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1.
BMC Plant Biol ; 21(1): 588, 2021 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-34895144

RESUMO

BACKGROUND: Frogeye leaf spot (FLS) is a destructive fungal disease that affects soybean production. The most economical and effective strategy to control FLS is the use of resistant cultivars. However, the use of a limited number of resistant loci in FLS management will be countered by the emergence of new high-virulence Cercospora sojina races. Therefore, we identified quantitative trait loci (QTL) that control resistance to FLS and identified novel resistant genes using a genome-wide association study (GWAS) on 234 Chinese soybean cultivars. RESULTS: A total of 30,890 single nucleotide polymorphism (SNP) markers were used to estimate linkage disequilibrium (LD) and population structure. The GWAS results showed four loci (p < 0.0001) distributed over chromosomes (Chr.) 5 and 20, that are significantly associated with FLS resistance. No previous studies have reported resistance loci in these regions. Subsequently, 45 genes in the two resistance-related haplotype blocks were annotated. Among them, Glyma20g31630 encoding pyruvate dehydrogenase (PDH), Glyma05g28980, which encodes mitogen-activated protein kinase 7 (MPK7), and Glyma20g31510, Glyma20g31520 encoding calcium-dependent protein kinase 4 (CDPK4) in the haplotype blocks deserves special attention. CONCLUSIONS: This study showed that GWAS can be employed as an effective strategy for identifying disease resistance traits in soybean and narrowing SNPs and candidate genes. The prediction of candidate genes in the haplotype blocks identified by disease resistance loci can provide a useful reference to study systemic disease resistance.


Assuntos
Cercospora/patogenicidade , Resistência à Doença/genética , Doenças das Plantas/imunologia , Polimorfismo de Nucleotídeo Único/genética , Locos de Características Quantitativas/genética , Soja/genética , Estudo de Associação Genômica Ampla , Genótipo , Haplótipos , Modelos Lineares , Desequilíbrio de Ligação , Fenótipo , Doenças das Plantas/microbiologia , Soja/imunologia , Soja/microbiologia , Virulência
2.
G3 (Bethesda) ; 11(10)2021 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-34568928

RESUMO

Plant diseases caused by the Cercospora genus of ascomycete fungi are a major concern for commercial agricultural practices. Several Cercospora species can affect soybeans, such as Cercospora kikuchii which causes soybean leaf blight. Speciation in Cercospora on soybean has not been adequately studied. Some cryptic groups of Cercospora also cause diseases on soybean. Moreover, it has been known C. kikuchii population genetic structure is different between countries. Consequently, further genomic information could help to elucidate the covert differentiation of Cercospora diseases in soybean. Here, we report for the first time, a chromosome-level genome assembly for C. kikuchii. The genome assembly of 9 contigs was 34.44 Mb and the N50 was 4.19 Mb. Based on ab initio gene prediction, several candidates for pathogenicity-related genes, including 242 genes for putative effectors, 55 secondary metabolite gene clusters, and 399 carbohydrate-active enzyme genes were identified. The genome sequence and the features described in this study provide a solid foundation for comparative and evolutionary genomic analysis for Cercospora species that cause soybean diseases worldwide.


Assuntos
Ascomicetos , Soja , Ascomicetos/genética , Cercospora , Doenças das Plantas , Soja/genética , Virulência
3.
PLoS One ; 16(9): e0257008, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34478465

RESUMO

In this study, the feasibility of classifying soybean frogeye leaf spot (FLS) is investigated. Leaf images and hyperspectral reflectance data of healthy and FLS diseased soybean leaves were acquired. First, image processing was used to classify FLS to create a reference for subsequent analysis of hyperspectral data. Then, dimensionality reduction methods of hyperspectral data were used to obtain the relevant information pertaining to FLS. Three single methods, namely spectral index (SI), principal component analysis (PCA), and competitive adaptive reweighted sampling (CARS), along with a PCA and SI combined method, were included. PCA was used to select the effective principal components (PCs), and evaluate SIs. Characteristic wavelengths (CWs) were selected using CARS. Finally, the full wavelengths, CWs, effective PCs, SIs, and significant SIs were divided into 14 datasets (DS1-DS14) and used as inputs to build the classification models. Models' performances were evaluated based on the classification accuracy for both the overall and individual classes. Our results suggest that the FLS comprised of five classes based on the proportion of total leaf surface covered with FLS. In the PCA and SI combination model, 5 PCs and 20 SIs with higher weight coefficient of each PC were extracted. For hyperspectral data, 20 CWs and 26 effective PCs were also selected. Out of the 14 datasets, the model input variables provided by five datasets (DS2, DS3, DS4, DS10, and DS11) were more superior than those of full wavelengths (DS1) both in support vector machine (SVM) and least squares support vector machine (LS-SVM) classifiers. The models developed using these five datasets achieved overall accuracies ranging from 91.8% to 94.5% in SVM, and 94.5% to 97.3% in LS-SVM. In addition, they improved the classification accuracies by 0.9% to 3.6% (SVM) and 0.9% to 3.7% (LS-SVM).


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Micoses/microbiologia , Doenças das Plantas/microbiologia , Folhas de Planta , Soja/ultraestrutura , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Cercospora , Folhas de Planta/microbiologia , Folhas de Planta/ultraestrutura , Soja/microbiologia , Máquina de Vetores de Suporte
4.
Microb Cell Fact ; 20(1): 100, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33992112

RESUMO

BACKGROUND: Owing to the excellent properties of photosensitization, cercosporin, one of naturally occurring perylenequinonoid pigments, has been widely used in photodynamic therapy, or as an antimicrobial agent and an organophotocatalyst. However, because of low efficiency of total chemical synthesis and low yield of current microbial fermentation, the limited production restricts its broad applications. Thus, the strategies to improve the production of cercosporin were highly desired. Besides traditional optimization methods, here we screened leaf-spot-disease-related endophytic bacteria to co-culture with our previous identified Cercospora sp. JNU001 to increase cercosporin production. RESULTS: Bacillus velezensis B04 and Lysinibacillus sp. B15 isolated from leaves with leaf spot diseases were found to facilitate cercosporin secretion into the broth and then enhance the production of cercosporin. After 4 days of co-culture, Bacillus velezensis B04 allowed to increase the production of cercosporin from 128.2 mg/L to 984.4 mg/L, which was 7.68-fold of the previously reported one. Lysinibacillus sp. B15 could also enhance the production of cercosporin with a yield of 626.3 mg/L, which was 4.89-fold higher than the starting condition. More importantly, we found that bacteria B04 and B15 employed two different mechanisms to improve the production of cercosporin, in which B04 facilitated cercosporin secretion into the broth by loosening and damaging the hyphae surface of Cercospora sp. JNU001 while B15 could adsorb cercosporin to improve its secretion. CONCLUSIONS: We here established a novel and effective co-culture method to improve the production of cercosporin by increasing its secretion ability from Cercospora sp. JNU001, allowing to develop more potential applications of cercosporin.


Assuntos
Cercospora/metabolismo , Endófitos/metabolismo , Interações Microbianas/fisiologia , Perileno/análogos & derivados , Doenças das Plantas/microbiologia , Bacillaceae/crescimento & desenvolvimento , Bacillaceae/metabolismo , Bacillus/crescimento & desenvolvimento , Bacillus/metabolismo , Cercospora/genética , Cercospora/crescimento & desenvolvimento , Endófitos/genética , Endófitos/crescimento & desenvolvimento , Regulação Fúngica da Expressão Gênica , Técnicas In Vitro , Perileno/análise , Perileno/metabolismo
5.
Mol Biol Rep ; 48(4): 3379-3392, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33890197

RESUMO

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.


Assuntos
Resistência à Doença/genética , Genoma de Planta , Micoses , Doenças das Plantas , Locos de Características Quantitativas , Zea mays/genética , Cercospora , Mapeamento Cromossômico , Genômica , Análise de Sequência de DNA , Zea mays/microbiologia , Zea mays/fisiologia
6.
Theor Appl Genet ; 134(7): 2221-2234, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33825949

RESUMO

KEY MESSAGE: The genetic architecture of resistance to Cercospora janseana was examined, and a single resistance locus was identified. A SNP marker was identified and validated for utilization in U.S. breeding germplasm Cercospora janseana (Racib.) is a fungal pathogen that causes narrow brown leaf spot (NBLS) in rice. Although NBLS is a major disease in the southern United States and variation in resistance among U.S. rice germplasm exists, little is known about the genetic architecture underlying the trait. In this study, a recombinant inbred line population was evaluated for NBLS resistance under natural disease infestation in the field across three years. A single, large-effect QTL, CRSP-2.1, was identified that explained 81.4% of the phenotypic variation. The QTL was defined to a 532 kb physical interval and 13 single nucleotide polymorphisms (SNPs) were identified across the region to characterize the haplotype diversity present in U.S. rice germplasm. A panel of 387 U.S. rice germplasm was genotyped with the 13 haplotype SNPs and phenotyped over two years for NBLS resistance. Fourteen haplotypes were identified, with six haplotypes accounting for 94% of the panel. The susceptible haplotype from the RIL population was the only susceptible haplotype observed in the U.S. germplasm. A single SNP was identified that distinguished the susceptible haplotype from all resistant haplotypes, explaining 52.7% of the phenotypic variation for NBLS resistance. Pedigree analysis and haplotype characterization of historical germplasm demonstrated that the susceptible haplotype was introduced into Southern U.S. germplasm through the California line L-202 into the Louisiana variety Cypress. Cypress was extensively used as a parent over the last 25 years, resulting in the susceptible CRSP-2.1 allele increasing in frequency from zero to 44% in the modern U.S. germplasm panel.


Assuntos
Cercospora/patogenicidade , Resistência à Doença/genética , Oryza/genética , Doenças das Plantas/genética , Mapeamento Cromossômico , Genes de Plantas , Marcadores Genéticos , Genótipo , Haplótipos , Oryza/microbiologia , Fenótipo , Doenças das Plantas/microbiologia , Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas , Estados Unidos
7.
Fungal Genet Biol ; 149: 103527, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33524555

RESUMO

Cercospora zeina is a causal pathogen of gray leaf spot (GLS) disease of maize in Africa. This fungal pathogen exhibits a high genetic diversity in South Africa. However, little is known about the pathogen's population structure in the rest of Africa. In this study, we aimed to assess the diversity and gene flow of the pathogen between major maize producing countries in East and Southern Africa (Kenya, Uganda, Zambia, Zimbabwe, and South Africa). A total of 964 single-spore isolates were made from GLS lesions and confirmed as C.zeina using PCR diagnostics. The other causal agent of GLS, Cercospora zeae-maydis, was absent. Genotyping all the C.zeina isolates with 11 microsatellite markers and a mating-type gene diagnostic revealed (i) high genetic diversity with some population structure between the five African countries, (ii) cryptic sexual recombination, (iii) that South Africa and Kenya were the greatest donors of migrants, and (iv) that Zambia had a distinct population. We noted evidence of human-mediated long-distance dispersal, since four haplotypes from one South African site were also present at five sites in Kenya and Uganda. There was no evidence for a single-entry point of the pathogen into Africa. South Africa was the most probable origin of the populations in Kenya, Uganda, and Zimbabwe. Continuous annual maize production in the tropics (Kenya and Uganda) did not result in greater genetic diversity than a single maize season (Southern Africa). Our results will underpin future management of GLS in Africa through effective monitoring of virulent C.zeina strains.


Assuntos
Cercospora/genética , Cercospora/patogenicidade , Zea mays/microbiologia , África Oriental , Ascomicetos/genética , Resistência à Doença/genética , Fluxo Gênico/genética , Variação Genética/genética , Genética Populacional/métodos , Haplótipos/genética , Repetições de Microssatélites/genética , Doenças das Plantas/microbiologia , Locos de Características Quantitativas/genética , África do Sul
8.
Pest Manag Sci ; 77(3): 1226-1234, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33051963

RESUMO

BACKGROUND: Metyltetraprole is a new quinone outside inhibitor (QoI) fungicide showing potent activity against QoI-resistant fungi that possess the G143A cytochrome b mutation, which confers resistance to existing QoIs such as trifloxystrobin. For its sustainable use, monitoring of metyltetraprole sensitivity is necessary and the establishment of appropriate methodology is important in each pathogen species. RESULTS: In Cercospora beticola, the causal agent of sugar beet leaf spot, some isolates were less sensitive to metyltetraprole (EC50 > 1 mg L-1 , higher than the saturated concentration) using the common agar plate method, even with 100 mg L-1 salicylhydroxamic acid, an alternative oxidase inhibitor. However, microtiter tests (EC50 < 0.01 mg L-1 ), conidial germination tests (EC50 < 0.01 mg L-1 ) and in planta tests (>80% control at 75 mg L-1 run-off spraying) confirmed that all tested isolates were highly sensitive to metyltetraprole. For trifloxystrobin, G143A mutants were clearly resistant upon microtiter plate tests (median EC50 > 2 mg L-1 ) and distinct from wild-type isolates (median EC50 < 0.01 mg L-1 ). Notably, mycelium fragments were usable for the microtiter plate tests and the test was applicable for isolates that do not form sufficient conidia. Our monitoring study by microtiter plate tests did not indicate the presence of metyltetraprole-resistant C. beticola isolates in populations in Hokkaido, Japan. CONCLUSION: The microtiter tests were revealed to be useful for monitoring the sensitivity of C. beticola to metyltetraprole and trifloxystrobin. © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Assuntos
Farmacorresistência Fúngica , Fungicidas Industriais , Cercospora , Citocromos b , Farmacorresistência Fúngica/genética , Fungicidas Industriais/farmacologia , Japão
9.
Theor Appl Genet ; 134(2): 701-714, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33188437

RESUMO

KEY MESSAGE: This paper reports fine mapping of qCLS for resistance to Cercospora leaf spot disease in mungbean and identified LOC106765332encoding TATA-binding-protein-associated factor 5 (TAF5) as the candidate gene for the resistance Cercospora leaf spot (CLS) caused by the fungus Cercospora canescens is an important disease of mungbean. A QTL mapping using mungbean F2 and BC1F1 populations developed from the "V4718" (resistant) and "Kamphaeng Saen 1" (KPS1; susceptible) has identified a major QTL controlling CLS resistance (qCLS). In this study, we finely mapped the qCLS and identified candidate genes at this locus. A BC8F2 [KPS1 × (KPS1 × V4718)] population developed in this study and the F2 (KPS1 × V4718) population used in a previous study were genotyped with 16 newly developed SSR markers. QTL analysis in the BC8F2 and F2 populations consistently showed that the qCLS was mapped to a genomic region of ~ 13 Kb on chromosome 6, which contains only one annotated gene, LOC106765332 (designated "VrTAF5"), encoding TATA-binding-protein-associated factor 5 (TAF5), a subunit of transcription initiation factor IID and Spt-Ada-Gcn5 acetyltransferase complexes. Sequence comparison of VrTAF5 between KPS1 and V4718 revealed many single nucleotide polymorphisms (SNPs) and inserts/deletions (InDels) in which eight SNPs presented in eight different exons, and an SNP (G4,932C) residing in exon 8 causes amino acid change (S250T) in V4718. An InDel marker was developed to detect a 24-bp InDel polymorphism in VrTAF5 between KPS1 and V4718. Analysis by RT-qPCR showed that expression levels of VrTAF5 in KPS1 and V4718 were not statistically different. These results indicated that mutation in VrTAF5 causing an amino acid change in the VrTAF5 protein is responsible for CLS resistance in V4718.


Assuntos
Cercospora/fisiologia , Mapeamento Cromossômico/métodos , Resistência à Doença/genética , Proteínas de Plantas/metabolismo , Locos de Características Quantitativas , Fator de Transcrição TFIID/metabolismo , Vigna/genética , Cromossomos de Plantas/genética , Resistência à Doença/imunologia , Regulação da Expressão Gênica de Plantas , Fenótipo , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/microbiologia , Proteínas de Plantas/genética , Polimorfismo Genético , Fator de Transcrição TFIID/genética , Vigna/crescimento & desenvolvimento , Vigna/microbiologia
10.
Plant Dis ; 105(5): 1272-1280, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-32954981

RESUMO

Cercospora nicotianae, the causal agent of frogeye leaf spot (FLS) of tobacco, has been exposed to quinone outside inhibitor (QoI) fungicides for more than a decade through azoxystrobin applications targeting other major foliar diseases. From 2016 to 2018, a total of 124 isolates were collected from tobacco fields throughout Kentucky. Sensitivity of these isolates to azoxystrobin was previously characterized by determining the effective concentration to inhibit 50% conidial germination (EC50). Based on azoxystrobin EC50, isolates were categorized into three discrete groups: high sensitivity (<0.08 µg/ml), moderate sensitivity (0.14 to 0.64 µg/ml), and low sensitivity (>1.18 µg/ml). Variability in sensitivity in a limited number of C. nicotianae isolates was previously shown to be a result of resistance mutations in the fungicide target gene. To improve understanding of C. nicotianae cytochrome b (cytb) structure, the gene was cloned from three isolates representing each EC50 group, and sequences were compared. Our analysis showed that cytb gene in C. nicotianae consists of 1,161 nucleotides encoding 386 amino acids. The cytb sequence among the cloned isolates was identical with the exception of the F129L and G143A point mutations. To more rapidly determine the resistance status of C. nicotianae isolates to azoxystrobin, a polymerase chain reaction (PCR) assay was developed to screen for mutations. According to this assay, 80% (n = 99) of tested C. nicotianae isolates carried an F129L mutation and were moderately resistant to azoxystrobin, and 7% (n = 9) carried the G143A mutation and were highly resistant. A receiver operating characteristic curve analysis suggested the PCR assay was a robust diagnostic tool to identify C. nicotianae isolates with different sensitivity to azoxystrobin in Kentucky tobacco production. The prevalence of both the F129L and G143A mutations in C. nicotianae from Kentucky differs from that of other pathosystems where resistance to QoI fungicides has been identified, in which the majority of sampled isolates of the pathogen species have a broadly occurring cytb mutation.


Assuntos
Cercospora , Farmacorresistência Fúngica , Farmacorresistência Fúngica/genética , Mutação , Pirimidinas , Estrobilurinas/farmacologia
11.
Pest Manag Sci ; 77(4): 1765-1774, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33236506

RESUMO

BACKGROUND: Cercospora leaf spot caused by Cercospora beticola is the most relevant foliar disease in sugar beet cultivation. In the last decade a decreasing sensitivity of C. beticola towards demethylation inhibitors (DMIs) occurred. Different mechanisms mediating a reduced sensitivity towards DMIs have been identified in different plant pathogens to date, such as target site mutations, over-expression or active excretion of the fungicide. RESULTS: A sequencing of the cytochrome P450-dependent sterol 14α-demethylase gene sequence (cyp51) of diverse C. beticola isolates collected in different European countries with reduced DMI sensitivity was performed in order to find a possible correlation of mutations with higher EC50 values. The amino acid alterations Y464S, L144F and I309T combined with L144F were found to be associated with a reduced sensitivity. Furthermore, mutations I387M, M145W and M145W with E460Q were found uniquely. Additionally, constitutive and fungicide triggered expression of cyp51 was assayed by means of RT-qPCR. A very strong induction of cyp51 mRNA expression in sensitive isolates suggests that the fungal cells upregulate expression to maintain ergosterol biosynthesis in DMI presence. The less intensive cyp51 induction in isolates with higher EC50 values underlines the possible correlation of the found target-site mutations with reduced sensitivity. CONCLUSION: This study provides new results about possible alterations in the target gene mediating reduced sensitivity of C. beticola towards DMIs and hypothesized a fungicide induced over-expression of the target enzyme CYP51 as natural reaction of the fungus to fungicide application. © 2020 Society of Chemical Industry.


Assuntos
Ascomicetos , Fungicidas Industriais , Ascomicetos/genética , Cercospora , Farmacorresistência Fúngica/genética , Europa (Continente) , Fungicidas Industriais/farmacologia , Esterol 14-Desmetilase/genética
12.
Mol Plant Pathol ; 22(3): 301-316, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33369055

RESUMO

Cercospora beticola is a hemibiotrophic fungus that causes cercospora leaf spot disease of sugar beet (Beta vulgaris). After an initial symptomless biotrophic phase of colonization, necrotic lesions appear on host leaves as the fungus switches to a necrotrophic lifestyle. The phytotoxic secondary metabolite cercosporin has been shown to facilitate fungal virulence for several Cercospora spp. However, because cercosporin production and subsequent cercosporin-initiated formation of reactive oxygen species is light-dependent, cell death evocation by this toxin is only fully ensured during a period of light. Here, we report the discovery of the effector protein CbNip1 secreted by C. beticola that causes enhanced necrosis in the absence of light and, therefore, may complement light-dependent necrosis formation by cercosporin. Infiltration of CbNip1 protein into sugar beet leaves revealed that darkness is essential for full CbNip1-triggered necrosis, as light exposure delayed CbNip1-triggered host cell death. Gene expression analysis during host infection shows that CbNip1 expression is correlated with symptom development in planta. Targeted gene replacement of CbNip1 leads to a significant reduction in virulence, indicating the importance of CbNip1 during colonization. Analysis of 89 C. beticola genomes revealed that CbNip1 resides in a region that recently underwent a selective sweep, suggesting selection pressure exists to maintain a beneficial variant of the gene. Taken together, CbNip1 is a crucial effector during the C. beticola-sugar beet disease process.


Assuntos
Beta vulgaris/microbiologia , Cercospora/genética , Proteínas Fúngicas/metabolismo , Genoma Fúngico/genética , Perileno/análogos & derivados , Doenças das Plantas/microbiologia , Cercospora/crescimento & desenvolvimento , Cercospora/patogenicidade , Proteínas Fúngicas/genética , Interações Hospedeiro-Patógeno , Necrose , Perileno/metabolismo , Fenótipo , Filogenia , Folhas de Planta/microbiologia , Virulência , Fatores de Virulência
13.
Phytopathology ; 111(7): 1228-1237, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33289403

RESUMO

Cercospora leaf blight (CLB), primarily caused by Cercospora cf. flagellaris, is one of the most important diseases of soybean (Glycine max) in Louisiana. The pathogen produces cercosporin, a nonspecific toxin and an important virulence factor. There are no commercial cultivars with CLB resistance, and the pathogen has developed substantial resistance to the frequently used fungicides. Consequently, alternative methods are needed to manage CLB. One possibility is the RNA interference-based topical application of double-stranded (ds)RNA. The present study addressed the two most critical steps for this novel approach to be practical: inexpensively producing large quantities of dsRNA and identifying the right target genes for silencing. A screening method was developed to compare the effectiveness of Escherichia coli-produced dsRNAs targeting five fungal genes involved in cercosporin production for silencing in liquid culture. As much as 151.6 mg of dsRNA-containing total nucleic acids (TNAs) was produced from 1 liter of E. coli Luria broth culture using the L4440 vector. All tested dsRNAs reduced cercosporin production. However, significant target gene suppression was only detected in the cultures treated with dsRNAs from Avr4 and CTB8. The most potent dsRNA was from Avr4, which reduced 50% of cercosporin production at an estimated TNA concentration of 10.4 µg/ml (half maximal effective concentration [EC50]), and the least potent dsRNA was from HN-2, with an estimated EC50 of 46.7 µg/ml TNA. The present study paves the road for managing CLB under field conditions using dsRNA. Additionally, this approach could be adapted to identify the best dsRNAs to manage other fungal diseases.


Assuntos
Ascomicetos , Ascomicetos/genética , Cercospora , Escherichia coli/genética , Perileno/análogos & derivados , Doenças das Plantas , RNA de Cadeia Dupla/genética
14.
Pak J Biol Sci ; 23(10): 1276-1284, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32981261

RESUMO

BACKGROUND AND OBJECTIVE: Trichoderma species are of utmost importance in agro-biotechnological applications because, in their interactions with plant hosts, they out-compete most pathogenic microorganisms. This study aimed at exploiting the potential of Trichoderma harzianum together with Glomus versiforme and its mutants, in inhibiting cowpea leaf spot rot induced due to Cercospora canescens infestation and improving agronomic growth parameter in a screen house experiment. MATERIALS AND METHODS: The experiment was designed using single and co-inoculation of the bioagents: in all, eleven treatments were applied, consisting of Glom_verwild, Glom_ver30, Glom_ver60, Glom_ver90, Trich_h, Glom_verwild+Trich_h, Glom_ver30+Trich_h, Glom_ver60+Trich_h, Glom_ver90+Trich_h, Pathogen alone and control. Cowpea growth yield parameters and disease severity were assessed after 7 weeks. RESULTS: The deployed treatments improved agronomic growth parameters substantially (p<0.05) relative to control. Glom_ver 60+Trich_h treatment exerted the highest agronomic growth improvement yield. In addition, the best reduction in the incidence and severity of cowpea leaf spot disease was obtained using Glom_ver 60+Trich_h. A significantly higher germination rate in seeding, confirms both inhibitory and growth improvement potency of the bio inoculants treatment. CONCLUSION: This study's findings confirmed the beneficial impacts of the treatment of seed and soil with dual T. harzianum and G. versiforme, in improving the immunity of cowpea to Cercospora canescens leaf spot infection and improve cowpea growth.


Assuntos
Agricultura/métodos , Cercospora/metabolismo , Fungos/metabolismo , Germinação , Hypocreales/fisiologia , Doenças das Plantas , Folhas de Planta/metabolismo , Solo , Vigna/metabolismo , Mutação , Nigéria , Controle Biológico de Vetores , Raízes de Plantas/crescimento & desenvolvimento
15.
Mol Plant Pathol ; 21(8): 1020-1041, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32681599

RESUMO

Cercospora leaf spot, caused by the fungal pathogen Cercospora beticola, is the most destructive foliar disease of sugar beet worldwide. This review discusses C. beticola genetics, genomics, and biology and summarizes our current understanding of the molecular interactions that occur between C. beticola and its sugar beet host. We highlight the known virulence arsenal of C. beticola as well as its ability to overcome currently used disease management strategies. Finally, we discuss future prospects for the study and management of C. beticola infections in the context of newly employed molecular tools to uncover additional information regarding the biology of this pathogen. TAXONOMY: Cercospora beticola Sacc.; Kingdom Fungi, Phylum Ascomycota, Class Dothideomycetes, Order Capnodiales, Family Mycosphaerellaceae, Genus Cercospora. HOST RANGE: Well-known pathogen of sugar beet (Beta vulgaris subsp. vulgaris) and most species of the Beta genus. Reported as pathogenic on other members of the Chenopodiaceae (e.g., lamb's quarters, spinach) as well as members of the Acanthaceae (e.g., bear's breeches), Apiaceae (e.g., Apium), Asteraceae (e.g., chrysanthemum, lettuce, safflower), Brassicaceae (e.g., wild mustard), Malvaceae (e.g., Malva), Plumbaginaceae (e.g., Limonium), and Polygonaceae (e.g., broad-leaved dock) families. DISEASE SYMPTOMS: Leaves infected with C. beticola exhibit circular lesions that are coloured tan to grey in the centre and are often delimited by tan-brown to reddish-purple rings. As disease progresses, spots can coalesce to form larger necrotic areas, causing severely infected leaves to wither and die. At the centre of these spots are black spore-bearing structures (pseudostromata). Older leaves often show symptoms first and younger leaves become infected as the disease progresses. MANAGEMENT: Application of a mixture of fungicides with different modes of action is currently performed although elevated resistance has been documented in most employed fungicide classes. Breeding for high-yielding cultivars with improved host resistance is an ongoing effort and prudent cultural practices, such as crop rotation, weed host management, and cultivation to reduce infested residue levels, are widely used to manage disease. USEFUL WEBSITE: https://www.ncbi.nlm.nih.gov/genome/11237?genome_assembly_id=352037.


Assuntos
Beta vulgaris/microbiologia , Cercospora/patogenicidade , Doenças das Plantas/microbiologia , Acanthaceae/microbiologia , Apiaceae/microbiologia , Asteraceae/microbiologia , Brassicaceae/microbiologia , Cercospora/efeitos dos fármacos , Fungicidas Industriais/farmacologia , Malvaceae/microbiologia , Plumbaginaceae/microbiologia , Polygonaceae/microbiologia
16.
BMC Microbiol ; 20(1): 166, 2020 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-32546122

RESUMO

BACKGROUND: Cercospora sojina is a fungal pathogen that causes frogeye leaf spot in soybean-producing regions, leading to severe yield losses worldwide. It exhibits variations in virulence due to race differentiation between strains. However, the candidate virulence-related genes are unknown because the infection process is slow, making it difficult to collect transcriptome samples. RESULTS: In this study, virulence-related differentially expressed genes (DEGs) were obtained from the highly virulent Race 15 strain and mildly virulent Race1 strain under nitrogen starvation stress, which mimics the physiology of the pathogen during infection. Weighted gene co-expression network analysis (WGCNA) was then used to find co-expressed gene modules and assess the relationship between gene networks and phenotypes. Upon comparison of the transcriptomic differences in virulence between the strains, a total of 378 and 124 DEGs were upregulated, while 294 and 220 were downregulated in Race 1 and Race 15, respectively. Annotation of these DEGs revealed that many were associated with virulence differences, including scytalone dehydratase, 1,3,8-trihydroxynaphthalene reductase, and ß-1,3-glucanase. In addition, two modules highly correlated with the highly virulent strain Race 15 and 36 virulence-related DEGs were found to contain mostly ß-1,4-glucanase, ß-1,4-xylanas, and cellobiose dehydrogenase. CONCLUSIONS: These important nitrogen starvation-responsive DEGs are frequently involved in the synthesis of melanin, polyphosphate storage in the vacuole, lignocellulose degradation, and cellulose degradation during fungal development and differentiation. Transcriptome analysis indicated unique gene expression patterns, providing further insight into pathogenesis.


Assuntos
Cercospora/patogenicidade , Perfilação da Expressão Gênica/métodos , Nitrogênio/metabolismo , Fatores de Virulência/genética , Cercospora/classificação , Cercospora/genética , Cercospora/metabolismo , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica , Redes Reguladoras de Genes , Anotação de Sequência Molecular , Fenótipo , Análise de Sequência de RNA , Soja/microbiologia , Especificidade da Espécie , Estresse Fisiológico
17.
Theor Appl Genet ; 133(8): 2521-2533, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32468093

RESUMO

KEY MESSAGE: The genetic basis of GLS resistance was dissected using two DH populations sharing a common resistant parent. A major QTL repeatedly detected in multiple developmental stages and environments was fine mapped in a backcross population. Grey leaf spot (GLS), caused by Cercospora zeae-maydis or Cercospora zeina, is a highly destructive foliar disease worldwide. However, the mechanism of resistance against GLS is not well understood. To study the inheritance of this resistance, we developed two doubled haploid (DH) populations sharing a common resistant parent. The two DH populations were grown in two locations representing the typical maize-growing mountain area in Southwest China for 2 years. GLS disease severity was investigated 2 or 3 times until maturity in the 2 years, and the area under the disease progress curve was calculated. Two high-density linkage maps were constructed by genotyping-by-sequencing. A total of 22 quantitative trait loci (QTLs) were detected for GLS resistance, with most QTLs being repeatedly detected in different stages, locations and years. The confidence intervals of two major QTLs (qGLS_Y2-2 and qGLS_Z2-1) on chromosome 2 from the two DH populations overlapped with each other and were integrated into one consensus QTL (qGLS_YZ2-1). Using highly resistant and highly susceptible plants from a BC3 population, we fine mapped this genetic locus to a genomic region of 2.4 Mb. Using a panel of 255 inbred lines from breeding programmes, we detected associations between markers in the qGLS_YZ2-1 region and GLS resistance. The peak marker (ID-B1) will be very useful for marker-assisted breeding for GLS resistance.


Assuntos
Mapeamento Cromossômico/métodos , Resistência à Doença/genética , Doenças das Plantas/genética , Zea mays/genética , Cercospora , China , Cromossomos de Plantas , Ligação Genética , Marcadores Genéticos , Genótipo , Haploidia , Sequenciamento de Nucleotídeos em Larga Escala , Fenótipo , Locos de Características Quantitativas , Zea mays/crescimento & desenvolvimento , Zea mays/microbiologia
18.
Mol Plant Pathol ; 21(1): 53-65, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31642594

RESUMO

One of the most devastating fungal diseases of soybean in the southern USA is Cercospora leaf blight (CLB), which is caused mainly by Cercospora cf. flagellaris. Recent studies found that the fungal effector AVR4, originally identified in Cladosporium fulvum as a chitin-binding protein, is highly conserved among other Cercospora species. We wanted to determine whether it is present in C. cf. flagellaris and, if so, whether it plays a role in the pathogen infection of soybean. We cloned the Avr4 gene and created C. cf. flagellaris ∆avr4 mutants, which produced little cercosporin and significantly reduced expression of cercosporin biosynthesis genes. The ∆avr4 mutants were also more sensitive to chitinase and showed reduced virulence on soybean compared to the wild-type. The observed reduced virulence of C. cf. flagellaris ∆avr4 mutants on detached soybean leaves is likely due to reduced cercosporin biosynthesis. The phenotypes of reduced cercosporin production and cercosporin pathway gene expression, similar to those of the ∆avr4 mutants, were reproduced when wild-type C. cf. flagellaris was treated with double-stranded RNA targeting Avr4 in vitro. These two independent approaches demonstrated for the first time the direct involvement of AVR4 in the biosynthesis of cercosporin.


Assuntos
Cercospora/patogenicidade , Proteínas Fúngicas/metabolismo , Perileno/análogos & derivados , Doenças das Plantas/microbiologia , Soja/microbiologia , Quitinases/metabolismo , Clonagem Molecular , Meios de Cultura , DNA Fúngico , Proteínas Fúngicas/genética , Mutação , Perileno/metabolismo , Doenças das Plantas/genética , Análise de Sequência de DNA , Virulência/genética
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