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CtIP is a DNA end resection factor widely implicated in alternative end-joining (A-EJ)-mediated translocations in cell-based reporter systems. To address the physiological role of CtIP, an essential gene, in translocation-mediated lymphomagenesis, we introduced the T855A mutation at murine CtIP to nonhomologous end-joining and Tp53 double-deficient mice that routinely succumbed to lymphomas carrying A-EJ-mediated IgH-Myc translocations. T855 of CtIP is phosphorylated by ATM or ATR kinases upon DNA damage to promote end resection. Here, we reported that the T855A mutation of CtIP compromised the neonatal development of Xrcc4-/-Tp53-/- mice and the IgH-Myc translocation-driven lymphomagenesis in DNA-PKcs-/-Tp53-/- mice. Mechanistically, the T855A mutation limits DNA end resection length without affecting hairpin opening, translocation frequency, or fork stability. Meanwhile, after radiation, CtIP-T855A mutant cells showed a consistent decreased Chk1 phosphorylation and defects in the G2/M cell cycle checkpoint. Consistent with the role of T855A mutation in lymphomagenesis beyond translocation, the CtIP-T855A mutation also delays splenomegaly in λ-Myc mice. Collectively, our study revealed a role of CtIP-T855 phosphorylation in lymphomagenesis beyond A-EJ-mediated chromosomal translocation.
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Proteínas Portadoras/genética , Proteínas de Ciclo Celular/genética , Daño del ADN/genética , Linfoma/genética , Linfoma/patología , Fosforilación/genética , Animales , Proteínas de la Ataxia Telangiectasia Mutada/genética , Puntos de Control de la Fase G2 del Ciclo Celular/genética , Ratones , Mutación/genética , Translocación Genética/genéticaRESUMEN
BACKGROUND: Rice stripe virus (RSV) caused a serious disease pandemic in rice in East China between 2001 and 2010. The continuous integrated managements reduced virus epidemic year by year until it was non-epidemic. As an RNA virus, its genetic variability after undergoing a long-term non-epidemic period was meaningful to study. While in 2019, the sudden occurrence of RSV in Jiangsu provided an opportunity for the study. METHODS AND RESULTS: The complete genome of JY2019, an RSV isolate from Jiangyan, was determined. A genotype profile of 22 isolates from China, Japan and Korea indicated that the isolates from Yunnan formed the subtype II, and other isolates clustered the subtype I. RNA 1-3 of JY2019 isolate well-clustered in the subtype I clade, and RNA 4 was also in subtype I, but it had a slight separation from other intra-group isolates. After phylogenetic analyses, it was considered NSvc4 gene contributed to the tendency, because it exhibited an obvious trend towards the subtype II (Yunnan) group. High sequence identity (100%) of NSvc4 between JY2019 and barnyardgrass isolate from different regions demonstrated genetic variation of NSvc4 was consistent in RSV natural populations in Jiangsu in the non-epidemic period. In the phylogenetic tree of all 74 NSvc4 genes, JY2019 belonged to a minor subtype Ib, suggesting the subtype Ib isolates might have existed in natural populations before the non-epidemic period, but not a dominant population. CONCLUSIONS: Our results suggested that NSvc4 gene was susceptible to selection pressure, and the subtype Ib might be more adaptable for the interaction between RSV and hosts in the non-epidemic ecological conditions.
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Oryza , Tenuivirus , Tenuivirus/genética , Filogenia , Pandemias , China/epidemiología , ARN , Oryza/genéticaRESUMEN
Nonhomologous end-joining (NHEJ) is a major DNA double-strand break repair pathway that is conserved in eukaryotes. In vertebrates, NHEJ further acquires end-processing capacities (e.g., hairpin opening) in addition to direct end-ligation. The catalytic subunit of DNA-PK (DNA-PKcs) is a vertebrate-specific NHEJ factor that can be autophosphorylated or transphosphorylated by ATM kinase. Using a mouse model expressing a kinase-dead (KD) DNA-PKcs protein, we show that ATM-mediated transphosphorylation of DNA-PKcs regulates end-processing at the level of Artemis recruitment, while strict autophosphorylation of DNA-PKcs is necessary to relieve the physical blockage on end-ligation imposed by the DNA-PKcs protein itself. Accordingly, DNA-PKcs(KD/KD) mice and cells show severe end-ligation defects and p53- and Ku-dependent embryonic lethality, but open hairpin-sealed ends normally in the presence of ATM kinase activity. Together, our findings identify DNA-PKcs as the molecular switch that coordinates end-processing and end-ligation at the DNA ends through differential phosphorylations.
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Linfocitos B/metabolismo , Reparación del ADN por Unión de Extremidades/genética , Proteína Quinasa Activada por ADN/genética , Proteínas de Unión al ADN/genética , Endonucleasas/genética , Proteínas Nucleares/genética , Animales , Antígenos Nucleares/genética , Antígenos Nucleares/metabolismo , Proteínas de la Ataxia Telangiectasia Mutada/genética , Proteínas de la Ataxia Telangiectasia Mutada/metabolismo , Linfocitos B/citología , Línea Celular , Roturas del ADN de Doble Cadena , Proteína Quinasa Activada por ADN/metabolismo , Proteínas de Unión al ADN/metabolismo , Endonucleasas/metabolismo , Femenino , Regulación de la Expresión Génica , Autoantígeno Ku , Masculino , Ratones , Ratones Transgénicos , Proteínas Nucleares/metabolismo , Fosforilación , Transducción de Señal , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
Rice black-streaked dwarf virus disease (RBSDVD) and southern rice black-streaked dwarf virus disease (SRBSDVD) are the most destructive viral diseases in rice. Progress is limited in breeding due to lack of resistance resource and inadequate knowledge on the underlying functional gene. Using genome-wide association study (GWAS), linkage disequilibrium (LD) decay analyses, RNA-sequencing, and genome editing, we identified a highly RBSDVD-resistant variety and its first functional gene. A highly RBSDVD-resistant variety W44 was identified through extensive evaluation of a diverse international rice panel. Seventeen quantitative trait loci (QTLs) were identified among which qRBSDV6-1 had the largest phenotypic effect. It was finely mapped to a 0.8-1.2 Mb region on chromosome 6, with 62 annotated genes. Analysis of the candidate genes underlying qRBSDV6-1 showed high expression of aspartic proteinase 47 (OsAP47) in a susceptible variety, W122, and a low resistance variety, W44. OsAP47 overexpressing lines exhibited significantly reduced resistance, while the knockout mutants exhibited significantly reduced SRBSDVD and RBSDVD severity. Furthermore, the resistant allele Hap1 of OsAP47 is almost exclusive to Indica, but rare in Japonica. Results suggest that OsAP47 knockout by editing is effective for improving RBSDVD and SRBSDVD resistance. This study provides genetic information for breeding resistant cultivars.
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Proteasas de Ácido Aspártico , Oryza , Virosis , Estudio de Asociación del Genoma Completo , Oryza/genética , Péptido Hidrolasas , Fitomejoramiento , Enfermedades de las Plantas/genética , ReoviridaeRESUMEN
Research on plant-virus-vector interactions has revealed that viruses can enhance their spread to new host plants by attracting nonviruliferous vectors to infected plants or driving viruliferous vectors to noninfected plants. However, whether viruses can also modulate the feeding preference of viruliferous vectors for different plant parts remains largely unknown. Here, by using rice stripe virus (RSV) and its vector, the small brown planthopper (SBPH), as a model, the effect of the virus on the feeding preference of its vector was studied by calculating the number of nonviruliferous and viruliferous SBPHs settling on different parts of rice plants. The results showed that the RSV-free SBPHs significantly preferred feeding on the stems of rice plants, whereas RSV-carrying SBPHs fed more on rice leaves. Moreover, the rice plants inoculated with RSV on the leaves showed more severe symptoms, with enhanced disease incidence and virus accumulation compared with rice plants inoculated at the top and bottom of stems, suggesting that the leaves are more susceptible to RSV than the stems of rice plants. These results demonstrate that RSV modulates the feeding preference of its transmitting vector SBPH from the stems to leaves of rice plants to promote virus infection. Interestingly, we also found that the leaves were more susceptible than the stems to rice black-streaked dwarf virus. This study proves that the feeding preference of insect vectors can be modulated by plant viruses to facilitate virus transmission.
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Hemípteros , Oryza , Tenuivirus , Virosis , Animales , Enfermedades de las Plantas , Tenuivirus/genéticaRESUMEN
Gray leaf spot (GLS) caused by Cercospora zeae-maydis or Cercospora zeina is one of the devastating maize foliar diseases worldwide. Identification of GLS-resistant quantitative trait loci (QTL)/genes plays an urgent role in improving GLS resistance in maize breeding practice. Two groups of recombinant inbred line (RIL) populations derived from CML373 × Ye107 and Chang7-2 × Ye107 were generated and subjected to genotyping-by-sequencing (GBS). A total of 1,929,222,287 reads in CML373 × Ye107 (RIL-YCML) and 2,585,728,312 reads in Chang7-2 × Ye107 (RIL-YChang), with an average of 10,961,490 (RIL-YCML) and 13,609,096 (RIL-YChang) reads per individual, were got, which was roughly equal to 0.70-fold and 0.87-fold coverage of the maize B73 RefGen_V4 genome for each F7 individual, respectively. 6418 and 5139 SNP markers were extracted to construct two high-density genetic maps. Comparative analysis using these physically mapped marker loci demonstrated a satisfactory colinear relationship with the reference genome. 11 GLS-resistant QTL have been detected. The individual QTL accounted for 1.53-24.00% of the phenotypic variance explained (PVE). The new consensus QTL (qYCM-DS3-3/qYCM-LT3-1/qYCM-LT3-2) with the largest effect was located in chromosome bin 3.05, with an interval of 2.7 Mb, representing 13.08 to 24.00% of the PVE. Further gene annotation indicated that there were four candidate genes (GRMZM2G032384, GRMZM2G041415, GRMZM2G041544, and GRMZM2G035992) for qYCM-LT3-1, which may be related to GLS resistance. Combining RIL populations and GBS-based high-density genetic maps, a new larger effect QTL was delimited to a narrow genomic interval, which will provide a new resistance source for maize breeding programs.
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Resistencia a la Enfermedad/genética , Genoma de Planta , Micosis , Enfermedades de las Plantas , Sitios de Carácter Cuantitativo , Zea mays/genética , Cercospora , Mapeo Cromosómico , Genómica , Análisis de Secuencia de ADN , Zea mays/microbiología , Zea mays/fisiologíaRESUMEN
Increasing evidence has demonstrated that oxidative phosphorylation (OXPHOS) is closely associated with the progression of pancreatic cancer (PC). Given its central role in mitochondrial transcription, the human mitochondrial RNA polymerase (POLRMT) is a promising target for developing PC treatments. Herein, structure-activity relationship exploration led to the identification of compound S7, which was the first reported POLRMT inhibitor possessing single-digit nanomolar potency of inhibiting PC cells proliferation. Mechanistic studies showed that compound S7 exerted antiproliferative effects without affecting the cell cycle, apoptosis, mitochondrial membrane potential (MMP), or intracellular reactive oxygen species (ROS) levels specifically in MIA PaCa-2 cells. Notably, compound S7 inhibited tumor growth in MIA PaCa-2 xenograft tumor model with a tumor growth inhibition (TGI) rate of 64.52% demonstrating significant improvement compared to the positive control (44.80%). In conclusion, this work enriched SARs of POLRMT inhibitors, and compound S7 deserved further investigations of drug-likeness as a candidate for PC treatment.
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Antineoplásicos , Proliferación Celular , Cumarinas , ARN Polimerasas Dirigidas por ADN , Neoplasias Pancreáticas , Humanos , Neoplasias Pancreáticas/tratamiento farmacológico , Neoplasias Pancreáticas/patología , Animales , Relación Estructura-Actividad , Antineoplásicos/farmacología , Antineoplásicos/química , Antineoplásicos/síntesis química , Antineoplásicos/uso terapéutico , Cumarinas/farmacología , Cumarinas/química , Cumarinas/síntesis química , Cumarinas/uso terapéutico , Proliferación Celular/efectos de los fármacos , ARN Polimerasas Dirigidas por ADN/antagonistas & inhibidores , ARN Polimerasas Dirigidas por ADN/metabolismo , Línea Celular Tumoral , Ratones , Ratones Desnudos , Flúor/química , Apoptosis/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Ensayos Antitumor por Modelo de Xenoinjerto , Inhibidores Enzimáticos/farmacología , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/uso terapéutico , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Ratones Endogámicos BALB C , Ensayos de Selección de Medicamentos AntitumoralesRESUMEN
The rice blight poses a significant threat to the rice industry, and the discovery of disease-resistant genes is a crucial strategy for its control. By exploring the rich genetic resources of Yuanjiang common wild rice (Oryza rufipogon) and analyzing their expression patterns, genetic resources can be provided for molecular rice breeding. The target genes' expression patterns, subcellular localization, and interaction networks were analyzed based on the annotated disease-resistant genes on the 9th and 10th chromosomes in the rice genome database using fluorescent quantitative PCR technology and bioinformatics tools. Thirty-three disease-resistant genes were identified from the database, including 20 on the 9th and 13 on the 10th. These genes were categorized into seven subfamilies of the NLR family, such as CNL and the G subfamily of the ABC family. Four genes were not expressed under the induction of the pathogen Y8, two genes were significantly down-regulated, and the majority were up-regulated. Notably, the expression levels of nine genes belonging to the ABCG, CN, and CNL classes were significantly up-regulated, yet the expression levels varied among roots, stems, and leaves; one was significantly expressed in the roots, one in the stems, and the remaining seven were primarily highly expressed in the leaves. Two interaction network diagrams were predicted based on the seven highly expressed genes in the leaves: complex networks regulated by CNL proteins and specific networks controlled by ABCG proteins. The disease-resistant genes on the 9th chromosome are actively expressed in response to the induction of rice blight, forming a critical gene pool for the resistance of Yuanjiang common wild rice (O. rufipogon) to rice blight. Meanwhile, the disease-resistant genes on the 10th chromosome not only participate in resisting the rice blight pathogen but may also be involved in the defense against other stem diseases.
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Resistencia a la Enfermedad , Regulación de la Expresión Génica de las Plantas , Oryza , Enfermedades de las Plantas , Proteínas de Plantas , Oryza/genética , Oryza/microbiología , Resistencia a la Enfermedad/genética , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/microbiología , Proteínas de Plantas/genética , Perfilación de la Expresión Génica/métodos , Cromosomas de las Plantas/genética , TranscriptomaRESUMEN
A large number of defense genes are activated in plants when responding to pathogen infection. Furthermore, transcription factors are suggested to play important roles in regulating huge defense network in plants. The necrotrophic fungus Botrytis cinerea is one of the most destructive pathogens which could result in massive economic losses in the agriculture. Our review summarized the study results of members from transcription factor ERF, WRKY and MYB families which function in resistance of Botrytis cinerea in Arabidopsis thaliana. The transcription factors come into more elaborate regulation network through interacting with target genes at mRNA or protein levels aiming at activating expression of defense genes which lead to resistance against the fungus. Some transcriptional factors were discovered to be the main nodes and regulators in different phytohormones crosstalk, illustrating and connecting the molecular mechanisms of plants against different types of pathogens. Study on the transcription factor mentioned above, provides us clues for the study of other plant pathogen defense mechanism. Further understanding of disease mechanisms will help researchers to utilize the resis-tance genes in crop improvement and protection practice.
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Arabidopsis , Botrytis , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Regulación de la Expresión Génica de las Plantas , Enfermedades de las Plantas/genética , Factores de Transcripción/genéticaRESUMEN
Autophagy can be induced by viral infection and plays antiviral roles in plants, but the underlying mechanism is not well understood. In our previous reports, we have demonstrated that the plant ATG5 plays an essential role in activating autophagy in rice stripe virus (RSV)-infected plants. We also showed that eIF4A, a negative factor of autophagy, interacts with and inhibits ATG5. We here found that RSV p2 protein interacts with ATG5 and can be targeted by autophagy for degradation. Expression of p2 protein induced autophagy and p2 protein was shown to interfere with the interaction between ATG5 and eIF4A, while eIF4A had no effect on the interaction between ATG5 and p2. These results indicate an additional information on the induction of autophagy in RSV-infected plants.
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OBJECTIVES: The goal of this study was to assess the clinicopathological and ultrasound (US) features of breast cancer for predicting the risk of axillary lymph node metastasis. METHODS: Patients with breast cancer were included in this retrospective, monocentric, observational study. Their preoperative ultrasound features, clinical data, laboratory results and postoperative pathologic results and immunophenotyping were collected. The association of these factors of breast cancer with axillary lymph node metastasis was evaluated by univariate and multivariate analysis. RESULTS: In this study, 471 patients diagnosed with breast cancer at the First Affiliated Hospital of Xi'an Jiaotong University between July 2016 and September 2019 were collected, with a total of 471 nodules, of which 231(49.0%) had axillary lymph node metastasis, and 240(51.0%) did not. The parameters of hyperechoic halo, posterior acoustic decrease, microcalcification, carcinogenic embryonic antigen (CEA), cancer antigen-153 (CA153), CK5/6 (+), Ki67 (≥40%), AR (+) and histological grade (grade II and grade III) were significantly and independently associated with axillary lymph node metastasis (pâ<â0.05 for all). CONCLUSIONS: The combination of ultrasound features, tumor markers, pathology, and immunohistochemistry can predict axillary lymph node metastasis in breast cancer patients.
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Neoplasias de la Mama , Humanos , Femenino , Neoplasias de la Mama/patología , Metástasis Linfática/diagnóstico por imagen , Metástasis Linfática/patología , Estudios Retrospectivos , Ultrasonografía/métodos , Ganglios Linfáticos/diagnóstico por imagen , Ganglios Linfáticos/patologíaRESUMEN
The ATR kinase, which coordinates cellular responses to DNA replication stress, is also essential for the proliferation of normal unstressed cells. Although its role in the replication stress response is well defined, the mechanisms by which ATR supports normal cell proliferation remain elusive. Here, we show that ATR is dispensable for the viability of G0-arrested naïve B cells. However, upon cytokine-induced proliferation, Atr-deficient B cells initiate DNA replication efficiently, but by mid-S phase they display dNTP depletion, fork stalling, and replication failure. Nonetheless, productive DNA replication and dNTP levels can be restored in Atr-deficient cells by suppressing origin firing, such as partial inhibition of CDC7 and CDK1 kinase activities. Together, these findings indicate that ATR supports the proliferation of normal unstressed cells by tempering the pace of origin firing during the early S phase to avoid exhaustion of dNTPs and importantly also other replication factors.
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Replicación del ADN , Proteínas Serina-Treonina Quinasas , Fase S , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas de la Ataxia Telangiectasia Mutada/genética , Proteínas de la Ataxia Telangiectasia Mutada/metabolismo , Proliferación Celular , Daño del ADNRESUMEN
The ATR kinase, which coordinates cellular responses to DNA replication stress, is also essential for the proliferation of normal unstressed cells. Although its role in the replication stress response is well defined, the mechanisms by which ATR supports normal cell proliferation remain elusive. Here, we show that ATR is dispensable for the viability of G0-arrested naïve B cells. However, upon cytokine-induced proliferation, Atr-deficient B cells initiate DNA replication efficiently in early S phase, but by mid-S phase they display dNTP depletion, fork stalling, and replication failure. Nonetheless, productive DNA replication can be restored in Atr-deficient cells by pathways that suppress origin firing, such as downregulation of CDC7 and CDK1 kinase activities. Together, these findings indicate that ATR supports the proliferation of normal unstressed cells by tempering the pace of origin firing during the early S phase to avoid exhaustion of dNTPs and other replication factors.
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BACKGROUND: Plant viruses transmitted by arthropod vectors threaten crop health worldwide. Rice stripe virus (RSV) is one of the most important rice viruses in East Asia and is transmitted by the small brown planthopper (SBPH). Previously, it was demonstrated that the viral glycoprotein NSvs2-N could mediate RSV infection of the vector midgut. Therefore, NSvc2-N protein could potentially be used to reduce RSV transmission by competitively blocking midgut receptors. RESULTS: Here, we report that transgenic rice plants expressing viral glycoprotein can interfere with RSV acquisition and transmission by SBPH. The soluble fraction (30-268 amino acids, designated NSvs2-NS ) of NSvs2-N was transformed into rice calli, which produced plants harboring the exogenous gene. When SBPH was fed on transgenic plants prior to RSV-infected rice (sequential feeding) and when insects were fed on RSV-infected transgenic plants (concomitant feeding), virus acquisition by the insect vector was inhibited, and subsequent viral titers were reduced. Immunofluorescence labeling also indicated that viral infection of the insect midgut was inhibited after SBPH was fed on transgenic plants. The system by which RSV infected insect cells in vitro was used to corroborate the role of NSvc2-NS in reducing viral infection. After the cells were incubated with transgenic rice sap, the virus infection rate of the cells decreased significantly, and viral accumulation in the cells was lower than that in the control group. CONCLUSION: These results demonstrated the negative effect of NSvs2-NS transgenic plants on RSV transmission by insect vectors, which provides a novel and effective way to control plant viral diseases. © 2022 Society of Chemical Industry.
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Hemípteros , Oryza , Tenuivirus , Animales , Tenuivirus/genética , Hemípteros/genética , Insectos Vectores , Insectos , Glicoproteínas , Enfermedades de las Plantas , Oryza/genéticaRESUMEN
Rice viral diseases adversely affect crop yield and quality. Most rice viruses are transmitted through insect vectors. However, the traditional whole-plant inoculation method cannot control the initial inoculation site in rice plants because the insect feeding sites in plants are random. To solve this problem, we established a determined-part inoculation approach in this study that restricted the insect feeding sites to specific parts of the rice plant. Rice stripe virus (RSV) was used as the model virus and was inoculated at the bottom of the stem using our method. Quantitative real-time PCR and Western blot analyses detected RSV only present at the bottom of the Nipponbare (NPB) stem at 1 day post-inoculation (dpi), indicating that our method successfully controlled the inoculation site. With time, RSV gradually moved from the bottom of the stem to the leaf in NPB rice plants, indicating that systemic viral spread can also be monitored using this method. In addition, a cultivar resistant to RSV, Zhendao 88 (ZD88), was inoculated using this method. We found that RSV accumulation in ZD88 was significantly lower than in NPB. Additionally, the expression level of the resistant gene STV11 in ZD88 was highly induced at the initial invasion stage of RSV (1 dpi) at the inoculation site, whereas it remained relatively stable at non-inoculated sites. This finding indicated that STV11 directly responded to RSV invasion to inhibit virus accumulation at the invasion site. We also proved that this approach is suitable for other rice viruses, such as Rice black-streaked dwarf virus (RBSDV). Interestingly, we determined that systemic infection with RSV was faster than that with RBSDV in NPB, which was consistent with findings in field trails. In summary, this approach is suitable for characterizing the viral infection process in rice plants, comparing the local viral accumulation and spread among different cultivars, analyzing the spatiotemporal expression pattern of resistance-associated genes, and monitoring the infection rate for different viruses.
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Bacillus spp. is effective biocontrol agents for Fusarium wilt of banana (FWB), tropical race 4 (TR4). This study explores the colonization by Bacillus subtilis, Bacillus velezensis, and Bacillus amyloliquefaciens of host banana plants and elucidates the mechanism of antagonistic TR4 biocontrol. The authors selected one B. subtilis strain, three B. velezensis strains, and three B. amyloliquefaciens strains that are proven to significantly inhibit TR4 in vitro, optimized the genetic transformation conditions and explored their colonization process in banana plants. The results showed that we successfully constructed an optimized fluorescent electro-transformation system (OD600 of bacteria concentration=0.7, plasmid concentration=50ng/µl, plasmid volume=2µl, transformation voltage=1.8kV, and transformation capacitance=400Ω) of TR4-inhibitory Bacillus spp. strains. The red fluorescent protein (RFP)-labeled strains were shown to have high stability with a plasmid-retention frequency above 98%, where bacterial growth rates and TR4 inhibition are unaffected by fluorescent plasmid insertion. In vivo colonizing observation by Laser Scanning Confocal Microscopy (LSCM) and Scanning Electron Microscopy (SEM) showed that Bacillus spp. can colonize the internal cells of banana plantlets roots. Further, fluorescent observation by LSCM showed these RFP-labeled bacteria exhibit chemotaxis (chemotaxis ratio was 1.85±0.04) toward green fluorescent protein (GFP)-labeled TR4 hyphae in banana plants. We conclude that B. subtilis, B. velezensis, and B. amyloliquefaciens can successfully colonize banana plants and interact with TR4. Monitoring its dynamic interaction with TR4 and its biocontrol mechanism is under further study.
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Huanglongbing (HLB) pathogen Candidatus Liberibacter asiaticus (CLas) brings a great concern about the phloem nutrient transport in diseased plants. There is an urgent need to find the best management strategies to reduce the losses in the citrus industry worldwide. Endophytic bacteria are negatively affected by CLas pathogen, and these endophytes are associated with improved availability of nutrients and pathogen resistance. This study underpins the relationship between CLas pathogen, endophyte population and nutrients availability in citrus plants. The citrus plants were treated with Bacillus subtilis L1-21 and Hoagland solution to find out synergism efficacy to mitigate citrus HLB. We showed that citrus shoots in the presence of 50% Hoagland solution displayed maximum number of endophytes with 6.28 × 103 to 3.04 × 105 CFU/g. Among 50 candidate strains, B. subtilis L1-21 emerged as potential antagonist against surrogate strain Xanthomonas citri subsp. citri. The citrus half-leaf method identified that application of endophyte L1-21 with 50% Hoagland solution successfully reduces the CLas abundance. We point out that this combination results in a higher number of endophytes population with 2.52 × 104 to 9.11 × 106 CFU/g after 60 days, and reduces CLas pathogen abundance in asymptomatic HLB plants. In HLB symptomatic citrus plants, B. subtilis L1-21 potentially increases the endophyte population from 1.11 × 104 to 5.26 × 107 CFU/g in the presence of Hoagland solution, and pathogen abundance was reduced from 9.51 × 105 to 1.06 × 104 copies/g. Altogether, we suggested that the presence of endophyte L1-21 with Hoagland solution is more effective in HLB asymptomatic citrus plants, but a slight reduction of pathogen was observed in symptomatic plants. The findings revealed the role of indigenous citrus endophyte B. subtilis L1-21 along with other nutrients in the reduction of CLas pathogen abundance inside symptomatic and asymptomatic plants in citrus endophyte-nutrient-pathogen interplay.
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Fusarium wilt disease, caused by Fusarium oxysporum f. sp. cubense, especially by tropical race 4 (Foc TR4), is threatening the global banana industry. Musa acuminata Pahang, a wild diploid banana that displays strong resistance to Foc TR4, holds great potential to understand the underlying resistance mechanisms. Microscopic examination reports that, in a wounding inoculation system, the Foc TR4 infection processes in roots of Pahang (resistant) and a triploid cultivar Brazilian (susceptible) were similar by 7 days post inoculation (dpi), but significant differences were observed in corms of both genotypes at 14 dpi. We compare transcriptomic responses in the corms of Pahang and Brazilian, and show that Pahang exhibited constitutive defense responses before Foc TR4 infection and inducible defense responses prior to Brazilian at the initial Foc TR4 infection stage. Most key enzymatic genes in the phenylalanine metabolism pathway were up-regulated in Brazilian, suggesting that lignin and phytotoxin may be triggered during later stages of Foc TR4 infection. This study unravels a few potential resistance candidate genes whose expression patterns were assessed by RT-qPCR assay and improves our understanding the defense mechanisms of Pahang response to Foc TR4.
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Fusarium/patogenicidad , Musa/genética , Enfermedades de las Plantas/genética , Transcriptoma , Catecol Oxidasa/metabolismo , Pared Celular , Resistencia a la Enfermedad/genética , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Genoma de Planta , Genotipo , Microscopía , Musa/microbiología , Enfermedades de las Plantas/microbiología , Raíces de PlantasRESUMEN
Although several genes involved in mitochondrial function are direct Myc targets, the role of Myc in mitochondrial biogenesis has not been directly established. We determined the effects of ectopic Myc expression or the loss of Myc on mitochondrial biogenesis. Induction of Myc in P493-6 cells resulted in increased oxygen consumption and mitochondrial mass and function. Conversely, compared to wild-type Myc fibroblasts, Myc null rat fibroblasts have diminished mitochondrial mass and decreased number of normal mitochondria. Reconstitution of Myc expression in Myc null fibroblasts partially restored mitochondrial mass and function and normal-appearing mitochondria. Concordantly, we also observed in primary hepatocytes that acute deletion of floxed murine Myc by Cre recombinase resulted in diminished mitochondrial mass in primary hepatocytes. Our microarray analysis of genes responsive to Myc in human P493-6 B lymphocytes supports a role for Myc in mitochondrial biogenesis, since genes involved in mitochondrial structure and function are overrepresented among the Myc-induced genes. In addition to the known direct binding of Myc to many genes involved in mitochondrial structure and function, we found that Myc binds the TFAM gene, which encodes a key transcriptional regulator and mitochondrial DNA replication factor, both in P493-6 lymphocytes with high ectopic MYC expression and in serum-stimulated primary human 2091 fibroblasts with induced endogenous MYC. These observations support a pivotal role for Myc in regulating mitochondrial biogenesis.
Asunto(s)
Mitocondrias/genética , Mitocondrias/fisiología , Proteínas Mitocondriales/genética , Proteínas Proto-Oncogénicas c-myc/fisiología , Animales , Linfocitos B/metabolismo , Núcleo Celular/genética , Células Cultivadas , Inmunoprecipitación de Cromatina , ADN Mitocondrial/metabolismo , Proteínas de Unión al ADN/metabolismo , Eliminación de Gen , Perfilación de la Expresión Génica , Hepatocitos/metabolismo , Proteínas del Grupo de Alta Movilidad , Humanos , Ratones , Mitocondrias/ultraestructura , Proteínas Mitocondriales/metabolismo , Proteínas Nucleares/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , Proteínas Proto-Oncogénicas c-myc/genética , Ratas , Factores de Transcripción/metabolismoRESUMEN
The fungus Magnaporthe oryzae threatens the rice production of Kongyu 131 (KY131), a leading japonica variety in Northeast China. In this study, two rice lines, KP1 and KP2-Hd1, were obtained by introgressing the blast resistance genes Pi1 and Pi2 into KY131, respectively. However, both lines headed later than KY131. RICE60K SNP array analysis showed that Hd1 closely linked to Pi2 was introgressed into KP2-Hd1, and the linkage drag of Hd1 was broken by recombination. On the other hand, no known flowering genes were introgressed into KP1. Gene diagnosis by resequencing six flowering genes showed that KP1 carried functional Hd16 and Ghd8 alleles. Due to its suppression role in heading under long-day conditions, Ghd8 was chosen as the target for gene editing to disrupt its function. Four sgRNAs targeting different sites within Ghd8 were utilized to induce large-deletion mutations, which were easy to detect via agarose gel electrophoresis. All the ghd8-mutated KP1 lines were resistant to rice blast disease and headed earlier than the control KP1, even than KY131, under natural long-day conditions, which ensures its growth in Northeast China. This study confirmed that a combination of gene diagnosis and targeted gene editing is a highly efficient way to quickly eliminate undesired traits in a breeding line.