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.

scholarly journals Integration of early disease-resistance phenotyping, histological characterization, and transcriptome sequencing reveals insights into downy mildew resistance in impatiens

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ze Peng ◽  
Yanhong He ◽  
Saroj Parajuli ◽  
Qian You ◽  
Weining Wang ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Downy Mildew ◽  
Transcriptome Sequencing ◽  
Early Stage ◽  
Economic Losses ◽  
Potential Candidate ◽  
Early Disease ◽  
True Leaf ◽  
Cotyledon Stage ◽  
Wide Range

AbstractDowny mildew (DM), caused by obligate parasitic oomycetes, is a destructive disease for a wide range of crops worldwide. Recent outbreaks of impatiens downy mildew (IDM) in many countries have caused huge economic losses. A system to reveal plant–pathogen interactions in the early stage of infection and quickly assess resistance/susceptibility of plants to DM is desired. In this study, we established an early and rapid system to achieve these goals using impatiens as a model. Thirty-two cultivars of Impatiens walleriana and I. hawkeri were evaluated for their responses to IDM at cotyledon, first/second pair of true leaf, and mature plant stages. All I. walleriana cultivars were highly susceptible to IDM. While all I. hawkeri cultivars were resistant to IDM starting at the first true leaf stage, many (14/16) were susceptible to IDM at the cotyledon stage. Two cultivars showed resistance even at the cotyledon stage. Histological characterization showed that the resistance mechanism of the I. hawkeri cultivars resembles that in grapevine and type II resistance in sunflower. By integrating full-length transcriptome sequencing (Iso-Seq) and RNA-Seq, we constructed the first reference transcriptome for Impatiens comprised of 48,758 sequences with an N50 length of 2060 bp. Comparative transcriptome and qRT-PCR analyses revealed strong candidate genes for IDM resistance, including three resistance genes orthologous to the sunflower gene RGC203, a potential candidate associated with DM resistance. Our approach of integrating early disease-resistance phenotyping, histological characterization, and transcriptome analysis lay a solid foundation to improve DM resistance in impatiens and may provide a model for other crops.

Development of SCAR marker associated with downy mildew disease resistance in pearl millet (Pennisetum glaucum L.)

2014 ◽  
Vol 41 (12) ◽  
pp. 7815-7824 ◽  
Author(s):  
Sudisha Jogaiah ◽  
R. G. Sharathchandra ◽  
Niranjan Raj ◽  
A. B. Vedamurthy ◽  
H. Shekar Shetty
Keyword(s):  
Disease Resistance ◽  
Downy Mildew ◽  
Pearl Millet ◽  
Scar Marker ◽  
Pennisetum Glaucum ◽  
Downy Mildew Disease

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.

A molecular linkage map of olive (Olea europaea L.) based on RAPD, microsatellite, and SCAR markers

Genome ◽  
2004 ◽  
Vol 47 (1) ◽  
pp. 26-35 ◽  
Author(s):  
Shu-Biao Wu ◽  
Graham Collins ◽  
Margaret Sedgley
Keyword(s):  
Disease Resistance ◽  
Linkage Map ◽  
Olea Europaea ◽  
Mapping Population ◽  
Average Distance ◽  
Linkage Groups ◽  
Integrated Map ◽  
Sequence Characterized Amplified Region ◽  
Olea Europaea L ◽  
Molecular Linkage Map

An integrated molecular linkage map of olive (Olea europaea L.) was constructed based on randomly amplified polymorphic DNA (RAPD), sequence characterized amplified region (SCAR), and microsatellite markers using the pseudo-testcross strategy. A mapping population of 104 individuals was generated from an F1 full-sib family of a cross between 'Frantoio' and 'Kalamata'. The hybridity of the mapping population was confirmed by genetic similarity and nonmetric multidimensional scaling. Twenty-three linkage groups were mapped for 'Kalamata', covering 759 cM of the genome with 89 loci and an average distance between loci of 11.5 cM. Twenty-seven linkage groups were mapped for 'Frantoio', covering 798 cM of the genome with 92 loci and an average distance between loci of 12.3 cM. For the integrated map, 15 linkage groups covered 879 cM of the genome with 101 loci and an average distance between loci of 10.2 cM. The size of the genomic DNA was estimated to be around 3000 cM. A sequence characterized amplified region marker linked to olive peacock disease resistance was mapped to linkage group 2 of the integrated map. These maps will be the starting point for studies on the structure, evolution, and function of the olive genome. When the mapping progeny pass through their juvenile phase and assume their adult characters, mapping morphological markers and identification of quantitative trait loci for adaptive traits will be the primary targets.Key words: genome mapping, RAPD, SSR, SCAR, Olea europea, peacock disease resistance.

scholarly journals Development of Sequence Characterized Amplified Region Markers Linked to Downy Mildew Resistance in Broccoli

2002 ◽  
Vol 127 (4) ◽  
pp. 597-601 ◽  
Author(s):  
Janel L. Giovannelli ◽  
Mark W. Farnham ◽  
Min Wang ◽  
Allan E. Strand
Keyword(s):  
Downy Mildew ◽  
Genetic Markers ◽  
Resistance Genes ◽  
Rapd Markers ◽  
Dominant Gene ◽  
Screening Tools ◽  
Resistance Locus ◽  
Downy Mildew Resistance ◽  
Scar Markers ◽  
Mildew Resistance

Downy mildew, caused by the fungal parasite Peronospora parasitica (Pers.: Fr.) Fr., is a destructive disease of Brassica oleracea L. crops, including broccoli (B. oleracea, Italica Group). The development and deployment of downy mildew resistant broccoli cultivars is a priority for breeders and producers. Identification of genetic markers linked to downy mildew resistance genes should facilitate selection for resistance and pyramiding of resistance genes into cultivars. The objectives of this study were to 1) identify RAPD markers linked to a single dominant gene for resistance in broccoli, 2) clone and sequence the linked RAPD markers, and 3) develop and evaluate SCAR markers as screening tools for resistance. Bulked segregant analysis led to the identification of eight linked RAPD markers following a screen of 848 decamers. Two of the linked RAPD fragments, UBC359620 and OPM16750, were converted to dominant SCAR markers linked in coupling to the resistance locus at 6.7 and 3.3 cM, respectively. The SCAR marker based on UBC359620 sequence exhibited less accuracy (94%) than the original RAPD (96%) in differentiating resistant and susceptible plants, but the accuracy (97%) of the OPM16750-SCAR was not different than the original RAPD. These SCAR markers are among the first genetic markers found linked to a gene conferring cotyledon-stage downy mildew resistance in B. oleracea. Results of this work provide breeders with useful information and tools for the systematic development of resistant cultivars.

scholarly journals High resolution mapping and candidate gene identification of downy mildew race 16 resistance in spinach

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Gehendra Bhattarai ◽  
Wei Yang ◽  
Ainong Shi ◽  
Chunda Feng ◽  
Braham Dhillon ◽  
...  
Keyword(s):  
Candidate Genes ◽  
Downy Mildew ◽  
Association Analysis ◽  
Spinacia Oleracea ◽  
Genotyping By Sequencing ◽  
Significant Snps ◽  
Snp Markers ◽  
Resistance Locus ◽  
Downy Mildew Resistance ◽  
Mildew Resistance

Abstract Background Downy mildew, the most devastating disease of spinach (Spinacia oleracea L.), is caused by the oomycete Peronospora effusa [=P. farinosa f. sp. spinaciae]. The P. effusa shows race specificities to the resistant host and comprises 19 reported races and many novel isolates. Sixteen new P. effusa races were identified during the past three decades, and the new pathogen races are continually overcoming the genetic resistances used in commercial cultivars. A spinach breeding population derived from the cross between cultivars Whale and Lazio was inoculated with P. effusa race 16 in an environment-controlled facility; disease response was recorded and genotyped using genotyping by sequencing (GBS). The main objective of this study was to identify resistance-associated single nucleotide polymorphism (SNP) markers from the cultivar Whale against the P. effusa race 16. Results Association analysis conducted using GBS markers identified six significant SNPs (S3_658,306, S3_692697, S3_1050601, S3_1227787, S3_1227802, S3_1231197). The downy mildew resistance locus from cultivar Whale was mapped to a 0.57 Mb region on chromosome 3, including four disease resistance candidate genes (Spo12736, Spo12784, Spo12908, and Spo12821) within 2.69–11.28 Kb of the peak SNP. Conclusions Genomewide association analysis approach was used to map the P. effusa race 16 resistance loci and identify associated SNP markers and the candidate genes. The results from this study could be valuable in understanding the genetic basis of downy mildew resistance, and the SNP marker will be useful in spinach breeding to select resistant lines.

scholarly journals Citizen views on genome editing: effects of species and purpose

2021 ◽  
Author(s):  
Gesa Busch ◽  
Erin Ryan ◽  
Marina A. G. von Keyserlingk ◽  
Daniel M. Weary
Keyword(s):  
Disease Resistance ◽  
Product Quality ◽  
Genome Editing ◽  
Total Sample ◽  
Moral Foundations ◽  
Perceived Risks ◽  
Public Response ◽  
The Public ◽  
Wide Range ◽  
The Us

AbstractPublic opinion can affect the adoption of genome editing technologies. In food production, genome editing can be applied to a wide range of applications, in different species and with different purposes. This study analyzed how the public responds to five different applications of genome editing, varying the species involved and the proposed purpose of the modification. Three of the applications described the introduction of disease resistance within different species (human, plant, animal), and two targeted product quality and quantity in cattle. Online surveys in Canada, the US, Austria, Germany and Italy were carried out with a total sample size of 3698 participants. Using a between-subject design, participants were confronted with one of the five applications and asked to decide whether they considered it right or wrong. Perceived risks, benefits, and the perception of the technology as tampering with nature were surveyed and were complemented with socio-demographics and a measure of the participants’ moral foundations. In all countries, participants evaluated the application of disease resistance in humans as most right to do, followed by disease resistance in plants, and then in animals, and considered changes in product quality and quantity in cattle as least right to do. However, US and Italian participants were generally more positive toward all scenarios, and German and Austrian participants more negative. Cluster analyses identified four groups of participants: ‘strong supporters’ who saw only benefits and little risks, ‘slight supporters’ who perceived risks and valued benefits, ‘neutrals’ who showed no pronounced opinion, and ‘opponents’ who perceived higher risks and lower benefits. This research contributes to understanding public response to applications of genome editing, revealing differences that can help guide decisions related to adoption of these technologies.

scholarly journals QTL Mapping of Seedling and Adult Plant Resistance to Septoria Tritici Blotch in Winter Wheat cv. Mandub (Triticum aestivum L.)

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1108
Author(s):  
Dominika Piaskowska ◽  
Urszula Piechota ◽  
Magdalena Radecka-Janusik ◽  
Paweł Czembor
Keyword(s):  
Mapping Population ◽  
Triticum Aestivum L ◽  
Seedling Stage ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Adult Plant ◽  
Resistance Locus ◽  
Phenotypic Variance ◽  
Breeding Programs ◽  
Plant Stage

Septoria tritici blotch (STB) is one of the most devastating foliar diseases of wheat worldwide. Host resistance is the most economical and safest method of controlling the disease, and information on resistance loci is crucial for effective breeding for resistance programs. In this study we used a mapping population consisting of 126 doubled-haploid lines developed from a cross between the resistant cultivar Mandub and the susceptible cultivar Begra. Three monopycnidiospore isolates of Z. tritici with diverse pathogenicity were used to test the mapping population and parents’ STB resistance at the seedling stage (under a controlled environment) and adult plant stage (polytunnel). For both types of environments, the percentage leaf area covered by necrosis (NEC) and pycnidia (PYC) was determined. A linkage map comprising 5899 DArTSNP and silicoDArT markers was used for the quantitative trait loci (QTL) analysis. The analysis showed five resistance loci on chromosomes 1B, 2B and 5B, four of which were derived from cv. Mandub. The location of QTL detected in our study on chromosomes 1B and 5B may suggest a possible identity or close linkage with Stb2/Stb11/StbWW and Stb1 loci, respectively. QStb.ihar-2B.4 and QStb.ihar-2B.5 detected on chromosome 2B do not co-localize with any known Stb genes. QStb.ihar-2B.4 seems to be a new resistance locus with a moderate effect (explaining 29.3% of NEC and 31.4% of PYC), conferring resistance at the seedling stage. The phenotypic variance explained by QTL detected in cv. Mandub ranged from 11.9% to 70.0%, thus proving that it is a good STB resistance source and can potentially be utilized in breeding programs.

scholarly journals Селекция лука репчатого с устойчивостью к пероноспорозу

2019 ◽  
Author(s):  
G.F. Monakhos ◽  
S.G. Monakhos ◽  
R.R. Alizhanova
Keyword(s):  
Disease Resistance ◽  
Downy Mildew ◽  
Resistance Gene ◽  
Inbred Lines ◽  
F1 Hybrids ◽  
Downy Mildew Resistance ◽  
European Origin ◽  
Molecular Genotyping ◽  
Breeding Station ◽  
Selection Of

На Селекционной станции имени Н.Н. Тимофеева гибридизацией с донором устойчивости к пероноспорозу F1 Santero, беккроссом, инбридингом и отбором на инфекционном фоне с помощью молекулярного маркера DMR1 создано 15 линий лука репчатого гомозиготного по гену устойчивости Pd1. Оценка в однолетней культуре позволила выделить линии с массой луковиц 100120 г с высокой сохранностью, которые могут быть использованы в селекции F1 гибридов в качестве отцовских компонентов.Fifteen homozygous for Pd1 downy mildew resistance gene onion lines were developed by hybridization followed backcrossing F1 Santero of downy mildew resistant onion accession of European origin and a collection of onion inbred lines from LC Breeding station after N.N. Timofeev. The resistant to downy mildew, caused by Peronospora destructor (Berk.), plants were selected in segregated populations based on disease resistance test and molecular genotyping using DMR1marker. The lines with a mass of bulbs 100 120 g with high preservation, which can be used in the selection of F1 hybrids as paternal components.

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