scholarly journals Analysis of mutations in West Australian populations ofBlumeria graminisf. sp.hordei CYP51conferring resistance to DMI fungicides

2019 ◽  
Author(s):  
M. A. Tucker ◽  
F. Lopez-Ruiz ◽  
H. J. Cools ◽  
J. G. L. Mullins ◽  
K. Jayasena ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Target Gene ◽  
Docking Studies ◽  
Protein Docking ◽  
Yeast Strains ◽  
Barley Powdery Mildew ◽  
Dmi Fungicides ◽  
Altered Sensitivity ◽  
Resistant Genotypes ◽  
Demethylation Inhibitor

SummaryPowdery mildew caused byBlumeria graminisf. sp.hordei(Bgh) is a constant threat to barley production but is generally well controlled through combinations of host genetics and fungicides. An epidemic of barley powdery mildew was observed from 2007 to 2013 in the West Australian wheatbelt (WA). We collected isolates, examined their sensitivity to demethylation inhibitor (DMI) fungicides and sequenced the Cyp51B target gene. Five amino acid substitutions were found of which four were novel. A clear association was established between combinations of mutations and altered levels of resistance to DMIs. The most resistant genotypes increased in prevalence from 0 in 2009 to 16% in 2010 and 90% in 2011. Yeast strains expressing theBghCyp51 genotypes replicated the altered sensitivity to various DMIs and these results were confirmed byin silicoprotein docking studies.

scholarly journals Overexpression of the 14α-Demethylase Target Gene (CYP51) Mediates Fungicide Resistance in Blumeriella jaapii

2006 ◽  
Vol 72 (4) ◽  
pp. 2581-2585 ◽  
Author(s):  
Zhonghua Ma ◽  
Tyre J. Proffer ◽  
Janette L. Jacobs ◽  
George W. Sundin
Keyword(s):  
Leaf Spot ◽  
Fungicide Resistance ◽  
Target Gene ◽  
Direct Repeat ◽  
Efflux Pumps ◽  
Blumeriella Jaapii ◽  
Cherry Leaf Spot ◽  
Dmi Fungicides ◽  
Long Interspersed Nuclear Element ◽  
Demethylation Inhibitor

ABSTRACT Sterol demethylation inhibitor (DMI) fungicides are widely used to control fungi pathogenic to humans and plants. Resistance to DMIs is mediated either through alterations in the structure of the target enzyme CYP51 (encoding 14α-demethylase), through increased expression of the CYP51 gene, or through increased expression of efflux pumps. We found that CYP51 expression in DMI-resistant (DMIR) isolates of the cherry leaf spot pathogen Blumeriella jaapii was increased 5- to 12-fold compared to that in DMI-sensitive (DMIS) isolates. Analysis of sequences upstream of CYP51 in 59 DMIR isolates revealed that various forms of a truncated non-long terminal direct repeat long interspersed nuclear element retrotransposon were present in all instances. Similar inserts upstream of CYP51 were not present in any of 22 DMIS isolates examined.

scholarly journals Distributions of Sensitivities to Three Sterol Demethylation Inhibitor Fungicides Among Populations of Uncinula necator Sensitive and Resistant to Triadimefon

1997 ◽  
Vol 87 (8) ◽  
pp. 784-791 ◽  
Author(s):  
Eugene O. Erickson ◽  
Wayne F. Wilcox
Keyword(s):  
Powdery Mildew ◽  
Active Form ◽  
Correlation Coefficients ◽  
The Other ◽  
Cross Resistance ◽  
Uncinula Necator ◽  
Previous Exposure ◽  
Grapevine Powdery Mildew ◽  
Dmi Fungicides ◽  
Demethylation Inhibitor

Single-conidial isolates of Uncinula necator from (i) a population representing two vineyards with no previous exposure to sterol demethylation inhibitor (DMI) fungicides (“unexposed,” n = 77) and (ii) a population representing two vineyards in which powdery mildew was poorly controlled by triadimefon after prolonged DMI use (“selected,” n = 82) were assayed to determine distributions of sensitivities to the DMI fungicides triadimenol (the active form of triadimefon), myclobutanil, and fenarimol. Median 50% effective dose (ED50) values (micrograms per milliliter) in the selected versus unexposed populations were 0.06 versus 1.9 for triadimenol, 0.03 versus 0.23 for myclobutanil, and 0.03 versus 0.07 for fenarimol, respectively. Isolates were grouped into sensitivity classes according to their ED50 values, and those from the selected population were categorized as resistant if the frequency of their sensitivity class had increased significantly relative to levels found in the unexposed population (ED50 values exceeding 0.56, 0.18, and 0.18 μg/ml for triadimenol, myclobutanil, and fenarimol, respectively). Of the 76 isolates defined as resistant to triadimenol, 64% were classified as cross-resistant to myclobutanil, 18% were classified as cross-resistant to fenarimol, and 17% were classified as resistant to all three fungicides; 25% of the isolates classified as resistant to myclobutanil also were classified as resistant to fenarimol. Similar cross-resistance relationships were revealed when all isolates were examined by regressing log ED50 values for each fungicide against those for the remaining two fungicides to determine the correlation coefficients (e.g., r = 0.85 for triadimenol versus myclobutanil and 0.56 for triadimenol versus fenarimol). The restricted levels of cross-resistance indicated by these data, particularly between fenarimol and the other two fungicides, is in sharp contrast to the high levels of cross-resistance among DMIs reported for some other pathogens and has significant implications with respect to programs for managing grapevine powdery mildew and DMI resistance.

scholarly journals Dissimilarity of barley powdery mildew resistances Lomerit and Heils Hanna

2011 ◽  
Vol 47 (No. 3) ◽  
pp. 95-100 ◽  
Author(s):  
A. Dreiseitl
Keyword(s):  
Powdery Mildew ◽  
Agricultural Research ◽  
Blumeria Graminis ◽  
The Other ◽  
Japanese Isolate ◽  
Agricultural Research Institute ◽  
Reaction Type ◽  
Barley Cultivars ◽  
Barley Powdery Mildew ◽  
Old Japanese

  The resistance Heils Hanna (HH) was postulated in several tens of 471 previously tested winter barley cultivars. In this paper, new tests on 29 of these cultivars are reported. Thirty-two reference isolates of Blumeria graminis f.sp. hordei held in the pathogen genebank at the Agricultural Research Institute in Kromeriz, Ltd. including a Japanese isolate and five Israeli isolates were used for response tests. However, the resistance HH conferred by the gene Mla8 and herein characterised by reaction type 0 to an old Japanese isolate known as Race I was now postulated only in four cultivars. In the other 25 cultivars another resistance, characterised by reaction type 0 to Race I and also to two Israeli isolates, was detected. In addition to the two mentioned resistances, eight known (Bw, Dr2, Ha, IM9, Ln, Lv, Ra and Sp) resistances were found in the set examined. Lomerit was the only registered cultivar tested here in which the newly detected resistance was present alone, therefore, it is recommended that this resistance be designated Lo.

scholarly journals Pre-selection of apple seedlings for partial powdery mildew (Podosphaera leucotricha Ell. et Ev. /Salm./) resistance

2011 ◽  
Vol 50 (No. 2) ◽  
pp. 65-69 ◽  
Author(s):  
J. Blažek
Keyword(s):  
Powdery Mildew ◽  
First Year ◽  
Podosphaera Leucotricha ◽  
Green House ◽  
Healthy State ◽  
The Mean ◽  
Resistant Genotypes ◽  
Different Levels ◽  
Final Selection ◽  
Selection Of

Incidences of powdery mildew were repeatedly evaluated for two years on 1 420 young seedlings of 20 progenies (of different levels of mildew susceptibility) in a green house, and then for 10 years on 642 seedlings in an orchard. Part of the seedlings in the orchard were pre-selected for the characteristic and others not. Except for the first scoring done in the first year, there was no correlation between mildew incidence on individual seedlings in the green house and their mean performance in the orchard. The seedlings with scores above 6 (resistant or tolerant) at the first stage of evaluation in the green house, however, yielded four times more desirable seedlings after final selection in the orchard than the mean of the total. The progenies that had a better healthy state as a whole yielded more partially resistant genotypes than those with low mean scores. Therefore, the progenies that most rapidly develop infestation on the whole lot should be discarded, whereas those that retain a healthy state longer should be subjected to individual selection according to the previous item.

scholarly journals The barley immune receptor Mla recognizes multiple pathogens and contributes to host range dynamics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jan Bettgenhaeuser ◽  
Inmaculada Hernández-Pinzón ◽  
Andrew M. Dawson ◽  
Matthew Gardiner ◽  
Phon Green ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Stripe Rust ◽  
Resistance Genes ◽  
Host Species ◽  
Plant Pathogens ◽  
Puccinia Striiformis ◽  
Species Specificity ◽  
Wheat Stripe Rust ◽  
Barley Powdery Mildew ◽  
Barley Stripe Rust

AbstractCrop losses caused by plant pathogens are a primary threat to stable food production. Stripe rust (Puccinia striiformis) is a fungal pathogen of cereal crops that causes significant, persistent yield loss. Stripe rust exhibits host species specificity, with lineages that have adapted to infect wheat and barley. While wheat stripe rust and barley stripe rust are commonly restricted to their corresponding hosts, the genes underlying this host specificity remain unknown. Here, we show that three resistance genes, Rps6, Rps7, and Rps8, contribute to immunity in barley to wheat stripe rust. Rps7 cosegregates with barley powdery mildew resistance at the Mla locus. Using transgenic complementation of different Mla alleles, we confirm allele-specific recognition of wheat stripe rust by Mla. Our results show that major resistance genes contribute to the host species specificity of wheat stripe rust on barley and that a shared genetic architecture underlies resistance to the adapted pathogen barley powdery mildew and non-adapted pathogen wheat stripe rust.

Diseases affecting wheat and barley: powdery mildew

2018 ◽  
pp. 69-93 ◽  
Author(s):  
Javier Sánchez-Martín ◽  
◽  
Salim Bourras ◽  
Beat Keller ◽  
◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Barley Powdery Mildew
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