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1.
Plant Dis ; 103(10): 2645-2651, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31453747

RESUMO

Chinese wheat landrace Dahongtou was resistant to 35 of 38 tested Chinese isolates of Blumeria graminis f. sp. tritici at the seedling stage. Genetic analysis of the F2 populations and their derived F2:3 families of crosses of Dahongtou with the susceptible varieties Mingxian 169 and Huixianhong indicated that the resistance of Dahongtou to B. graminis f. sp. tritici isolate E09 was conferred by a single recessive gene, tentatively designated as pmDHT. The gene was mapped to chromosome arm 7BL and flanked by markers Xwmc526/XBE443877 and Xgwm611/Xwmc511 at genetic distances of 0.8 and 0.3 cM, respectively. The chromosomal position of pmDHT was similar to the multi-allelic Pm5 locus on 7BL. Allelism tests with crosses of Dahongtou with Fuzhuang 30 (Pm5e) and Xiaobaidong (mlxbd) indicated that pmDHT was allelic to both Pm5e and mlxbd. However, pmDHT showed a different pattern of resistance to the 38 B. graminis f. sp. tritici isolates compared with wheat lines with Pm5a, Pm5b, Pm5e, mlxbd, and PmHYM and also differed from PmSGA. Thus, pmDHT was identified most likely as a new allele or at least a closely linked gene of the Pm5 locus. This gene can be transferred into susceptible wheat cultivars/lines and pyramided with other resistance genes through marker-assisted selection to improve powdery mildew resistance.


Assuntos
Ascomicetos , Resistência à Doença , Genes de Plantas , Triticum , Ascomicetos/fisiologia , Mapeamento Cromossômico , Resistência à Doença/genética , Genes de Plantas/genética , Marcadores Genéticos/genética , Doenças das Plantas/microbiologia , Triticum/genética , Triticum/microbiologia
2.
Mol Plant Microbe Interact ; 32(10): 1391-1401, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31408392

RESUMO

Salicylic acid (SA) is closely related to disease resistance of plants. WRKY transcription factors have been linked to the growth and development of plants, especially under stress conditions. However, the regulatory mechanism of WRKY proteins involved in SA production and disease resistance in apple is not clear. In this study, MdPBS3.1 responded to Botryosphaeria dothidea and enhanced resistance to B. dothidea. Electrophoretic mobility shift assays, yeast one-hybrid assays, and chromatin immunoprecipitation and quantitative PCR demonstrated that MdWRKY46 can directly bind to a W-box motif in the promoter of MdPBS3.1. Glucuronidase transactivation and luciferase analysis further showed that MdWRKY46 can activate the expression of MdPBS3.1. Finally, B. dothidea inoculation in transgenic apple calli and fruits revealed that MdWRKY46 improved resistance to B. dothidea by the transcriptional activation of MdPBS3.1. Viral vector-based transformation assays indicated that MdWRKY46 elevates SA content and transcription of SA-related genes, including MdPR1, MdPR5, and MdNPR1 in an MdPBS3.1-dependent way. These findings provide new insights into how MdWRKY46 regulates plant resistance to B. dothidea through the SA signaling pathway.


Assuntos
Ascomicetos , Resistência à Doença , Regulação da Expressão Gênica de Plantas , Malus , Proteínas de Plantas , Transdução de Sinais , Ascomicetos/fisiologia , Resistência à Doença/genética , Malus/genética , Malus/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Ácido Salicílico/metabolismo , Transdução de Sinais/genética
3.
Plant Dis ; 103(10): 2548-2558, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31432774

RESUMO

Several Pestalotiopsis-like species cause gray blight disease in tea plants, resulting in severe tea production losses. However, systematic and comprehensive research on the diversity, geographical distribution, and pathogenicity of pathogenic species associated with tea plants in China is limited. In this study, 168 Pestalotiopsis-like isolates were obtained from diseased tea plant leaves from 13 primary tea-producing provinces and cities in China. Based on a multilocus (internal transcribed spacer, translation elongation factor 1-α, and ß-tubulin gene region) phylogenetic analysis coupled with an assessment of conidial characteristics, 20 Neopestalotiopsis unclassified isolates, seven Pestalotiopsis species, including two novel (Pestalotiopsis menhaiensis and Pestalotiopsis sichuanensis), four known (Pestalotiopsis camelliae, Pestalotiopsis chamaeropis, Pestalotiopsis kenyana, and Pestalotiopsis rhodomyrtus) and one indistinguishable species, and three Pseudopestalotiopsis species, including two known (Pseudopestalotiopsis camelliae-sinensis and Pseudopestalotiopsis chinensis) and one indistinguishable species, were identified. This study is the first to evaluate Pestalotiopsis chamaeropis on tea plants in China. The geographical distribution and pathogenicity tests showed Pseudopestalotiopsis camelliae-sinensis to be the dominant cause of gray blight of tea plants in China. In vitro antifungal assays demonstrated that theobromine not only derepressed mycelial growth of the 29 representative isolates but also increased their growth. Correlation analysis revealed a linear positive relationship between the mycelial growth rate and pathogenicity (P = 0.0148).


Assuntos
Ascomicetos , Biodiversidade , Camellia sinensis , Doenças das Plantas , Ascomicetos/classificação , Ascomicetos/patogenicidade , Ascomicetos/fisiologia , Camellia sinensis/microbiologia , China , Filogenia , Doenças das Plantas/microbiologia , Especificidade da Espécie , Virulência
4.
BMC Evol Biol ; 19(1): 139, 2019 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-31286867

RESUMO

BACKGROUND: Pathogens evolve in an arms race, frequently evolving virulence that defeats resistance genes in their hosts. Infection of multiple hosts may accelerate this virulence evolution. Theory predicts that host diversity affects pathogen diversity, with more diverse hosts expected to harbour more diverse pathogens that reproduce sexually. We tested this hypothesis by comparing the microsatellite (SSR) genetic diversity of the barley leaf pathogen Pyrenophora teres f. teres (Ptt) from barley (monoculture) and barley grass (outbreeding). We also aim to investigate host specificity and attempt to track virulence on two barley cultivars, Maritime and Keel. RESULTS: Genetic diversity in barley Ptt populations was higher than in populations from barley grass. Barley Ptt populations also had higher linkage disequilibrium levels, indicating less frequent sexual reproduction, consistent with the Red Queen hypothesis theory that genetically diverse hosts should select for higher levels of sexual reproduction of the pathogen. SSR analyses indicate that host-associated Ptt populations do not share genotypes and have independent evolutionary histories. Pathogenicity studies showed host specificity as host-associated Ptt isolates could not cross-infect hosts. Minimum spanning network analyses indicated two major clusters of barley Ptt. One cluster represents Maritime virulent and isolates from Western Australia (WA). Low PhiPt population differentiation between WA populations and those from Maritime and Keel, indicated a WA origin of the Maritime and Keel virulences. The main minimum spanning network cluster is represented by a panmictic population structure, represented by isolates from all over Australia. CONCLUSIONS: Although barley Ptt populations are more diverse than barley grass Ptt populations, this may be a result of the size and number of founder Ptt populations to Australia, with larger and more barley Ptt populations introduced. More frequent sexual reproduction of Ptt on barley grass support the Red Queen Hypothesis and suggest evolutionary potential of pathogens on diverse hosts are high. Extensive gene flow of Ptt between regions in Australia is suggested to maintain a panmictic population structure, with human-mediated dispersal aiding in virulence evolution of Ptt on barley.


Assuntos
Ascomicetos/genética , Ascomicetos/fisiologia , Evolução Molecular , Hordeum/microbiologia , Especificidade de Hospedeiro/genética , Doenças das Plantas/microbiologia , Genótipo , Desequilíbrio de Ligação , Repetições de Microssatélites/genética
5.
Plant Dis ; 103(9): 2374-2384, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31306090

RESUMO

The Botryosphaeriaceae family is considered a fungal family that includes pathogens causing latent infection of woody plants, and a number of species were identified as causal pathogens of canker and shoot blight diseases. To better understand the process of latent infection of major canker-causing pathogens in woody tissues in different tree crops important in California, shoot and bud samples were randomly collected from four tree crops: almond, dried plum, pistachio, and walnut. The previously developed DNA primers and quantitative real-time PCR (qPCR) assay systems were applied to detect six canker-causing pathogen groups, including Botryosphaeria dothidea, and species of Cytospora, Diplodia, Lasiodiplodia, Neofusicoccum, and Phomopsis. The concepts of molecular severity (MS) and latent infection index (LII) were introduced and applied to quantify the latent infection levels for these samples. Variation in incidence of latent infection among pathogen groups was observed, whereas the incidences were relatively low among species of Phomopsis and Diplodia. High incidences of Cytospora spp. were observed in two dried plum (prune) orchards. Most orchards showed high incidences of B. dothidea and Lasiodiplodia spp. and moderate incidences of Neofusicoccum spp. Variations in MS were observed among samples of the studied orchards, ranging from 4 to 8. The overall results of LII demonstrated that species of Diplodia and Phomopsis were less important in population development of canker-causing pathogens at the latent phase. Lasiodiplodia spp. were the most aggressive and had been well developed in populations among the studied tree crops. Cytospora spp. became predominant in two of the three dried plum orchards, whereas B. dothidea and Neofusicoccum spp. showed trends of increase in incidence across various tree crops. This study also demonstrated the usefulness of this sensitive qPCR approach in providing evidence of the latent phase of major canker-causing pathogens of stone fruit and nut crops at an early stage of latent infection in woody plant tissues.


Assuntos
Ascomicetos , Frutas , Nozes , Árvores , Ascomicetos/classificação , Ascomicetos/fisiologia , California , DNA Fúngico , Frutas/microbiologia , Nozes/microbiologia , Filogenia , Doenças das Plantas , Árvores/microbiologia
6.
Plant Dis ; 103(9): 2417-2424, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31322978

RESUMO

Macrophomina phaseolina, the causal agent of charcoal rot, affects strawberry crowns, inducing plant collapse. The fungus survives in the soil through the production of microsclerotia and is usually controlled by preplant fumigation of soil. However, in the 2016 to 2017 Florida strawberry season, even after soil fumigation, about 30% plant mortality still occurred in plastic-covered beds that were used for a second season and where crop residue (mainly old strawberry crowns) was disposed of between beds. Therefore, this study was conducted to determine if M. phaseolina can survive on strawberry debris over summer in Florida and if so, verify whether strawberry debris might act as a source of inoculum for new transplants. Crowns from the previous season were collected from commercial farms where charcoal rot had been reported, and M. phaseolina was recovered from all samples. In a research field, infected crowns were buried in the soil at different depths and retrieved every 2 weeks during the summer. After 8 weeks, M. phaseolina could be recovered at all depths. Moreover, inoculation of strawberry plants by drenching the soil, dipping roots, or spraying leaves with a M. phaseolina microsclerotial suspension from pure cultures or infected crowns produced symptoms with differences in incubation periods depending on cultivar susceptibility. Furthermore, infected crowns disposed of in the aisles between beds or buried next to new transplants of cultivars Strawberry Festival, Florida Beauty, and Winterstar induced charcoal rot, with the level of aggressiveness depending on the cultivar susceptibility and inoculum placement in the field.


Assuntos
Ascomicetos , Fragaria , Doenças das Plantas , Ascomicetos/fisiologia , Florida , Fragaria/microbiologia , Doenças das Plantas/microbiologia , Raízes de Plantas/microbiologia
7.
Plant Mol Biol ; 101(1-2): 149-162, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31267255

RESUMO

KEY MESSAGE: Here we describe that the regulation of MdWRKY31 on MdHIR4 in transcription and translation levels associated with disease in apple. The phytohormone salicylic acid (SA) is a main factor in apple (Malus domestica) production due to its function in disease resistance. WRKY transcription factors play a vital role in response to stress. An RNA-seq analysis was conducted with 'Royal Gala' seedlings treated with SA to identify the WRKY regulatory mechanism of disease resistance in apple. The analysis indicated that MdWRKY31 was induced. A quantitative real-time polymerase chain reaction (qPCR) analysis demonstrated that the expression of MdWRKY31 was induced by SA and flg22. Ectopic expression of MdWRKY31 in Arabidopsis and Nicotiana benthamiana increased the resistance to flg22 and Pseudomonas syringae tomato (Pst DC3000). A yeast two-hybrid screen was conducted to further analyze the function of MdWRKY31. As a result, hypersensitive-induced reaction (HIR) protein MdHIR4 interacted with MdWRKY31. Biomolecular fluorescence complementation, yeast two-hybrid, and pull-down assays demonstrated the interaction. In our previous study, MdHIR4 conferred decreased resistance to Botryosphaeria dothidea (B. dothidea). A viral vector-based transformation assay indicated that MdWRKY31 evaluated the transcription of SA-related genes, including MdPR1, MdPR5, and MdNPR1 in an MdHIR4-dependent way. A GUS analysis demonstrated that the w-box, particularly w-box2, of the MdHIR4 promoter played a major role in the responses to SA and B. dothidea. Electrophoretic mobility shift assays, yeast one-hybrid assay, and chromatin immunoprecipitation-qPCR demonstrated that MdWRKY31 directly bound to the w-box2 motif in the MdHIR4 promoter. GUS staining activity and a protein intensity analysis further showed that MdWRKY31 repressed MdHIR4 expression. Taken together, our findings reveal that MdWRKY31 regulated plant resistance to B. dothidea through the SA signaling pathway by interacting with MdHIR4.


Assuntos
Resistência à Doença , Malus/genética , Doenças das Plantas/imunologia , Reguladores de Crescimento de Planta/farmacologia , Proteínas de Plantas/metabolismo , Ácido Salicílico/farmacologia , Arabidopsis/genética , Arabidopsis/imunologia , Arabidopsis/microbiologia , Ascomicetos/fisiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Frutas/genética , Frutas/imunologia , Frutas/microbiologia , Regulação da Expressão Gênica de Plantas , Genes Reporter , Malus/imunologia , Malus/microbiologia , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Regiões Promotoras Genéticas/genética , Pseudomonas syringae/fisiologia , Plântula/genética , Plântula/imunologia , Plântula/microbiologia , Transdução de Sinais , Tabaco/genética , Tabaco/imunologia , Tabaco/microbiologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Técnicas do Sistema de Duplo-Híbrido
8.
BMC Evol Biol ; 19(1): 142, 2019 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-31299905

RESUMO

BACKGROUND: Understanding the mechanisms by which diversity is maintained in pathogen populations is critical for epidemiological predictions. Life-history trade-offs have been proposed as a hypothesis for explaining long-term maintenance of variation in pathogen populations, yet the empirical evidence supporting trade-offs has remained mixed. This is in part due to the challenges of documenting successive pathogen life-history stages in many pathosystems. Moreover, little is understood of the role of natural enemies of pathogens on their life-history evolution. RESULTS: We characterize life-history-trait variation and possible trade-offs in fungal pathogen Podosphaera plantaginis infecting the host plant Plantago lanceolata. We measured the timing of both asexual and sexual stages, as well as resistance to a hyperparasite of seven pathogen strains that vary in their prevalence in nature. We find significant variation among the strains in their life-history traits that constitute the infection cycle, but no evidence for trade-offs among pathogen development stages, apart from fast pathogen growth coninciding with fast hyperparasite growth. Also, the seemingly least fit pathogen strain was the most prevalent in the nature. CONCLUSIONS: We conclude that in the nature environmental variation, and interactions with the antagonists of pathogens themselves may maintain variation in pathogen populations.


Assuntos
Ascomicetos/fisiologia , Interações Hospedeiro-Patógeno , Imunidade Inata , Plantago/microbiologia , Doenças das Plantas/microbiologia
9.
Plant Dis ; 103(9): 2277-2287, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31215851

RESUMO

To increase phenylpropanoid constituents and energy content in the versatile C4 grass sorghum (Sorghum bicolor [L.] Moench), sorghum genes for proteins related to monolignol biosynthesis were overexpressed: SbMyb60 (transcriptional activator), SbPAL (phenylalanine ammonia lyase), SbCCoAOMT (caffeoyl coenzyme A [CoA] 3-O-methyltransferase), Bmr2 (4-coumarate:CoA ligase), and SbC3H (coumaroyl shikimate 3-hydroxylase). Overexpression lines were evaluated for responses to stalk pathogens under greenhouse and field conditions. Greenhouse-grown plants were inoculated with Fusarium thapsinum (Fusarium stalk rot) and Macrophomina phaseolina (charcoal rot), which cause yield-reducing diseases. F. thapsinum-inoculated overexpression plants had mean lesion lengths not significantly different than wild-type, except for significantly smaller lesions on two of three SbMyb60 and one of two SbCCoAOMT lines. M. phaseolina-inoculated overexpression lines had lesions not significantly different from wild-type except one SbPAL line (of two lines studied) with mean lesion lengths significantly larger. Field-grown SbMyb60 and SbCCoAOMT overexpression plants were inoculated with F. thapsinum. Mean lesions of SbMyb60 lines were similar to wild-type, but one SbCCoAOMT had larger lesions, whereas the other line was not significantly different than wild-type. Because overexpression of SbMyb60, Bmr2, or SbC3H may not render sorghum more susceptible to stalk rots, these lines may provide sources for development of sorghum with increased phenylpropanoid concentrations.


Assuntos
Ascomicetos , Fusarium , Regulação da Expressão Gênica de Plantas , Lignina , Sorghum , Ascomicetos/fisiologia , Fusarium/fisiologia , Genes de Plantas/genética , Lignina/biossíntese , Lignina/genética , Sorghum/genética , Sorghum/microbiologia
10.
J Sci Food Agric ; 99(13): 6060-6065, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31226223

RESUMO

BACKGROUND: Chestnuts are gluten-free, low-fat, cholesterol-free products. Postharvest decay reduces chestnut shelf life and can cause severe economic losses. In this study we investigated the effect of ozone (O3 ) gaseous treatment on chestnut rot caused by Gnomoniopsis castanea and the quality parameters of chestnuts. RESULTS: The results showed that ozone treatment (150 ppb during the day, and 300 ppb during the night) reduced the decay of chestnuts and had a fungistatic effect on isolates of G. castanea. The exposure of chestnuts to ozone did not alter weight losses, sugar content and titratable acidity. The concentration of total phenolics decreased during the storage period, both for treated and untreated nuts. However, after 150 days of treatment the polyphenol content of the chestnuts exposed to ozone was significantly higher than in control nuts. CONCLUSIONS: Our results suggested that ozone is an appropriate and economical tool to maximize the quality of chestnut shelf life, enabling it to be stored for long periods. © 2019 Society of Chemical Industry.


Assuntos
Fagaceae/química , Conservação de Alimentos/métodos , Conservantes de Alimentos/farmacologia , Nozes/química , Ozônio/farmacologia , Ascomicetos/efeitos dos fármacos , Ascomicetos/fisiologia , Carboidratos/química , Fagaceae/microbiologia , Conservação de Alimentos/instrumentação , Conservantes de Alimentos/química , Armazenamento de Alimentos , Nozes/microbiologia , Ozônio/química , Fenóis/química , Controle de Qualidade
11.
Rev Bras Parasitol Vet ; 28(2): 333-337, 2019 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-31188945

RESUMO

The objectives of this study were to describe occurrences of Rhabditis spp. causing parasitic otitis in dairy cattle of Gir breed in the state of Espírito Santo, southeastern Brazil, and to evaluate the biological control of this nematode using the nematophagous fungi Duddingtonia flagrans (AC001) and Monacrosporium thaumasium (NF34). After nematode detection and collection, three groups were formed: two groups that were treated, respectively, with the fungal isolates; and a control group, without fungus. The treatments were as follows: (a) Petri dishes containing the culture medium 2% water agar (WA) + 250 nematodes + AC001; (b) Petri dishes containing 2% WA + 250 nematodes + NF34; and (c) Petri dishes containing only 2% WA + 250 nematodes. After seven days at 27 °C the treatments with fungi were able to capture and destroy the nematodes, with percentages of 82.0% (AC001) and 39.0% (NF34) in relation to the control group. The results demonstrate the occurrence of Rhabditis spp. after animals physical examination and that there was efficacy of the in vitro predatory activity of both fungal isolates. Thus, these results are important because they can assist in future in vivo control of this nematode in cattle.


Assuntos
Doenças dos Bovinos/parasitologia , Otite/veterinária , Controle Biológico de Vetores/métodos , Infecções por Rhabditida/veterinária , Rhabditoidea/microbiologia , Animais , Ascomicetos/fisiologia , Bovinos , Duddingtonia/fisiologia , Otite/parasitologia , Otite/terapia , Infecções por Rhabditida/terapia
12.
Plant Dis ; 103(8): 1889-1901, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31161920

RESUMO

Apple fruit spot disease has caused serious economic losses for years in China since the widespread application of fruit bagging in production. Although the three genera Trichothecium, Alternaria, and Acremonium have been reported to be the causal agents, studies on the disease etiology and pathogen biology are still sparse. Here, we report characterization of eight fungal isolates from lesions on 126 symptomatic fruit samples collected in Shaanxi Province, China. Pathogenicity of the isolates was assessed. DNA sequences were obtained at four loci, including D1/D2 domains of the large-subunit nrRNA gene, internal transcribed spacer regions 1 and 2, 5.8S nrDAN gene, a fragment of the actin gene, and a fragment of the ß-tubulin. Based on phylogenetic analysis and morphological features, three new species were found: Acremonium mali, Sarocladium liquanensis, and Sarocladium mali. In addition, we made the first report of Sarocladium terricola as a plant pathogen. Temperature and moisture significantly affected in vitro conidial germination of five Acremonium-like species, and their impact on infection of apple fruit was tested using Acremonium sclerotigenum. Conidia of five species germinated from 15 to 35°C in free water; four of the species had optimum temperature around 25°C, whereas conidia of S. terricola had an optimum temperature of 30°C. Conidial germination rate increased as relative humidity (RH) increased. The five isolates had relatively high conidial germination rates at RH > 97%, with a significant decline at 95% RH. Incidence of infection also increased in proportion to RH. In free water, conidial germination was relatively unaffected by temperature.


Assuntos
Acremonium , Ascomicetos , Frutas , Malus , Acremonium/classificação , Acremonium/fisiologia , Ascomicetos/classificação , Ascomicetos/fisiologia , China , Frutas/microbiologia , Malus/microbiologia , Filogenia , Temperatura Ambiente
13.
Plant Dis ; 103(8): 1931-1939, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31188738

RESUMO

California produces 99.1% of pistachios grown in the United States, and diseases affecting pistachio rootstocks represent a constant challenge to the industry. Field surveys of fungi associated with pistachio rootstocks with symptoms of crown rot and stem canker in three central California counties followed by phylogenetic analyses of translation elongation factor 1-α and second largest subunit of RNA polymerase II gene fragments identified three Fusarium species (Fusarium equiseti, Fusarium oxysporum, and Fusarium proliferatum) and two Neocosmospora species (Neocosmospora falciformis and Neocosmospora solani). F. oxysporum and N. falciformis were the fungal species most frequently recovered from symptomatic pistachio trees. Inoculations of detached twigs of cultivar Kerman pistachio Pioneer Gold I and clonal University of California, Berkeley I (UCBI) rootstocks showed that all five species could colonize pistachio wood and cause vascular discolorations. Pathogenicity tests in potted pistachio trees completed Koch's postulates and confirmed that F. oxysporum, F. proliferatum, N. falciformis, and N. solani were capable of producing rot and discoloration in stems of clonal UCBI rootstocks, the most widely planted pistachio rootstock in California. To our knowledge, this study is the first to present insights into the biodiversity and biology of Fusarium and Neocosmospora species associated with pistachio trees in California.


Assuntos
Ascomicetos , Fusarium , Pistacia , Ascomicetos/classificação , Ascomicetos/fisiologia , California , Fusarium/classificação , Fusarium/fisiologia , Filogenia , Pistacia/microbiologia , Doenças das Plantas/microbiologia
14.
Plant Dis ; 103(8): 1809-1827, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31232653

RESUMO

In recent decades, the cultivated area and production of nuts and olives have increased, driven by an increasing consumer interest in healthier food. Diseases of almond, pistachio, olive, and walnut crops caused by species belonging to the Botryosphaeriaceae family have caused concern worldwide. Although considerable progress has been made in elucidating the etiology of these diseases, scientific knowledge of other aspects of these diseases is more limited. In this article, we present an overview of the most important diseases caused by Botryosphaeriaceae fungi affecting almond, pistachio, olive, and walnut crops by focusing on ecology and epidemiology, primarily in California and Spain.


Assuntos
Ascomicetos , Nozes , Olea , Doenças das Plantas , Ascomicetos/fisiologia , California , Ecologia , Nozes/microbiologia , Olea/microbiologia , Doenças das Plantas/microbiologia , Espanha
15.
Plant Dis ; 103(8): 1983-1990, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31242133

RESUMO

Cercospora beticola, the cause of Cercospora leaf spot (CLS) of sugar beet and table beet, has a broad range of potential alternative hosts. The role of these hosts as inoculum sources in the field is unclear and has had limited investigation since the advent of DNA-based pathogen identification. The presence of C. beticola on alternative hosts associated with table beet fields of New York was assessed in field surveys during 2016. Lesions were collected, and 71 cercosporoid conidia were isolated for phylogenetic comparison. C. beticola was identified from Solanum ptycanthum (n = 4), Chenopodium album (n = 2), and Spinacia oleracea (n = 1), whereas C. chenopodii was identified on Chenopodium album (n = 51). Artificial inoculation of 21 plants species demonstrated that C. beticola was pathogenic to Brassica kaber, Chenopodium album, Carthamus tinctorius, Rumex obtusifolius, and Spinacia oleracea. These results indicate that although C. beticola may be pathogenic to a range of plant species, the role of symptomatic tissue for inoculum production on alternative hosts in the field appears limited. Observations of C. beticola on necrotic and naturally senescent tissue suggest saprophytic survival on plant debris of a range of species, which has implications for CLS epidemics and disease management.


Assuntos
Ascomicetos , Beta vulgaris , Ascomicetos/classificação , Ascomicetos/fisiologia , Beta vulgaris/microbiologia , Especificidade de Hospedeiro , New York , Filogenia , Inquéritos e Questionários
16.
Plant Mol Biol ; 101(1-2): 21-40, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31049793

RESUMO

KEY MESSAGE: Arabidopsis thaliana mlo3 mutant plants are not affected in pathogen infection phenotypes but-reminiscent of mlo2 mutant plants-exhibit spontaneous callose deposition and signs of early leaf senescence. The family of Mildew resistance Locus O (MLO) proteins is best known for its profound effect on the outcome of powdery mildew infections: when the appropriate MLO protein is absent, the plant is fully resistant to otherwise virulent powdery mildew fungi. However, most members of the MLO protein family remain functionally unexplored. Here, we investigate Arabidopsis thaliana MLO3, the closest relative of AtMLO2, AtMLO6 and AtMLO12, which are the Arabidopsis MLO genes implicated in the powdery mildew interaction. The co-expression network of AtMLO3 suggests association of the gene with plant defense-related processes such as salicylic acid homeostasis. Our extensive analysis shows that mlo3 mutants are unaffected regarding their infection phenotype upon challenge with the powdery mildew fungi Golovinomyces orontii and Erysiphe pisi, the oomycete Hyaloperonospora arabidopsidis, and the bacterial pathogen Pseudomonas syringae (the latter both in terms of basal and systemic acquired resistance), indicating that the protein does not play a major role in the response to any of these pathogens. However, mlo3 genotypes display spontaneous callose deposition as well as signs of early senescence in 6- or 7-week-old rosette leaves in the absence of any pathogen challenge, a phenotype that is reminiscent of mlo2 mutant plants. We hypothesize that de-regulated callose deposition in mlo3 genotypes might be the result of a subtle transient aberration of salicylic acid-jasmonic acid homeostasis during development.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Resistência à Doença/genética , Glucanos/metabolismo , Doenças das Plantas/imunologia , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Ascomicetos/fisiologia , Ciclopentanos/metabolismo , Genótipo , Homeostase , Mutação , Oomicetos/fisiologia , Oxilipinas/metabolismo , Fenótipo , Doenças das Plantas/microbiologia , Reguladores de Crescimento de Planta/metabolismo , Folhas de Planta/genética , Folhas de Planta/fisiologia , Pseudomonas syringae/fisiologia , Ácido Salicílico/metabolismo
17.
Int J Mol Sci ; 20(9)2019 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-31083412

RESUMO

Apple (Malus × domestica Borkh.) is one of the most important cultivated tree fruit crops worldwide. However, sustainable apple production is threatened by powdery mildew (PM) disease, which is caused by the obligate biotrophic fungus Podosphaera leucotricha. To gain insight into the molecular basis of the PM infection and disease progression, RNA-based transcriptional profiling (RNA-seq) was used to identify differentially expressed genes (DEGs) in apples following inoculation with P. leucotricha. Four RNA-seq libraries were constructed comprising a total of 214 Gb of high-quality sequence. 1177 DEGs (661 upregulated and 629 downregulated) have been identified according to the criteria of a ratio of infection/control fold change > 2, and a false discovery rate (FDR) < 0.001. The majority of DEGs (815) were detected 12 h after inoculation, suggesting that this is an important time point in the response of the PM infection. Gene annotation analysis revealed that DEGs were predominately associated with biological processes, phenylpropanoid biosynthesis, hormone signal transduction and plant-pathogen interactions. Genes activated by infection corresponded to transcription factors (e.g., AP2/ERF, MYB, WRKY and NAC) and synthesis of defense-related metabolites, including pathogenesis-related genes, glucosidase and dehydrin. Overall, the information obtained in this study enriches the resources available for research into the molecular-genetic mechanisms of the apple/powdery mildew interactions, and provides a theoretical basis for the development of new apple varieties with resistance to PM.


Assuntos
Ascomicetos/fisiologia , Perfilação da Expressão Gênica , Malus/genética , Malus/microbiologia , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Folhas de Planta/genética , Folhas de Planta/microbiologia , Clorofila/metabolismo , Regulação da Expressão Gênica de Plantas , Interações Hospedeiro-Patógeno , Malondialdeído/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Transdução de Sinais/genética , Fatores de Tempo , Fatores de Transcrição/metabolismo
18.
Plant Dis ; 103(7): 1515-1524, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31059385

RESUMO

Powdery mildew, caused by the fungus Podosphaera xanthii, is one of the most economically important diseases affecting cucurbit crops in Spain. Currently, chemical control offers the most efficient management of the disease; however, P. xanthii isolates resistant to multiple classes of site-specific fungicides have been reported in the Spanish cucurbit powdery mildew population. In previous studies, resistance to the fungicides known as methyl benzimidazole carbamates (MBCs) was found to be caused by the amino acid substitution E198A on ß-tubulin. To detect MBC-resistant isolates in a faster, more efficient, and more specific way than the traditional methods used to date, a loop-mediated isothermal amplification (LAMP) system was developed. In this study, three sets of LAMP primers were designed. One set was designed for the detection of the wild-type allele and two sets were designed for the E198A amino acid change. Positive results were only obtained with both mutant sets; however, LAMP reaction conditions were only optimized with primer set 2, which was selected for optimal detection of the E198A amino acid change in P. xanthii-resistant isolates, along with the optimal temperature and duration parameters of 65°C for 75 min, respectively. The hydroxynaphthol blue (HNB) metal indicator was used for quick visualization of results through the color change from violet to sky blue when the amplification was positive. HNB was added before the amplification to avoid opening the lids, thus decreasing the probability of contamination. To confirm that the amplified product corresponded to the ß-tubulin gene, the LAMP product was digested with the enzyme LweI and sequenced. Our results show that the LAMP technique is a specific and reproducible method that could be used for monitoring MBC resistance of P. xanthii directly in the field.


Assuntos
Ascomicetos , Farmacorresistência Fúngica , Doenças das Plantas , Ascomicetos/efeitos dos fármacos , Ascomicetos/genética , Ascomicetos/fisiologia , Benzimidazóis/farmacologia , Carbamatos/farmacologia , Técnicas de Amplificação de Ácido Nucleico , Espanha
19.
Parasite ; 26: 29, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31106730

RESUMO

Fungal species identities are often based on morphological features, but current molecular phylogenetic and other approaches almost always lead to the discovery of multiple species in single morpho-species. According to the morphological species concept, the ant-parasitic fungus Rickia wasmannii (Ascomycota, Laboulbeniales) is a single species with pan-European distribution and a wide host range. Since its description, it has been reported from ten species of Myrmica (Hymenoptera, Formicidae), of which two belong to the rubra-group and the other eight to the phylogenetically distinct scabrinodis-group. We found evidence for R. wasmannii being a single phylogenetic species using sequence data from two loci. Apparently, the original morphological description (dating back to 1899) represents a single phylogenetic species. Furthermore, the biology and host-parasite interactions of R. wasmannii are not likely to be affected by genetic divergence among different populations of the fungus, implying comparability among studies conducted on members of different ant populations. We found no differences in total thallus number on workers between Myrmica species, but we did observe differences in the pattern of thallus distribution over the body. The locus of infection is the frontal side of the head in Myrmica rubra and M. sabuleti whereas in M. scabrinodis the locus of infection differs between worker ants from Hungary (gaster tergites) and the Netherlands (frontal head). Possible explanations for these observations are differences among host species and among populations of the same species in (i) how ant workers come into contact with the fungus, (ii) grooming efficacy, and (iii) cuticle surface characteristics.


Assuntos
Formigas/microbiologia , Ascomicetos/fisiologia , Interações Hospedeiro-Parasita , Animais , Hungria , Micoses , Filogenia
20.
Mol Plant Microbe Interact ; 32(10): 1336-1347, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31125282

RESUMO

Tritrophic interactions involving a biocontrol agent, a pathogen, and a plant have been analyzed predominantly from the perspective of the biocontrol agent. To explore the adaptive strategies of wheat in response to beneficial, pathogenic, and combined microorganisms, we performed the first comprehensive transcriptomic, proteomic, and biochemical analysis in wheat roots after exposure to Bacillus velezensis CC09, Gaeumannomyces graminis var. tritici, and their combined colonization, respectively. The transcriptional or translational programming of wheat roots inoculated with beneficial B. velezensis showed mild alterations compared with that of pathogenic G. graminis var. tritici. However, the combination of B. velezensis and G. graminis var. tritici activated a larger transcriptional or translational program than for each single microorganism, although the gene expression pattern was similar to that of individual infection by G. graminis var. tritici, suggesting a prioritization of defense against G. graminis var. tritici infection. Surprisingly, pathogen-associated molecular pattern-triggered immunity and effector-triggered immunity made wheat pretreated with B. velezensis more sensitive to subsequent G. graminis var. tritici infection. Additionally, B. velezensis triggered a salicylic acid (SA)-dependent mode of induced systemic resistance that resembles pathogen-induced systemic acquired resistance. Wheat plants mainly depend on SA-mediated resistance, and not that mediated by jasmonic acid (JA), against the necrotrophic pathogen G. graminis var. tritici. Moreover, SA-JA interactions resulted in antagonistic effects regardless of the type of microorganisms in wheat. Further enhancement of SA-dependent defense responses such as lignification to the combined infection was shown to reduce the level of induced JA-dependent defense against subsequent infection with G. graminis var. tritici. Altogether, our results demonstrate how the hexaploid monocot wheat responds to beneficial or pathogenic microorganisms and prolongs the onset of take-all disease through modulation of cell reprogramming and signaling events.


Assuntos
Ascomicetos , Bacillus , Proteoma , Transcriptoma , Triticum , Ascomicetos/fisiologia , Bacillus/fisiologia , Triticum/genética , Triticum/microbiologia
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