Temperature Influences on Powdery Mildew Susceptibility and Development in the Hop Cultivar Cascade

Plant Disease ◽  
2022 ◽  
Author(s):  
David H. Gent ◽  
Briana Claassen ◽  
Michele S. Wiseman ◽  
Sierra N Wolfenbarger
Keyword(s):  
Powdery Mildew ◽  
Partial Resistance ◽  
Disease Risk ◽  
Rapid Onset ◽  
Risk Assessments ◽  
Temperature Regimes ◽  
Moderate Disease ◽  
Ontogenic Resistance ◽  
Specific Temperature ◽  
Podosphaera Macularis

The hop cultivar Cascade possesses partial resistance to powdery mildew (Podosphaera macularis) that can be overcome by recently emerged, virulent isolates of the fungus. Given that hop is a long-lived perennial and that brewers still demand Cascade, there is a need to better understand factors that influence the development of powdery mildew on this cultivar. Growth chamber experiments were conducted to quantify the effect of constant, transient, and fluctuating temperature on Cascade before, concurrent to, and after inoculation as contrasted with another powdery mildew susceptible cultivar, Symphony. Exposure of plants to supraoptimal temperature (26 and 32°C) prior to inoculation led to more rapid onset of ontogenic resistance in intermediately aged leaves in Cascade as compared to Symphony. Cascade was overall less susceptible to powdery mildew when exposed to constant temperature ranging from 18 to 32°C directly after inoculation. However, cultivar also interacted with temperature such that proportionately fewer and smaller colonies developed on Cascade than Symphony at supraoptimal yet permissive temperatures for disease. When plants were inoculated and then exposed to high temperature, colonies became progressively more tolerant to temperatures of 26 to 30°C with increasing time from inoculation to exposure, as moderated by cultivar, the specific temperature, and their interaction. Subjecting plants to simulated diurnal temperature regimes at the time of inoculation or 24 h later indicated Cascade and Symphony responded proportionately similar on days predicted to be marginally unfavorable or marginally favorable for powdery mildew, although Cascade was quantitatively less susceptible than Symphony. In sum, this research indicates that Cascade is overall less susceptible to powdery mildew than Symphony, and supraoptimal temperature before, concurrent to, or after infection may interact differentially to moderate disease risk in Cascade. Therefore, cultivar-specific risk assessments for powdery mildew appear warranted.

scholarly journals Adaptation to Partial Resistance to Powdery Mildew in the Hop Cultivar Cascade by Podosphaera macularis

Plant Disease ◽  
2017 ◽  
Vol 101 (6) ◽  
pp. 874-881 ◽  
Author(s):  
David H. Gent ◽  
Stephen T. Massie ◽  
Megan C. Twomey ◽  
Sierra N. Wolfenbarger
Keyword(s):  
Powdery Mildew ◽  
Partial Resistance ◽  
Quantitative Resistance ◽  
Washington State ◽  
R Genes ◽  
Powdery Mildew Fungus ◽  
Field Surveys ◽  
The Pacific ◽  
Qualitative Resistance ◽  
Podosphaera Macularis

The hop cultivar Cascade has been grown in the Pacific Northwestern U.S. and elsewhere with minimal input for management of powdery mildew (Podosphaera macularis) for nearly 15 years due to the putatively quantitative resistance in this cultivar. While partial resistance is generally thought to be more durable than qualitative resistance, in 2012, powdery mildew was reported on Cascade in Washington State. Field surveys conducted during 2013 to 2016 indicated increasing prevalence of powdery mildew on Cascade, as well as an increasing number of fungicide applications applied to this cultivar in Washington State. Nearly all isolates of P. macularis tested were able to infect Cascade in laboratory inoculations. However, the greatest number of colonies, most conidia produced, and the shortest latent period was only observed with isolates derived originally from Cascade, as compared with other isolates derived from other cultivars. Further, the enhanced aggressiveness of these isolates was only manifested on Cascade and not six other susceptible cultivars, further indicating a specific adaptation to Cascade by the isolates. There was no evidence of a known major R-gene in Cascade, as seven isolates of P. macularis with contrasting virulence all infected Cascade. Among 158 isolates obtained from hop yards planted to Cascade, only two (1.3%) were able to infect the cultivar Nugget, which possesses the resistance factor termed R6, indicating that isolates of P. macularis virulent on Nugget are largely distinct from those adapted to Cascade. Further, race characterization indicated Cascade-adapted isolates of P. macularis were able to overcome R-genes Rb, R3, and R5, but not other known R-genes. Therefore, multiple R-genes and other sources of partial resistance are expected to provide resistance to Cascade-adapted strains of the fungus. Given the plasticity of the powdery mildew fungus, breeding strategies for powdery mildew need to consider the potential for adaptation to both qualitative and partial resistance in the host.

scholarly journals Effect of Variable Temperature on Infection Severity of Podosphaera macularis on Hops

2003 ◽  
Vol 93 (12) ◽  
pp. 1587-1592 ◽  
Author(s):  
Walter F. Mahaffee ◽  
William W. Turechek ◽  
Cynthia M. Ocamb
Keyword(s):  
Disease Risk ◽  
Variable Temperature ◽  
Optimal Conditions ◽  
Risk Assessment Models ◽  
Temperature Regimes ◽  
Uninoculated Control ◽  
Growth Chambers ◽  
Simulated Field ◽  
Favorable Conditions ◽  
Podosphaera Macularis

The effect of variable temperature on the infection severity of Podosphaera macularis was investigated. Potted ‘Symphony’ hop plants were inoculated and exposed to different temperature regimes that included supraconducive temperatures (30 to 42°C) for varying periods of time (2 to 9 h). Infection severity (lesions per cm2 of leaf area) was calculated 7 to 10 days after inoculation. Immediately exposing inoculated plants to 30°C for as little as 2 h significantly (P ≤ 0.05) reduced infection severity compared with exposure at a constant 18°C. However, exposure of inoculated plants to optimal conditions for 24 or 48 h prior to exposure to supraconducive conditions reduced this effect for plants exposed to 30, 33, or 36°C. Exposure to 39 or 42°C for 2 or more hours resulted in infection frequencies not significantly different from that of the uninoculated control regardless of prior exposure to favorable conditions. Exposure to simulated field temperatures programmed into growth chambers indicated that inoculation at 1700 or 2100 h resulted in significantly more disease than did inoculation at 0900 or 1300 h. Plants exposed to supraconducive or simulated field temperatures for 7 days prior to inoculation developed significantly lower disease severity than did plants maintained at 18°C for 7 days. The magnitude, length, and time of exposure to supraconducive temperatures in relation to time of inoculation plays an important role in the development of hop powdery mildew, and rules addressing these variables could be a useful addition to disease risk assessment models.

Characterization of Podosphaera macularis Derived from the Hop Cultivar ‘Strata’ and Strata’s Resistance to Powdery Mildew in Oregon

2021 ◽  
Author(s):  
Mary Block ◽  
Michele S. Wiseman ◽  
David H. Gent
Keyword(s):  
Powdery Mildew ◽  
Disease Risk ◽  
Severe Disease ◽  
Patent Application ◽  
State University ◽  
Single Chain ◽  
Differential Cultivars ◽  
Oregon State University ◽  
Podosphaera Macularis

Powdery mildew is one of the most destructive diseases of hop. Host resistance is a most efficient means of managing the disease, but resistance may not be durable. The cultivar Strata was developed by Oregon State University, and the patent application stated the plant was resistant to powdery mildew based on initial greenhouse screening and 8 years of observations at three locations in western Oregon. In 2019, powdery mildew colonies were reported in a commercial yard of Strata near Woodburn, Oregon. Two clonal isolates of Podosphaera macularis were isolated via single-chain transfers from colonies and characterized by inoculating each of seven differential cultivars. Cultivars with Rb, R3, and R5 were susceptible to the isolates. The susceptibility of Strata to powdery mildew was characterized by inoculating seven isolates of P. macularis with known virulences onto leaves of Strata. Sporulation appeared on Strata leaves with all of the differential isolates independent of their specific virulence, but only at trace levels with isolates possessing V6-virulence. Strata-derived isolates were phenotypically indistinguishable from Cascade-adapted isolates when inoculated onto the cultivars Cascade, Strata, and Symphony, as only Strata-derived and Cascade-adapted isolates could cause severe disease on Cascade and Strata. Like Cascade-adapted isolates, Strata-derived isolates also lack virulence on hop plants possessing the R-gene R6. These findings should inform both disease risk assessment in the field and future breeding tactics and strategies involving Strata. Further characterization of Strata is warranted to determine if its resistance is under the same genetic control as Cascade.

scholarly journals Feasibility of cardiovascular disease risk assessments in rheumatology outpatient clinics: experiences from the nationwide NOCAR project

RMD Open ◽  
2018 ◽  
Vol 4 (2) ◽  
pp. e000737 ◽  
Author(s):  
Eirik Ikdahl ◽  
Silvia Rollefstad ◽  
Grunde Wibetoe ◽  
Anne Salberg ◽  
Frode Krøll ◽  
...  
Keyword(s):  
Risk Factors ◽  
Cardiovascular Disease ◽  
Risk Evaluation ◽  
Disease Risk ◽  
High Risk Patient ◽  
Risk Assessments ◽  
Joint Diseases ◽  
Cvd Risk Factors ◽  
Cvd Risk ◽  
Rheumatology Outpatient

ObjectiveThe European League Against Rheumatism recommends implementing cardiovascular disease (CVD) risk assessments for patients with inflammatory joint diseases (IJDs) into clinical practice. Our goal was to design a structured programme for CVD risk assessments to be implemented into routine rheumatology outpatient clinic visits.MethodsThe NOrwegian Collaboration on Atherosclerosis in patients with Rheumatic joint diseases (NOCAR) started in April 2014 as a quality assurance project including 11 Norwegian rheumatology clinics. CVD risk factors were recorded by adding lipids to routine laboratory tests, self-reporting of CVD risk factors and blood pressure measurements along with the clinical joint examination. The patients’ CVD risks, calculated by the European CVD risk equation SCORE, were evaluated by the rheumatologist. Patients with high or very high CVD risk were referred to their primary care physician for initiation of CVD preventive measures.ResultsData collection (autumn 2015) showed that five of the NOCAR centres had implemented CVD risk assessments. There were 8789 patients eligible for CVD risk evaluation (rheumatoid arthritis (RA), 4483; ankylosing spondylitis (AS), 1663; psoriatic arthritis (PsA), 1928; unspecified and other forms of spondyloarthropathies (SpA), 715) of whom 41.4 % received a CVD risk assessment (RA, 44.7%; AS, 43.4%; PsA, 36.3%; SpA, 30.6%). Considerable differences existed in the proportions of patients receiving CVD risk evaluations across the NOCAR centres.ConclusionPatients with IJD represent a patient group with a high CVD burden that seldom undergoes CVD risk assessments. The NOCAR project lifted the offer of CVD risk evaluation to over 40% in this high-risk patient population.

scholarly journals Introducing HumanAPOEinto AβTransgenic Mouse Models

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Leon M. Tai ◽  
Katherine L. Youmans ◽  
Lisa Jungbauer ◽  
Chunjiang Yu ◽  
Mary Jo LaDu
Keyword(s):  
Head Injury ◽  
Mouse Models ◽  
Disease Risk ◽  
Rapid Onset ◽  
Temporal Delay ◽  
Wild Type ◽  
Significant Delay ◽  
Human Apoe ◽  
Plaque Deposition ◽  
5Xfad Mice

Apolipoprotein E (apoE) and apoE/amyloid-β(Aβ) transgenic (Tg) mouse models are critical to understanding apoE-isoform effects on Alzheimer's disease risk. Compared to wild type,apoE−/−mice exhibit neuronal deficits, similar to apoE4-Tg compared to apoE3-Tg mice, providing a model for Aβ-independent apoE effects on neurodegeneration. To determine the effects of apoE on Aβ-induced neuropathology,apoE−/−mice were crossed with Aβ-Tg mice, resulting in a significant delay in plaque deposition. Surprisingly, crossing human-apoE-Tg mice withapoE−/−/Aβ-Tg mice further delayed plaque deposition, which eventually developed in apoE4/Aβ-Tg mice prior to apoE3/Aβ-Tg. One approach to address hAPOE-induced temporal delay in Aβpathology is an additional insult, like head injury. Another is crossing human-apoE-Tg mice with Aβ-Tg mice that have rapid-onset Aβpathology. For example, because 5xFAD mice develop plaques by 2 months, the prediction is that human-apoE/5xFAD-Tg mice develop plaques around 6 months and 12 months before other human-apoE/Aβ-Tg mice. Thus, tractable models for human-apoE/Aβ-Tg mice continue to evolve.

Development of a diagnostic assay for race differentiation of Podosphaera macularis

Plant Disease ◽  
2020 ◽  
Author(s):  
Mary Block ◽  
Brian Knaus ◽  
Michele S. Wiseman ◽  
Niklaus J. Grünwald ◽  
David H. Gent
Keyword(s):  
Powdery Mildew ◽  
Pacific Northwest ◽  
The United States ◽  
Epidemiological Studies ◽  
Locked Nucleic Acid ◽  
Nucleotide Polymorphisms ◽  
Practical Applications ◽  
Powdery Mildew Fungi ◽  
Perfect Discrimination ◽  
Podosphaera Macularis

Hop powdery mildew (caused by Podosphaera macularis) was confirmed in the Pacific Northwest in 1996. Before 2012, the most common race of P. macularis was able to infect plants that possessed powdery mildew resistance based on the R-genes Rb, R3, and R5. After 2012, two additional races of P. macularis were discovered that can overcome the resistance gene R6 and the partial resistance found in the cultivar Cascade. These three races now occur throughout the region, which can complicate management and research efforts because of uncertainty on which race(s) may be present in the region and able to infect susceptible hop genotypes. Current methods for determining the races of P. macularis are labor intensive, costly, and typically require more than 14 days to obtain results. We sought to develop a molecular assay to differentiate races of the fungus possessing virulence on plants with R6, referred to as V6-virulent, from other races. The transcriptomes of 46 isolates of P. macularis were sequenced to identify loci and variants unique to V6-isolates. Fourteen primer pairs were designed for 10 candidate loci that contained single nucleotide polymorphisms (SNP) and short insertion-deletion polymorphisms. Two differentially-labeled locked nucleic acid probes were designed for a contig that contained a conserved SNP associated with V6-virulence. The resulting duplexed real-time PCR assay was validated against 46 V6 and 54 non-V6 P. macularis isolates collected from the United States and Europe. The assay had perfect discrimination of V6-virulence among isolates of P. macularis originating from the western U.S. but failed to predict V6-virulence in three isolates collected from Europe. The specificity of the assay was tested with different species of powdery mildew fungi and other microorganisms associated with hop. Weak non-specific amplification occurred with powdery mildew fungi collected from Vitis vinifera, Fragaria sp., and Zinnia sp.; however, non-specification amplification is not a concern when differentiating pathogen race from colonies on hop. The assay has practical applications in hop breeding, epidemiological studies, and other settings where rapid confirmation of pathogen race is needed.

Evaluation of cowpea genotypes for partial resistance to powdery mildew

Euphytica ◽  
1990 ◽  
Vol 50 (3) ◽  
pp. 191-195 ◽  
Author(s):  
S. G. Raju ◽  
T. B. Anilkumar
Keyword(s):  
Powdery Mildew ◽  
Partial Resistance
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