scholarly journals Transcriptional analyses of differential cultivars during resistant and susceptible interactions with Peronospora effusa, the causal agent of spinach downy mildew

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Shyam L. Kandel ◽  
Amanda M. Hulse-Kemp ◽  
Kevin Stoffel ◽  
Steven T. Koike ◽  
Ainong Shi ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Causal Agent ◽  
Differential Cultivars ◽  
Spinach Downy Mildew

scholarly journals Three New Races of the Spinach Downy Mildew Pathogen Identified by a Modified Set of Spinach Differentials

Plant Disease ◽  
2007 ◽  
Vol 91 (11) ◽  
pp. 1392-1396 ◽  
Author(s):  
B. M. Irish ◽  
J. C. Correll ◽  
S. T. Koike ◽  
T. E. Morelock
Keyword(s):  
United States ◽  
European Union ◽  
Downy Mildew ◽  
The United States ◽  
The European Union ◽  
The Past ◽  
Differential Cultivars ◽  
Spinach Downy Mildew ◽  
New Races ◽  
Important Disease

Spinach downy mildew, caused by Peronospora farinosa f. sp. spinaciae, is the most economically important disease of spinach worldwide. During the past few years, spinach cultivars resistant to the seven previously described races of P. farinosa f. sp. spinaciae were observed to be severely affected by downy mildew in both the United States and the European Union. Four new isolates of P. farinosa f. sp. spinaciae were collected from California and The Netherlands and characterized based on disease reactions on two modified sets of spinach differentials. The results led to the description of three new races of the downy mildew pathogen, designated races 8, 9, and 10. Four differential cultivars with resistance to races 1 to 7 were used to distinguish the three new races. Dolphin was susceptible to races 8 and 10 but resistant to race 9; Lion was susceptible to race 10 but resistant to races 8 and 9; Lazio was resistant to races 1 to 7 as well as races 8, 9, and 10; and Tarpy was susceptible to all three new races. The three new races also were used to evaluate the disease reactions on 43 contemporary commercial spinach cultivars in greenhouse trials. A survey of 58 isolates of P. farinosa f. sp. spinaciae collected in California and Arizona between 2004 and 2006 revealed that race 10 predominated in the areas sampled.

scholarly journals Identification and Cultivar Reaction to Three New Races of the Spinach Downy Mildew Pathogen from the United States and Europe

Plant Disease ◽  
2003 ◽  
Vol 87 (5) ◽  
pp. 567-572 ◽  
Author(s):  
B. M. Irish ◽  
J. C. Correll ◽  
S. T. Koike ◽  
J. Schafer ◽  
T. E. Morelock
Keyword(s):  
United States ◽  
The Netherlands ◽  
Downy Mildew ◽  
Quantitative Resistance ◽  
The United States ◽  
True Leaf ◽  
Differential Cultivars ◽  
Spinach Downy Mildew ◽  
New Races ◽  
Inoculation Assay

Since 1996, commercial spinach cultivars with resistance to four previously described races of Peronospora farinosa f. sp. spinaciae (races 1, 2, 3, and 4) were observed with high incidences of downy mildew both in California and Europe. Isolates of P. farinosa f. sp. spinaciae collected in California between 1997 and 2001, Arizona in 1999, and a single isolate collected in the Netherlands in 1996 were examined for their disease reaction on differential spinach cultivars and a set of commercial spinach cultivars. Disease reactions on the differential cultivars indicated the occurrence of three new races of P. farinosa f. sp. spinaciae. Two newly identified races, designated race 5 (isolate CA1) and race 6 (isolate SP1), were detected in the United States. The isolate from the Netherlands also was distinct and designated race 7 (isolate JVN7). Some cultivars with resistance to races 1, 2, 3, and 4 were susceptible to race 5, whereas others were resistant, indicating that resistance to a given race may be governed by different genes (or alleles) depending on the source of resistance. A survey of races in California indicated that races 5 and 6 predominated. Although the majority of the cultivars examined were susceptible to race 6 based on the traditional qualitative cotyledon inoculation assay, significant quantitative differences in resistance to race 6 were observed using a true-leaf greenhouse screening procedure. Although more work is needed to confirm the results of the true-leaf assays, the quantitative resistance observed using this procedure appears to be race specific.

scholarly journals Identification of New Races and Deviating Strains of the Spinach Downy Mildew Pathogen Peronospora farinosa f. sp. spinaciae

Plant Disease ◽  
2014 ◽  
Vol 98 (1) ◽  
pp. 145-152 ◽  
Author(s):  
Chunda Feng ◽  
James C. Correll ◽  
Katherine E. Kammeijer ◽  
Steven T. Koike
Keyword(s):  
Downy Mildew ◽  
Spinacia Oleracea ◽  
Resistance Locus ◽  
Rapid Rate ◽  
The Past ◽  
Differential Cultivars ◽  
Spinach Downy Mildew ◽  
New Races ◽  
Obligate Pathogen ◽  
Downy Mildew Disease

Spinach downy mildew disease, caused by the obligate pathogen Peronospora farinosa f. sp. spinaciae, is the most economically important spinach (Spinacia oleracea) disease. New races of this pathogen have been emerging at a rapid rate over the last 15 years. This is likely due to production changes, particularly in California, such as high-density plantings and year-round spinach production. As of 2004, 10 races of P. farinosa f. sp. spinaciae had been identified, and the spinach resistance locus RPF2 provided resistance to races 1 to 10. Based on disease reactions on a set of spinach differentials containing six hypothesized resistance loci (RPF1-RPF6), races 11, 12, 13, and 14 of P. farinosa f. sp. spinaciae were characterized based on samples collected in the past 5 years as part of this study. Race 11, identified in 2008, could overcome the resistance of spinach cultivars resistant to races 1 to 10. Spinach resistance loci RPF1, RPF3, and RPF6 provided resistance to race 11. Race 12 was identified in 2009 and could overcome the resistances of the RPF1 and RPF2 loci. The RPF3 locus was effective against race 12. Race 13 was identified in 2010 and could overcome the resistance imparted by the RPF2 and RPF3 loci, whereas the RPF1 locus was effective against race 13. Race 14 was similar to race 12 and caused identical disease responses on the standard differentials but could be distinguished from race 12 by its ability to cause disease on a number of newly released cultivars, including ‘Pigeon’, ‘Cello’, and ‘Celesta’. Five novel strains of P. farinosa f. sp. spinaciae were also identified. For example, isolate UA4711 of the pathogen, collected from Spain in 2011, was able to overcome the resistance imparted by the RPF1 and RPF3 loci, while RPF2 and RPF4 were effective against this strain. A total of 116 spinach cultivars, including 103 commercial lines and 13 differential cultivars, were evaluated for resistance to race 10 and the newly designated races 11, 12, 13, and 14.

scholarly journals Genome reconstruction of the non-culturable spinach downy mildew Peronospora effusa by metagenome filtering

2019 ◽  
Author(s):  
Joël Klein ◽  
Manon Neilen ◽  
Marcel van Verk ◽  
Guido Van den Ackerveken ◽  
Bas E. Dutilh
Keyword(s):  
Downy Mildew ◽  
Dna Isolation ◽  
Spinacia Oleracea ◽  
Gene Repertoire ◽  
Phylogenetic Distance ◽  
Annotate Orfs ◽  
A Genome ◽  
Spinach Downy Mildew ◽  
Insight Into ◽  
Spinach Leaves

Peronospora effusa (previously known as  P. farinosa f. sp. spinaciae, and here referred to as Pfs) is an obligate biotrophic oomycete that causes downy mildew on spinach (Spinacia oleracea). To combat this destructive disease resistant cultivars are continually bred. However, new Pfs races rapidly break the employed resistance genes. To get insight into the gene repertoire of Pfs and identify infection-related genes, the genome of the first reference race, Pfs1, was sequenced, assembled, and annotated. Due to the obligate biotrophic nature of this pathogen, material for DNA isolation can only be collected from infected spinach leaves that, however, also contain many other microorganisms. The obtained sequences are, therefore, considered a metagenome. To filter and obtain Pfs sequences we utilized the CAT tool to taxonomically annotate ORFs residing on long sequences of a genome pre-assembly. This study is the first to show that CAT filtering performs well on eukaryotic contigs. Based on the taxonomy, determined on multiple ORFs, contaminating long sequences and corresponding reads were removed. Filtered reads were re-assembled to provide a clean and improved Pfs genome sequence of 32.40 Mbp consisting of 8,635 scaffolds. Transcript sequencing of a range of infection time points aided the prediction of a total of 13,277 gene models, including 99 RXLR(-like) effector, and 14 putative Crinkler genes. Comparative analysis identified common features in the secretomes of different obligate biotrophic oomycetes, regardless of their phylogenetic distance. Their secretomes are generally smaller, compared to hemibiotrophic and necrotrophic oomycete species. We observe a reduction in proteins involved cell wall degradation, in Nep1-like proteins (NLPs), proteins with PAN/apple domains, and host translocated effectors. The genome of Pfs1 will be instrumental in studying downy mildew virulence and for understanding the molecular adaptations by which new isolates break spinach resistance.

scholarly journals Characterisation of pathogenic and molecular diversity inSclerospora graminicola, the causal agent of pearl millet downy mildew

2010 ◽  
Vol 43 (6) ◽  
pp. 538-551 ◽  
Author(s):  
R. Sharma ◽  
V. P. Rao ◽  
R. K. Varshney ◽  
V. P. Prasanth ◽  
S. Kannan ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Pearl Millet ◽  
Molecular Diversity ◽  
Causal Agent

scholarly journals Characterization of a Resistance Locus (Pfs-1) to the Spinach Downy Mildew Pathogen (Peronospora farinosa f. sp. spinaciae) and Development of a Molecular Marker Linked to Pfs-1

2008 ◽  
Vol 98 (8) ◽  
pp. 894-900 ◽  
Author(s):  
B. M. Irish ◽  
J. C. Correll ◽  
C. Feng ◽  
T. Bentley ◽  
B. G. de los Reyes
Keyword(s):  
Disease Resistance ◽  
Downy Mildew ◽  
Scar Marker ◽  
Mapping Population ◽  
Dominant Gene ◽  
Resistance Locus ◽  
Sequence Characterized Amplified Region ◽  
Wide Range ◽  
Spinach Downy Mildew ◽  
Homozygous Resistant

Downy mildew is a destructive disease of spinach worldwide. There have been 10 races described since 1824, six of which have been identified in the past 10 years. Race identification is based on qualitative disease reactions on a set of diverse host differentials which include open-pollinated cultivars, contemporary hybrid cultivars, and older hybrid cultivars that are no longer produced. The development of a set of near-isogenic open-pollinated spinach lines (NILs), having different resistance loci in a susceptible and otherwise common genetic background, would facilitate identification of races of the downy mildew pathogen, provide a tool to better understand the genetics of resistance, and expedite the development of molecular markers linked to these disease resistance loci. To achieve this objective, the spinach cv. Viroflay, susceptible to race 6 of Peronospora farinosa f. sp. spinaciae, was used as the recurrent susceptible parent in crosses with the hybrid spinach cv. Lion, resistant to race 6. Resistant F1 progeny were subsequently backcrossed to Viroflay four times with selection for race 6 resistance each time. Analysis of the segregation data showed that resistance was controlled by a single dominant gene, and the resistance locus was designated Pfs-1. By bulk segregant analysis, an amplified fragment length polymorphism (AFLP) marker (E-ACT/M-CTG) linked to Pfs-1 was identified and used to develop a co-dominant Sequence characterized amplified region (SCAR) marker. This SCAR marker, designated Dm-1, was closely linked (≈1.7 cM) to the Pfs-1 locus and could discriminate among spinach genotypes that were homozygous resistant (Pfs-1Pfs-1), heterozygous resistant (Pfs-1pfs-1), or homozygous susceptible (pfs-1pfs-1) to race 6 within the original mapping population. Evaluation of a wide range of commercial spinach lines outside of the mapping population indicated that Dm-1 could effectively identify Pfs-1 resistant genotypes; the Dm-1 marker correctly predicted the disease resistance phenotype in 120 out of 123 lines tested. In addition, the NIL containing the Pfs-1 locus (Pfs-1Pfs-1) was resistant to multiple races of the downy mildew pathogen indicating Pfs-1 locus may contain a cluster of resistance genes.

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