scholarly journals Plant Genetic Background Increasing the Efficiency and Durability of Major Resistance Genes to Root-knot Nematodes Can Be Resolved into a Few Resistance QTLs

2016 ◽  
Vol 7 ◽  
Author(s):  
Arnaud Barbary ◽  
Caroline Djian-Caporalino ◽  
Nathalie Marteu ◽  
Ariane Fazari ◽  
Bernard Caromel ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Genetic Background ◽  
Resistance Qtls ◽  
Root Knot Nematodes ◽  
Major Resistance Genes

THE PRODUCTION OF A DDT-RESISTANT STRAIN OF AEDES AEGYPTI MARKED ON ALL THREE LINKAGE GROUPS

1974 ◽  
Vol 16 (4) ◽  
pp. 883-888 ◽  
Author(s):  
J. P. Margham ◽  
R. J. Wood
Keyword(s):  
Aedes Aegypti ◽  
Resistance Genes ◽  
Resistant Strain ◽  
Genetic Background ◽  
Adult Stage ◽  
Susceptible Strain ◽  
Linkage Studies ◽  
Linkage Groups ◽  
Resistant Strains ◽  
Major Resistance Genes

DDT-resistant strains marked on all three linkage groups have been produced by selection at the adult stage after outcrossing a resistant strain (BANGKOK-HR) to a marked susceptible strain (64). The most resistant and viable line (BANGKOK-MR) was kept for linkage studies. The production of a marked resistant strain was not entirely straightforward. In the absence of a suitable genetic background, major resistance genes conferred little or no DDT tolerance and could not be selected. Selection at the adult stage produced resistance in larvae as well as in adults. Resistance was achieved more rapidly in larvae than in adults

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

1999 ◽  
Vol 89 (11) ◽  
pp. 1066-1072 ◽  
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.

A set of near-isogenic lines for blast resistance genes with an Indica-type rainfed lowland elite rice (Oryza sativa L.) genetic background

2011 ◽  
Vol 123 (1) ◽  
pp. 19-27 ◽  
Author(s):  
Yohei Koide ◽  
Leodegario A. Ebron ◽  
Hiroshi Kato ◽  
Hiroshi Tsunematsu ◽  
Mary Jeanie Telebanco-Yanoria ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Resistance Genes ◽  
Genetic Background ◽  
Oryza Sativa L ◽  
Blast Resistance ◽  
Near Isogenic Lines ◽  
Isogenic Lines ◽  
Rainfed Lowland ◽  
Blast Resistance Genes

Phytophthora sojae pathotype distribution and fungicide sensitivity in Michigan

Plant Disease ◽  
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.

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

2011 ◽  
Vol 59 (3) ◽  
pp. 241-248 ◽  
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.

scholarly journals Mating type, mefenoxam sensitivity, and pathotype diversity in Phytophthora infestans isolates from tomato in Brazil

2010 ◽  
Vol 45 (7) ◽  
pp. 671-679 ◽  
Author(s):  
Bruno Eduardo Cardozo de Miranda ◽  
Nelson Dias Suassuna ◽  
Ailton Reis
Keyword(s):  
Phytophthora Infestans ◽  
Mating Type ◽  
Resistance Genes ◽  
Virulence Genes ◽  
Average Frequency ◽  
Breeding Programs ◽  
Low Frequencies ◽  
Distrito Federal ◽  
Tomato Breeding ◽  
Major Resistance Genes

The objective of this work was to characterize 79 Phytophthora infestans isolates collected in tomato (Solanum lycopersicum) fields, as to mating type, mefenoxam sensitivity, and pathotype composition. The isolates were sampled in 2006 and 2007 in seven Brazilian states as well as in the Distrito Federal. They were characterised as to mating type (n=79), sensitivity to fungicide mefenoxam (n=79), and virulence to three major resistance genes Ph-1, Ph-2, and Ph-3/Ph-4 (n=62). All isolates were of the mating type A1. Resistant isolates were detected in all sampled states, and its average frequency was superior to 50%. No difference was detected in pathotype diversity, neither between subpopulations collected in 2006 and 2007 nor between isolates grouped as resistant or intermediately sensitive to mefenoxam. All major resistance genes were overcome at different frequencies: Ph-1, 88.7%; Ph-2, 64.5%; and Ph-3/Ph-4, 25.8%. Isolates with virulence genes able to overcome all major resistance genes were detected at low frequencies. Tomato breeding programs in Brazil must avoid the development of cultivars with resistance based exclusively on major genes.

scholarly journals Response of Bell Pepper Cultivars to Bacterial Spot Pathogen Races that Individually Overcome Major Resistance Genes

Plant Disease ◽  
1998 ◽  
Vol 82 (2) ◽  
pp. 181-186 ◽  
Author(s):  
C. S. Kousik ◽  
D. F. Ritchie
Keyword(s):  
Resistance Genes ◽  
Xanthomonas Campestris ◽  
Field Experiments ◽  
King Arthur ◽  
Bacterial Spot ◽  
Initial Inoculum ◽  
Bell Peppers ◽  
Or Gene ◽  
Major Resistance Genes ◽  
Significant Disease

The effect of major resistance genes (Bs1, Bs2, and Bs3) or gene combinations for resistance to bacterial spot of bell peppers (Xanthomonas campestris pv. vesicatoria) in 15 commercial cultivars on disease reduction and yield were studied during 1995 and 1996. Reaction of cultivars to specific races (races 1, 2, or 3) of the pathogen corresponded with seed company claims for resistance against these races. Races 1 to 4 were used as initial inoculum in 1995, and races 1 to 6 in 1996 field experiments. Cultivars with no known resistance genes to bacterial spot (e.g., Camelot, Jupiter, and Valiant), a single resistance gene (X3R Camelot, King Arthur), or a combination of Bs1 and Bs3 genes (Guardian, Sentinel, and Admiral) were severely diseased. Yields were reduced in all inoculated cultivars compared to non-inoculated cultivars used as controls. Although races 4 and 6 caused significant disease in cultivars with only Bs1 (King Arthur) or Bs2 (X3R Camelot) genes, cultivars with a combination of Bs1 and Bs2 (Boynton Bell, PR9300-8) had much lower levels of bacterial spot. Roger 4178, a hybrid with a combination of Bs1, Bs2, and Bs3 genes, had the lowest disease ratings. Overall, race 3 was predominant during 1995, while races 3 and 6 were recovered most frequently in 1996.

scholarly journals First Report on Pathogenic Variability of Different Isolates of Diaporthe phaseolorum var. meridionalis on Soybean in Argentina

Plant Disease ◽  
1999 ◽  
Vol 83 (11) ◽  
pp. 1071-1071 ◽  
Author(s):  
R. N. Pioli ◽  
E. N. Morandi ◽  
C. O. Gosparini ◽  
A. L. Borghi
Keyword(s):  
Resistance Genes ◽  
Stem Canker ◽  
Growing Seasons ◽  
Diaporthe Phaseolorum ◽  
Glycine Max L ◽  
Glucose Agar ◽  
Soybean Plants ◽  
Pathogenic Variability ◽  
Major Resistance Genes ◽  
Phomopsis Phaseoli

The objective of this study was to characterize the pathogenicity of several local isolates of Diaporthe phaseolorum (Cooke & Ellis) Sacc. var. meridionalis Fernández and its anamorph, Phomopsis phaseoli (Desmaz.) Sacc. meridionalis Morgan-Jones, the causal agent of southern stem canker of soybean (Glycine max (L.) Merr.), in soybean lines carrying major resistance genes. Soybean plants with typical stem canker symptoms were collected during the 1996 to 1997 and 1997 to 1998 growing seasons in the central and southern areas of Santa Fe Province, Argentina. The pathogen was isolated from the internal tissues of infected stems, cultured on potato glucose agar acidified with 0.2% lactic acid (APGA), amended with streptomycin at 100 mg/liter, and maintained in the dark at 25 ± 1°C. Isolates were characterized based on the morphology of colonies, perithecia, and pycnidia and measurement of asci, bicellular, biguttulate ascospores, and alpha conidia (1). Soybean cultivars used to assay pathogenicity included Tracy M (Rdc1 and Rdc2 genes), Isoline I (Tracy Misoline with only the Rdc1 gene), Isoline II (Tracy M isoline with only the Rdc2 gene), Crockett (Rdc3 gene), Hutchinson (Rdc4 gene), and RA 702 (susceptible cultivar). Hypocotyls of 14-day-old seedlings grown in the greenhouse were inoculated by the toothpick method. Four replicates of nine seedlings each were used. Seedlings punctured with sterile toothpicks served as controls. The experiment was repeated twice with similar results. The D. phaseolorum var. meridionalis isolates assayed and their collection locations were Dpm1 (Malabrigo), Dpm2 (Los Molinos), Dpm3 (San Justo), Dpm5 (Oliveros), Dpm6 (San Jerónimo), and Dpm7 (Clarke). Twenty-eight days after inoculation, stem canker reactions were measured as the percentage of dead plants. The pathogen was reisolated from stems of randomly chosen symptomatic plants on day 14 after inoculation. These plants were included in the calculation of the percentage of dead plants. In control plants, lesions were not detected, and mycelial growth did not occur from stem portions plated on APGA. Tracy M and RA 702 had 0 to 7% dead plants and 70 to 95% dead plants, respectively, with all assayed isolates. Cultivars with single resistance genes reacted differently to various isolates. Isolates Dpm1 and Dpm3 caused little or no stem canker (<10% dead plants) on all cultivars with resistance genes. Isolates Dpm2 and Dpm6 killed 56 and 52%, respectively, of Isoline II (Rdc2 gene) plants. Isolates Dpm2 and Dpm7 killed 25% of cv. Hutchinson (Rdc4 gene) and Isoline I (Rdc1 gene) plants, respectively. Isolate Dpm5 killed <12% of plants with genes Rdc1, Rdc2, or Rdc3. The reaction of isolate Dpm5 with Hutchinson (Rdc4 gene) was not evaluated. The pathogenic diversity of these isolates of D. phaseolorum var. meridionalis may have been induced by the wide diffusion of resistant host cultivars (2). References: (1) F. A. Fernández and R. T. Hanlin. Mycologia 88:425, 1996. (2) A. W. Zhang et al. Phytopathology 88:1306, 1998.

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