scholarly journals A. Lebeda, P.T.N. Spencer-Phillips (eds) – Advances in Downy Mildew Research. Vol. 3 (Proceedings of the 2nd International Downy Mildews Symposium) – Book Review

2008 ◽  
Vol 43 (No. 3) ◽  
pp. 125-126
Author(s):  
K. Veverka
Keyword(s):  
Downy Mildew ◽  
Downy Mildews

scholarly journals A High-Quality Grapevine Downy Mildew Genome Assembly Reveals Rapidly Evolving and Lineage-Specific Putative Host Adaptation Genes

2019 ◽  
Vol 11 (3) ◽  
pp. 954-969 ◽  
Author(s):  
Yann Dussert ◽  
Isabelle D Mazet ◽  
Carole Couture ◽  
Jérôme Gouzy ◽  
Marie-Christine Piron ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Genome Assembly ◽  
Population Genomics ◽  
Plasmopara Viticola ◽  
Plant Diseases ◽  
Host Specialization ◽  
Grapevine Downy Mildew ◽  
Downy Mildews ◽  
Genes Encoding ◽  
High Level

Abstract Downy mildews are obligate biotrophic oomycete pathogens that cause devastating plant diseases on economically important crops. Plasmopara viticola is the causal agent of grapevine downy mildew, a major disease in vineyards worldwide. We sequenced the genome of Pl. viticola with PacBio long reads and obtained a new 92.94 Mb assembly with high contiguity (359 scaffolds for a N50 of 706.5 kb) due to a better resolution of repeat regions. This assembly presented a high level of gene completeness, recovering 1,592 genes encoding secreted proteins involved in plant–pathogen interactions. Plasmopara viticola had a two-speed genome architecture, with secreted protein-encoding genes preferentially located in gene-sparse, repeat-rich regions and evolving rapidly, as indicated by pairwise dN/dS values. We also used short reads to assemble the genome of Plasmopara muralis, a closely related species infecting grape ivy (Parthenocissus tricuspidata). The lineage-specific proteins identified by comparative genomics analysis included a large proportion of RxLR cytoplasmic effectors and, more generally, genes with high dN/dS values. We identified 270 candidate genes under positive selection, including several genes encoding transporters and components of the RNA machinery potentially involved in host specialization. Finally, the Pl. viticola genome assembly generated here will allow the development of robust population genomics approaches for investigating the mechanisms involved in adaptation to biotic and abiotic selective pressures in this species.

scholarly journals Chamomile Floricolous Downy Mildew Caused by Peronospora radii

2019 ◽  
Vol 109 (11) ◽  
pp. 1900-1907
Author(s):  
Bojan Duduk ◽  
Nataša Duduk ◽  
Ivana Vico ◽  
Jelena Stepanović ◽  
Tatjana Marković ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Plant Pathogens ◽  
Systemic Infection ◽  
Downy Mildews ◽  
New Findings ◽  
High Production ◽  
The Impact ◽  
Chamomile Flowers ◽  
Production Losses

Floricolous downy mildews (Peronospora, oomycetes) are a small, monophyletic group of mostly inconspicuous plant pathogens that induce symptoms exclusively on flowers. Characterization of this group of pathogens, and information about their biology, is particularly sparse. The recurrent presence of a disease causing flower malformation which, in turn, leads to high production losses of the medicinal herb Matricaria chamomilla in Serbia has enabled continuous experiments focusing on the pathogen and its biology. Peronospora radii was identified as the causal agent of the disease, and morphologically and molecularly characterized. Diseased chamomile flowers showed severe malformations of the disc and ray florets, including phyllody and secondary inflorescence formation, followed by the onset of downy mildew. Phylogeny, based on internal transcribed spacer and cox2, indicates clustering of the Serbian P. radii with other P. radii from chamomile although, in cox2 analyses, they formed a separate subcluster. Evidence pointing to systemic infection was provided through histological and molecular analyses, with related experiments validating the impact of soilborne and blossom infections. This study provides new findings in the biology of P. radii on chamomile, thus enabling the reconstruction of this floricolous Peronospora species’ life cycle.

Book Review: The Downy Mildews.

1982 ◽  
Vol 11 (3) ◽  
pp. 135-135
Author(s):  
K. J. Brent
Keyword(s):  
Downy Mildews

scholarly journals Fantastic Downy Mildew Pathogens and How to Find Them: Advances in Detection and Diagnostics

Plants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 435
Author(s):  
Andres F. Salcedo ◽  
Savithri Purayannur ◽  
Jeffrey R. Standish ◽  
Timothy Miles ◽  
Lindsey Thiessen ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Pathogen Detection ◽  
Plant Pathogens ◽  
High Throughput Sequencing ◽  
Rapid Development ◽  
Target Selection ◽  
Nucleic Acid Amplification ◽  
Accurate Identification ◽  
Downy Mildews ◽  
Pathogen Variability

Downy mildews affect important crops and cause severe losses in production worldwide. Accurate identification and monitoring of these plant pathogens, especially at early stages of the disease, is fundamental in achieving effective disease control. The rapid development of molecular methods for diagnosis has provided more specific, fast, reliable, sensitive, and portable alternatives for plant pathogen detection and quantification than traditional approaches. In this review, we provide information on the use of molecular markers, serological techniques, and nucleic acid amplification technologies for downy mildew diagnosis, highlighting the benefits and disadvantages of the technologies and target selection. We emphasize the importance of incorporating information on pathogen variability in virulence and fungicide resistance for disease management and how the development and application of diagnostic assays based on standard and promising technologies, including high-throughput sequencing and genomics, are revolutionizing the development of species-specific assays suitable for in-field diagnosis. Our review provides an overview of molecular detection technologies and a practical guide for selecting the best approaches for diagnosis.

scholarly journals Peronosclerospora philippinensis (Philippine downy mildew of maize).

2021 ◽  
Author(s):  
Fe M. dela Cueva ◽  
Alyssa M. de Castro ◽  
Rachele L. de Torres
Keyword(s):  
Downy Mildew ◽  
Crop Production ◽  
Disease Incidence ◽  
The Philippines ◽  
Yield Reduction ◽  
Maize Production ◽  
Downy Mildews ◽  
Tropical Areas ◽  
Causal Pathogen ◽  
Warm Temperate

Abstract Peronosclerospora philippinensis, a causal pathogen of maize downy mildews, is one of the major maize diseases reported in some maize-growing countries, especially in the Philippines. High disease incidence has been reported in many parts in the country specifically in northern Luzon and in many parts of Mindanao despite breakthroughs in controlling or mitigating the disease using cultural and chemical control (Pascual et al., 2005). P. philippinensis is considered the most virulent of the downy mildew pathogens affecting maize, causing substantial losses to crop production (Murray, 2009). Under normal conditions, a 40-60% yield reduction is observed; however, favourable conditions for disease development can amplify these losses to 80-100% (Exconde and Raymundo, 1974). As the pathogen is able to survive in seeds, is able to spread rapidly and occasionally forms resting spores that can survive for more than 1 year, the pathogen has the potential to become a threat to local maize production in warm temperate and tropical areas.

Peronosclerospora philippinensis (Philippine downy mildew of maize).

2021 ◽  
Author(s):  
Fe M. Dela Cueva ◽  
Alyssa M. De Castro ◽  
Rachele L. De Torres
Keyword(s):  
Downy Mildew ◽  
Crop Production ◽  
Disease Incidence ◽  
The Philippines ◽  
Yield Reduction ◽  
Maize Production ◽  
Downy Mildews ◽  
Tropical Areas ◽  
Causal Pathogen ◽  
Warm Temperate

Abstract Peronosclerospora philippinensis, a causal pathogen of maize downy mildews, is one of the major maize diseases reported in some maize-growing countries, especially in the Philippines. High disease incidence has been reported in many parts in the country specifically in northern Luzon and in many parts of Mindanao despite breakthroughs in controlling or mitigating the disease using cultural and chemical control (Pascual et al., 2005). P. philippinensis is considered the most virulent of the downy mildew pathogens affecting maize, causing substantial losses to crop production (Murray, 2009). Under normal conditions, a 40-60% yield reduction is observed; however, favourable conditions for disease development can amplify these losses to 80-100% (Exconde and Raymundo, 1974). As the pathogen is able to survive in seeds, is able to spread rapidly and occasionally forms resting spores that can survive for more than 1 year, the pathogen has the potential to become a threat to local maize production in warm temperate and tropical areas.

scholarly journals Genetic Variation of the Pathogen Causing Impatiens Downy Mildew Predating and Including Twenty-first Century Epidemics on Impatiens walleriana

Plant Disease ◽  
2018 ◽  
Vol 102 (12) ◽  
pp. 2411-2420 ◽  
Author(s):  
Catalina Salgado-Salazar ◽  
Nicholas LeBlanc ◽  
Adnan Ismaiel ◽  
Yazmín Rivera ◽  
Colleen Y. Warfield ◽  
...  
Keyword(s):  
United States ◽  
Genetic Variation ◽  
Downy Mildew ◽  
Amplicon Sequencing ◽  
The United States ◽  
First Century ◽  
Herbarium Specimens ◽  
Downy Mildews ◽  
Impatiens Walleriana ◽  
The Relationship

Impatiens downy mildew (IDM) of cultivated Impatiens walleriana has had a significant economic impact on the ornamental horticulture industry in the United States and globally. Although recent IDM outbreaks started in 2003, downy mildews on noncultivated Impatiens species have been documented since the 1880s. To understand the relationship between the pathogen causing recent epidemics and the pathogen historically present in the United States, this work characterized genetic variation among a collection of 1,000 samples on 18 plant hosts. Samples included collections during recent IDM epidemics and historical herbarium specimens. Ten major genotypes were identified from cloned rDNA amplicon sequencing and endpoint SNP genotyping. Three genotypes accounted for >95% of the samples, with only one of these three genotypes found on samples predating recent IDM outbreaks. Based on phylogenetic analysis integrating data from three markers and the presence of individual genotypes on multiple Impatiens species, there was some evidence of pathogen-specific infection of I. noli-tangere, but the distinction between genotypes infecting I. walleriana and I. balsamina was not upheld. Overall, this work provides evidence that the majority of rDNA genotypes recovered from recent IDM epidemics are different from historical U.S. genotypes, and that these genotypes can infect Impatiens spp. other than I. walleriana.

scholarly journals Albugo candida (white rust) suppresses resistance to downy mildew pathogens in Arabidopsis thaliana

2017 ◽  
Vol 38 (SI 2 - 6th Conf EFPP 2002) ◽  
pp. 474-476 ◽  
Author(s):  
A.J. Cooper ◽  
A. Woods-Tör ◽  
E.B. Holub
Keyword(s):  
Arabidopsis Thaliana ◽  
Downy Mildew ◽  
Rust Resistance ◽  
Downy Mildew Resistance ◽  
Bremia Lactucae ◽  
Structural Class ◽  
Albugo Candida ◽  
White Rust ◽  
Downy Mildews ◽  
Hyaloperonospora Parasitica

Arabidopsis thaliana accessions were inoculated with incompatible isolates of downy mildews, following pre-inoculation with compatible Albugo candida. Three isolates of Hyaloperonospora parasitica subsp. A. thaliana, an isolate of H. parasitica subsp. Brassica oleracea and one Bremia lactucae (lettuce) isolate were included. All downy mildews sporulated on A. thaliana, suggesting A. candida suppresses broad-spectrum downy mildew resistance. The white rust resistance gene, RAC5, is being investigated. The resistance phenotype associated with RAC5 seems not to involve a hypersensitive response. RAC5 has been mapped telomeric of nga106 on chromosome 5, in a region lacking NB-LRR genes, the most common structural class of resistance genes known in A. thaliana.

scholarly journals Sequencing of the Litchi Downy Blight Pathogen Reveals It Is a Phytophthora Species With Downy Mildew-Like Characteristics

2016 ◽  
Vol 29 (7) ◽  
pp. 573-583 ◽  
Author(s):  
Wenwu Ye ◽  
Yang Wang ◽  
Danyu Shen ◽  
Delong Li ◽  
Tianhuizi Pu ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Gc Content ◽  
Specific Protein ◽  
Phytophthora Species ◽  
Effector Proteins ◽  
Morphological Development ◽  
Downy Mildews ◽  
Genome Features ◽  
Genomic Adaptation ◽  
Species Specific

On the basis of its downy mildew–like morphology, the litchi downy blight pathogen was previously named Peronophythora litchii. Recently, however, it was proposed to transfer this pathogen to Phytophthora clade 4. To better characterize this unusual oomycete species and important fruit pathogen, we obtained the genome sequence of Phytophthora litchii and compared it to those from other oomycete species. P. litchii has a small genome with tightly spaced genes. On the basis of a multilocus phylogenetic analysis, the placement of P. litchii in the genus Phytophthora is strongly supported. Effector proteins predicted included 245 RxLR, 30 necrosis-and-ethylene-inducing protein-like, and 14 crinkler proteins. The typical motifs, phylogenies, and activities of these effectors were typical for a Phytophthora species. However, like the genome features of the analyzed downy mildews, P. litchii exhibited a streamlined genome with a relatively small number of genes in both core and species-specific protein families. The low GC content and slight codon preferences of P. litchii sequences were similar to those of the analyzed downy mildews and a subset of Phytophthora species. Taken together, these observations suggest that P. litchii is a Phytophthora pathogen that is in the process of acquiring downy mildew–like genomic and morphological features. Thus P. litchii may provide a novel model for investigating morphological development and genomic adaptation in oomycete pathogens.

scholarly journals First Report of Peronospora parasitica on Wild Rocket (Diplotaxis tenuifolia) in Italy

Plant Disease ◽  
2004 ◽  
Vol 88 (12) ◽  
pp. 1381-1381 ◽  
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
M. L. Gullino
Keyword(s):  
New York ◽  
Downy Mildew ◽  
Causal Agent ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Peronospora Parasitica ◽  
First Report ◽  
Downy Mildews ◽  
Air Temperatures ◽  
Wild Rocket

Several species of Diplotaxis (D. tenuifolia, D. erucoides, and D. muralis), known as wild rocket, are now widely cultivated in Italy. Wild rocket is used in Mediterranean cuisine as salad, a component of packaged salad products, and as a garnish for food. During the fall of 2002, a foliar disease of D. tenuifolia was observed in the field or greenhouse on several commercial farms in the Liguria Region of northern Italy. Symptoms appeared as small, irregular, dark brown-to-black speckling on the adaxial surfaces of leaves. The speckled areas sometimes expanded into larger spots. These symptoms were followed by leaf yellowing and the appearance of sporangiophores and sporangia on the lower and upper leaf surfaces. Sporangiophores were dichotomously branched with slender curved tips. Sporangia were ovoid, measuring 20 to 28 (average 22) μm long and 15 to 25 (average 19) μm wide. The causal agent of the disease was identified as Peronospora parasitica (3). Pathogenicity was established by inoculating 10 30-day-old plants of D. tenuifolia grown in pots in a peat/pumice/clay/composted bark mix (60:20:10:10), with a conidial suspension (102 conidia per ml). Ten noninoculated plants maintained under the same conditions served as the control. Plants were maintained in a glasshouse at air temperatures ranging between 10 and 26°C (average 16°C) and relative humidity at 85%. The pathogenicity test was done twice. Downy mildew symptoms developed within 12 days, and the same fungus was observed on inoculated plants. Noninoculated plants did not develop symptoms. To our knowledge, this is the first report of P. parasitica on D. tenuifolia in Italy. P. parasitca has been reported as the causal agent of downy mildew on D. muralis in England (1) and on cultivated rocket (Eruca sativa) in California (2). References: (1) J. Fraymouth. Trans. Br. Mycol. Soc. 39:79, 1956. (2) S. T. Koike. Plant Dis. 82:1063, 1998. (3) D. M. Spencer. The Downy Mildews. Academic Press. New York, 1981.

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