disc degeneration and lower back pain. Finally, promising new applications of DTI to anterior cruciate ligament grafts and synovium are presented. The review ends with an overview of the use of DWI in clinical routine. EVIDENCE LEVEL: 5 TECHNICAL EFFICACY: Stage 3.
Assuntos
Doenças da Medula Óssea , Sistema Musculoesquelético , Fraturas da Coluna Vertebral , Criança , Humanos , Imagem de Difusão por Ressonância Magnética/métodos , Sistema Musculoesquelético/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Fraturas da Coluna Vertebral/patologiaRESUMO
Citrus Huanglongbing (HLB) caused by 'Candidatus Liberibacter asiaticus' (CLas) is the most devastating citrus disease worldwide. CLas induces systemic and chronic reactive oxygen species (ROS) production, which has been suggested to be a primary cause of cell death in phloem tissues and subsequent HLB symptoms. Mitigating oxidative stress caused by CLas using horticultural approaches has been suggested as a useful strategy to reduce HLB damages. To provide information regarding the application timing to mitigate ROS, we investigated monthly dynamics of CLas concentration, CLas-triggered ROS, and phloem cell death in the bark tissues of asymptomatic and symptomatic branches of HLB-positive Hamlin and Valencia sweet orange trees in the field. Healthy branches in the screenhouse were used as controls. CLas concentration exhibited significant variations over the course of the year, with two distinct peaks observed in Florida citrus groves-late spring/early summer and late fall. Within both Hamlin and Valencia asymptomatic tissues, CLas concentration demonstrated a negative correlation with the deviation between the monthly average mean temperature and the optimal temperature for CLas colonization in plants (25.7°C). However, such a correlation was not evident in symptomatic tissues of Hamlin or Valencia sweet oranges. ROS levels were consistently higher in symptomatic or asymptomatic branches than in healthy branches in most months. ROS concentrations were higher in symptomatic branches than in asymptomatic branches in most months. CLas triggered significant increases in ion leakage in most months for asymptomatic and symptomatic branches compared with healthy controls. In asymptomatic branches of Hamlin, a positive correlation was observed between CLas concentration and ROS concentrations, CLas concentration and ion leakage levels, as well as ROS and ion leakage. Intriguingly, such a relationship was not observed in Valencia asymptomatic branches or in the symptomatic branches of Hamlin and Valencia. This study sheds light on the pathogenicity of CLas by providing useful information on the temporal dynamics of ROS production, phloem cell death, and CLas growth, as well as provides useful information in determining the timing for application of antioxidants and antimicrobial agents to control HLB.
Assuntos
Citrus sinensis , Doenças das Plantas , Espécies Reativas de Oxigênio , Rhizobiaceae , Espécies Reativas de Oxigênio/metabolismo , Citrus sinensis/microbiologia , Doenças das Plantas/microbiologia , Rhizobiaceae/fisiologia , Floema/microbiologia , Casca de Planta/microbiologia , Liberibacter , Íons/metabolismoRESUMO
In this review, we highlight studies in which whole-genome sequencing, comparative genomics, and population genomics have provided unprecedented insights into past and ongoing pathogen evolution. These include new understandings of the adaptive evolution of secretion systems and their effectors. We focus on Xanthomonas pathosystems that have seen intensive study and improved our understanding of pathogen emergence and evolution, particularly in the context of host specialization: citrus canker, bacterial blight of rice, and bacterial spot of tomato and pepper. Across pathosystems, pathogens appear to follow a pattern of bursts of evolution and diversification that impact host adaptation. There remains a need for studies on the mechanisms of host range evolution and genetic exchange among closely related but differentially host-specialized species and to start moving beyond the study of specific strain and host cultivar pairwise interactions to thinking about these pathosystems in a community context.
Assuntos
Doenças das Plantas , Xanthomonas , Xanthomonas/genética , Xanthomonas/patogenicidade , Xanthomonas/fisiologia , Doenças das Plantas/microbiologia , Evolução Biológica , Interações Hospedeiro-Patógeno , Especificidade de Hospedeiro , Genoma Bacteriano/genética , Oryza/microbiologia , Citrus/microbiologia , Capsicum/microbiologia , Genômica , Evolução MolecularRESUMO
Plant diseases significantly impact food security and food safety. It was estimated that food production needs to increase by 50% to feed the projected 9.3 billion people by 2050. Yet, plant pathogens and pests are documented to cause up to 40% yield losses in major crops, including maize, rice, and wheat, resulting in annual worldwide economic losses of approximately US$220 billion. Yield losses due to plant diseases and pests are estimated to be 21.5% (10.1 to 28.1%) in wheat, 30.3% (24.6 to 40.9%) in rice, and 22.6% (19.5 to 41.4%) in maize. In March 2023, The American Phytopathological Society (APS) conducted a survey to identify and rank key challenges in plant pathology in the next decade. Phytopathology subsequently invited papers that address those key challenges in plant pathology, and these were published as a special issue. The key challenges identified include climate change effect on the disease triangle and outbreaks, plant disease resistance mechanisms and its applications, and specific diseases including those caused by Candidatus Liberibacter spp. and Xylella fastidiosa. Additionally, disease detection, natural and man-made disasters, and plant disease control strategies were explored in issue articles. Finally, aspects of open access and how to publish articles to maximize the Findability, Accessibility, Interoperability, and Reuse of digital assets in plant pathology were described. Only by identifying the challenges and tracking progress in developing solutions for them will we be able to resolve the issues in plant pathology and ultimately ensure plant health, food security, and food safety.