Septoria leaf blotch of wheat is a major biotic factor limiting the grain yield. To determine the nature of inheritance involving selected genotypes, three resistant semidwarf spring wheat lines exhibiting durable global resistance and one susceptible cultivar were crossed in all possible combinations, excluding reciprocals. Parents, Fl, F2, and F3 generations were inoculated with one pathogenic strain of Septoria tritici and evaluated under field conditions. Data were collected on an individual plant basis. F2 and F3 frequency distributions were computed to determine the nature of inheritance. Combining ability analysis of the 4x4 diallel cross and narrow-sense heritability were employed to estimate the nature of gene action. Phenotypic correlations were obtained to examined the possible association between disease severity traits and their relationship with heading date and plant height. The continuous distribution of the F2 and F3 populations among crosses made it impossible to classify plants into discrete classes in crosses between resistant x susceptible genotypes. Mean values of the disease traits Septoria progress coefficient, Relative coefficient of infection, and Septoria severity of flag leaf among the segregating populations were similar to the midparent values. Transgressive segregation was also observed in the F2 and F3 suggesting that parents had different resistance genes. Additive gene effects were found to be the major component of variation although nonadditive gene action played an important role in the expression of all three disease traits. The resistant parents Bobwhite"S" and Kavkaz /K4500 L.A.4 were found to have the largest negative general combining ability effects for the disease traits suggesting that these parents would be the best source for resistance to Septoria leaf blotch. High general combining ability and high narrow sense heritability estimates in the F3 population, indicated that substantial progress for resistance to Septoria tritici would be effective selecting in this generation. Of the three disease measures it would appear that selection for the lowest percentage of Septoria infection on the flag leaf would provide the most progress in developing resistant cultivars. Moderate and low negative phenotypic correlations were found among generations for the disease traits with heading date and plant height. From the results of this study the selection of early maturing short stature progeny would be possible within the genetic materials employed in this study. / Graduation date: 1993

Rhinichthys osculus, the Speckled Dace, is one of the most ubiquitous fish in western North America. Within the Southern California region, the local taxon is known as the Santa Ana Speckled Dace. The purpose of this study was to characterize and identify polymorphic microsatellite markers for R. osculus in which twenty-three were identified through Illumina pair-end sequencing. Seven of these loci were then used to examine the patterns of genetic variation and population structure that occurred within and among the watersheds in the Southern California. The study also examined the regional relationships among Southern California, Central California and Owen’s River Valley. Analysis of the microsatellite data revealed highly significant moderate levels of population structure exist within the Southern California region (RST=0.160, p=0.001). This structure is best explained by watershed as well as isolation by distance (R2=.2286, p=0.010). Highly significant geographic structure also exists among the geographic regions of Southern California, Central Coast, and Owen’s River Valley regions (RST= 0.600, p-value=0.001) that are congruent with the regional differentiation elucidated by mtDNA sequence data. In both cases, the degree of population differentiation was correlated with isolation by distance. Utilizing this information we were able gain a better understanding of the evolutionary relationships among the Southern California populations of Santa Ana Speckled Dace. Within the Santa Ana Speckled Dace populations we examined four models to explain the geographic structure: watershed, mountain range, tributary, and isolation by distance. While all were significant, the tributary model exhibited the higher level of population structure (RST= 0.160, p-value=0.001) and a significant correlation was exhibited between geographic distance and population structure, suggesting isolation by distance may be playing a role. The results of the microsatellite analysis are congruent with an earlier broad scale analysis of mtDNA sequence data that suggests the Central California and the Owens Valley populations diverged from each other prior to the divergence of the Santa Ana Speckled Dace populations from the Colorado Basin populations, and that the Central Coast populations were not established as a result of a migration event from the Southern California populations, as was previously hypothesized. Primarily due to human activity, Santa Ana Speckled Dace habitat has become highly fragmented resulting in some populations becoming extirpated. We hope this study will guide the strategies for the conservation of the remaining populations of Santa Ana Speckled Dace and watershed management in Southern California.

In this study, I sequenced the mitochondrial cytochrome b gene to elucidate the extent and pattern of genetic variations among and within populations of Rhinichthys osculus (Santa Ana Speckled Dace) found in the different watersheds in Southern California, Central California Coast and Eastern California Desert. I described and analyzed the structural characteristics and pattern of base sequence substitutions in the cytochrome b gene to understand the molecular evolution of the gene. The Phylogenetic analyses showed that the Southern California Santa Ana Speckled dace is a distinct population from the Central California Coast dace population and Eastern California Desert dace population, and is more closely related to the Colorado River speckled dace population. There is a high degree of genetic variation among all populations including a significant genetic structure associated with watersheds, mountain ranges, and geographic grouping based on locations. The SWISS-Model automated protein structure homology elucidated the conserved and invariant residues within the cytochrome b gene where the amino acid substitutions are located in the trans-membrane of the protein sequence. The implication for conservation and management of the Southern California Santa Ana Speckled dace is high because of habitat lost for this distinct dace population. The data from this study will contribute to preserving the genetic variability of the Santa Ana Speckled Dace as a separate taxa and species, as well as to help maintain intact the population in the different Southern California creeks.

Mycosphaerella graminicola (anamorph Septoria tritici) causes Septoria tritici blotch, a globally important disease of winter wheat. Resistance and pathogenicity generally vary quantitatively. The pathogen reproduces both sexually and asexually, and the pathogen population is highly genetically variable. Several unresolved questions about the epidemiology of this pathosystem are addressed by this research. Among them are whether cultivar-isolate specificity exists, how partial host resistance affects pathogen aggressiveness and sexual reproduction, and how host genotype mixtures influence epidemic progression and pathogenicity. At its release in 1992, the cultivar Gene was highly resistant to M. graminicola, but that resistance had substantially dissolved by 1995. Six of seven isolates collected in 1997 from field plots of Gene were virulent to Gene seedlings in the greenhouse, while 14 of 15 isolates collected from two other cultivars were avirulent to Gene. Gene apparently selected for strains of M. graminicola with specific virulence to it. In a two-year experiment, isolates were collected early and late in the growing season from field plots of three moderately resistant and three susceptible cultivars, and tested on seedlings of the same cultivars in the greenhouse. Isolates were also collected from plots of two susceptible cultivars sprayed with a fungicide to suppress epidemic development. Isolate populations were more aggressive when derived from moderately resistant than from susceptible cultivars, and more aggressive from fungicide-sprayed plots than from unsprayed plots of the same cultivars. Over 5,000 fruiting bodies were collected in three years from replicated field plots of eight cultivars with different levels of resistance. The fruiting bodies were identified as M. graminicola ascocarps or pycnidia, or other. In all three years, the frequency of ascocarps was positively correlated with cultivar susceptibility, as measured by area under the disease progress curve, and was also positively associated with epidemic intensity. For three years, four 1:1 mixtures of a moderately resistant and a susceptible wheat cultivar were planted in replicated field plots. Isolates from the plots were inoculated as bulked populations on greenhouse-grown seedlings of the same four cultivars. Mixture effects on disease progression varied among the years, and were moderately correlated with mixture effects on pathogenicity. / Graduation date: 2002

Made available in DSpace on 2014-06-12T18:02:43Z (GMT). No. of bitstreams: 2 arquivo4052_1.pdf: 1926198 bytes, checksum: a394edbf4f303fa7b25af920df83cf25 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2008 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este trabalho propõe uma técnica não-paramétrica para detecção de bordas em imagens speckle. As imagens SAR ("Synthetic aperture Radar"), sonar, B-ultrasound e laser são corrompidas por um ruído não aditivo chamado speckle. Vários modelos estatísticos foram propostos para desrever este ruído, levando ao desenvolvimento de técnicas especiais para melhoramento e análise de imagens. A distribuição G0 é um modelo estatístico que consegue descrever uma ampla gama de áreas, como, por exemplo, em dados SAR, pastos (lisos), florestas (rugosos) e áreas urbanas (muito rugosos). O objetivo deste trabalho é estudar ténicas alternativas na detecção de imagens speckled, tomando como ponto de partida Gambini et al. (2006, 2008). Um novo detector de borda baseado no teste de Kruskal Wallis é proposto. Os nossos resultados numéricos mostram que esse detector é uma alternativa atraente ao detector de M. Gambini, que é baseado na função de verossimilhançaa. Neste trabalho fornecemos evidências de que a técnica de M. Gambini pode ser substituída om sucesso pelo método Kruskal Wallis. O ganho reside em ter um algoritmo 1000 vezes mais rápido, sem omprometer a qualidade dos resultados

Most breeding programs aim at developing superior germplasm and better cultivars that combine high yield, disease and pest resistance, and end-use quality to satisfy the requirements of the growers as well as industry. A population, consisting of 138 F2-8 recombinant inbred lines (RILs) derived from a cross between ‘Steele-ND’ and ND 735, was evaluated to study the inheritance pattern of the septoria tritici blotch (STB)-resistant genes, agronomic and quality traits. The framework map made of 392 markers, including 28 simple sequence repeat (SSR) markers and 364 DArT markers, spanned a total distance of 1789.3 cM and consisted of 17 linkage groups. The map position of quantitative trait loci (QTL) found in this study coincided with the map position of durable STB resistance genes, Stb1. Thirteen QTL were detected for agronomic and quality traits. More saturation of the current map is needed to explore more QTL for this population.

The purpose of this genetic study of the Santa Ana Speckled Dace Rhinichthys osculus was three-fold. The first goal was to characterize the molecular structure of the mtDNA control region of R. osculus. An 1143 base-pair region of the mitochondrial DNA genome, which included the complete control region was sequenced for all individuals. Analysis of the sequence data revealed that the molecular structure of the speckled dace control region was similar to the molecular structure described for other vertebrate taxa. The speckled dace control region contains three major domains, which vary in base frequency as well as in the frequency of nucleotide polymorphisms. Domain II was observed to be the most conserved, and Domain I was the most variable domain of the control region, in agreement with studies of other vertebrate control regions. The second goal of this study was to ascertain the phylogeny of R. osculus in Southern California in relation to other speckled dace in California. Seventy-four specimens of R. osculus were collected from five different watersheds located in three geographic regions of California: Southern California, the Central California Coast, and the Eastern Desert of the Owens River valley. Phylogenetic analysis of sequence data revealed that the Santa Ana Speckled Dace is a genetically distinct population from R. osculus inhabiting the Central Coast or Eastern Desert regions, which both differ from the Santa Ana Speckled Dace by a genetic distance of more than 7 percent. The Santa Ana Speckled Dace inhabiting the watersheds of Southern California form a reciprocally monophyletic clade with respect to the Central Coast dace and the Eastern Desert dace, which are sister clades to one another. The third goal of this study was to describe the population genetics of R. osculus in Southern California. Population genetic analysis demonstrated that a high degree of geographic population structure exists for the Speckled Dace in California, with 96% of molecular variance attributable to regional differences through isolation by distance. A high degree of population structure also exists among populations within the Southern California region as well. It was found that 45% of molecular variance in the Santa Ana Speckled Dace is attributable to differences among tributaries. This study finds that the distribution of speckled dace in Southern California best fits a model of population structure by individual tributary, with episodes of localized population bottlenecks followed by sudden population expansion, most likely linked to climatic variation. It is proposed the Santa Ana Speckled Dace constitutes an Evolutionarily Significant Unit (ESU) that qualifies it as a separate subspecies on the basis that it is geographically separated from other populations, genetically distinct from other dace populations due to restricted gene flow, and possesses unique phenotypic characteristics. This information suggests conservation and management strategies for the speckled dace populations which remain in existence in Southern California.

Swimming performance strongly influences fitness in aquatic organisms and is closely tied to external body morphology. Although this connection has been closely examined at the individual and species level, few studies have focused on this relationship as it pertains to functional group assemblages. Using functional groups based on similarities in habitat use and morphology, I tested the hypothesis that swimming performance can be reliably predicted by functional group composition. I measured swimming performance as burst speed using a simulated predator attack and as prolonged speed using a step-endurance test in a laboratory flume. I measured morphology using geometric morphometric techniques. A difference in swimming behavior in four of the seven species was observed in the step-endurance test. Benthic species exhibited bracing behavior as an alternative to body-caudal fin (BCF) propulsion in the prolonged speed trials. Swimming performance exhibited a weak relationship with functional groups based on habitat or morphology. Rather a species-based model was the best predictor of swimming performance. Although species exhibited variation in swimming performance, body size was the strongest predictor of absolute swimming performance across all models. Relative swimming performance (measured in body lengths/sec) was negatively related to body size. The results of this study suggest that functional groups are not always reliable predictors of performance and they necessitate empirical testing to validate their effectiveness. This study also provides critical swimming performance data for previously unstudied Great Basin fishes which could be valuable for predicting fish passage through culverts, weirs and fish ladders.

Studies were conducted on three field trials of wheat cv. Kopara to investigate the lack of compensation by later determined components of yield because of early disease constraints. The investigation was based on the hypothesis that early disease reduces root development and thus causes the plants to be water constrained at later growth stages when soil water deficits usually occur. The reduced root development and soil water deficits may reduce the ability of the plant to compensate for reductions in early determined components. The hypothesis was tested by the application of irrigation to alleviate water stress. In a disease free crop, the possible phytotonic effects of the fungicides benomyl and triadimefon on wheat were investigated. These fungicides had no phytotonic effects on shoot, root growth, or yield under the prevailing conditions. The effect of disease on root development was analysed by root length measurements. Disease present in the crop at any stage of growth affected root development. Root development in the upper zones of the soil profile was reduced more by disease compared to those zones below 35 cm. A full disease epidemic reduced root development more than an early or late disease epidemic. The early and late disease epidemics had similar effects on root length. Alleviation of early disease constraints enabled greater development of roots to offset any earlier reductions. Soil water deficits increased root development in the lower zones of the nil disease plants. The presence of adequate soil water from irrigation reduced the requirement for further root growth in all treatments. In the 1981-1982 field trial a full disease epidemic reduced yield by 14% whereas an early disease epidemic reduced yield by 7%. The reduction in yield was attributed to a lower grain number. With irrigation the yield reduction in the full disease plants was 12% whereas in the early disease plants the reduction was only 2.4%. This indicated that plants affected by the early disease epidemic were water constrained. In this study, the results suggested that, for conditions prevailing in Canterbury, the supply of water at later growth stages increased grain weight in plants which were subject to early disease epidemics. This suggests that reduced root development caused by early disease and soil water deficits may prevent compensation by grain weight. Water use was similar in all disease treatments. After irrigation the irrigated plants of all treatments used more water. Disease affected water use in relation to yield production however, and was better expressed by water use efficiency. Water use efficiency was reduced in the full disease plants. A stepwise regression analysis suggested that water use efficiency was affected directly by disease at later growth stages, and indirectly via an effect on total green leaf area at early growth stages. This study partially proves the hypothesis that reductions in root development caused by an early disease epidemic may constrain the plants at later growth stages when water deficits usually occur. It was shown that the reduction in root development caused by disease could be counteracted by irrigation. In this respect, water served as a tool to study the effect of disease constraints on the yield of wheat. A knowledge of cereal crop physiology, root growth and function is used to explain and discuss the observations made in this research programme. The results are discussed in relation to the way in which disease affects yield through its effect on root development. The possible reasons for the continued effects of disease even after the control of disease at later growth stages are discussed. The economic use of fungicides and water in diseased crops are also outlined. Suggestions for future studies on disease-yield loss relationships are provided. The repetition of these experiments in different sites and climatic regions could provide information which may be incorporated in disease-yield loss simulation models. This could then be used to predict root development and water requirements of diseased plants, and provide a basis for economic use of fungicides and water, and for better disease management programmes.