Consensus mapping of major resistance genes and independent QTL for quantitative resistance to sunflower downy mildew

Abstract Key message Eleven new major resistance genes for lettuce downy mildew were introgressed from wild Lactuca species and mapped to small regions in the lettuce genome. Abstract Downy mildew, caused by the oomycete pathogen Bremia lactucae Regel, is the most important disease of lettuce (Lactuca sativa L.). The most effective method to control this disease is by using resistant cultivars expressing dominant resistance genes (Dm genes). In order to counter changes in pathogen virulence, multiple resistance genes have been introgressed from wild species by repeated backcrosses to cultivated lettuce, resulting in numerous near-isogenic lines (NILs) only differing for small chromosome regions that are associated with resistance. Low-pass, whole genome sequencing of 11 NILs was used to identify the chromosome segments introgressed from the wild donor species. This located the candidate chromosomal positions for resistance genes as well as additional segments. F2 segregating populations derived from these NILs were used to genetically map the resistance genes to one or two loci in the lettuce reference genome. Precise knowledge of the location of new Dm genes provides the foundation for marker-assisted selection to breed cultivars with multiple genes for resistance to downy mildew.

Download Full-text

Development of Bacterial Spot on Near-Isogenic Lines of Bell Pepper Carrying Gene Pyramids Composed of Defeated Major Resistance Genes

Phytopathology ◽

10.1094/phyto.1999.89.11.1066 ◽

1999 ◽

Vol 89 (11) ◽

pp. 1066-1072 ◽

Cited By ~ 18

Author(s):

C. S. Kousik ◽

D. F. Ritchie

Keyword(s):

Disease Severity ◽

Resistance Genes ◽

Field Studies ◽

Residual Effects ◽

Specific Gene ◽

Near Isogenic Lines ◽

Bacterial Spot ◽

Isogenic Lines ◽

Major Resistance Genes ◽

Race 4

Disease severity caused by races 1 through 6 of Xanthomonas campestris pv. vesicatoria on eight near-isogenic lines (isolines) of Early Calwonder (ECW) with three major resistance genes (Bs1, Bs2, and Bs3) in different combinations was evaluated in the greenhouse and field. Strains representing races 1, 3, 4, and 6 caused similar high levels of disease severity, followed by races 2 and 5 on susceptible ECW. Race 3 caused severe disease on all isolines lacking resistance gene Bs2. Race 4, which defeats Bs1 and Bs2, caused less disease on isoline ECW-12R (carries Bs1 + Bs2), than on isolines ECW, ECW-10R (carries Bs1), and ECW-20R (carries Bs2). Similar results were obtained with race 4 strains in field studies conducted during 1997 and 1998. In greenhouse studies, race 6, which defeats all three major genes, caused less disease on isoline ECW-13R (carries Bs1 + Bs3) and ECW-123R (carries Bs1 + Bs2 + Bs3) than on isolines ECW, ECW-10R, ECW-20R, and ECW-30R (carries Bs3), but not on ECW-23R (carries Bs2 + Bs3). In greenhouse studies with commercial hybrids, strains of races 4 and 6 caused less disease on Boynton Bell (carries Bs1 + Bs2) than on Camelot (carries no known resistance genes), King Arthur (carries Bs1), and X3R Camelot (carries Bs2). Race 6 caused less disease on hybrid R6015 (carries Bs1 + Bs2 + Bs3) and Sentinel (carries Bs1 + Bs3) than on Camelot. Residual effects were not as evident in field studies with race 6 strains. Defeated major resistance genes deployed in specific gene combinations (i.e., gene pyramids) were associated with less area under the disease progress curve than when genes were deployed individually in isolines of ECW or commercial hybrids. Successful management of bacterial spot of pepper is achieved incrementally by integrating multiple tactics. Although there is evidence of residual effects from defeated genes, these effects alone likely will not provide acceptable bacterial spot control in commercial production fields. However, when combined with sanitation practices and a judicious spray program, pyramids of defeated resistance genes may aid in reducing the risk of major losses due to bacterial spot.

Download Full-text

Corrigendum to: Integrated transcriptomics and metabolomics reveal induction of hierarchies of resistance genes in potato against late blight

Functional Plant Biology ◽

10.1071/fp16028_co ◽

2016 ◽

Vol 43 (12) ◽

pp. 1205 ◽

Cited By ~ 1

Author(s):

Kalenahalli N. Yogendra ◽

Ajjamada C. Kushalappa

Keyword(s):

Late Blight ◽

Resistance Genes ◽

Quantitative Resistance ◽

Potato Production ◽

Metabolic Reprogramming ◽

Specific Gene ◽

Molecular Events ◽

Pathway Regulation ◽

Molecular And Biochemical Mechanisms ◽

Resistant Genotypes

Late blight caused by Phytophthora infestans is a devastating disease affecting potato production worldwide. The quantitative resistance is durable, but the underlying molecular and biochemical mechanisms are poorly understood, limiting its application in breeding. Integrated transcriptomics and metabolomics approach was used for the first time to study the hierarchies of molecular events occurring, following inoculation of resistant and susceptible potato genotypes with P. infestans. RNA sequencing revealed a total of 4216 genes that were differentially expressed in the resistant than in the susceptible genotype. Genes that were highly expressed and associated with their biosynthetic metabolites that were highly accumulated, through metabolic pathway regulation, were selected. Quantitative real-time PCR was performed to confirm the RNA-seq expression levels. The induced leucine-rich repeat receptor-like kinases (LRR-RLKs) are considered to be involved in pathogen recognition. These receptor genes are considered to trigger downstream oxidative burst, phytohormone signalling-related genes, and transcription factors that regulated the resistance genes to produce resistance related metabolites to suppress the pathogen infection. It was noted that several resistance genes in metabolic pathways related to phenylpropanoids, flavonoids, alkaloids and terpenoid biosynthesis were strongly induced in the resistant genotypes. The pathway specific gene induction provided key insights into the metabolic reprogramming of induced defence responses in resistant genotypes.

Download Full-text

Mapping of Resistance Genes to Brown Planthopper in Untup Rajab, an Indonesian Local Rice Variety

Jurnal AgroBiogen ◽

10.21082/jbio.v14n2.2018.p75-84 ◽

2018 ◽

Vol 14 (2) ◽

pp. 75

Author(s):

Muhamad Yunus ◽

Diani Damayanti ◽

Ahmad Dadang ◽

Ahmad Warsun ◽

Dani Satyawan ◽

...

Keyword(s):

Resistance Genes ◽

Quantitative Resistance ◽

Insect Pest ◽

Rice Variety ◽

Brown Planthopper ◽

Snp Markers ◽

Chromosome 8 ◽

F2 Population ◽

Resistant Varieties ◽

Test Population

<p>Brown planthopper (BPH) is a major rice pest in Indonesia. The most economical and effective approach to control the insect pest is by using resistant varieties. Exploring for resistance genes is, therefore, a prerequisite for effective breeding program for BPH resistance. This study aimed to map BPH resistance genes in Untup Rajab, an Indonesian local rice variety. Genetic map was constructed using an F2 population from a cross between TN-1 and Untup Rajab, and SNP markers from RiceLD SNP Chip. Phenotyping was performed using bulk seedling test on F2:3 seedlings against two BPH populations, i.e. X1 and S1. Four QTLs<br />were identified on chromosomes 5, 6, 8, and 11 with PVE values of 7.63%, 9.40%, 17.66%, and 3.05%, respectively. Relatively normal distribution of resistance phenotype and the relatively low PVE values indicate that Untup Rajab has a quantitative resistance to BPH with two different resistance loci identified for each BPH test population. The QTL on chromosome 8 overlaps with OsHI-LOX gene, which is associated with resistance to BPH, and adjacent to another QTL for resistance to green leafhopper. The QTL on chromosome 6 was found near OsPLDα4 and OsPLDα5 genes which are related to BPH resistance. Meanwhile, the QTL intervals on chromosome 5 and 11 did not overlap with any known BPH QTLs or genes, which make them attractive candidates for novel BPH resistance gene discovery.</p>

Download Full-text

Colocation of downy mildew (Plasmopara halstedii) resistance genes in sunflower (Helianthus annuus L.)

Euphytica ◽

10.1007/bf00021074 ◽

1996 ◽

Vol 91 (2) ◽

pp. 225-228 ◽

Cited By ~ 2

Author(s):

Patricia Roeckel-Drevet ◽

Geneviève Gagne ◽

Said Mouzeyar ◽

Laurent Gentzbittel ◽

Jacqueline Philippon ◽

...

Keyword(s):

Helianthus Annuus ◽

Downy Mildew ◽

Resistance Genes ◽

Plasmopara Halstedii ◽

Helianthus Annuus L

Download Full-text

Phytophthora sojae pathotype distribution and fungicide sensitivity in Michigan

Plant Disease ◽

10.1094/pdis-03-21-0443-re ◽

2021 ◽

Author(s):

Austin Glenn McCoy ◽

Zachary Albert Noel ◽

Janette L Jacobs ◽

Kayla M Clouse ◽

Martin I Chilvers

Keyword(s):

Resistance Genes ◽

Phytophthora Sojae ◽

Significant Shift ◽

Seed Treatments ◽

Fungicide Sensitivity ◽

History Of ◽

Plant Stand ◽

Rps Gene ◽

Major Resistance Genes ◽

Pathogen Populations

Identifying the pathotype structure of a Phytophthora sojae population is crucial for the effective management of Phytophthora stem and root rot of soybean (PRR). P. sojae has been successfully managed with major resistance genes, partial resistance, and fungicide seed treatments. However, prolonged use of resistance genes or fungicides can cause pathogen populations to adapt over time, rendering resistance genes or fungicides ineffective. A statewide survey was conducted to characterize the current pathotype structure and fungicide sensitivity of P. sojae within Michigan. Soil samples were collected from 69 fields with a history of PRR and fields having consistent plant stand establishment issues. Eighty-three isolates of P. sojae were obtained, and hypocotyl inoculations were performed on 14 differential soybean cultivars, all of which carry a single Rps gene or no resistance gene. The survey identified a loss of effectiveness of Rps genes 1b, 1k, 3b and 6, compared to a previous survey conducted in Michigan from 1993-1997. Three effective resistance genes were identified for P. sojae management in Michigan; Rps 3a, 3c, and 4. Additionally, the effective concentration of common seed treatment fungicides to inhibit mycelial growth by 50% (EC50) was determined. No P. sojae isolates were insensitive to the tested chemistries with mean EC50 values of 2.60x10-2 µg/ml for ethaboxam, 3.03x10-2 µg/ml for mefenoxam, 2.88x10-4 µg/ml for oxathiapiprolin, and 5.08x10-2 µg/ml for pyraclostrobin. Results suggest that while there has been a significant shift in Rps gene effectiveness, seed treatments are still effective for early season management of this disease.

Download Full-text

Effectiveness of major resistance genes and identification of new sources for disease resistance in wheat

Acta Agronomica Hungarica ◽

10.1556/aagr.59.2011.3.7 ◽

2011 ◽

Vol 59 (3) ◽

pp. 241-248 ◽

Cited By ~ 2

Author(s):

G. Vida ◽

M. Cséplő ◽

G. Gulyás ◽

I. Karsai ◽

T. Kiss ◽

...

Keyword(s):

Disease Resistance ◽

Powdery Mildew ◽

Leaf Rust ◽

Resistance Genes ◽

Rust Resistance ◽

Genetic Material ◽

Leaf Rust Resistance ◽

Wheat Varieties ◽

Major Resistance Genes ◽

Greenhouse Tests

Among the factors which determine yield reliability an important role is played by disease resistance. One of the breeding aims in the Martonvásár institute is to develop wheat varieties with resistance to major diseases. The winter wheat varieties bred in Martonvásár are examined in artificially inoculated nurseries and greenhouses for resistance to economically important pathogens. The effectiveness of designated genes for resistance to powdery mildew and leaf rust has been monitored over a period of several decades. None of the designated major resistance genes examined in greenhouse tests is able to provide complete resistance to powdery mildew; however, a number of leaf rust resistance genes provide full protection against pathogen attack (Lr9, Lr19, Lr24, Lr25, Lr28 and Lr35). In the course of marker-assisted selection, efficient resistance genes (Lr9, Lr24, Lr25 and Lr29) have been incorporated into Martonvásár wheat varieties. The presence of Lr1, Lr10, Lr26, Lr34 and Lr37 in the Martonvásár gene pool was identified using molecular markers. New sources carrying alien genetic material have been tested for powdery mildew and leaf rust resistance. Valuable Fusarium head blight resistance sources have been identified in populations of old Hungarian wheat varieties. Species causing leaf spots (Pyrenophora tritici-repentis, Septoria tritici and Stagonospora nodorum) have gradually become more frequent over the last two decades. Tests on the resistance of the host plant were begun in Martonvásár four years ago and regular greenhouse tests on seedlings have also been initiated.

Download Full-text

Validation of Microsatellite Markers of Pl Resistance Genes to Downy Mildew of Sunflower

Helia ◽

10.1515/helia-2017-0026 ◽

2018 ◽

Vol 41 (68) ◽

pp. 73-82

Author(s):

A. Solodenko

Keyword(s):

Downy Mildew ◽

Ssr Markers ◽

Resistance Genes ◽

Microsatellite Loci ◽

Marker Assisted Selection ◽

Parental Line ◽

Gene Control ◽

Genetically Determined ◽

Ssr Polymorphism ◽

Simple Sequence

AbstractSimple sequence repeats (SSR) polymorphism of 34 microsatellite loci (LG1, 8 and 13) was studied in lines carrying the downy mildew resistance genes Pl and lines with no Pl. The microsatellite loci ORS328 and ORS781 were selected as markers for genes Pl6 and Pl8 in lines HA 335 and QHP-1, respectively. Markers were identified for gene PlARG in RHA 419 and some accessions of H. argophyllus. The SSR markers ORS509, ORS605, ORS610, ORS1182 and ORS1039 were proven to reliably identify the parental line carrying PlARG gene, control and select the heterozygous F1 hybrids and identify homozygous genotypes in F2 generations. Obtained results indicate the necessity of validation of the markers in various germplasm pools and breeding collections. The SSR markers that are tightly linked to Pl6, Pl8, PlARG would be useful in the sunflower breeding. PlARG homozygous F2 segregants, developed and identified with marker assisted selection in this study, are recommended for further breeding as a new source of genetically determined resistance to downy mildew.

Download Full-text