The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Hartwig H. Geiger - One of the best experts on this subject based on the ideXlab platform.
-
Lack of Association between Fusarium Foot Rot and Head Blight Resistance in Winter Rye
Crop Science, 1997Co-Authors: Thomas Miedaner, G. Gang, Carsten Reinbrecht, Hartwig H. GeigerAbstract:Foot Rot and head blight caused by Fusarium culmorum (W.G. Sm.) Sacc. may lead to considerable loss of yield and grain quality in winter rye (Secale cereale L.). Breeding for resistance to the two diseases would be facilitated if the same resistance mechanisms were involved. The purpose of this study was to estimate the genetic correlation between the resistance to the two diseases in advanced winter rye breeding materials. Twenty self-fertile inbred lines were grown at two locations in South Germany in 1992, 1993, and 1994 (six environments). Lines were arranged in three adjacent treatment blocks: no inoculation, inoculation for Foot Rot, and inoculation for head blight. Disease severity was rated on a 1-to-9 scale for Foot Rot and head blight. Besides the Foot Rot and head blight rating scale, ELISA (enzyme-linked immunosorbent assay) was used to quantify the amount of Fusarium pRotein within stem issue from the Foot Rot treatment and relative grain weight was measured from the head blight treatment. In all but one environment, F. culmorum was re-isolated from diseased stems at high percentages (≥90%). Disease severity was moderate for Foot Rot and head blight rating at all environments. Mean ELISA absorbance was 0.55 and mean relative grain weight 77.4%. Significant genotypic variation existed for all resistance traits. Broad-sense heritabilities, calculated on an entry-mean basis, were high for Foot Rot and head blight rating (h 2 0.8) and somewhat lower for ELISA absorbance and relative grain weight (h 2 0.5-0.6). No significant correlation was found between the resistances to Foot Rot and head blight. This was confirmed by a highly significant (P = 0.01) genotype-plant organ interaction. Thus, resistance mechanisms most likely differ for the two diseases. Resistance selection requires separate multi-environmental screening tests for F. culmorum Foot Rot and head blight.
-
Genetic variation for Foot-Rot and Fusarium head-blight resistances among full-sib families of a self-incompatible winter rye (Secale cereale L.) population.
Theoretical and Applied Genetics, 1995Co-Authors: Thomas Miedaner, Franz Joachim Fromme, Hartwig H. GeigerAbstract:The amount of genetic variation for resistance to Foot Rot caused by Pseudocercosporella herpotrichoides, Fusarium spp., and Microdochium nivale and for resistance to head blight caused by Fusarium culmorum are important parameters when estimating selection gain from recurrent selection in winter rye. One-hundred and eighty-six full-sib families of the selfincompatible population variety Halo, representing the Petkus gene pool, were tested for Foot-Rot resistance at five German location-year combinations (environments) and for head-blight resistance in three environments with artificial inoculation in all but one environment. Foot-Rot rating was based on 25 stems per plot scored individually on a 1–9 scale. Head-blight resistance was plotwise scored on a 1–9 scale and, additionally, grain-weight per spike was measured relative to the non-inoculated control plots. Significant estimates of genotypic variance and medium-sized heritabilities (h2=0.51–0.69) were observed in the combined analyses for all resistance traits. In four out of five environments, the amount of genetic variance was substantially smaller for Foot-Rot than for head-blight rating. Considerable environmental effects and significant genotype-environment interactions were found for both Foot-Rot and head-blight resistance. Coefficients of error-corrected correlation among environments were considerably closer than phenotypic correlations. No significant association was found between the resistances to both diseases (r=-0.20 to 0.17). In conclusion, intra-population improvement by recurrent selection should lead to substantial higher Foot-Rot and head-blight resistances due to significant quantitative genetic variation within Halo. Selection should be carried out in several environments. Lack of correlation between Foot-Rot and head-blight resistance requires separate infection tests for improving both resistances.
-
Inheritance of Foot Rot resistance in winter rye
Crop Science, 1995Co-Authors: Thomas Miedaner, W. F. Ludwig, Hartwig H. GeigerAbstract:Foot Rot in winter rye (Secale cereale L.) caused by Pseudocercosporella herpotrichoides, Fusarium spp., and Microdochium nivale (syn Fusarium nivale) can be controlled best by host resistance. In this study, the inheritance of Foot Rot resistance was examined using 15 diallel and 11 factorial crosses tested along with their parent inbred lines. Four out of six test environments in southern Germany were artificially inoculated with either P. herpotrichoides, F. culmorum, or M. nivale. In the other two environments, naturally occuring field epidemics were used. At milk ripening, 50 stems per plot were rated individually for Foot Rot on a 1 to 9 scale. Significant estimates of genotypic variance and high heritabilities (h 2 =0.82-0.92) were observed in all genetic materials. General combining ability (GCA) was the main source of genetic variation among crosses, while specific combining ability was negligible. Considerable environmental effects and significant genotype×environment interactions were found. Strong phenotypic correlations (r0.9) existed between line per se performance and GCA effects. Heterosis was not important. For optimizing disease assessment, H 2 was estimated for varying numbers of stems, environments, and replicates. For inbred lines tested in two environments with two replicates or for single crosses tested in four environments with two replicates, a sample size of 15 plants per plot should result in a h 2 of about 0.7. In conclusion, substantial progress can be expected from selection for Foot Rot resistance in hybrid rye on the basis of line per se performance by rating unspecific Foot Rot lesions
-
Estimation of Genetic Parameters for Foot Rot Resistance in RYE (Secale cereale)
Durability of Disease Resistance, 1993Co-Authors: W. F. Ludwig, Thomas Miedaner, Hartwig H. GeigerAbstract:Foot Rot in rye is mainly caused by the fungi Pseudocercosporella herpotrichoides, Fusarium spp. and Microdochium nivale. Plants infected by these pathogens develop necRotic lesions at the culm base which can lead to preharvest lodging. Due to reduced water and nutrient transport in necRotic or lodged stems, the number of kernels per ear and the kernel weight are often reduced. Yield losses up to 30% have been reported (Meyer 1985). In previous studies considerable genetic variation for resistance to Foot Rot fungi was observed (Bojarczuk and Bojarczuk 1985). However, little is known about the genetic basis of resistance. The aim of the present study was to estimate genetic parameters important for the improvement of Foot Rot resistance.
Thomas Miedaner - One of the best experts on this subject based on the ideXlab platform.
-
Lack of Association between Fusarium Foot Rot and Head Blight Resistance in Winter Rye
Crop Science, 1997Co-Authors: Thomas Miedaner, G. Gang, Carsten Reinbrecht, Hartwig H. GeigerAbstract:Foot Rot and head blight caused by Fusarium culmorum (W.G. Sm.) Sacc. may lead to considerable loss of yield and grain quality in winter rye (Secale cereale L.). Breeding for resistance to the two diseases would be facilitated if the same resistance mechanisms were involved. The purpose of this study was to estimate the genetic correlation between the resistance to the two diseases in advanced winter rye breeding materials. Twenty self-fertile inbred lines were grown at two locations in South Germany in 1992, 1993, and 1994 (six environments). Lines were arranged in three adjacent treatment blocks: no inoculation, inoculation for Foot Rot, and inoculation for head blight. Disease severity was rated on a 1-to-9 scale for Foot Rot and head blight. Besides the Foot Rot and head blight rating scale, ELISA (enzyme-linked immunosorbent assay) was used to quantify the amount of Fusarium pRotein within stem issue from the Foot Rot treatment and relative grain weight was measured from the head blight treatment. In all but one environment, F. culmorum was re-isolated from diseased stems at high percentages (≥90%). Disease severity was moderate for Foot Rot and head blight rating at all environments. Mean ELISA absorbance was 0.55 and mean relative grain weight 77.4%. Significant genotypic variation existed for all resistance traits. Broad-sense heritabilities, calculated on an entry-mean basis, were high for Foot Rot and head blight rating (h 2 0.8) and somewhat lower for ELISA absorbance and relative grain weight (h 2 0.5-0.6). No significant correlation was found between the resistances to Foot Rot and head blight. This was confirmed by a highly significant (P = 0.01) genotype-plant organ interaction. Thus, resistance mechanisms most likely differ for the two diseases. Resistance selection requires separate multi-environmental screening tests for F. culmorum Foot Rot and head blight.
-
Genetic variation for Foot-Rot and Fusarium head-blight resistances among full-sib families of a self-incompatible winter rye (Secale cereale L.) population.
Theoretical and Applied Genetics, 1995Co-Authors: Thomas Miedaner, Franz Joachim Fromme, Hartwig H. GeigerAbstract:The amount of genetic variation for resistance to Foot Rot caused by Pseudocercosporella herpotrichoides, Fusarium spp., and Microdochium nivale and for resistance to head blight caused by Fusarium culmorum are important parameters when estimating selection gain from recurrent selection in winter rye. One-hundred and eighty-six full-sib families of the selfincompatible population variety Halo, representing the Petkus gene pool, were tested for Foot-Rot resistance at five German location-year combinations (environments) and for head-blight resistance in three environments with artificial inoculation in all but one environment. Foot-Rot rating was based on 25 stems per plot scored individually on a 1–9 scale. Head-blight resistance was plotwise scored on a 1–9 scale and, additionally, grain-weight per spike was measured relative to the non-inoculated control plots. Significant estimates of genotypic variance and medium-sized heritabilities (h2=0.51–0.69) were observed in the combined analyses for all resistance traits. In four out of five environments, the amount of genetic variance was substantially smaller for Foot-Rot than for head-blight rating. Considerable environmental effects and significant genotype-environment interactions were found for both Foot-Rot and head-blight resistance. Coefficients of error-corrected correlation among environments were considerably closer than phenotypic correlations. No significant association was found between the resistances to both diseases (r=-0.20 to 0.17). In conclusion, intra-population improvement by recurrent selection should lead to substantial higher Foot-Rot and head-blight resistances due to significant quantitative genetic variation within Halo. Selection should be carried out in several environments. Lack of correlation between Foot-Rot and head-blight resistance requires separate infection tests for improving both resistances.
-
Inheritance of Foot Rot resistance in winter rye
Crop Science, 1995Co-Authors: Thomas Miedaner, W. F. Ludwig, Hartwig H. GeigerAbstract:Foot Rot in winter rye (Secale cereale L.) caused by Pseudocercosporella herpotrichoides, Fusarium spp., and Microdochium nivale (syn Fusarium nivale) can be controlled best by host resistance. In this study, the inheritance of Foot Rot resistance was examined using 15 diallel and 11 factorial crosses tested along with their parent inbred lines. Four out of six test environments in southern Germany were artificially inoculated with either P. herpotrichoides, F. culmorum, or M. nivale. In the other two environments, naturally occuring field epidemics were used. At milk ripening, 50 stems per plot were rated individually for Foot Rot on a 1 to 9 scale. Significant estimates of genotypic variance and high heritabilities (h 2 =0.82-0.92) were observed in all genetic materials. General combining ability (GCA) was the main source of genetic variation among crosses, while specific combining ability was negligible. Considerable environmental effects and significant genotype×environment interactions were found. Strong phenotypic correlations (r0.9) existed between line per se performance and GCA effects. Heterosis was not important. For optimizing disease assessment, H 2 was estimated for varying numbers of stems, environments, and replicates. For inbred lines tested in two environments with two replicates or for single crosses tested in four environments with two replicates, a sample size of 15 plants per plot should result in a h 2 of about 0.7. In conclusion, substantial progress can be expected from selection for Foot Rot resistance in hybrid rye on the basis of line per se performance by rating unspecific Foot Rot lesions
-
Estimation of Genetic Parameters for Foot Rot Resistance in RYE (Secale cereale)
Durability of Disease Resistance, 1993Co-Authors: W. F. Ludwig, Thomas Miedaner, Hartwig H. GeigerAbstract:Foot Rot in rye is mainly caused by the fungi Pseudocercosporella herpotrichoides, Fusarium spp. and Microdochium nivale. Plants infected by these pathogens develop necRotic lesions at the culm base which can lead to preharvest lodging. Due to reduced water and nutrient transport in necRotic or lodged stems, the number of kernels per ear and the kernel weight are often reduced. Yield losses up to 30% have been reported (Meyer 1985). In previous studies considerable genetic variation for resistance to Foot Rot fungi was observed (Bojarczuk and Bojarczuk 1985). However, little is known about the genetic basis of resistance. The aim of the present study was to estimate genetic parameters important for the improvement of Foot Rot resistance.
Jacqueline D Hunt - One of the best experts on this subject based on the ideXlab platform.
-
antigenic competition in a multivalent Foot Rot vaccine
Vaccine, 1994Co-Authors: David C Jackson, Jacqueline D Hunt, Lorena E Brown, P R Wood, D J StewartAbstract:The antigenic competition that occurs when pilus antigens of different serogroups are combined in multivalent vaccines for Foot Rot has been investigated using recombinant pilus antigens. Our pRototype vaccine contains pili from nine serogroups of Dichelobacter nodosus which are expressed in Pseudomonas aeruginosa. Sheep inoculated with this multivalent vaccine were not as well pRotected against Foot Rot as those given the monovalent vaccine. Levels of agglutinating and total antibody specific for any particular pili serogroup were found to be significantly reduced in sheep vaccinated with six or more closely related pili. This effect was more pronounced for agglutinating antibody, which is thought to mediate pRotection, but was also observed with total antibody levels measured by ELISA. The antigenic competition was not associated with the total antigen load as a tenfold higher dose of monovalent pili induced high titres of antibody. Furthermore, distributing the vaccine to four sites, each draining to a different lymph node, failed to overcome the competition. Experiments with mixtures of monospecific sera indicate that the phenomenon is unlikely to be due to blocking of serogroup-specific pRotective antibodies by an excess of cross-reactive non-pRotective antibody elicited by heterologous pili.
F. Prieto Montana - One of the best experts on this subject based on the ideXlab platform.
-
Technical Note Failure of oral zinc supplementation to control ovine Foot Rot
1999Co-Authors: J. Rejas Lopez, J. R. González Montaña, A. J. Alonso Diez, F. Prieto MontanaAbstract:The efficacy of oral zinc supplementation on ovine Foot Rot was studied. The severity of Foot Rot lesions in animals receiving 2g SO 4Zn7H2O twice weekly during 4 months was not different from control animals receiving no zinc supplementation. Serum zinc levels were not influenced by zinc treatment. Serum zinc concentrations were within normal range (greater than 12.2 mmol/l) in treated and control group ewes at the beginning of the trial and remained so throughout the experiment. It is concluded that the therapeutic effect of zinc on Foot Rot may be related to a pre-existing condition of zinc deficiency and that animal with normal zinc levels are non-responsive to zinc supplementation. # 1999 Elsevier Science B.V. All rights reserved.
-
Failure of oral zinc supplementation to control ovine Foot Rot
Small Ruminant Research, 1999Co-Authors: J. Rejas Lopez, J. R. González Montaña, A. J. Alonso Diez, F. Prieto MontanaAbstract:Abstract The efficacy of oral zinc supplementation on ovine Foot Rot was studied. The severity of Foot Rot lesions in animals receiving 2 g SO 4 Zn·7H 2 O twice weekly during 4 months was not different from control animals receiving no zinc supplementation. Serum zinc levels were not influenced by zinc treatment. Serum zinc concentrations were within normal range (greater than 12.2 μmol/l) in treated and control group ewes at the beginning of the trial and remained so throughout the experiment. It is concluded that the therapeutic effect of zinc on Foot Rot may be related to a pre-existing condition of zinc deficiency and that animal with normal zinc levels are non-responsive to zinc supplementation.
D J Stewart - One of the best experts on this subject based on the ideXlab platform.
-
antigenic competition in a multivalent Foot Rot vaccine
Vaccine, 1994Co-Authors: David C Jackson, Jacqueline D Hunt, Lorena E Brown, P R Wood, D J StewartAbstract:The antigenic competition that occurs when pilus antigens of different serogroups are combined in multivalent vaccines for Foot Rot has been investigated using recombinant pilus antigens. Our pRototype vaccine contains pili from nine serogroups of Dichelobacter nodosus which are expressed in Pseudomonas aeruginosa. Sheep inoculated with this multivalent vaccine were not as well pRotected against Foot Rot as those given the monovalent vaccine. Levels of agglutinating and total antibody specific for any particular pili serogroup were found to be significantly reduced in sheep vaccinated with six or more closely related pili. This effect was more pronounced for agglutinating antibody, which is thought to mediate pRotection, but was also observed with total antibody levels measured by ELISA. The antigenic competition was not associated with the total antigen load as a tenfold higher dose of monovalent pili induced high titres of antibody. Furthermore, distributing the vaccine to four sites, each draining to a different lymph node, failed to overcome the competition. Experiments with mixtures of monospecific sera indicate that the phenomenon is unlikely to be due to blocking of serogroup-specific pRotective antibodies by an excess of cross-reactive non-pRotective antibody elicited by heterologous pili.