scholarly journals Accumulation of a Protein Associated with Plant Defense in Powdery Mildew Resistant Dogwood (Cornus florida)

2006 ◽  
Vol 24 (2) ◽  
pp. 115-118
Author(s):  
M.T. Mmbaga ◽  
F.J. Avila ◽  
E.F. Howard ◽  
E.L. Myles
Keyword(s):  
Powdery Mildew ◽  
Plant Defense ◽  
Powdery Mildew Resistance ◽  
Cornus Florida ◽  
Defense Proteins ◽  
Mildew Resistance ◽  
Flowering Dogwood ◽  
Plant Defense Proteins ◽  
Powdery Mildew Pathogen ◽  
High Level

Abstract This study was conducted to better understand the nature of powdery mildew resistance in flowering dogwood (Cornus florida L.) and in particular to determine if inducible plant defense proteins are associated with powdery mildew resistance. Results from this study showed an accumulation of a new protein in resistant plants, but not in susceptible plants that were challenged with powdery mildew pathogen (Erysiphe (Sect. Microsphaera) pulchra). The protein accumulated in a high level in the resistant selections at 48 hr after inoculation with the pathogen and that was consistent with the production of pathogenesis related (PR) proteins. The protein was characterized as having an isoelectric point of 7.5 ± 0.5 and molecular weight of 18 ± 2 KD. Partial sequence analysis of this protein revealed homology with PR-10 protein associated with drought resistance in potato and was analogous to other proteins related to resistance in other crops. Repeated analysis showed similar results and suggested that a biochemical mode of resistance involving plant defense proteins may be associated with powdery mildew resistance in flowering dogwood.

scholarly journals Evaluation of Powdery Mildew Resistance in Hydrangea macrophylla

2011 ◽  
Vol 29 (2) ◽  
pp. 60-64 ◽  
Author(s):  
Mark T. Windham ◽  
Sandra M. Reed ◽  
Margaret T. Mmbaga ◽  
Alan S. Windham ◽  
Yonghao Li ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Powdery Mildew Resistance ◽  
Late Summer ◽  
Sources Of Resistance ◽  
Mildew Resistance ◽  
Potted Plants ◽  
Hydrangea Macrophylla ◽  
Erysiphe Polygoni ◽  
High Level ◽  
Moderately Resistant

Abstract Powdery mildew, Erysiphe polygoni DC, can be a significant problem on Hydrangea macrophylla (Thunb.) Ser. in the landscape in late summer to fall and during greenhouse propagation or production of potted plants. Because very little information related to sources of resistance is available, 90 H. macrophylla cultivars were evaluated for resistance to powdery mildew over a 3-year period. This included 69 H. macrophylla ssp. macrophylla and 18 H. macrophylla ssp. serrata (Thunb.) Makino cultivars, along with three cultivars that are hybrids between the two subspecies. Significant differences among cultivars to powdery mildew were found in all three study years. Three cultivars, ‘Amagi Amacha’, ‘Shirofuji’ and ‘Veitchii’, were among the most resistant each year. ‘Diadem’, ‘Komachi’, and ‘Omacha’ were highly resistant in 2006 and 2008, but only moderately resistant in 2007. ‘Komachi’ and ‘Shirofuji’ were considered unsuitable for breeding purposes as they do not appear to produce fertile flowers. ‘Veitchii’ was the only member of H. macrophylla ssp. macrophylla with a high level of powdery mildew resistance; while all other resistant cultivars were members of H. macrophylla ssp. serrata, not all members of this subspecies are resistant. Results of this study will be useful in breeding powdery mildew resistant H. macrophylla.

scholarly journals Naturally Occurring Resistance to Powdery Mildew in Seedlings of Cornus florida

1998 ◽  
Vol 16 (3) ◽  
pp. 173-177 ◽  
Author(s):  
Mark T. Windham ◽  
Willard T. Witte
Keyword(s):  
Powdery Mildew ◽  
Powdery Mildew Resistance ◽  
Resistance Mechanisms ◽  
Cornus Florida ◽  
Field Surveys ◽  
Flowering Dogwood ◽  
Naturally Occurring ◽  
High Incidence ◽  
Low Levels ◽  
Symptoms And Signs

Abstract Two production nursery fields of flowering dogwood, Cornus florida L., seedlings with a high incidence of powdery mildew were surveyed for plants free of symptoms and signs of the disease. In greenhouse trials most of the seedlings selected in the field survey for being free of powdery mildew were found to be escapes (had no disease resistance) or to exhibit partial resistance (unacceptable low levels of resistance). In those trials, twenty seedlings, representing approximately 0.1% of the seedlings examined in the field surveys, displayed resistance to powdery mildew similar to that of C. florida ‘Cherokee Brave’. This group of disease resistant seedlings will be used to develop new cultivars of white flowering dogwood resistant to powdery mildew and to investigate the inheritance of powdery mildew resistance mechanisms in flowering dogwood.

scholarly journals Inheritance of Powdery Mildew Resistance in Sugar Beet Derived from Beta vulgaris subsp. maritima

Plant Disease ◽  
2001 ◽  
Vol 85 (6) ◽  
pp. 627-631 ◽  
Author(s):  
R. T. Lewellen ◽  
J. K. Schrandt
Keyword(s):  
Powdery Mildew ◽  
Sugar Beet ◽  
Beta Vulgaris ◽  
Powdery Mildew Resistance ◽  
Major Gene ◽  
Mildew Resistance ◽  
Breeding Lines ◽  
Erysiphe Polygoni ◽  
Moderate Resistance ◽  
High Level

Powdery mildew of sugar beet (Beta vulgaris), caused by Erysiphe polygoni, was introduced into North American in 1974. Since then, chemical control has been needed. Moderate resistance of a slow-mildewing type is known and has been used commercially. High resistance was identified recently in B. vulgaris subsp. maritima accessions WB97 and WB242 and has been backcrossed into sugar beet breeding lines. These enhanced lines were used as sources of powdery mildew resistance to determine the inheritance of resistance. Analyses of segregating testcross families showed that resistance from both sources is inherited as a single, dominant, major gene. The gene symbol Pm is proposed for the resistant allele. The allelism of the resistance from the two wild beet sources was not determined. Pm conditions a high level of resistance, but disease developed on matured leaves late in the season. This late development of mildew on lines and the slow-mildewing trait in susceptible, recurrent lines tended to obfuscate discrete disease ratings.

scholarly journals Chemical suppressors of mlo-mediated powdery mildew resistance

2017 ◽  
Vol 37 (6) ◽  
Author(s):  
Hongpo Wu ◽  
Mark Kwaaitaal ◽  
Roxana Strugala ◽  
Ulrich Schaffrath ◽  
Paweł Bednarek ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Powdery Mildew Resistance ◽  
Brefeldin A ◽  
Loss Of Function ◽  
Mildew Resistance ◽  
Inhibitor Analysis ◽  
Guanine Derivatives ◽  
Powdery Mildew Pathogen ◽  
Inhibitor Screen ◽  
Molecular Components

Loss-of-function of barley mildew locus o (Mlo) confers durable broad-spectrum penetration resistance to the barley powdery mildew pathogen, Blumeria graminis f. sp. hordei (Bgh). Given the importance of mlo mutants in agriculture, surprisingly few molecular components have been identified to be required for this type of resistance in barley. With the aim to identify novel cellular factors contributing to mlo-based resistance, we devised a pharmacological inhibitor screen. Of the 41 rationally chosen compounds tested, five caused a partial suppression of mlo resistance in barley, indicated by increased levels of Bgh host cell entry. These chemicals comprise brefeldin A (BFA), 2′,3′-dideoxyadenosine (DDA), 2-deoxy-d-glucose, spermidine, and 1-aminobenzotriazole. Further inhibitor analysis corroborated a key role for both anterograde and retrograde endomembrane trafficking in mlo resistance. In addition, all four ribonucleosides, some ribonucleoside derivatives, two of the five nucleobases (guanine and uracil), some guanine derivatives as well as various polyamines partially suppress mlo resistance in barley via yet unknown mechanisms. Most of the chemicals identified to be effective in partially relieving mlo resistance in barley also to some extent compromised powdery mildew resistance in an Arabidopsis mlo2 mlo6 double mutant. In summary, our study identified novel suppressors of mlo resistance that may serve as valuable probes to unravel further the molecular processes underlying this unusual type of disease resistance.

scholarly journals Powdery mildew resistance of barley in Southern Dagestan

2021 ◽  
Vol 182 (1) ◽  
pp. 153-156
Author(s):  
B. A. Batasheva ◽  
R. A. Abdullaev ◽  
O. N. Kovaleva ◽  
I. A. Zveinek ◽  
E. E. Radchenko
Keyword(s):  
Powdery Mildew ◽  
Western Europe ◽  
Field Experiments ◽  
Powdery Mildew Resistance ◽  
Intraspecific Variability ◽  
Barley Plant ◽  
Southern Plains ◽  
Mildew Resistance ◽  
Long Term Study ◽  
High Level

Background.The most effective way of protecting crops from diseases and pests is the breeding and cultivation of resistant varieties. The hydrothermal regime in the southern plains of Dagest an favors damage to barley plant s by the causative agent of powdery mildew. The high level of disease progress observed annually helps to reliably assess the resistance of collection accessions to the pathogen.Materials and methods.The research material included 1361 barley accessions (570 improved cultivars and 791 landraces) of different ecogeographic origin and growth habit. Field experiments were launched concurrently with winter sowing. Powdery mildew resistance was scored during the heading period and in the milk ripeness phase using a point scale. Each accession was assessed for at least three years.Results and conclusions.The results of a long-term study disclosed a significant intraspecific variability of barley collection accessions in their resistance to powdery mildew. A significant part of the studied barley accessions (63.1%) appeared susceptible to the pathogen. The occurrence frequency of disease-resistant accessions was 11.0%, while those with medium resistance reached 25.9%. Among the landraces, four resistant accessions from the Abyssinian, West Asian and Mediterranean centers of crop origin were identified. Seventeen barley varieties resistant to powdery mildew (predominantly originated from Western Europe) are recommended for use in breeding for immunity.

scholarly journals Physiological Changes in Barley mlo-11 Powdery Mildew Resistance Conditioned by Tandem Repeat Copy Number

2020 ◽  
Vol 21 (22) ◽  
pp. 8769
Author(s):  
Cynthia Ge ◽  
Paula Moolhuijzen ◽  
Lee Hickey ◽  
Elzette Wentzel ◽  
Weiwei Deng ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Copy Number ◽  
Powdery Mildew Resistance ◽  
Binding Motif ◽  
Small Interfering Rnas ◽  
Mildew Resistance ◽  
Barley Powdery Mildew ◽  
Highly Expressed Genes ◽  
Normal Gene ◽  
High Level

Wild barley accessions have evolved broad-spectrum defence against barley powdery mildew through recessive mlo mutations. However, the mlo defence response is associated with deleterious phenotypes with a cost to yield and fertility, with implications for natural fitness and agricultural productivity. This research elucidates the mechanism behind a novel mlo allele, designated mlo-11(cnv2), which has a milder phenotype compared to standard mlo-11. Bisulphite sequencing and histone ChIP-seq analyses using near-isogenic lines showed pronounced repression of the Mlo promoter in standard mlo-11 compared to mlo-11(cnv2), with repression governed by 24 nt heterochromatic small interfering RNAs. The mlo-11(cnv2) allele appears to largely reduce the physiological effects of mlo while still endorsing a high level of powdery mildew resistance. RNA sequencing showed that this is achieved through only partly restricted expression of Mlo, allowing adequate temporal induction of defence genes during infection and expression close to wild-type Mlo levels in the absence of infection. The two mlo-11 alleles showed copy number proportionate oxidase and peroxidase expression levels during infection, but lower amino acid and aromatic compound biosynthesis compared to the null allele mlo-5. Examination of highly expressed genes revealed a common WRKY W-box binding motif (consensus ACCCGGGACTAAAGG) and a transcription factor more highly expressed in mlo-11 resistance. In conclusion, mlo-11(cnv2) appears to significantly mitigate the trade-off between mlo defence and normal gene expression.

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