Virulence genes of new population of coffee rust (Hemileia vastatrix) affecting coffee variety 'Lempira', in Honduras; resistant and susceptible varieties.

2021 ◽  
pp. 338-343
Author(s):  
Yonis Morales ◽  
Rolando Grajeda
Keyword(s):  
Relative Humidity ◽  
Virulence Genes ◽  
Central American ◽  
Virulence Determinants ◽  
Sources Of Resistance ◽  
Hemileia Vastatrix ◽  
Leaf Discs ◽  
Coffee Rust ◽  
Temperature Conditions ◽  
Resistant Varieties

Abstract The coffee variety 'Lempira', released in Honduras in 1998, was classified 100% resistant to races I and II of coffee rust identified by Portugal's Centre for Research into Coffee Rusts (Centro de Investigação das Ferrugens do Cafeeiro) (CIFC) in 1997. However, since 2007, the disease has been reported in seed foundation plots and producer farms, the most recent epidemic report being in April 2016 in Vegas de Jalan, Juticalpa Olancho, affecting 210 ha. Since this variety constitutes 45% of the cultivated area under coffee in the country, there is a need to identify the virulence genes of the new strain and to determine the resistance and susceptibility of other cultivated varieties. For these purposes, mass samples of rust were inoculated on leaf discs of the differential clones 1343/269, 110/5, 147/1, 152/3, 33/1, 419/20, 832/1 and 832/2, together with 87/1, 1006/10, 420/10 and 420/2 from the Federal University of Vicosa, as well as on the two main cultivated resistant varieties ('Parainema' and 'IHCAFE- 90'), and seven promising genotypes, under controlled temperature conditions and relative humidity. After 20-60 days of inoculation, seven virulence genes were identified (v1, v2, v4, v5, v6, v7, v9), of which v1, v4, v6, v7 and v9 had not been reported in Honduras previously. It is inferred that this rust population arose by recombination of race v5 with v6, v7 or v9. Races with 3, 4, 5, 6 or 7 virulence determinants were identified as the most complex and aggressive strains described but they lacked the v3 and v8 determinants. In addition, it was found that 'Parainema', 'H27', 'T5296-170', 'Central American', 'Pacamara yellow' and 'Anacafe-14' are resistant because they possess the SH8 gene, absent from 'Lempira'. 'IHCAFE-90' and 'Obatá' showed 20% susceptibility, and 'Ruiru 11' was susceptible. The results reveal the diversity of rust virulence genes in Honduras and emphasize the importance of the SH3 and SH8 genes as sources of resistance.

scholarly journals Burden, Antibiotic Resistance, and Clonality of Shigella spp. Implicated in Community-Acquired Acute Diarrhoea in Lilongwe, Malawi

2021 ◽  
Vol 6 (2) ◽  
pp. 63
Author(s):  
Abel F.N.D. Phiri ◽  
Akebe Luther King Abia ◽  
Daniel Gyamfi Amoako ◽  
Rajab Mkakosya ◽  
Arnfinn Sundsfjord ◽  
...  
Keyword(s):  
Real Time ◽  
Antibiotic Susceptibility ◽  
Virulence Genes ◽  
Shigella Flexneri ◽  
Acute Diarrhoea ◽  
Virulence Determinants ◽  
African Countries ◽  
Shigella Species ◽  
Shigella Spp ◽  
Sub Saharan

Although numerous studies have investigated diarrhoea aetiology in many sub-Saharan African countries, recent data on Shigella species’ involvement in community-acquired acute diarrhoea (CA-AD) in Malawi are scarce. This study investigated the incidence, antibiotic susceptibility profile, genotypic characteristics, and clonal relationships of Shigella flexneri among 243 patients presenting with acute diarrhoea at a District Hospital in Lilongwe, Malawi. Shigella spp. were isolated and identified using standard microbiological and serological methods and confirmed by identifying the ipaH gene using real-time polymerase chain reaction. The isolates’ antibiotic susceptibility to 20 antibiotics was determined using the VITEK 2 system according to EUCAST guidelines. Genes conferring resistance to sulfamethoxazole (sul1, sul2 and sul3), trimethoprim (dfrA1, dfrA12 and dfrA17) and ampicillin (oxa-1 and oxa-2), and virulence genes (ipaBCD, sat, ial, virA, sen, set1A and set1B) were detected by real-time PCR. Clonal relatedness was assessed using ERIC-PCR. Thirty-four Shigella flexneri isolates were isolated (an overall incidence of 14.0%). All the isolates were fully resistant to sulfamethoxazole/trimethoprim (100%) and ampicillin (100%) but susceptible to the other antibiotics tested. The sul1 (79%), sul2 (79%), sul3 (47%), dfrA12 (71%) and dfrA17 (56%) sulfonamide and trimethoprim resistance genes were identified; Oxa-1, oxa-2 and dfrA1 were not detected. The virulence genes ipaBCD (85%), sat (85%), ial (82%), virA (76%), sen (71%), stx (71%), set1A (26%) and set1B (18%) were detected. ERIC-PCR profiling revealed that the Shigella isolates were genetically distinct and clonally unrelated, indicating the potential involvement of genetically distinct S. flexneri in CA-AD in Malawi. The high percentage resistance to ampicillin and sulfamethoxazole/trimethoprim and the presence of several virulence determinants in these isolates emphasises a need for continuous molecular surveillance studies to inform preventive measures and management of Shigella-associated diarrhoeal infections in Malawi.

scholarly journals Transcription of Candidate Virulence Genes ofHaemophilus ducreyi during Infection of Human Volunteers

2001 ◽  
Vol 69 (3) ◽  
pp. 1483-1487 ◽  
Author(s):  
Robert E. Throm ◽  
Stanley M. Spinola
Keyword(s):  
Experimental Infection ◽  
Virulence Genes ◽  
Human Model ◽  
Specific Gene ◽  
Gene Products ◽  
Virulence Determinants ◽  
Reverse Transcription Pcr ◽  
Human Volunteers

ABSTRACT Haemophilus ducreyi expresses several putative virulence factors in vitro. Isogenic mutant-to-parent comparisons have been performed in a human model of experimental infection to examine whether specific gene products are involved in pathogenesis. Several mutants (momp, ftpA, losB, lst, cdtC, and hhdB) were as virulent as the parent in the human model, suggesting that their gene products did not play a major role in pustule formation. However, we could not exclude the possibility that the gene of interest was not expressed during the initial stages of infection. Biopsies of pustules obtained from volunteers infected with H. ducreyiwere subjected to reverse transcription-PCR. Transcripts corresponding to momp, ftpA, losB, lst, cdtB, and hhdA were expressed in vivo. In addition, transcripts for other putative virulence determinants such as ompA2, tdhA, lspA1, andlspA2 were detected in the biopsies. These results indicate that although several candidate virulence determinants are expressed during experimental infection, they do not have a major role in the initial stages of pathogenesis.

scholarly journals A linkage of gene of resistance to a broomrape race G with microsatellite loci of a sunflower linedonor RGP1 of VNIIMK’s breeding

2021 ◽  
Vol 186 (2) ◽  
pp. 3-9
Author(s):  
S.Z. Guchetl ◽  
◽  
D.L. Savichenko ◽  
Keyword(s):  
Microsatellite Loci ◽  
Physical Map ◽  
Pcr Analysis ◽  
Sources Of Resistance ◽  
Resistant Varieties ◽  
Literary Sources ◽  
Ssr Loci ◽  
Environmentally Safe ◽  
Yield Formation ◽  
Sunflower Genome

Broomrape (Orobanche cumana Wallr.) is one of the main biotic factors limiting high sunflower yield formation. The most effective and environmentally safe method of protection is cultivation of resistant varieties and hybrids of sunflower. Development of resistant sunflower genotypes includes search and usage of sources of resistance in breeding process as well as accurate and productive procedures of material assessment. The purpose of the research is to analyze a linkage of a gene Or7 with microsatellite loci of the line-donor of resistance to broomrape race G from the VNIIMK’s collection. The objects of the research are the line RGP1 – a donor of resistance to broomrape race G and a susceptible to this race line VR 678 from the VNIIMK’s collection. Sunflower plants were crossed in field to produce F1. Also we conducted self-pollination of F1 plants to obtain F2 progeny. Plants were tested in a greenhouse in soil infected with seeds of broomrape race G using a method of early diagnostic. Sunflower DNA was extracted from the top leaves of the young sprouts of the vegetative plants. For PCR-analysis we used three SSR-primers demonstrated polymorphism in parental lines: ORS 683, ORS 1040, and ORS 1112. We tested joint inheritance of the gene Or7 and these loci, and inheritance between SSR-loci. An independent inheritance of the gene Or7 with DNA-loci ORS 683, ORS 1040, and ORS 1112, as well as SSR-loci between ORS 1040 and ORS 1112, ORS 1040 and ORS 683 was showed. Loci ORS683 – ORS 1112 are linked with a frequency of recombination of 0.27 ± 0.41 (27 cM). As a result of our research location of the gene Or7 in the nearest area to microsatellite loci ORS 683, ORS 1040, and ORS 1112 was excluded. Basing on studied literary sources and a representative sunflower genome HanXRQr2.0-SUNRISE we made a partial physical map LG3 for determination of an area for the further search of a localization of the Or7 and DNAmarkers co-segregating with this gene.

Occurrence of virulence-associated genes in clinical Enterococcus faecalis strains isolated in Londrina, Brazil

2004 ◽  
Vol 53 (11) ◽  
pp. 1069-1073 ◽  
Author(s):  
Elisa Bittencourt de Marques ◽  
Sérgio Suzart
Keyword(s):  
Enterococcus Faecalis ◽  
Virulence Genes ◽  
Epidemiological Studies ◽  
Wide Distribution ◽  
Virulence Determinants ◽  
Simultaneous Presence ◽  
Common Pattern ◽  
Clinical Strains ◽  
Virulence Markers ◽  
Serious Infections

Epidemiological studies have reinforced the importance of Enterococcus faecalis in causing serious infections, and to date, our understanding of how certain virulence factors are involved in the pathogenesis of enterococcal infections is still limited. The aim of the present study was to examine the occurrence of known virulence determinants in a group of E. faecalis strains isolated from different clinical sources in Brazil. A total of 95 E. faecalis strains were investigated for the presence of nine virulence genes including aggA, cylA, cylB, cylM, eep, efaA, enlA, esp and gelE by using PCR. The data showed a relatively wide distribution of the virulence genes among the investigated strains. The clinical strains carried at least one and concomitantly up to as many as eight virulence markers, with two or three being the most common pattern. Most of the strains carried efaA (58.9 %), eep (58.9 %) and esp (57.9 %) genes, whereas the remaining virulence markers were detected in variable percentages ranging from 9.5 to 45 %. Simultaneous presence of virulence markers was observed among clinical strains regardless of their sources. In this study, the efaA + esp + gelE + profile was the virulence genotype most frequently detected among E. faecalis strains. Finally, there was no significant association between virulence markers and clinical sources.

SOURCES OF RESISTANCE IN BARLEY TO PYRENOPHORA TERES

1965 ◽  
Vol 45 (2) ◽  
pp. 189-193 ◽  
Author(s):  
K. W. Buchannon ◽  
W. C. McDonald
Keyword(s):  
North Dakota ◽  
Quality Characteristics ◽  
Seedling Stage ◽  
Malting Quality ◽  
Western Canada ◽  
Pyrenophora Teres ◽  
Net Blotch ◽  
Sources Of Resistance ◽  
Highly Pathogenic ◽  
Resistant Varieties

The reaction to infection by Pyrenophora teres Drechs., the incitant of net blotch of barley, was determined for 6,174 varieties in the U.S.D.A. World Barley Collection. Forty varieties, seventeen of them from Ethiopia, were resistant in the seedling stage to a highly pathogenic strain of the fungus prevalent in Western Canada and to composites of isolates from Manitoba, Saskatchewan, Alberta, Ontario, North Dakota, California, and Mexico. They were also resistant in the field at three locations in Western Canada. Agronomic and malting quality characteristics for the resistant varieties were also recorded.

scholarly journals Current Virulence of Pyrenophora teres on Barley in Western Australia

Plant Disease ◽  
2001 ◽  
Vol 85 (9) ◽  
pp. 960-966 ◽  
Author(s):  
Sanjiv Gupta ◽  
Robert Loughman
Keyword(s):  
Western Australia ◽  
Error Variance ◽  
Geographic Area ◽  
Australian Isolate ◽  
Pyrenophora Teres ◽  
Sources Of Resistance ◽  
Pathogenic Variation ◽  
Resistant Varieties ◽  
Significant Line ◽  
Spot Type

Studies on variation, occurrence, and distribution of virulence in Pyrenophora teres are helpful to identify effective sources of resistance that can be used for barley breeding in Western Australia. Seventy-nine isolates of Pyrenophora teres were collected from different barley fields of Western Australia in 1995-96. Seventy-four induced net type symptoms (P. teres f. teres) and five induced spot type symptoms (P. teres f. maculata). Net type isolate responses on 47 barley lines were similar to the range of responses induced by nine historical isolates collected in the region between 1975 and 1985. These net type isolates were classified into two distinct groups based on virulence to the cultivar Beecher. Isolates were further classified into eight groups based on minor pathogenic variation among the population. The virulence phenotype present in an eastern Australian isolate was not observed in any isolates collected from Western Australia. An analysis of variance on a subset of 12 net type isolates indicated a significant line × isolate interaction (P < 0.001), with the interaction term variance component four times larger than the error variance. Based on these studies, the virulence among net type isolates has remained stable in Western Australia for the last 19 years. Spot type isolates were collected from a wider geographic area than previously reported and varied in virulence based on response to barley line Herta. Variation in spot-type isolates is reported for the first time from the region. The results from this study are being used in the development of resistant varieties.

scholarly journals Screening Methods and Further Sources of Resistance to Peanut Rust1

1980 ◽  
Vol 7 (1) ◽  
pp. 10-12 ◽  
Author(s):  
P. Subrahmanyam ◽  
R. W. Gibbons ◽  
S. N. Nigam ◽  
V. R. Rao
Keyword(s):  
Relative Humidity ◽  
Irrigation System ◽  
Germplasm Collection ◽  
Sprinkler Irrigation ◽  
Test Material ◽  
Screening Methods ◽  
Point Scale ◽  
Sources Of Resistance ◽  
Moderately Resistant ◽  
Different Levels

Abstract A germplasm collection of 6000 peanut entries was screened for resistance to rust at ICRISAT, India. Preliminary field screening was done during the 1977 rainy season when a natural epidemic of rust was in progress. The cultivars or lines which were rated between 2 and 5 on a 9-point scale during this screening were further tested during the 1977/78 dry season employing an infector row system of susceptible cultivars and spreader plants systematically interplanted with the test material. High relative humidity was maintained in the field by operating an overhead sprinkler irrigation system. Percentage leaf area damaged on the test material was estimated at 10 day intervals from approximately 90 days after their emergence until harvest. Each entry was also assessed on a scale proposed by Mazzani and Hinojosa. Two land races, NC.Ac. 17090 and EC. 76446 (292) were more resistant than either PI. 259747 or PI. 298115 which were reported resistant by other workers. In addition, NCAc. 17030, NCAc. 17132, NC.Ac. 17129, NC. Ac. 17135 and NC.Ac. 17124 were moderately resistant. Four cultivars or lines with different levels of resistance in the field were tested in the greenhouse at three different stages in development. The results indicated that resistance increased as the plants aged.

scholarly journals Manganese Phosphite in Coffee Defence against Hemileia vastatrix , the Coffee Rust Fungus: Biochemical and Molecular Analyses

2016 ◽  
Vol 164 (11-12) ◽  
pp. 1043-1053 ◽  
Author(s):  
Ana Cristina Andrade Monteiro ◽  
Mário Lúcio Vilela de Resende ◽  
Thaís Cainã Teixeira Valente ◽  
Pedro Martins Ribeiro Junior ◽  
Vanessa Foresti Pereira ◽  
...  
Keyword(s):  
Rust Fungus ◽  
Hemileia Vastatrix ◽  
Molecular Analyses ◽  
Coffee Rust

scholarly journals Incidence of virulence determinants in clinical Enterococcus faecium and Enterococcus faecalis isolates collected in Sardinia (Italy)

2003 ◽  
Vol 52 (6) ◽  
pp. 491-498 ◽  
Author(s):  
I. Duprè ◽  
S. Zanetti ◽  
A. M. Schito ◽  
G. Fadda ◽  
L. A. Sechi
Keyword(s):  
Enterococcus Faecalis ◽  
Enterococcus Faecium ◽  
Virulence Genes ◽  
Protein Gene ◽  
Surface Protein ◽  
Virulence Determinants ◽  
Colonization Factor ◽  
Aggregation Substance ◽  
Epithelial Cell Lines ◽  
Surface Protein Gene

Enterococci are widely distributed in the environment; within the human body, they are normal commensals of the oral cavity, gastrointestinal tract and vagina. In recent years, enterococci have become one of the most frequent causes of acquired nosocomial infections worldwide. The molecular mechanism of virulence of these bacteria is still not completely understood. The aims of this work were to characterize phenotypically 47 isolates of Enterococcus faecalis and Enterococcus faecium collected in Sardinia (Italy) by their abilities to adhere to different epithelial cell lines (Vero and Caco-2 cells) and to associate their phenotypes with the presence of known virulence genes detected within their genomes by PCR. The following genes were amplified: AS (aggregation substance), esp (surface protein gene), ace (accessory colonization factor), efaA (E. faecalis endocarditis antigen) and gelE (gelatinase). The virulence genes were detected in E. faecalis isolates only, with the exception of esp, which was found in both species. The phenotypic and genotypic results were also compared with the susceptibility of isolates to various antibiotics.

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