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1.
Front Microbiol ; 15: 1386923, 2024.
Article in English | MEDLINE | ID: mdl-38756725

ABSTRACT

Seventeen Gram-negative, facultatively anaerobic bacterial strains were isolated from bleeding cankers of various broadleaf hosts and oak rhizosphere soil in Great Britain. The strains were tentatively identified as belonging to the genus Raoultella based on 16S rRNA gene sequencing. Multilocus sequence analysis (MLSA), based on four protein-encoding genes (fusA, leuS, pyrG, and rpoB), separated the strains into three clusters within the Raoultella genus clade. The majority of strains clustered with the type strain of Raoultella terrigena, with the remaining strains divided into two clusters with no known type strain. Whole genome sequencing comparisons confirmed these two clusters of strains as belonging to two novel Raoultella species which can be differentiated phenotypically from their current closest phylogenetic relatives. Therefore, two novel species are proposed: Raoultella scottia sp. nov. (type strain = BAC 10a-01-01T = LMG 33072T = CCUG 77096T) and Raoultella lignicola sp. nov. (type strain = TW_WC1a.1T = LMG 33073T = CCUG 77094T).

3.
Article in English | MEDLINE | ID: mdl-38621708

ABSTRACT

Sjögren disease (SD) is a chronic, autoimmune disease of unknown aetiology with significant impact on quality of life. Although dryness (sicca) of the eyes and mouth are the classically described features, dryness of other mucosal surfaces and systemic manifestations are common. The key management aim should be to empower the individual to manage their condition-conserving, replacing and stimulating secretions; and preventing damage and suppressing systemic disease activity. This guideline builds on and widens the recommendations developed for the first guideline published in 2017. We have included advice on the management of children and adolescents where appropriate to provide a comprehensive guideline for UK-based rheumatology teams.

4.
Plants (Basel) ; 12(3)2023 Jan 20.
Article in English | MEDLINE | ID: mdl-36771570

ABSTRACT

The aim of any breeding process is to fully express the targeted, superior/desirable parent characteristic in the progeny. Hybrids are often used in this dynamic, and complex process for which homozygous parents-which may require up to eight generations of back crossing and selection-are required. Doubled haploid (DH) technologies can facilitate the production of true breeding lines faster and in a more efficient manner than the traditional back crossing and selection strategies. Sunflower is the third most important oilseed crop in the world and has no available double haploid induction procedure/technique that can be efficiently used in breeding programs. A reproducible and efficient doubled haploid induction method would be a valuable tool in accelerating the breeding of new elite sunflower varieties. Although several attempts have been made, the establishment of a sunflower doubled haploid induction protocol has remained a challenge owing recalcitrance to in vitro culture regeneration. Approaches for haploid development in other crops are often cultivar specific, difficult to reproduce, and rely on available tissue culture protocols-which on their own are also cultivar and/or species specific. As an out-crossing crop, the lack of a double haploid system limits sunflower breeding and associated improvement processes, thereby delaying new hybrid and trait developments. Significant molecular advances targeting genes, such as the centromeric histone 3 (CenH3) and Matrilineal (MTL) gene with CRISPR/Cas9, and the successful use of viral vectors for the delivery of CRISPR/Cas9 components into plant cells eliminating the in vitro culture bottleneck, have the potential to improve double haploid technology in sunflower. In this review, the different strategies, their challenges, and opportunities for achieving doubled haploids in sunflower are explored.

5.
Front Microbiol ; 13: 1063107, 2022.
Article in English | MEDLINE | ID: mdl-36466697

ABSTRACT

Following a screening campaign of bleeding cankers of broadleaf hosts in Great Britain, numerous bacterial strains were isolated, identified by 16S rRNA and protein-coding gene sequencing and ultimately classified. During the course of the study, several Gram-negative, facultatively anaerobic strains were isolated from bleeding Platanus x acerifolia (London plane) and Tilia x europaea (common lime) cankers that could not be assigned to an existing species. Partial 16S rRNA gene sequencing placed these strains in the genus Erwinia, as a close phylogenetic relative of Erwinia toletana. In an effort to determine the taxonomic position of the strains, a polyphasic approach was followed including genotypic, genomic, phenotypic, and chemotaxonomic assays. Multilocus sequence analysis based on four protein-coding genes (gyrB, rpoB, infB, and atpD) confirmed the phylogenetic position of the strains as a novel taxon of subgroup 3 of the genus Erwinia, along with E. toletana and E. iniecta, and furthermore, provided support for their reclassification in a novel genus. Whole genome comparisons allowed the delimitation of the novel species and also supported the proposed transfer of subgroup 3 species to a novel genus in the Erwiniaeae. Phenotypically the novel species could be differentiated from E. toletana and E. iniecta, and the novel genus could be differentiated from the closely related genera Erwinia and Mixta. Therefore, we propose (1) the reclassification of E. toletana and E. iniecta in a novel genus, Winslowiella gen. nov., as Winslowiella toletana comb. nov. and Winslowiella iniecta comb. nov., with W. toletana comb. nov. as the type species (type strain A37T = CFBP 6631T = ATCC 700880T = CECT 5263T), and (2) classification of the novel strains as Winslowiella arboricola sp. nov. (type strain BAC 15a-03bT = LMG 32576T = NCPPB 4696T).

6.
BMC Neurol ; 22(1): 99, 2022 Mar 17.
Article in English | MEDLINE | ID: mdl-35300599

ABSTRACT

BACKGROUND: To test, in a two-arm, single center, superiority, randomized controlled trial, the effectiveness of and costs associated with a patient-initiated treatment model for people with hemifacial spasm (HFS) and blepharospasm (BEB) in comparison to usual care. METHODS: One hundred and thirty patients with HFS or BEB, aged 18 years or over, were recruited from a nurse-led botulinum toxin type A clinic at an eye hospital in the United Kingdom (UK), completed baseline measures and were randomized (1:1). The intervention group determined their own botulinum toxin type A (BoNT/A) treatment schedule during the trial period (9 months) and received an information leaflet with a "hotline" number to book an appointment. Usual care appointments were scheduled by treating clinicians. Data analysts were blind to study group. The primary outcomes were disease severity and functional disability, as measured by the Jankovic Rating Scale and Blepharospasm Disability Index, respectively. Secondary outcomes included quality of life, anxiety and depression, satisfaction with care, confidence in the service, economic costs and employment days lost. RESULTS: Sixty-five patients were randomized to each group. The intervention demonstrated no statistically significant difference to usual care for any of primary outcomes. On secondary outcomes the levels of anxiety differed significantly (F2, 142.39 = 1.65, p = 0.02), with the intervention arm exhibiting a decrease and the control arm an increase (Hedges' g = - 0.26 [99% CI -0.83, 0.32]). No other statistically significant differences were found for secondary outcomes. Overall healthcare costs and costs to the patient were on average £198.95 less (95% CI -£256.76, £654.67; p = 0.10) per participant for those in the intervention compared to usual care, although this finding was not significant. CONCLUSIONS: We did not observe differences between the patient-initiated treatment model and usual care for people with BEB or HFS, on any primary outcome measure, quality of life, or depression. The patient-initiated treatment model may, however, have the potential to save healthcare costs and reduce anxiety. Patients using this new model were also equally as satisfied in the service and confident in their care as those receiving treatment as usual. TRIAL REGISTRATION: Clinicaltrials.gov ID NCT02577224 , 16th October 2015.


Subject(s)
Blepharospasm , Botulinum Toxins, Type A , Hemifacial Spasm , Adolescent , Adult , Aged , Aged, 80 and over , Blepharospasm/drug therapy , Botulinum Toxins, Type A/therapeutic use , Health Care Costs , Hemifacial Spasm/drug therapy , Humans , Middle Aged , Quality of Life , Young Adult
7.
Article in English | MEDLINE | ID: mdl-35133259

ABSTRACT

Bacteria isolated from onion bulbs suffering from bacterial decay in the United States and Norway were previously shown to belong to the genus Rahnella based on partial housekeeping gene sequences and/or fatty acid analysis. However, many strains could not be assigned to any existing Rahnella species. Additionally, strains isolated from creek water and oak as well as a strain with bioremediation properties were assigned to Rahnella based on partial housekeeping gene sequences. The taxonomic status of these 21 strains was investigated using multilocus sequence analysis, whole genome analyses, phenotypic assays and fatty acid analysis. Phylogenetic and phylogenomic analyses separated the strains into five clusters, one of which corresponded to Rahnella aceris. The remaining four clusters could be differentiated both genotypically and phenotypically from each other and existing Rahnella species. Based on these results, we propose the description of four novel species: Rahnella perminowiae sp. nov. (type strain SL6T=LMG 32257T=DSM 112609T), Rahnella bonaserana sp. nov. (H11bT=LMG 32256T=DSM 112610T), Rahnella rivi sp. nov. (FC061912-KT=LMG 32259T=DSM 112611T) and Rahnella ecdela sp. nov. (FRB 231T=LMG 32255T=DSM 112612T).


Subject(s)
Phylogeny , Rahnella , Bacterial Typing Techniques , DNA, Bacterial/genetics , Multilocus Sequence Typing , Onions/microbiology , Quercus/microbiology , RNA, Ribosomal, 16S/genetics , Rahnella/classification , Rahnella/isolation & purification , Rivers/microbiology , Sequence Analysis, DNA
8.
Orbit ; 40(2): 110-119, 2021 Apr.
Article in English | MEDLINE | ID: mdl-32116098

ABSTRACT

Purpose: Benign essential blepharospasm (BEB) and hemifacial spasm (HFS) are debilitating conditions causing spasms to the eyes and/or face and can significantly impact on quality of life (QoL). Initial research has highlighted potential factors impacting on QoL in BEB, but there remains a wealth of demographic, clinical, and psychosocial factors that may contribute to QoL but have not received attention. Methods: Cross-sectional baseline data were collected before a single-masked randomised controlled trial from 130 adults with BEB and HFS recruited from botulinum toxin clinics at Moorfields Eye Hospital, London. QoL was measured using the 24-item Craniocervical Dystonia Questionnaire (CDQ24), which provides a total score and five subscale scores relating to Stigma, Emotional state, Pain, Activities of daily living (ADL), and Social/family life. Treating clinicians provided clinical data. Hierarchical multiple regressions were performed on this baseline data to identify significant predictors of QoL. Results: ADL and Stigma were the areas most impacted upon whilst patients experienced better adjustment in relation to Pain, Social/family life, and Emotional state. CDQ24 Total scores were explained by the model (80% variance) and were significantly associated with appearance concerns, emotional representations, perceived negative consequences of the condition, mood, and dose of botulinum toxin. Conclusions: Patients with BEB and HFS report a detrimental impact on ADL and perceived stigma in relation to their condition. Predominantly, individual perceptions and mood are associated with QoL in this population, rather than demographic and clinical factors, signifying areas to target in the design of future healthcare services or interventions.


Subject(s)
Blepharospasm , Botulinum Toxins, Type A , Hemifacial Spasm , Activities of Daily Living , Adult , Blepharospasm/drug therapy , Botulinum Toxins, Type A/therapeutic use , Cross-Sectional Studies , Hemifacial Spasm/drug therapy , Humans , Quality of Life
9.
Rheumatology (Oxford) ; 60(5): 2122-2127, 2021 05 14.
Article in English | MEDLINE | ID: mdl-33331922

ABSTRACT

The guideline will be developed using the methods and processes outlined in Creating Clinical Guidelines: Our Protocol [1]. This development process to produce guidance, advice and recommendations for practice has National Institute for Health and Care Excellence (NICE) accreditation.


Subject(s)
Antirheumatic Agents/therapeutic use , Rheumatology/standards , Sjogren's Syndrome/drug therapy , Humans
10.
Front Microbiol ; 11: 360, 2020.
Article in English | MEDLINE | ID: mdl-32265851

ABSTRACT

Exserohilum turcicum (sexual stage Setosphaeria turcica) is the hemibiotrophic causal agent of northern leaf blight of maize and sorghum. This study aimed to identify the genes involved in host colonization during the biotrophic and necrotrophic phases of infection. It also aimed to identify race-specific differences in gene expression. RNAseq of maize seedlings inoculated with a race 13N or 23N E. turcicum isolate was conducted before inoculation and at 2, 5, 7, and 13 days post-inoculation (dpi). Biological replicates were pooled per time point for each race and sequenced. A bioinformatics pipeline was used to identify candidate effectors, and expression was validated for selected candidates. Fungal biomass was positively correlated with the percentages of E. turcicum reads mapped, which were low at early time points (2-7 dpi) with a significant increase at 13 dpi, indicating a lifestyle switch from biotrophy to necrotrophy between 7 and 13 dpi. AVRHt1 is the putative E. turcicum effector recognized by the maize resistance gene Ht1. Consistent with this, AVRHt1 was expressed in planta by race 23N, but transcripts were absent in race 13N. In addition, specific transposable elements were expressed in 23N only. Genes encoding the virulence-associated peptidases leupeptin-inhibiting protein 1 and fungalysin were expressed in planta. Transcriptional profiles of genes involved in secondary metabolite synthesis or cell wall degradation revealed the importance of these genes during late stages of infection (13 dpi). A total of 346 expressed candidate effectors were identified, including Ecp6 and proteins similar to the secreted in xylem (SIX) effectors common to formae speciales of Fusarium oxysporum, SIX13 and SIX5. Expression profiling of Ecp6 and SIX13-like indicated a peak in expression at 5 and 7 dpi compared to 2 and 13 dpi. Sequencing of SIX13-like from diverse isolates of E. turcicum revealed host-specific polymorphisms that were mostly non-synonymous, resulting in two groups of SIX13-like proteins that corresponded to the maize or sorghum origin of each isolate. This study suggests putative mechanisms whereby E. turcicum causes disease. Identification of the candidate effector SIX13-like is consistent with the infection mode of E. turcicum through the xylem of susceptible hosts.

11.
PLoS One ; 13(10): e0205705, 2018.
Article in English | MEDLINE | ID: mdl-30332458

ABSTRACT

Phytophthora cinnamomi Rands (Pc) is a hemibiotrophic oomycete and the causal agent of Phytophthora root rot (PRR) of the commercially important fruit crop avocado (Persea americana Mill.). Plant defense against pathogens is modulated by phytohormone signaling pathways such as salicylic acid (SA), jasmonic acid (JA), ethylene (ET), auxin and abscisic acid. The role of specific signaling pathways induced and regulated during hemibiotroph-plant interactions has been widely debated. Some studies report SA mediated defense while others hypothesize that JA responses restrict the spread of pathogens. This study aimed to identify the role of SA- and JA- associated genes in the defense strategy of a resistant avocado rootstock, Dusa in response to Pc infection. Transcripts associated with SA-mediated defense pathways and lignin biosynthesis were upregulated at 6 hours post-inoculation (hpi). Results suggest that auxin, reactive oxygen species (ROS) and Ca2+ signaling was also important during this early time point, while JA signaling was absent. Both SA and JA defense responses were shown to play a role during defense at 18 hpi. Induction of genes associated with ROS detoxification and cell wall digestion (ß-1-3-glucanase) was also observed. Most genes induced at 24 hpi were linked to JA responses. Other processes at play in avocado at 24 hpi include cell wall strengthening, the formation of phenolics and induction of arabinogalactan, a gene linked to Pc zoospore immobility. This study represents the first transcriptome wide analysis of a resistant avocado rootstock treated with SA and JA compared to Pc infection. The results provide evidence of a biphasic defense response against the hemibiotroph, which initially involves SA-mediated gene expression followed by the enrichment of JA-mediated defense from 18 to 24 hpi. Genes and molecular pathways linked to Pc resistance are highlighted and may serve as future targets for manipulation in the development of PRR resistant avocado rootstocks.


Subject(s)
Gene Expression Regulation, Plant/immunology , Host-Pathogen Interactions/immunology , Persea/immunology , Phytophthora/pathogenicity , Plant Diseases/immunology , Abscisic Acid/immunology , Abscisic Acid/metabolism , Cyclopentanes/immunology , Cyclopentanes/metabolism , Ethylenes/immunology , Ethylenes/metabolism , Gene Expression Profiling , Host-Pathogen Interactions/genetics , Indoleacetic Acids/immunology , Indoleacetic Acids/metabolism , Oxylipins/immunology , Oxylipins/metabolism , Persea/genetics , Persea/microbiology , Plant Diseases/microbiology , Plant Proteins/genetics , Plant Proteins/metabolism , Plant Roots/genetics , Plant Roots/immunology , Plant Roots/microbiology , Salicylic Acid/immunology , Salicylic Acid/metabolism , Signal Transduction/genetics , Signal Transduction/immunology
12.
IMA Fungus ; 8(2): 385-396, 2017 Dec.
Article in English | MEDLINE | ID: mdl-29242781

ABSTRACT

The genomes of Cercospora zeina, Fusarium pininemorale, Hawksworthiomyces lignivorus, Huntiella decipiens, and Ophiostoma ips are presented in this genome announcement. Three of these genomes are from plant pathogens and otherwise economically important fungal species. Fusarium pininemorale and H. decipiens are not known to cause significant disease but are closely related to species of economic importance. The genome sizes range from 25.99 Mb in the case of O. ips to 4.82 Mb for H. lignivorus. These genomes include the first reports of a genome from the genus Hawksworthiomyces. The availability of these genome data will allow the resolution of longstanding questions regarding the taxonomy of these species. In addition these genome sequences through comparative studies with closely related organisms will increase our understanding of how these species or close relatives cause disease.

16.
Mol Plant Microbe Interact ; 30(9): 710-724, 2017 09.
Article in English | MEDLINE | ID: mdl-28535078

ABSTRACT

Gray leaf spot (GLS), caused by the sibling species Cercospora zeina or Cercospora zeae-maydis, is cited as one of the most important diseases threatening global maize production. C. zeina fails to produce cercosporin in vitro and, in most cases, causes large coalescing lesions during maize infection, a symptom generally absent from cercosporin-deficient mutants in other Cercospora spp. Here, we describe the C. zeina cercosporin toxin biosynthetic (CTB) gene cluster. The oxidoreductase gene CTB7 contained several insertions and deletions as compared with the C. zeae-maydis ortholog. We set out to determine whether complementing the defective CTB7 gene with the full-length gene from C. zeae-maydis could confer in vitro cercosporin production. C. zeina transformants containing C. zeae-maydis CTB7 were generated by Agrobacterium tumefaciens-mediated transformation and were evaluated for in vitro cercosporin production. When grown on nitrogen-limited medium in the light-conditions conducive to cercosporin production in other Cercospora spp.-one transformant accumulated a red pigment that was confirmed to be cercosporin by the KOH assay, thin-layer chromatography, and ultra performance liquid chromatography-quadrupole-time-of-flight mass spectrometry. Our results indicated that C. zeina has a defective CTB7, but all other necessary machinery required for synthesizing cercosporin-like molecules and, thus, C. zeina may produce a structural variant of cercosporin during maize infection.


Subject(s)
Ascomycota/genetics , Fungal Proteins/genetics , Genetic Complementation Test , Perylene/analogs & derivatives , Zea mays/microbiology , Alternative Splicing/genetics , Amino Acid Sequence , Ascomycota/isolation & purification , Base Sequence , Biosynthetic Pathways/genetics , Computer Simulation , Conserved Sequence/genetics , DNA, Fungal/genetics , Fungal Proteins/chemistry , Fungal Proteins/metabolism , Gene Deletion , Gene Expression Regulation, Fungal , Genes, Fungal , Introns/genetics , Mass Spectrometry , Multigene Family , Oxidoreductases/metabolism , Perylene/metabolism , Transcription, Genetic , Transformation, Genetic
17.
Plant J ; 89(4): 746-763, 2017 Feb.
Article in English | MEDLINE | ID: mdl-27862526

ABSTRACT

We used a systems genetics approach to elucidate the molecular mechanisms of the responses of maize to grey leaf spot (GLS) disease caused by Cercospora zeina, a threat to maize production globally. Expression analysis of earleaf samples in a subtropical maize recombinant inbred line population (CML444 × SC Malawi) subjected in the field to C. zeina infection allowed detection of 20 206 expression quantitative trait loci (eQTLs). Four trans-eQTL hotspots coincided with GLS disease QTLs mapped in the same field experiment. Co-expression network analysis identified three expression modules correlated with GLS disease scores. The module (GY-s) most highly correlated with susceptibility (r = 0.71; 179 genes) was enriched for the glyoxylate pathway, lipid metabolism, diterpenoid biosynthesis and responses to pathogen molecules such as chitin. The GY-s module was enriched for genes with trans-eQTLs in hotspots on chromosomes 9 and 10, which also coincided with phenotypic QTLs for susceptibility to GLS. This transcriptional network has significant overlap with the GLS susceptibility response of maize line B73, and may reflect pathogen manipulation for nutrient acquisition and/or unsuccessful defence responses, such as kauralexin production by the diterpenoid biosynthesis pathway. The co-expression module that correlated best with resistance (TQ-r; 1498 genes) was enriched for genes with trans-eQTLs in hotspots coinciding with GLS resistance QTLs on chromosome 9. Jasmonate responses were implicated in resistance to GLS through co-expression of COI1 and enrichment of genes with the Gene Ontology term 'cullin-RING ubiquitin ligase complex' in the TQ-r module. Consistent with this, JAZ repressor expression was highly correlated with the severity of GLS disease in the GY-s susceptibility network.


Subject(s)
Plant Leaves/genetics , Plant Leaves/microbiology , Zea mays/genetics , Zea mays/microbiology , Ascomycota/pathogenicity , Chromosomes, Plant/genetics , Gene Regulatory Networks/genetics , Gene Regulatory Networks/physiology , Plant Diseases/genetics , Plant Diseases/microbiology , Quantitative Trait Loci/genetics
18.
Bioorg Med Chem ; 24(22): 5953-5959, 2016 11 15.
Article in English | MEDLINE | ID: mdl-27720556

ABSTRACT

Greyia radlkoferi ethanol extract and its five compounds were tested for their inhibitory activity against the mushroom tyrosinase enzyme and melanin production on melanocytes. The crude extract showed significant tyrosinase inhibition with IC50 of 17.96µg/ml. This is the first report of the isolation of these 5 compounds from Greyia radlkoferi. 2',4',6'-Trihydroxydihydrochalcone showed the highest tyrosinase inhibition at 17.70µg/ml (68.48µM), with low toxicity when compared with crude extract. This compound is therefore, a key component in the crude extract, which is responsible for tyrosinase inhibitory activity. The RT-qPCR indicated that the mechanism of action is most likely post transcriptional. Further, the molecular docking study showed that tyrosinase inhibitory activity depends on interaction of the compound with Cu2+ ions at the active site. This is the first report of the tyrosinase inhibitory activity of the G. radlkoferi extract and molecular insights on interaction of its compounds with Cu2+ ions as the driving factor for tyrosinase inhibition. These results suggest that the extract of G. radlkoferi and the compound 2',4',6'-trihydroxydihydrochalcone have great potential to be further developed as pharmaceutical or cosmetic agents for use against dermatological disorders associated with melanin.


Subject(s)
Enzyme Inhibitors/pharmacology , Magnoliopsida/chemistry , Molecular Docking Simulation , Monophenol Monooxygenase/antagonists & inhibitors , Plant Extracts/pharmacology , Animals , Cell Line, Tumor , Cell Survival/drug effects , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/isolation & purification , Gene Expression Profiling , Humans , Mice , Molecular Structure , Monophenol Monooxygenase/genetics , Monophenol Monooxygenase/metabolism , Plant Extracts/chemistry , Plant Extracts/isolation & purification , Structure-Activity Relationship
19.
Phytopathology ; 106(11): 1386-1392, 2016 11.
Article in English | MEDLINE | ID: mdl-27392177

ABSTRACT

Exserohilum turcicum is the causal agent of northern corn leaf blight, a destructive foliar disease of maize that results in yield losses worldwide. In South Africa, typical yield losses range from 15 to 30%. Previous studies found high haplotypic diversity with evidence for sexual recombination in E. turcicum populations from tropical climates such as Kenya. However, the population genetic structure and method of reproduction of E. turcicum in South Africa is unknown and, therefore, was investigated. Twelve polymorphic microsatellite markers were screened on 258 E. turcicum isolates from maize collected during 2012 and 2013 from three maize fields in South Africa. A multiplex polymerase chain reaction assay amplifying both mating type idiomorphs was applied to investigate the distribution of mating types. No distinct genetic clusters were observed. Shared haplotypes were identified between isolates separated by distances of up to 762 km, which provided evidence of migration. High haplotypic diversity indicated that sexual reproduction is occurring among E. turcicum isolates, although mating type ratios and linkage disequilibrium analyses did not support the hypothesis of random mating. The population genetic structure of E. turcicum in South Africa is likely due to the direct movement and spread of isolates undergoing a mixed reproductive lifecycle.


Subject(s)
Ascomycota/genetics , Genetics, Population , Plant Diseases/microbiology , Zea mays/microbiology , Ascomycota/isolation & purification , Genes, Mating Type, Fungal/genetics , Genetic Linkage , Genetic Structures , Geography , Haplotypes , Microsatellite Repeats/genetics , South Africa
20.
Phytopathology ; 106(10): 1194-1205, 2016 10.
Article in English | MEDLINE | ID: mdl-27392176

ABSTRACT

South Africa is one of the leading maize-producing countries in sub-Saharan Africa. Since the 1980s, Cercospora zeina, a causal agent of gray leaf spot of maize, has become endemic in South Africa, and is responsible for substantial yield reductions. To assess genetic diversity and population structure of C. zeina in South Africa, 369 isolates were collected from commercial maize farms in three provinces (KwaZulu-Natal, Mpumalanga, and North West). These isolates were evaluated with 14 microsatellite markers and species-specific mating type markers that were designed from draft genome sequences of C. zeina isolates from Africa (CMW 25467) and the United States (USPA-4). Sixty alleles were identified across 14 loci, and gene diversity values within each province ranged from 0.18 to 0.35. High levels of gene flow were observed (Nm = 5.51), and in a few cases, identical multilocus haplotypes were found in different provinces. Overall, 242 unique multilocus haplotypes were identified with a low clonal fraction of 34%. No distinct population clusters were identified using STRUCTURE, principal coordinate analysis, or Weir's theta θ statistic. The lack of population differentiation was supported by analysis of molecular variance tests, which indicated that only 2% of the variation was attributed to variability between populations from each province. Mating type ratios of MAT1-1 and MAT1-2 idiomorphs from 335 isolates were not significantly different from a 1:1 ratio in all provinces, which provided evidence for sexual reproduction. The draft genome of C. zeina CMW 25467 exhibited a complete genomic copy of the MAT1-1 idiomorph as well as exonic fragments of MAT genes from both idiomorphs. The high level of gene diversity, shared haplotypes at different geographical locations within South Africa, and presence of both MAT idiomorphs at all sites indicates widespread dispersal of C. zeina between maize fields in the country as well as evidence for sexual recombination. The outcomes of this genome-enabled study are important for disease management since the high diversity has implications for dispersal of fungicide resistance should it emerge and the need for diversified resistance breeding.


Subject(s)
Ascomycota/genetics , Genetic Variation , Genetics, Population , Genome, Fungal/genetics , Plant Diseases/microbiology , Zea mays/microbiology , Ascomycota/isolation & purification , Gene Flow , Geography , Microsatellite Repeats/genetics , Sequence Analysis, DNA , South Africa
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