Detection and Characterization of QoI-Resistant Phytophthora cactorum and P. nicotianae Causing Leather Rot in Florida Strawberry

Plant Disease ◽  
2021 ◽  
Author(s):  
Marcus Vinicius Marin ◽  
Teresa E Seijo ◽  
Ellias Zuchelli ◽  
Natalia A. Peres
Keyword(s):  
Point Mutations ◽  
Crown Rot ◽  
Cytb Gene ◽  
Phytophthora Cactorum ◽  
Phytophthora Spp ◽  
Mitochondrial Cytochrome B ◽  
Qualitative Resistance ◽  
Selection Of ◽  
Qoi Resistance

Phytophthora cactorum and P. nicotianae cause leather rot (LR) of fruit and Phytophthora crown rot (PhCR) in strawberry. LR occurs sporadically but can cause up to 70% fruit loss when weather is conducive. In Florida's annual strawberry winter production system, PhCR can be severe, resulting in plant stunting, mortality, and severe yield loss. Currently, azoxystrobin is labeled for control of LR but not for PhCR. The aims of this research were i) to determine the sensitivity of P. cactorum and P. nicotianae isolates from strawberry to azoxystrobin and ii) to investigate mechanisms of QoI-resistance present in P. cactorum and P. nicotianae based on the known point mutations within the cytb gene. Isolates of both Phytophthora spp. causing LR and PhCR were collected from multiple strawberry fields in Florida between 1997 and 2020. Isolates were tested for sensitivity to azoxystrobin at 0, 0.01, 0.1, 1.0, 10, and 50 µg/ml on potato dextrose agar (PDA) amended with SHAM (100 µg/ml). Isolates were separated into two groups, sensitive isolates, with the 50% effective concentration (EC50) values lower than 1.0 µg/ml, and resistant isolates having EC50 values higher than 50 µg/ml. P. cactorum and P. nicotianae resistance to azoxystrobin was found for isolates collected after 2010. The first 450 nucleotides of the mitochondrial cytochrome b (cytb) gene were sequenced from a selection of resistant and sensitive isolates of both species. The G143A mutation reported to confer resistance to azoxystrobin was found in all resistant P. cactorum isolates. However, in P. nicotianae, qualitative resistance was observed, but the isolates lacked all the known mutations in the cytb gene. This is the first report of resistance to azoxystrobin in P. cactorum and P. nicotianae.

Phytophthora crown rot of Florida Strawberry: Inoculum Sources and Thermotherapy of Transplants for Disease Management

Plant Disease ◽  
2021 ◽  
Author(s):  
Juliana Silveira Baggio ◽  
Marcus Vinicius Marin ◽  
Natalia A. Peres
Keyword(s):  
Heat Treatment ◽  
Chemical Control ◽  
Pathogen Resistance ◽  
Crown Rot ◽  
Phytophthora Cactorum ◽  
Inoculum Sources ◽  
Phytophthora Spp ◽  
Commercial Farms ◽  
Important Disease

Phytophthora crown rot, caused mainly by Phytophthora cactorum, and also by the recently reported P. nicotianae, is an important disease in the Florida strawberry annual production system. Mefenoxam is the most effective and widely used fungicide to manage this disease. However, due to pathogen resistance, alternatives to chemical control are needed. Phytophthora spp. were rarely recovered during the summer from soil of commercial farms where the disease was observed during the season. In a more detailed survey on research plots, neither of the two species was recovered one month after the crop was terminated and water was shut off. Therefore, Phytophthora spp. does not seem to survive in the soil over summer in Florida. In a field trial, asymptomatic nursery transplants harboring quiescent infections were confirmed as the major source of inoculum for these pathogens in Florida. Heat treatment of P. cactorum zoospores at 44oC for as little as 5 min was effective in inhibiting germination and colony formation; however, oospore germination was not inhibited by any of the tested temperatures in vitro. In the field, thermotherapy treatment of inoculated plants was shown to have great potential to serve as a non-chemical approach for managing Phytophthora crown rot in production fields and reducing mefenoxam-resistant populations in nursery transplants.

scholarly journals “Shining a LAMP” (Loop-Mediated Isothermal Amplification) on the Molecular Detection of Phytopathogens Phytophthora spp. and Phytophthora cactorum in Strawberry Fields

Pathogens ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1453
Author(s):  
Dominika G. Siegieda ◽  
Jacek Panek ◽  
Magdalena Frąc
Keyword(s):  
Molecular Detection ◽  
Detection Method ◽  
Molecular Techniques ◽  
Isothermal Amplification ◽  
Crown Rot ◽  
Phytophthora Cactorum ◽  
Loop Mediated Isothermal Amplification ◽  
Phytophthora Spp ◽  
Freeze Dried ◽  
Starting Point

Phytopathogenic microorganisms belonging to the genus Phytophthora have been recognized many times as causal agents of diseases that lower the yield of many plants important for agriculture. Meanwhile, Phytophthora cactorum causes crown rot and leather rot of berry fruits, mainly strawberries. However, widely-applied culture-based methods used for the detection of pathogens are time-consuming and often inaccurate. What is more, molecular techniques require costly equipment. Here we show a rapid and effective detection method for the aforementioned targets, deploying a simple molecular biology technique, Loop-Mediated Isothermal Amplification (LAMP). We optimized assays to amplify the translation elongation factor 1-α (EF1a) gene for two targets: Phytophthora spp. And Phytophthora cactorum. We optimized the LAMP on pure strains of the pathogens, isolated from organic plantations of strawberry, and successfully validated the assay on biological material from the environment including soil samples, rhizosphere, shoots and roots of strawberry, and with SYBR Green. Our results demonstrate that a simple and reliable molecular detection method, that requires only a thermoblock and simple DNA isolation kit, can be successfully applied to detect pathogens that are difficult to separate from the field. We anticipate our findings to be a starting point for developing easier and faster modifications of the isothermal detection methods and which can be applied directly in the plantation, in particular with the use of freeze-dried reagents and chemistry, allowing observation of the results with the naked eye.

scholarly journals In Vitro Pathogenesis Caused by Phytophthora cactorum and DNA Analysis of the Strawberry-Resistant Microplants with ISSR Markers

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1279
Author(s):  
Wojciech Marecki ◽  
Jadwiga Żebrowska
Keyword(s):  
Genetic Similarity ◽  
In Vitro Selection ◽  
Dna Analysis ◽  
Pathogenic Fungus ◽  
Inter Simple Sequence Repeat ◽  
Issr Markers ◽  
Crown Rot ◽  
Phytophthora Cactorum ◽  
Selection Of

The soil pathogenic fungus Phytophthora cactorum causes the most dangerous diseases occurring in strawberry plantations—strawberry crown rot and leather rot. Modern biotechnology methods, e.g., in vitro culture selection and molecular diagnostics can be utilized in the selection of cultivars that are less susceptible or resistant to Phytophthora diseases. In this study, in vitro selection of four strawberry microclones: ‘Elsanta’, ‘Feltar’, ‘Teresa’ and ‘Plena SVdT’ against Phytophthora cactorum (Lebert and Cohn) J. Schröt was carried out. Molecular analysis with inter simple sequence repeat (ISSR) markers was also used to evaluate genetic similarity of the selected resistant plants. None of the analyzed microclones showed complete resistance to the selection factor, but there were plants in all tested microclones that survived the pressure of the pathogen. Results showed that susceptibility to this pathogenic fungus was significantly differentiated and depended on the microclone. The ‘Feltar’ microclone had the significantly lowest susceptibility to Phytophthora disease, followed by the microclones ‘Elsanta’ and ‘Teresa’ with significantly higher susceptibility. The ‘Plena SVdT’ microclone showed the highest susceptibility to Phytophthora disease. This differentiation was linked to the genetic similarity observed at deoxyribonucleic acid (DNA) level between the resistant plants selected from microclones. Cluster analysis revealed that microclones with similar susceptibility to phytophthorosis, i.e., ‘Elsanta’, ‘Feltar’ and ‘Teresa’, appeared to be genetically similar. The microclone ‘Plena SVdT’ revealed a different course of phytophthorosis from the aforementioned microclones, being the least genetically similar to them.

scholarly journals Location of an Intron in the Cytochrome b Gene Indicates Reduced Risk of QoI Fungicide Resistance in Fusicladium effusum

Plant Disease ◽  
2016 ◽  
Vol 100 (11) ◽  
pp. 2294-2298 ◽  
Author(s):  
J. R. Standish ◽  
H. F. Avenot ◽  
T. B. Brenneman ◽  
K. L. Stevenson
Keyword(s):  
Cytochrome B ◽  
Gene Sequence ◽  
Intron Loss ◽  
Phytopathogenic Fungi ◽  
Cytb Gene ◽  
Gene Sequence Analysis ◽  
Pecan Scab ◽  
Partial Fragment ◽  
Selection Of ◽  
Qoi Resistance

Pecan scab, caused by Fusicladium effusum, is most effectively managed using multiple fungicide applications, including quinone outside inhibitors (QoIs). However, QoIs have a high risk for resistance developing in phytopathogenic fungi. QoI resistance is generally associated with amino-acid substitutions at positions 129, 137, and 143 of the cytochrome b (cytb) gene. A substitution at position 143 confers complete resistance, while an intron immediately downstream of this position prevents the substitution. The objective of this study was to assess the risk of QoI resistance by characterizing a partial fragment of the F. effusum cytb gene. Sequence analysis of the 1,919-bp fragment revealed the presence of a 1,407-bp intron immediately downstream of position 143. This intron was identified in 125 isolates collected from 16 counties across the state of Georgia. No substitutions were identified at positions 129 or 143 but, in seven of the isolates, glycine was replaced with serine at position 137. The ubiquitous nature of the detected intron provided strong evidence that the G143A substitution may not occur in F. effusum isolates, although resistance could still develop through intron loss events or the selection of intron-lacking genotypes, or as the result of other mutations in the cytb gene.

scholarly journals Induced Resistance as a Possible Means to Control Diseases of Strawberry Caused by Phytophthora spp.

Plant Disease ◽  
2003 ◽  
Vol 87 (4) ◽  
pp. 345-350 ◽  
Author(s):  
H. Eikemo ◽  
A. Stensvand ◽  
A. M. Tronsmo
Keyword(s):  
Growth Rate ◽  
Disease Resistance ◽  
Crown Rot ◽  
Fragaria Vesca ◽  
Disease Score ◽  
Phytophthora Cactorum ◽  
Phytophthora Spp ◽  
Retarding Effect ◽  
Severity Of The Disease

Two putative elicitors of disease resistance (acibenzolar-S-methyl and chitosan) were tested for their effect on crown rot (Phytophthora cactorum) in strawberry. The effect of both compounds was enhanced when the time between treatment and inoculation was prolonged from 2 to 20 days. There were no significant differences between treatments when the concentration of acibenzolar-S-methyl was increased from 10 to 1,000 μg a.i./plant. The lowest tested concentrations of chitosan (10 and 50 μg a.i./plant) resulted in a lower disease score compared with the highest concentrations (250 or 1,000 μg a.i./plant). There were no differences in disease score between treatment with fosetyl-Al, acibenzolar-S-methyl, or chitosan when applied 5 or 15 days before inoculation. The effect of acibenzolar-S-methyl and chitosan also was tested against P. fragariae var. fragariae in alpine strawberry (Fragaria vesca var. alpina cv. Alexandria). Chitosan had no effect, whereas fosetyl-Al and all treatments with acibenzolar-S-methyl (50 or 250 μg a.i./plant; 5, 10, 20, or 40 days before inoculation) reduced the severity of the disease. There were no significant differences between acibenzolar-S-methyl and fosetyl-Al when applied at the same time. Acibenzolar-S-methyl and chitosan at concentrations of 0.5, 5, 50, and 500 μg a.i. ml-1 in V8 juice agar were tested for possible effects on P. cactorum and P. fragariae var. fragariae in vitro. Only chitosan at concentrations of 50 and 500 μg a.i. ml-1 had a growth-retarding effect on P. cactorum. Both acibenzolar-S-methyl and chitosan at a concentration of 500 μg a.i. ml-1 reduced the growth rate of P. fragariae var. fragariae.

Applications of Transmission Electron Microscopy in the Characterization of Metal Machinability

1968 ◽  
Vol 26 ◽  
pp. 442-443 ◽  
Author(s):  
L.E. Murr ◽  
A.B. Draper
Keyword(s):  
Electron Microscopy ◽  
State Physics ◽  
Test Material ◽  
Milling Machine ◽  
Rotary Table ◽  
Solid State Physics ◽  
Materials Properties ◽  
Transmission Electron ◽  
Selection Of

The industrial characterization of the machinability of metals and alloys has always been a very arbitrarily defined property, subject to the selection of various reference or test materials; and the adoption of rather naive and misleading interpretations and standards. However, it seems reasonable to assume that with the present state of knowledge of materials properties, and the current theories of solid state physics, more basic guidelines for machinability characterization might be established on the basis of the residual machined microstructures. This approach was originally pursued by Draper; and our presentation here will simply reflect an exposition and extension of this research.The technique consists initially in the production of machined chips of a desired test material on a horizontal milling machine with the workpiece (specimen) mounted on a rotary table vice. A single cut of a specified depth is taken from the workpiece (0.25 in. wide) each at a new tool location.

Caracterização da Peneira Média em Clones de Coffea canephora

REVISTA FIMCA ◽  
2018 ◽  
Vol 5 (2) ◽  
pp. 28-31
Author(s):  
Darlan Darlan Sanches Barbosa Alves ◽  
Victor Mouzinho Spinelli ◽  
Marcos Santana Moraes ◽  
Carolina Augusto De Souza ◽  
Rodrigo da Silva Ribeiro ◽  
...  
Keyword(s):  
Genetic Improvement ◽  
Block Design ◽  
Coffea Canephora ◽  
Coffee Production ◽  
Randomized Block Design ◽  
Significant Difference ◽  
The Mean ◽  
Four Blocks ◽  
Selection Of

Introdução: O estado de Rondônia se destaca como tradicional produtor de café, sendo o segundo maior produtor brasileiro de C. canephora. No melhoramento genético de C. canephora, a seleção de plantas de elevada peneira média está associada à bebida de qualidade superior. Objetivos: O objetivo desse estudo foi avaliar a variabilidade genética de clones de C. canephora para o tamanho dos grãos, mensurado a partir da avaliação da peneira média (PM). Materiais e Métodos: Para isso, foi conduzido ao longo de dois anos agrícolas experimento no campo experimental da Embrapa no município de Ouro Preto do Oeste-RO, para a avaliação da peneira média de 130 genótipos (clones) com características das variedades botânicas Conilon, Robusta e híbridos intervarietais. O delineamento experimental utilizado foi de blocos ao acaso, com quatro repetições de quatro plantas por parcela. Resultados: Não houve resultados significativos para a interação clones X anos, indicando uma maior consistência no comportamento das plantas ao longo do tempo. Porém foram observadas diferenças significativas para o tamanho dos grãos entre os genótipos avaliados, possibilitando selecionar genótipos superiores. Conclusão: Os genótipos agruparam-se em cinco classes de acordo com o teste de média, subsidiando a caracterização de um gradiente de variabilidade da característica avaliada ABSTRACTIntroduction: Coffea canephora accounts for approximately 35% of the world's coffee production. The state of Rondônia stands out as a traditional coffee producer, being the second largest Brazilian producer of C. canephora. In the classical genetic improvement of C. anephora, the selection of plants of high average sieve is associated with a drink of superior quality. Objectives: The objective of this udy was to evaluate the genetic variability of Coffea canephora clones for the agronomic medium sieve (PM). Materials and Methods: The experiment was conducted in the experimental field of Embrapa, municipality of OuroPreto do Oeste-RO, located at coordinates 10º44'53 "S and 62º12'57". One hundred thirty genotypes (clones) of botanical characteristics Conilon, Robusta and intervarietal hybrids were evaluated in the agricultural years 2013-2014 and 2014-2015. The experimental design was a randomized block design with four blocks and four plants per plot, spacing 3.5 x 1.5 meters between plants. Results: Significant difference was found for the grain size. According to the F test, at 5% probability, the genotypes were grouped into five classes according to the mean test. Conclusion: The results obtained subsidized the characterization of a variability gradient of the evaluated trait.

Elaboration and Characterization of the Properties of Refractory Cr Base Alloys

2010 ◽  
Vol 72 ◽  
pp. 46-52 ◽  
Author(s):  
Laurent Royer ◽  
Stéphane Mathieu ◽  
Christophe Liebaut ◽  
Pierre Steinmetz
Keyword(s):  
Mechanical Properties ◽  
Melting Point ◽  
Molten Glass ◽  
Energy Production ◽  
Creep Properties ◽  
Refractory Alloys ◽  
Industrial Use ◽  
Kinetics Of ◽  
Selection Of

For energy production and also for the glass industry, finding new refractory alloys which could permit to increase the process temperatures to 1200°C or more is a permanent challenge. Chromium base alloys can be good candidates, considering the melting point of Cr itself, and also its low corrosion rate in molten glass. Two families of alloys have been studied for this purpose, Cr-Mo-W and Cr-Ta-X alloys (X= Mo, Si..). A finer selection of compositions has been done, to optimize their chemical and mechanical properties. Kinetics of HT oxidation by air, of corrosion by molten glass and also creep properties of several alloys have been measured up to 1250°C. The results obtained with the best alloys (Cr-Ta base) give positive indications as regards the possibility of their industrial use.

scholarly journals Organelle Genetics in Plants

2021 ◽  
Vol 22 (4) ◽  
pp. 2104
Author(s):  
Pedro Robles ◽  
Víctor Quesada
Keyword(s):  
Rna Editing ◽  
Posttranscriptional Regulation ◽  
Genome Engineering ◽  
Plant Mitochondria ◽  
Plastid Dna ◽  
Chloroplast Genomes ◽  
Wide Range ◽  
Organelle Genetics ◽  
Selection Of

Eleven published articles (4 reviews, 7 research papers) are collected in the Special Issue entitled “Organelle Genetics in Plants.” This selection of papers covers a wide range of topics related to chloroplasts and plant mitochondria research: (i) organellar gene expression (OGE) and, more specifically, chloroplast RNA editing in soybean, mitochondria RNA editing, and intron splicing in soybean during nodulation, as well as the study of the roles of transcriptional and posttranscriptional regulation of OGE in plant adaptation to environmental stress; (ii) analysis of the nuclear integrants of mitochondrial DNA (NUMTs) or plastid DNA (NUPTs); (iii) sequencing and characterization of mitochondrial and chloroplast genomes; (iv) recent advances in plastid genome engineering. Here we summarize the main findings of these works, which represent the latest research on the genetics, genomics, and biotechnology of chloroplasts and mitochondria.

Selection of lactose-adapted cells in vinca minor and Dantura innoxia cultures; location and characterization of β-galactosidase and lactase activities

Plant Science ◽  
1988 ◽  
Vol 54 (1) ◽  
pp. 83-91 ◽  
Author(s):  
O.C. Elavummoottil ◽  
S. Duret ◽  
A. Vannereau ◽  
L. Cosson ◽  
J.C. Mestre
Keyword(s):  
Vinca Minor ◽  
Selection Of
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