No description available.

No description available.

An evaluation of nineteen barley lines using three artificial inoculation methods concluded that spray inoculation was the most reproducible method and provided the greatest discrimination of resistance. Six of the nineteen barley lines were used for proteomic studies to identify defense responses following F. graminearum infection. All lines responded by inducing an oxidative burst and pathogenesis-related proteins. Differences in response magnitude and the proteins activated could be attributed to varying levels of FHB resistance amongst the barley lines. RNA microarray profiling and iTRAQ technology were used to study the interaction between two barley lines under five different treatments testing the effect of the fungus, trichothecene, and their interaction. Resistance was differentiated by the early induction of defense-related genes and the activation of the JA and ethylene defense pathways in Chevron, compared to the induction of a less efficient defense pathway in Stander; observed intra- and inter-cultivar differential responses are discussed. / xvii, 196 leaves : ill. ; 29 cm.

During the summer 1988 and 1989, surveys were conducted on the muck soils, South of Montreal to estimate the prevalence and incidence of the carrot diseases. Cercospora blight was the most prevalent disease; 91% and 96% of the fields and 99% and 92% of the plants sampled were diseased in 1988 and 1989, respectively. In decreasing order of occurrence the diseases present were: Crown gall, Alternaria blight, Root Knot, Sclerotinia rot and Aster yellows. / Greenhouse and field studies were carried out to evaluate partial resistance to Cercospora blight in 111 carrot cultivars based on the mean incubation period (MIP), the proportion of leaf area diseased (PLAD), and the sporulation / mm$ sp2$ lesion area (SPO). Significant differences among varieties were observed for all the parameters studied under greenhouse conditions and a significant negative correlation was found between PLAD and MIP (r = $-$0.29). Resistance equivalents were calculated for the PLAD, as proportions of the cultivar Dagger, so that they could be incorporated in a fundamental forecast model.

Nineteen cultivars and fourteen breeding lines were evaluated for partial resistance to crown rust Puccinia coronata race 264. Multivariate statistical methods such as principal component and cluster analyses were employed to identify significant resistance parameters and to group oat genotypes with similar rust resistance characteristics. This involved two separate investigations consisting of two experiments each, the first experiment conducted under field conditions and the second conducted under growth bench conditions. From both of the investigations a group of oat genotypes with high partial resistance to P. coronata race 264 was obtained. These are OA 712-17, OA 712-33, Glen, Woodstock, QO 220.13, and QO 574.21. These oat genotypes are currently being used as parents in crosses in the Macdonald Campus of McGill University oat breeding program.

The introduction of Quality Protein Maize (QPM), hard endosperm opaque-2 maize, into northern temperate maize growing areas is a desirable breeding objective. In topcrosses with opaque-2 testers, in diallel combination, as inbreds per se, and in inbred disease screening nurseries, some QPM lines performed better than or equal to the best local checks. In general, while agronomic potential is high for some lines and gains from selection are statistically possible, longer days to flowering intervals and higher levels of moisture at harvest than check hybrids indicated a need to improve adaptation for the locations studied. Methodology experiments indicated that detasselling of check hybrids is a suitable experimental method to facilitate the inclusion of normal endosperm local checks into QPM performance tests. The screening for Fusarium graminearum resistance in the seedling stage has not been proven to be a viable alternative to field scale ear inoculation screening procedures. (Abstract shortened by UMI.)

In Lactuca sativa, the dominant gene Tu confers resistance to infection by turnip mosaic virus (TuMV). Tu and Dm5/8, a gene for resistance to Bremia lactucae, are linked in L. sativa. The area surrounding Dm5/8 on the genetic map of L. sativa contains restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) markers. The orientation of Tu relative to Dm5/8 was not known. Locating Tu would indicate which markers are on the map of lettuce close to Tu. To locate Tu on the L. sativa genetic map, F$ sb3$ families from recombinant F$ sb2$ in the Dm5/8 area of a cross between TuMV-resistant (Cobbham Green) and susceptible (Calmar) cultivars were inoculated with TuMV and phenotyped for Tu by indirect enzyme-linked immunosorbent assay. Polyclonal antibodies for immunodetection were produced using turnip mosaic virus coat protein expressed in E. coli. Phenotypic ratios within F$ sb3$ families were used to determine individual F$ sb2$ genotypes for Tu. With these genotypes, Tu was located on the genetic map of L. sativa relative to data present for Dm5/8 and surrounding markers, between OPM18 and OPY13. Using bulked segregant analysis, bulks created for the Dm5/8 locus were screened for genetic polymorphisms by the RAPD technique. Five new RAPD markers, UBC346, UBC517, UBC563, UBC599, and UBC675 were found linked to Tu after mapping relative to F$ sb2$ genotypes for Tu and other RAPD markers. The resulting three-point mapping information indicates that Tu is flanked by two markers, OPM18/OPL08 and UBC346, at respective genetic distances of 0.4 and 0.7 cM.

No description available.

The characteristics and inheritance of maize silk resistance to Fusarium graminearum ear rot were investigated. In an in vitro test, genotypic differences in the degradation of detached silk tissue by F. graminearum were correlated to field evaluations of resistance. Susceptibility to infection decreased with silk age. Total phenolics of silk channel silk tissue increased in response to infection in resistant inbreds but decreased in susceptible inbreds. The flavones iso-orientin, iso-vitexin, maysin, luteolin, and apigenin were identified in the silk. No significant genotype by isolate interaction effects were found when 13 inbred lines were inoculated with three F. graminearum isolates. Simple models of quantitative and qualitative inheritance were not adequate to explain the inheritance of resistance. Disease severity ratings were bimodally distributed in the F$ sb1$, F$ sb2$, and backcross generations. In a complete diallel cross among 12 inbred lines, general and specific combining ability effects were significant for both disease incidence and disease severity. A screening of 12 accessions of exotic maize germplasm with resistance to either Aspergillus flavus or Heliothis zeae, identified several possible new sources of resistance to F. graminearum. Visual evaluations of resistance were correlated to deoxynivalenol levels of the ear.

The response of Arabidopsis thaliana (Columbia) to infection with turnip mosaic virus (TuMV) was characterized at the level of: disease symptom expression, cell content and protein composition. Visual symptoms observed were chlorotic and mottled leaf colouring, severely stunted growth, distortion of leaf blades and delayed bolting. All plants died before seed cases dehisced. Electron microscopy revealed three types of cylindrical inclusion bodies: pinwheels, scrolls and laminated aggregates, in the cytoplasm of infected plants similar to those observed in other plants infected with TuMV. Inoculation of Arabidopsis with TuMV resulted in quantitative changes in several proteins in both soluble and membrane proteins, as revealed by electrophoresis on 12% polyacrylamide gels. Antibodies were made to both infected membrane and soluble proteins. Western blots of infected and uninfected, soluble and membrane proteins probed with antibodies revealed quantitative changes in the same proteins identified by polyacrylamide gels. A CNBr 4B activated sepharose column was used to make infection-specific antibodies to infected soluble proteins. No infection-specific host proteins were detected in Arabidopsis infected with TuMV.