Thesis (M.Sc.)--Memorial University of Newfoundland, 2005. / Restricted until October 2007. Bibliography: leaves 133-164.

Plant resistance hypothesis says that under a period of time when a plant is exposed to powerful herbivore attack it will prioritise defence as a major metabolic function. In theory, induced plant defence (resistance) will provide opportunities for this organism to “invest” in other functions, in example growth when attackers are absent. One of the compounds taking part in plant defence is callose. This β-1,3-glucan is synthesised by callose synthase and broken down by β-1,3-glucanase. Deposition of callose occurs as a reaction to aphid attack an varies, depending on cultivars, and aphid species. In this experiment barley (Hordeum vulgare) cultivar Clipper is being infested with two types of aphids: Russian wheat aphid (RWA, Diuraphis noxia) and bird cherry-oat aphid (BCA, Rhopalosiphium padi) over a time period. Infestation by those two insects results in different callose formation and deposition level. Six sequences encoding for putative callose synthase genes and nine sequences encoding for β-1,3-glucanase were examined by RT-PCR and Real – Time PCR methods for different expression patterns. The results did not show any significant regulation of gene expression during RWA and BCA attack for any of these genes. Thus the pathway regulating aphid – induced callose deposition in barley reminds unresolved.

Dry matter, crude protein and starch degradation characteristics of one corn (Pioneer 39P78) and four barley grain varieties (CDC Bold, CDC Dolly, Harrington and Valier) were evaluated in two in situ nylon bag trials. Trial 1 compared ground and rolled treatments of Harrington barley and Pioneer 39P78 corn, whereas Trial 2 evaluated ground and rolled treatments of the four barley varieties. Rumen degradability characteristics were compared with analytical results from thermal- and synchrotron-source FTIRM. Infrared absorbance spectra were collected from corn and four barley varieties using thermal-source FTIRM on the mid-IR beamline at the Canadian Light Source, Ltd. (Saskatoon, SK). Synchrotron-source FTIRM spectral data was collected for corn, Harrington barley and Valier barley on the U2B mid-IR beamline at NSLS-BNL (Upton, NY). CHO:Amide I peak area ratios were compared to the in situ rumen degradation results to determine if FTIRM spectral data could be related to the rate and extent of rumen degradation, and if thermal- and synchrotron-source FTIRM yielded different results. A grain x processing method interaction (P<0.01) was observed in both in situ trials where grinding produced a greater increase in the rate and extent of rumen degradation for Harrington barley than it did for corn (Trial 1) along with a greater increase in the rate and extent of rumen degradation for CDC Bold and CDC Dolly than for Harrington and Valier (Trial 2). Among barley varieties, increasing rate and extent of rumen degradation (CDC Bold>CDC Dolly>Harrington>Valier) corresponded to increasing starch:protein ratio as estimated by chemical analysis. This relationship was reversed for corn and Harrington barley where corn had a higher starch:protein ratio yet slower rumen degradation kinetics. For both thermal- and synchrotron-source FTIRM, CHO:amide I peak area ratios were greater (P<0.05) for corn than for Harrington barley. Comparison of CHO:amide I peak area ratios of barley varieties measured with thermal-source FTIR showed that varieties with higher (P<0.05) CHO:Amide I peak area ratios generally had higher rate and extent of rumen degradation. This indicates that starch:protein ratio estimated with FTIRM may be an indicator of rumen degradability characteristics when comparing varieties of the same grain, but not for different species of grains.

Two trials were conducted to evaluate the effects of titrated levels of wheat-based dried distillers grains on feedlot performance, carcass characteristics and rumen fermentation parameters of cattle fed wheat-based dried distillers grains with solubles (DDGS). In trial 1, a barley grain-based diet (0% DDGS) was used as a control. It was formulated to 12% CP and 1.52 and 0.93 Mcal kg-1 net energy of maintenance (NEm ) and net energy of gain( NEg) respectively, during the backgrounding period and to 13% crude protein (CP) and 1.90 and 1.26 Mcal kg-1 NEm and NEg respectively, during finishing. Wheat-based DDGS replaced on a dry matter basis (DM) barley grain at levels of 8, 16, 24 and 32% during backgrounding and 6, 12, 18 and 23% during finishing. During backgrounding dry matter intake (P = 0.02), ADG (P = 0.04), and ultrasounded (US) longissimus. dorsi gain (P = 0.02) exhibited a cubic response to DDGS inclusion level with theoretical minima at 6.9, 8.1 and 6.9% DDGS respectively, and theoretical maxima responses at 27.2, 30.8 and 23.9% DDGS, respectively. Feed efficiency exhibited a quadratic response (P = 0.02) to DDGS inclusion level with a theoretical poorest response at 13.1% DDGS. Similar responses were noted during the first 56 d of the finishing period, however over the course of the finishing period no effect of DDGS inclusion level was noted on average daily gain (ADG), DMI, feed efficiency (FE), ultrasound measurements or on any carcass traits. <p>Trial 2 examined the effects of graded levels of wheat-based DDGS (0, 7, 14, 21% DM basis) on rumen fermentation characteristics using rumen cannulated heifers. Rumen pH measurements indicated that the pH mean at or below 5.8 and 5.5 decreased as DDGS inclusion level increased to 14% DM. The highest values (P<0.05) for pH area between the benchmarks of 5.5 and 5.2, pH area below 5.2 and time below pH 5.2 were found at the 14% DDGS inclusion level, pointing to rumen fermentation characteristics associated with severe rumen acidosis. Ammonia nitrogen levels, percent acetate, percent butyrate and the acetate: propionate ratio increased linearly (P < 0.0001) with DDGS. Propionate concentration decreased linearly (P = 0.006) as the level of DDGS increased. In situ rumen degradation kinetics showed that the DM and CP soluble fraction of DDGS to be significantly higher than that of rolled barley, however effective degradability of dry matter (EDDM) and effective degradability of crude protein (EDCP) were greater for barley. The results of this trial indicate that wheat-based DDGS has an energy value at least equal to that of barley grain with no adverse effects on cattle performance or carcass quality. Furthermore, since all treatments showed equal susceptibility to sub-acute ruminal acidosis (SARA) and therefore, wheat-based DDGS as a dietary ingredient is unable to mitigate rumen fermentation conditions associated with SARA.

Two trials were conducted to evaluate effects of feeding barley/canola meal pellets on feedlot performance, subacute ruminal acidosis (SARA), and feeding behaviour in feedlot steers. In trial 1, 350 beef steers (285 ± 22 kg) were backgrounded and finished on pelleted barley and canola meal (PB) or rolled barley and canola meal (RB) diets. Backgrounding DMI was lower (P < 0.05) for PB steers but ADG did not differ (P > 0.05) and feed efficiency (FE) tended (P < 0.1) to be improved. During finishing and the total trial DMI and ADG were lower (P < 0.05) but FE was improved (P < 0.05) for the PB treatment. Steers fed PB were on feed longer (P < 0.05). Steers fed PB showed more variation in DMI (P < 0.05) than steers fed RB. Carcass composition and quality were similar between the treatments.<p>Trial 2 utilized 4 ruminally fistulated beef steers in a 4 x 4 latin square, 2 x 2 factorial trial. Factors were processing (pelleted vs. rolled) and grain type (barley vs. corn). All treatments included canola meal. Each 23 d period consisted of a 19 d adaptation period followed by a 24 h rumen fluid collection period, and a 24 h eating behaviour study. There were no grain type x processing interactions (P > 0.05) or effect of grain type (P > 0.05) on any of the variables. Eating behaviour did not differ (P < 0.05) between treatments. Processing had no effect (P > 0.05) on rumen ammonia or volatile fatty acid (VFA) concentration, proportion of acetate or butyrate, or rumen osmolality. Steers fed pelleted grain had lower (P < 0.05) rumen pH measurements, a greater (P < 0.05) molar proportion of propionate, and decreased (P < 0.05) acetate:propionate ratio. To reflect the feedlot trial corn was removed from the model. Rumen VFA concentration was higher (P < 0.05) and pH lower (P < 0.05) for the PB steers. Results show performance during backgrounding was improved but finishing performance depressed in PB steers. Further research is necessary to reduce the risk of SARA when feeding PB during finishing.

Nickel contaminated wastewater from plating industries is a major environmental concern. Current treatment methods are often expensive and can also create additional problems. Biosorption is an alternative treatment method that uses inexpensive biomaterials to sequester metals from aqueous solutions. In this study, acid washed barley straw (AWBS) was used for adsorbing nickel ions (Ni2+) from simulated nickel plating wastewater. The adsorption process was rapid and the equilibrium was reached in about an hour. An increase in the initial nickel concentration increased the equilibrium nickel uptake, and the maximum uptake was found to be 8.45 mg/g of AWBS when the initial nickel concentration was1000 mg/L at pH 5. Nickel adsorption was favorable at room temperature than 5oC and 40oC, better adsorption rate and equilibrium uptake was observed at 23oC. Increasing the pH from 3 to 7 increased the equilibrium nickel uptake and the maximum uptake was observed at pH 7, whilst the initial nickel ion concentration was 100 mg/L. The Freundlich isotherm model exhibited better fit with the equilibrium data than the Langmuir equation. Nickel was desorbed using hydrochloric acid solution at pH 2 and the desorption efficiency was 86%. FT-IR studies indicated the participation of hydroxyl, carboxyl and amide groups from cellulose, hemi-cellulose, protein and lignin of barley straw.

<i>Pyrenophora teres</i> Drechs. (anamorph: <i>Drechslera teres</i> (Sacc.) Shoem.) is the causal agent of barley net blotch. Net blotch is an economically important disease commonly found throughout the barley producing regions of the world. Significant financial losses result from yield reductions, ranging from 15-35%, and decreased grain quality. Despite its prevalence, it is unclear if the P. teres-barley pathosystem follows a gene-for-gene model, and more generally, little is known about its genetic organization. Three studies were initiated to address these questions.<p>The first study investigated the genetic control of avirulence in <i>P. teres.</i> To establish an appropriate study system, a collection of ten net form (<i>P. teres f. teres</i>) and spot form (<i>P. teres f. maculata</i>) isolates were evaluated on a set of eight differential barley lines to identify two isolates with differential virulence on a specific host line. WRS 1906, exhibiting low virulence on the cultivar Heartland, and WRS 1607, exhibiting high virulence, were mated and 67 progeny were isolated and phenotyped for virulence on Heartland. The population segregated in a 1:1 ratio, 34 avirulent to 33 virulent (Chi-square = 0.0, P = 1.0), indicating single gene control of WRS 1906 avirulence on Heartland. Bulked segregant analysis was used to identify six amplified fragment length polymorphism (AFLP) markers closely linked to the avirulence gene (AvrHeartland). This work provides evidence that the P. teres-barley pathosystem conforms to the gene-for-gene model.<p>In the second study, five isolates of P. teres, representing both net and spot forms, were analyzed by the germ tube burst method (GTBM) and pulsed field gel electrophoresis (PFGE) to determine the species karyotype. Nine chromosomes were observed in all isolates using the GTBM and estimation of chromosome lengths varied from 0.5 to 3.0 µm. PFGE separated 7 to 8 bands depending on isolate, but analysis of bands by densitometry indicated nine chromosomes. Chromosome size ranged from 1.8 to ~6.0 Mb providing a genome size estimate of 32 to 39 Mb. Significant chromosome-length polymorphisms (CLP) were observed between isolates. These CLP did not hinder mating between mating-type compatible net form isolates. No particular CLP or individual chromosome could be associated with differences in disease symptoms observed between pathogen forms. This study provides the first karyotype of both P. teres forms and will assist genetic mapping of this pathogen.<p>A genetic linkage map of <i>P. teres f. teres</i>, was constructed in the third study using the population of 67 progeny derived from the WRS 1906  WRS 1607 cross. The map consists of 138 markers including 114 AFLPs, 21 telomere RFLPs, the mating-type (MAT) locus and an avirulence locus (AvrHeartland) controlling interaction with barley cultivar Heartland. Markers were distributed across 24 linkage groups ranging in length from 2 to 110 cM with an average marker interval of 8.5 cM. The total map length was 797 cM. A telomere-specific probe, consisting of the sequence (TTAGGC)4, was used to map 15 of the 18 telomeres. One of these telomeres mapped to within 3 cM of the AvrHeartland locus. Attempts to consolidate linkage groups by hybridizing markers to the electrophoretically separated chromosomes was unsuccessful because probes bound to multiple chromosomes, likely due to repetitive DNA within the probe. This is the first genetic map reported for this species and it will be a useful genetic tool for map-based cloning of the AvrHeartland gene tagged in this study. <p>This research has provided a number of new insights into the net blotch pathogen and provides a useful research tool in the form of a genetic map. This information lays the foundation for further genetic study of P. teres and will complement studies on barley resistance to net blotch that may potentially lead to more durable resistance.

The production of barley (Hordeum vulgare L.) haploids by crossing with H. bulbosum is a widely used tool in breeding and genetics. Certain barley genotypes have low seed set in this interspecific cross, a phenomenon known as partial incompatibility. Haploid production efficiency and gamete sampling are important issues with the bulbosum technique, particularly when partially incompatible genotypes are used. An in vitro floret culture system was developed that substantially increases haploid production efficiency by optimizing caryopsis growth, haploid embryo development, and plant regeneration. The individual and combined effects of three plant growth regulators (2,4-D, GA₃ and kinetin) on haploid production efficiency and its determinants were compared in the floret culture system. 2,4-D alone was superior to GA₃ alone in haploid production efficiency. 2,4-D alone or kinetin + 2,4-D are recommended for the purpose of haploid production in floret culture using the bulbosum method. Partial incompatibility between H. vulgare and H. bulbosum was studied by doubled haploid progeny analysis. Two different loci were hypothesized to account for the inheritance of partial incompatibility in the crosses of Vada x Klages, Harrington x Klages, and Vada x Harrington. The partial incompatibility gene in Harrington was found to be recessive. The dominant nature of the partial incompatibility gene (Inc) in Vada was confirmed. An association between the (Inc) gene and a deficiency in a stigma/stylodium-specific high pl protein was found in the cosegregation analysis of doubled haploid progeny. The Inc gene may be linked to the gene coding for the stigma/stylodium-specific protein, or the Inc gene may regulate expression of the protein-encoding locus. Segregation analysis of Mendelian markers in doubled haploid progeny showed that there is no evidence that the partial incompatibility status of the parents has an effect on gamete sampling by the bulbosum technique. / Graduation date: 1991

Three experiments were conducted to investigate the effects of various cereal grain types on the production performance of dairy cattle and the colonization of <i>Clostridium perfringens</i> in the intestinal tract of cattle. The first experiment investigated the effect of feeding two different cultivars of barley (cv. Harrington and Valier) and two different cultivars oat (cv. Derby and AC Assiniboia) grain on feed intake, milk yield and milk constituents. It was found that barley or oat may both be successfully incorporated into the concentrate portion of western Canadian dairy rations. NRC Dairy 2001 predictions for both oat and barley diets very closely predicted dry matter intake and milk production. AC Assiniboia oat fed cows produced the lowest percentage of fat (P<0.05) compared to the other dietary treatments. Oat fed cows produced milk with lower total solids (P<0.05) than barley fed cows. Experiment two investigated the effect of replacing barley with corn in the concentrate of a dairy ration on performance parameters as well as fecal shedding of <i>C. perfringens</i>. Corn can successfully replace a portion of the cereal grain in a typical western Canadian dairy ration without adverse effects on milk production, feed intake and feed efficiency. Corn fed cows produced significantly higher milk protein than barley fed cows (P<0.05). Dairy NRC 2001 milk production predictions were similar to observed milk yields. Mean (±SEM) level of colonization (log cfu/g) of <i>C. perfringens</i> in the feces was lower (P<0.05) in barley-fed (1.30±0.27) compared with corn-fed (2.47±0.27) cows. Experiment three was a survey to determine the level of shedding of <i>C. perfringens</i> in feces of dairy cattle at different ages and stages of lactation and in feedlot cattle through the backgrounding and finishing phases. No relationship was found between heifer age and level of shedding or between days in lactation and level of shedding. Sixteen percent of the sampled cows exhibited high levels of shedding (3.02±.46) log cfu/g feces) through all stages of lactation without exhibiting adverse effects on health. No relationship was found between age of heifer and level of <i>C. perfringens</i> shedding in the feces. Steers shed significantly higher (P<0.05) levels of <i>C. perfringens</i> during the last phase of finishing compared with other feeding phases. Further research investigating <i>C. perfringens</i> colonization in cattle is required.

<i>Pyrenophora teres</i> Drechs. (anamorph: <i>Drechslera teres</i> (Sacc.) Shoem.) is the causal agent of barley net blotch. Net blotch is an economically important disease commonly found throughout the barley producing regions of the world. Significant financial losses result from yield reductions, ranging from 15-35%, and decreased grain quality. Despite its prevalence, it is unclear if the P. teres-barley pathosystem follows a gene-for-gene model, and more generally, little is known about its genetic organization. Three studies were initiated to address these questions.<p>The first study investigated the genetic control of avirulence in <i>P. teres.</i> To establish an appropriate study system, a collection of ten net form (<i>P. teres f. teres</i>) and spot form (<i>P. teres f. maculata</i>) isolates were evaluated on a set of eight differential barley lines to identify two isolates with differential virulence on a specific host line. WRS 1906, exhibiting low virulence on the cultivar Heartland, and WRS 1607, exhibiting high virulence, were mated and 67 progeny were isolated and phenotyped for virulence on Heartland. The population segregated in a 1:1 ratio, 34 avirulent to 33 virulent (Chi-square = 0.0, P = 1.0), indicating single gene control of WRS 1906 avirulence on Heartland. Bulked segregant analysis was used to identify six amplified fragment length polymorphism (AFLP) markers closely linked to the avirulence gene (AvrHeartland). This work provides evidence that the P. teres-barley pathosystem conforms to the gene-for-gene model.<p>In the second study, five isolates of P. teres, representing both net and spot forms, were analyzed by the germ tube burst method (GTBM) and pulsed field gel electrophoresis (PFGE) to determine the species karyotype. Nine chromosomes were observed in all isolates using the GTBM and estimation of chromosome lengths varied from 0.5 to 3.0 µm. PFGE separated 7 to 8 bands depending on isolate, but analysis of bands by densitometry indicated nine chromosomes. Chromosome size ranged from 1.8 to ~6.0 Mb providing a genome size estimate of 32 to 39 Mb. Significant chromosome-length polymorphisms (CLP) were observed between isolates. These CLP did not hinder mating between mating-type compatible net form isolates. No particular CLP or individual chromosome could be associated with differences in disease symptoms observed between pathogen forms. This study provides the first karyotype of both P. teres forms and will assist genetic mapping of this pathogen.<p>A genetic linkage map of <i>P. teres f. teres</i>, was constructed in the third study using the population of 67 progeny derived from the WRS 1906  WRS 1607 cross. The map consists of 138 markers including 114 AFLPs, 21 telomere RFLPs, the mating-type (MAT) locus and an avirulence locus (AvrHeartland) controlling interaction with barley cultivar Heartland. Markers were distributed across 24 linkage groups ranging in length from 2 to 110 cM with an average marker interval of 8.5 cM. The total map length was 797 cM. A telomere-specific probe, consisting of the sequence (TTAGGC)4, was used to map 15 of the 18 telomeres. One of these telomeres mapped to within 3 cM of the AvrHeartland locus. Attempts to consolidate linkage groups by hybridizing markers to the electrophoretically separated chromosomes was unsuccessful because probes bound to multiple chromosomes, likely due to repetitive DNA within the probe. This is the first genetic map reported for this species and it will be a useful genetic tool for map-based cloning of the AvrHeartland gene tagged in this study. <p>This research has provided a number of new insights into the net blotch pathogen and provides a useful research tool in the form of a genetic map. This information lays the foundation for further genetic study of P. teres and will complement studies on barley resistance to net blotch that may potentially lead to more durable resistance.