Phytopathology最新文献

{"title":"Moderate and High Propiconazole Resistance Characterized in the Citrus Postharvest Sour Rot Pathogen <i>Geotrichum citri</i>-<i>aurantii</i> Is Based on Point Mutations in <i>CYP51A</i> but Not <i>CYP51B</i>.","authors":"Albert M Nguyen, Helga Forster, James E Adaskaveg","doi":"10.1094/PHYTO-02-25-0073-R","DOIUrl":"https://doi.org/10.1094/PHYTO-02-25-0073-R","url":null,"abstract":"<p><p>Moderate (MR) and high resistance (HR) in <i>Geotrichum citri</i>-<i>aurantii</i> to propiconazole (PPZ) have been detected in California citrus packinghouses. Fitness cost and resistance mechanisms were characterized in this study. No fitness cost was identified in resistant isolates, and they were highly virulent and competitive in the presence of sensitive (S) isolates. F1 ascospore progeny from crosses between MR or HR isolates and a S isolate mostly segregated in a 1:1 ratio of S to R isolates indicating involvement of a single gene in resistance. Resistance was associated with point mutations in <i>GcaCYP51A</i> resulting in Y143F and L389V amino acid substitutions in HR isolates and an A125V substitution in MR isolates. There were no sequence differences in the <i>GcaCYP51B</i> paralog between S and MR isolates, but missense and silent mutations were identified in HR isolates. Segregation of <i>GcaCYP51B</i> alleles was observed in crosses between S and HR isolates: some PPZ-S progeny carried the <i>GcaCYP51B</i>-<i>HR</i> allele, whereas some PPZ-HR isolates carried the <i>GcaCYP51B</i>-<i>S</i> allele. Therefore, mutations in <i>GcaCYP51B</i> have no major role in PPZ resistance. The direct involvement of mutations in <i>GcaCYP51A</i> in resistance was demonstrated by transformation of a PPZ-S isolate with cloned alleles from MR or HR isolates where transformants exhibited the expected resistance phenotype. Transformants carrying the <i>GcaCYP51B</i> allele of HR isolates, however, remained sensitive. No differences between S and R phenotypes were detected in the promoter sequences of <i>GcaCYP51A</i> or -<i>B</i>. Our data indicate that PPZ resistance in <i>G. citri</i>-<i>aurantii</i> is solely determined by point mutations in <i>GcaCYP51A</i>.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143991265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Eriophyid Mites Vector the Kitavirus Blueberry Necrotic Ring Blotch Virus: Insights into the Viral Transmission and Its Infection on Blueberries Plants.","authors":"Aline Daniele Tassi, Pedro Luis Ramos-Gonzalez, Carlos H W Flechtmann, James W Amrine, Ali Sarkhosh, Juliana Freitas-Astua, Elliot Watanabe Kitajima, João Paulo Rodrigues Marques, Philip F Harmon, Daniel Carrillo","doi":"10.1094/PHYTO-02-25-0063-R","DOIUrl":"https://doi.org/10.1094/PHYTO-02-25-0063-R","url":null,"abstract":"<p><p>Blunerviruses, family <i>Kitaviridae</i>, infect and cause diseases of important crop plants including tomato, tea, and blueberry. Despite the economic importance of blunerviruses, their epidemiology and the mechanism underlying plant-to-plant transmission are largely unknown. In 2006 the blunervirus blueberry necrotic ring blotch virus (BNRBV, <i>Blunervirus vaccinii</i>) was detected in Florida, USA, causing disease on blueberry plants and tentatively linked to an eriophyid mite vector. To gain insights into plant-virus interaction and plant-to-plant transmission of BNRBV, in this study, we investigated sap transmission and the potential vector of blueberry-infesting eriophyid and <i>Brevipalpus</i> mites collected in Florida during 2022 and 2023. While kitaviruses are vectored by several species of <i>Brevipalpus</i> mites, our experiments revealed a distinct vector for BNRBV. Both mite types acquired the virus, but only viruliferous eriophyids of the species <i>Calacarus corymbosi</i>, described for the first time in this work, transmitted the virus. Assays for BNRBV mechanical transmission were unsuccessful. This study marks the first demonstration of a characterized pathogen vectored by a mite in the genus <i>Calacarus</i> within kitavirus. Upon transmission by the eriophyid mite, BNRBV caused characteristic local necrotic ring blotch symptoms in blueberry leaves, and the virus was detected in symptomatic tissues and also in roots, but only at 6 months after inoculation, suggesting restricted or inefficient long-distance movement of the virus within the plant. This paper introduces a model for investigating the transmission of blunerviruses, a rapidly growing group of plant viruses.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144045252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Treatment with the Antimicrobial Product Diallyl Disulfide Is Associated with Major Changes to Soil Microbiota.","authors":"Martha A Sudermann, Gia Khuong Hoang Hua, Elizabeth G Kurth, Jared M LeBoldus, Jeff H Chang, Jeremiah K S Dung","doi":"10.1094/PHYTO-11-24-0366-SC","DOIUrl":"https://doi.org/10.1094/PHYTO-11-24-0366-SC","url":null,"abstract":"<p><p>Natural products derived from <i>Allium</i> spp., such as garlic oil, garlic powder, and diallyl disulfide (DADS), are strong elicitors of sclerotia germination in the fungus <i>Sclerotium cepivorum</i> (syn. <i>Stromatinia cepivora</i>), the causal agent of <i>Allium</i> white rot. However, these compounds can also have broad antimicrobial activity against a wide range of bacteria, oomycetes, and other fungi when they are applied to soil. The objective of this study was to determine the potential impacts that DADS application has on soil microbial communities. DADS was applied to two soil types and incubated under aerobic and anaerobic conditions. Metabarcodes for bacterial, fungal, and oomycete communities were analyzed to identify changes. A significant effect of DADS treatment on the overall compositions of bacterial, fungal, and oomycete communities was observed compared to the mock-treated control. Soil type and incubation conditions did not have a significant effect on soil microbial communities and significant interactions were not observed with DADS treatment in this study. Potential changes in soil microbial communities should be considered when applying DADS to field soils.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144007685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dispersal of <i>Colletotrichum acutatum</i> Sensu Lato Conidia from Infected Citrus and Strawberry Under Simulated Rainfall and Different Laminar and Turbulent Wind Speeds.","authors":"Andre B Gama, Maria Cândida de Godoy Gasparoto, Gavin H Poole, Clive H Bock, Timothy R Gottwald, Lilian Amorim, Natalia A Peres, Megan M Dewdney","doi":"10.1094/PHYTO-11-24-0342-R","DOIUrl":"10.1094/PHYTO-11-24-0342-R","url":null,"abstract":"<p><p>Species of the <i>Colletotrichum acutatum</i> complex cause postbloom fruit drop of citrus and anthracnose fruit rot of strawberries. <i>C</i>. <i>acutatum</i> produces acervuli in diseased citrus flowers and strawberry fruit, surviving asymptomatically on vegetative tissues. Previous studies have suggested that dispersal mechanisms other than windblown rain may be involved in the dispersal of conidia of <i>C</i>. <i>acutatum</i> sensu lato. Our hypothesis is that wind alone may play a role in dispersal, especially for inocula surviving on vegetative tissue. Our objectives were to study the dispersal pattern of <i>C</i>. <i>acutatum</i> sensu lato from strawberry fruit and leaves and citrus flowers and leaves by placing semiselective media at known distances away from inoculum sources in laminar flow and turbulent wind tunnels. The number of <i>C</i>. <i>acutatum</i> sensu lato colony-forming units on each plate was correlated with the distance from the inoculum sources. Conidia were dispersed up to 15 m in wind speeds greater than 10 m/s, but observed dispersal patterns were not described by the models we tested. A negative exponential model adequately described the dispersal gradient of the inoculum downwind, particularly for the dispersal gradient in turbulent wind. Dispersal in rain splash and wind was limited to short distances. Our data describe how conidia spread from inoculum sources and for the first time describe how the dispersal of <i>C</i>. <i>acutatum</i> sensu lato secondary conidia occurs from citrus and strawberry leaves. Knowledge of the dispersal of conidia of <i>C</i>. <i>acutatum</i> sensu lato can provide valuable information on epidemic development and, thus, approaches for disease management.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"507-520"},"PeriodicalIF":2.6,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143067649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inhibitory and Curative Effects and Mode of Action of Hydroxychloroquine on <i>Botrytis cinerea</i> of Tomato.","authors":"Chengyan Xia, Xiansu Wang, Zeqi Qi, Fenghua Liu, Dongxue Li, Xiaolin Zhang, Libo Zhang, Delu Wang, Zhuo Chen","doi":"10.1094/PHYTO-12-24-0397-R","DOIUrl":"10.1094/PHYTO-12-24-0397-R","url":null,"abstract":"<p><p>Gray mold is an important disease of crops and is widespread, harmful, difficult to control, and prone to developing fungicide resistance. Screening new fungicides is an important step in controlling this disease. Hydroxychloroquine is an anti-inflammatory and antimalarial agent that has shown marked inhibitory activity against many fungi in medicine. This study evaluated the inhibitory activity of hydroxychloroquine against several phytopathogenic fungi, finding a half-maximal effective concentration of 113.82 μg/ml against the hyphal growth of <i>Botrytis cinerea</i>, with significant in vivo curative effects of 92.37 or 78.37% for gray mold on detached tomato leaves or fruits at 10.0 or 200.0 mg/ml, respectively. Ultrastructural studies indicated that hydroxychloroquine induced collapse of hyphae, with a wrinkled surface, unclear organelle boundaries, and organelle disintegration. Transcriptomic assays revealed that hydroxychloroquine could affect the expression of metabolism-related genes. Molecular docking and molecular dynamics analyses indicated that hydroxychloroquine bound to glucose-methanol-choline oxidoreductase, with a low free energy value of -11.4 kcal/mol. Cell membrane permeability assays and hyphal staining confirmed that hydroxychloroquine damaged the cell membrane, causing leakage of hyphal contents and disturbing cell function. Biochemical assays indicated that hydroxychloroquine reduced the concentration of soluble proteins and reducing sugars in the hyphae. Overall, hydroxychloroquine disturbed amino acid metabolism, therefore inhibiting the production of biomacromolecules, damaging the cell membrane, and restraining the growth of hyphae, hence inhibiting gray mold on tomato. This study explored the use of medicine in the development of agricultural fungicides and their application in managing crop diseases, providing valuable background information.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"469-484"},"PeriodicalIF":2.6,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142984578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transcriptome Analysis Reveals That a Gti1/Pac2 Family Gene, <i>CpSge1</i>, Regulates Fungal Growth, Stress Response, and Virulence in <i>Cryphonectria parasitica</i>.","authors":"Xiaorong Lin, Yuchen Yang, Can Huang, Dianguang Xiong, Xiaolin Qiu, Chengming Tian","doi":"10.1094/PHYTO-11-24-0354-R","DOIUrl":"10.1094/PHYTO-11-24-0354-R","url":null,"abstract":"<p><p>The Gti1/Pac2 family comprises crucial transcription factors widely distributed in fungi with generally two members, Gti1 (also known as Wor1, Ryp1, or Sge1), and Pac2, where the Gti1 homologues play significant roles in the growth, spore production, and pathogenicity of various pathogenic fungi. Despite its recognized significance, the roles of this family in <i>Cryphonectria parasitica</i>, the pathogen responsible for chestnut blight (a globally significant forest disease), remain unexplored. In this study, <i>CpSge1</i> was identified in <i>C</i>. <i>parasitica</i> and then knocked out to explore its functions. The results showed that <i>CpSge1</i> significantly affected the vegetative growth, conidiation, hydrophobicity, and stress tolerance of <i>C</i>. <i>parasitica</i>. Notably, the <i>CpSge1</i> deletion mutants were significantly less pathogenic compared with the wild type. Transcriptomic analysis of the wild type and the <i>CpSge1</i> deletion mutant during the vegetative growth and infection stages revealed that <i>CpSge1</i> regulated a number of pathogenicity-related genes in <i>C</i>. <i>parasitica</i>. A yeast one-hybrid assay verified the direct binding of CpSge1 to the promoter regions of genes encoding pectin lyase <i>CpPL1</i> and major facilitator superfamily transporter <i>CpMF1</i>. In summary, these data suggest that <i>CpSge1</i> is the core regulator of fungal growth, stress tolerance, gene expression, and virulence in <i>C</i>. <i>parasitica</i>, which may improve our understanding of the molecular pathogenesis of <i>C</i>. <i>parasitica</i> and help us to develop effective control strategies.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"521-534"},"PeriodicalIF":2.6,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143391525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Overwintering Capability of <i>Xanthomonas arboricola</i> pv. <i>pruni</i> Strains with Different Bactericidal Sensitivities on Peach Trees.","authors":"Milan Panth, Enoch Noh, Alec Sherratt, Guido Schnabel, Daniel J Anco, Renato Carvalho, Jeffrey B Jones, Hehe Wang","doi":"10.1094/PHYTO-09-24-0298-R","DOIUrl":"10.1094/PHYTO-09-24-0298-R","url":null,"abstract":"<p><p><i>Xanthomonas arboricola</i> pv. <i>pruni</i> (XAP) causes bacterial spot of peach and is primarily managed in commercial South Carolina peach orchards with copper and oxytetracycline applications. The pathogen overwinters in peach twigs and forms spring cankers that generate the primary inoculum for early-season leaf and fruitlet infections. Copper-tolerant and oxytetracycline-resistant strains have recently been reported, but their overwintering capability in the absence of selection pressure is unknown. Similarly, the impact of infection during different phenological stages on XAP overwintering is unknown. To investigate these factors, peach twigs were sprayed with strains of XAP with different sensitivities to copper and oxytetracycline in an experimental orchard during bud set (June), after harvest (August), and during leaf drop (October) in the fall. Viable XAP from peach buds was quantified using quantitative PCR with or without propidium monoazide treatment. The results indicated that bud cankers were a major inoculum reservoir for XAP, and the overwintered XAP densities in buds were significantly and positively correlated with spring canker ratings (<i>R</i>² = ∼0.6, <i>P</i> < 0.001). Inoculation of peach twigs at all three time points yielded overwintering XAP populations and canker symptoms in the spring, with the highest amount of canker and XAP from the leaf drop (42.7% canker incidence, 31,258 CFU/bud) and after harvest (30.4% canker incidence, 8,511 CFU/bud) inoculations. There were no significant differences in the overwintering capability of XAP strains in the absence of copper or oxytetracycline sprays, suggesting that these oxytetracycline-resistant and copper-tolerant strains may persist and accumulate in peach orchards across seasons.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"444-453"},"PeriodicalIF":2.6,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143190233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prevalence of Mutations Associated with QoIs, QiIs, QioSIs, and CAA Fungicide Resistance Within <i>Plasmopara viticola</i> in North America and a Tool to Detect CAA-Resistant Isolates.","authors":"Nancy Sharma, Lexi Heger, David B Combs, Wendy McFadden Smith, Leslie Holland, Phillip Brannen, Kaitlin M Gold, Timothy Miles","doi":"10.1094/PHYTO-08-24-0257-R","DOIUrl":"10.1094/PHYTO-08-24-0257-R","url":null,"abstract":"<p><p>Grape downy mildew, caused by <i>Plasmopara viticola</i>, poses a significant threat to grape cultivation globally. Early detection of fungicide resistance is critical for effective management. This study aimed to assess the prevalence and distribution of mutations associated with resistance to quinone outside inhibitor (FRAC 11), quinone inside inhibitor (FRAC 21), carboxylic acid amide (CAA, FRAC 40), and quinone inside and outside inhibitor, stigmatellin binding mode (FRAC 45) fungicides in <i>P</i>. <i>viticola</i> populations in the eastern United States and Canada and to evaluate whether these mutations are linked to fungicide resistance correlated with specific <i>P</i>. <i>viticola</i> clades. A total of 658 <i>P</i>. <i>viticola</i> samples were collected from commercial vineyards across different states and years in the eastern United States and Canada and sequenced for the <i>PvCesA3</i> and <i>cytb</i> genes and the internal transcribed spacer (ITS)1 region. The results showed that <i>P</i>. <i>viticola</i> clades <i>aestivalis</i>, <i>vinifera</i>, and <i>riparia</i> were prevalent in the eastern United States and Canada. Quinone outside inhibitor resistance was widespread, and the A-143 resistant genotype was prevalent in <i>P</i>. <i>viticola</i> clades <i>aestivalis</i> and <i>vinifera</i>. The G143A mutation did not show specificity based on clade differentiation. CAA resistance, associated with the G1105S mutation, was mainly identified in <i>P</i>. <i>viticola</i> clade <i>aestivalis</i> from Georgia, New York, and Ontario. G1105-S1105 mixed-genotype samples were observed in <i>P</i>. <i>viticola</i> clades <i>vinifera</i> and <i>riparia</i> from Wisconsin, Michigan, and New York. However, mutations associated with quinone inside and outside inhibitor and quinone inside inhibitor fungicides were not detected. A TaqMan probe-based assay was developed to detect the G1105S mutation in <i>P</i>. <i>viticola</i> conferring CAA fungicide resistance. The TaqMan assay demonstrated sensitivity at low DNA concentrations and specificity in distinguishing between sensitive and resistant genotypes. The assay accurately distinguished the G1105S mutation in leaf and air samples. This study provides insight into the geographic distribution of fungicide resistance in <i>P</i>. <i>viticola</i> populations and presents a reliable method for detecting CAA resistance in <i>P</i>. <i>viticola</i>. These findings can be utilized to implement effective fungicide resistance management strategies in viticulture.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"495-506"},"PeriodicalIF":2.6,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143053370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genotype-Specific Responses of Common Bean to <i>Meloidogyne incognita</i>.","authors":"Nicole Orsi, João Paulo Rodrigues Marques, Líllian Beatriz Januário Bibiano, Luis Eduardo Aranha Camargo, Daniel Guariz Pinheiro, Maria Lucia Carneiro Vieira","doi":"10.1094/PHYTO-10-24-0313-R","DOIUrl":"10.1094/PHYTO-10-24-0313-R","url":null,"abstract":"<p><p>The root-knot nematode <i>Meloidogyne incognita</i> causes large galls on roots, interfering with the flow of water and nutrients to the plant. In the common bean, no major resistance (<i>R</i>) genes have been described. Instead, resistance is controlled by multiple genes, which have not proved effective so far. An RNA sequencing approach was used to identify genes involved in common bean response to <i>M</i>. <i>incognita</i> at the stages of nematode invasion and root galling. When comparing infected and uninfected treatments of a moderately resistant (MR) and a susceptible (S) genotype, several genes were identified as differentially expressed. Their functional annotation indicated that both genotypes underwent complex transcriptional reprogramming from early to later periods of the interaction, but defense-related genes were mostly upregulated in the MR genotype. At the early stage, a large set of genes was activated in both genotypes, including those involved in cell wall organization, signaling, hormonal pathways, transcription factors, oxidative stress, and putative resistance gene analogs. Later, most of the previously activated defense mechanisms were no longer expressed in the S genotype. There was an increased expression of genes encoding proteins involved in hormonal signaling pathways (salicylic acid and gibberellin-related), protein kinases, transcription factors, and oxidative stress in the MR genotype. However, a decreased expression of genes involved in signaling mediated by calcium and oxidative stress occurred in the S genotype, indicating susceptibility. The repertoire of genes identified herein will facilitate research in plant-nematode interactions, with possible applications for the improvement of the common bean.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"535-547"},"PeriodicalIF":2.6,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143190221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Functional Characterization of Transcriptional Regulator Rem in '<i>Candidatus</i> Liberibacter asiaticus'.","authors":"Wenting Wang, Jin Xu, Nian Wang","doi":"10.1094/PHYTO-10-24-0339-R","DOIUrl":"10.1094/PHYTO-10-24-0339-R","url":null,"abstract":"<p><p>Citrus Huanglongbing, caused by '<i>Candidatus</i> Liberibacter asiaticus' (CLas), is the most devastating citrus disease worldwide. The CLas genome is much smaller than those of its relatives, such as <i>Sinorhizobium meliloti</i>, due to its reductive evolution. Because CLas has not been cultured in artificial media, despite some progress in co-cultivating, and because genetic manipulation of CLas remains impossible, the understanding of CLas biology is very limited. Usually, 10% of total genes in bacteria are regulatory genes, but only 2% of CLas genes encode transcriptional factors. Here, 20 transcriptional regulators were predicted, including nine genes (<i>lsrB</i>, <i>ldtR</i>, <i>rem</i>, <i>visR</i>, <i>visN</i>, <i>ctrA</i>, <i>mucR</i>, <i>pelD</i>, and <i>atoC</i>) directly or indirectly involved in regulating motility, and five genes (<i>rpoH</i>, <i>prbP</i>, <i>phrR</i>, <i>rirA</i>, and <i>lsrB</i>) involved in oxidative stress response. We demonstrated that <i>rem</i>, <i>lsrB</i>, and <i>visNR</i> of CLas can complement the corresponding mutants of <i>S</i>. <i>meliloti</i> in their reduced motility. We further investigated traits controlled by Rem in <i>S</i>. <i>meliloti</i> and CLas using RNA sequencing analyses of <i>rem</i> mutant versus complementation strains with <i>rem_Smc</i> or <i>rem_Las</i>. Transcriptomic analysis showed that Rem_Las significantly regulates the expression of genes in <i>S</i>. <i>meliloti</i>, which was used to infer its regulation of CLas genes by identification of homologous genes. We found that Rem is involved in regulating motility, chemotaxis, transporters, and oxidative phosphorylation in <i>S</i>. <i>meliloti</i> and regulating flagellar and transporter genes in CLas. Among the 39 putative Rem_Las-regulated genes in CLas, 16 contain the Rem-binding motif, including 10 genes involved in flagellar assembly. Taken together, this study offers valuable insights regarding CLas regulatory genes, with many of them involved in regulating motility and oxidative stress response. The regulation of flagellar genes by Rem in CLas unravels critical information regarding motility in CLas infection of hosts.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"454-468"},"PeriodicalIF":2.6,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143075225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}