Thesis (PH. D)--University of Chicago, 1922. / "Private edition, distributed by the University of Chicago Libraries, Chicago, Illinois." "Contributions from the Hull Botanical Laboratory 299." "Reprinted from the Botanical gazette, Vol. LXXIV, No. 4, December, 1922." Literature cited": p. 368.

The microecosystems in the leaves of the pitcher plant, Sarracenia purpurea, were studied over a thirty day period. These plants were kept out of doors. One of these plants was later brought into the laboratory and four leaves were studied concurrently with four tubes. These studies were intended to show differences, if any, between leaves studied in the field and those in the laboratory, and between the leaves and an artificial environment. Organisms in all of these vessels were counted and their total biomass and oxygen consumption graphed. Three of the larger organisms found were typical of this species of pitcher plant, one through its entire life cycle and the other two for their larval stages. An interesting finding was that the alga, Microthamnion, seems to inhibit the growth of Tetrahymena, probably due to some extrametabolite. Paramecium was apparently excluded from all leaves in the field. The leaves of the pitcher plant were found to be ideal for the field and laboratory investigation of ecological forces due to their natural occurrance, small size, and rapid turnover of organisms. / Science, Faculty of / Zoology, Department of / Graduate

Weedy rice is a persistent weed of cultivated rice (Oryza sativa ) fields worldwide, which competes with the crop and drastically reduces yields. Within the US, two main populations of genetically differentiated weedy rice exist, the straw-hulled (SH) group and the black-hulled awned (BHA) group. Current research suggests that both groups are derived from Asian cultivated rice. However, the weeds differ from the cultivated groups in various morphological traits. My research focus is on the genetic basis of two such traits: seed shattering ability and differences in flowering time. The persistence of weedy rice has been partly attributed to its ability to shatter (disperse) seed prior to crop harvesting. I have investigated the shattering phenotype in a collection of US weedy rice accessions and find that all US weedy rice groups shatter seeds easily. Additionally, I characterized the morphology of the abscission layer at the site where seed release occurs and find that weeds begin to degrade their abscission layers at least five days prior to wild plants. I also assessed allelic identity and diversity at the major shattering locus, sh4, in weedy rice and find that all cultivated and weedy rice share similar haplotypes at sh4 . These haplotypes contain a single derived mutation associated with decreased seed shattering during domestication. The combination of a shared cultivar sh4 allele and a highly shattering phenotype suggests that US weedy rice have re-acquired the shattering trait after divergence from their crop progenitors through alternative genetic mechanisms. Additionally, my investigation into flowering time in weedy rice shows that weed populations differ in their flowering times. I also assessed allelic identity and diversity at two genes involved in the transition to flowering, Hd1 and Hd3a, and again found haplotype sharing between weeds and cultivars with Hd1 only accounting for some of the flowering time differences between weeds. In order to locate genomic regions containing additional candidate genes I conducted a QTL mapping study on two F2 populations derived from crosses of weedy rice with cultivated rice. My results show sharing of QTL for flowering time between populations, yet lack of sharing of QTL for shattering.

In the Northeast, powdery mildew (PM), caused by Uncinula necator (Schewein.) Burrill is one of the most important grape diseases in terms of economic loss. It has been established that cultural practices, including proper sanitation, are the first step in preventing disease, and fungicide sprays are regularly applied to manage the disease. Currently, fungicides that successfully control PM have a strong potential to develop pathogen resistance, and alternatives with low risk of initiating resistance are not as effective in disease control. Our approach to this emerging resistance dilemma is to combine a systemic acquired resistance inducer (salicylic acid and potassium phosphate) with a topical fungicide, potassium bicarbonate. To determine each treatment’s level of efficacy, multiple aspects of infection and defense were quantified and qualified, including germination rate, lethality, lignin formation, callose formation, and vine and leaf growth. The first trial showed potassium bicarbonate and the standard fungicide (Pristine) inhibited the most germination and was most lethal against PM conidia. Potassium phosphate had little effect on germination and conidia death, and when combined with bicarbonate there was no different than the water control. In the second trial, the biorational mixture was able to reduce the level of powdery mildew infection significantly more than the other compounds, including the commercial standard. The salicylic acid and potassium bicarbonate mix may be successful enough to use in the vineyard to determine if the compound can tolerate field conditions with the same level of efficacy.

The sooty blotch and flyspeck (SBFS) complex causes blemishes on apples in humid, temperate growing regions worldwide. In contrast to flyspeck etiology, the many species of fungi causing sooty blotch (SB) have not been well studied. The first set of objectives in this study was to use PCR to identify SB species isolated from apples and selected reservoir hosts in the northeastern United States, and to identify patterns of species distribution on hosts and among sites. Results indicated that Geastrumia polystigmatis was the predominant species on apples, whereas Peltaster species were more common on reservoir hosts. Species distribution varied among sites. Phylogenetic analysis of 54 G. polystigmatis isolates revealed little genetic variability in the ITS region. The second set of objectives involved investigating the response of G. polystigmatis to changes in nutrition, temperature, heat stress, and relative humidity, and in vitro responses of G. polystigmatis and Peltaster fructicola to fungicides commonly used in orchards. Observation of growth on half-strength potato dextrose agar, malt extract agar, and 2% water agar revealed that mycelial growth of G. polystigmatis was thicker and more melanized in the presence of readily available carbohydrates. Temperature range experiments demonstrated that the optimum temperature for growth was approximately 24ºC. The fungus was able to survive exposure to 32ºC for at least one week, 37ºC for at least 48 hours, and 42ºC for at least 8 hours. Growth was optimum at 99-100% relative humidity. Isolates of P. fructicola were very sensitive to thiophanate-methyl, mancozeb, cyprodinil, penthiopyrad, fenbuconazole, and trifloxystrobin. Isolates of G. polystigmatis were sensitive to thiophanate-methyl and cyprodinil, but significantly less sensitive to all other fungicides than P. fructicola. The addition of salicylhydroxamic acid to trifloxystrobin significantly reduced growth of P. fructicola, but not that of G. polystigmatis. This study represents the first in-depth investigation into the identity of species causing SB in the Northeast, the basic biology of G. polystigmatis, and the fungicide sensitivities of G. polystigmatis and P. fructicola.

No description available.

The propagation of wild-type virus and a transgenic viral vector was examined in cultured plant cells to identify factors affecting viral infection of and accumulation in cultured cells and to determine if viral vectors could be used to facilitate the expression of heterologous proteins in vitro. Tobacco mosaic virus (TMV) accumulation was examined in Nicotiana tabacum and N. benthamiana suspension and hairy root cultures. TMV accumulation was superior in N. benthamiana hairy roots. Hairy roots were infected by adding TMV to the liquid culture medium at the same time as root inoculation. Hairy root growth was unaffected by virus infection. The distribution of virus within root mats from shake-flask grown cultures was non-uniform and the concentration of virus accumulated in replicate cultures was variable. When N. benthamiana hairy roots were infected using 1.5 μg mL-1 TMV, the average maximum concentration of virus accumulated in the biomass was 1.6 ?? 0.25 mg g-1 dry weight, or 15-fold lower than in TMV infected N. tabacum leaves. Virus coat protein accumulated to a level of (26 ?? 10)% total soluble protein in the hairy roots. Inoculum virus concentration and the medium in which infection was performed affected the virus yield and the percentage of inoculated cultures that accumulated virus. When cultures were inoculated using 9.0 μg mL-1 TMV, virus accumulated in the biomass to 4.2 ?? 0.60 mg g-1 dry weight. Proportional scale-up of hairy root infection in shake flasks did not result in constant virus concentrations in the scaled cultures. TMV accumulation in bioreactor-infected and -grown hairy roots was poor. N. benthamiana hairy roots were infected with a TMV-based vector (30B-GFPC3) that encoded Cycle 3 green fluorescent protein (GFP). TMV-GFPC3 was (260 ?? 140)-fold less infectious than TMV as measured by local lesion assays. Propagation of TMV-GFPC3 could not be confirmed using mass balance. GFP was not detected in the infected hairy roots or the culture medium. Hairy roots represent a potentially viable culture-based system for the in vitro production of virus and virus products when field-grown agricultural systems do not adequately address issues of containment or product safety.

The purpose of this study is to provide effective strategies and suggestions of models for self-study tools suitable to fifth and sixth graders, by leading fifth and sixth grade students to establish hierarchal polycalve and dichotomous plant keys through observation, description, comparison, and synthesis in the activity-based courses of observation and classification of plant leaves, and by analyzing children¡¦s level of form cognition and capability of classification via children¡¦s observation records, the taxonomy model, and the contents of keys. In addition, this study aimed to realize students¡¦ learning difficulties regarding plants through their work, comments, interviews and the quantitative data. Also, by means of the reforms to relevant teaching methods and teaching material, this study showed how students could have a better learning experience with plants. Based on the quantitative and qualitative data, the major findings of this study are summarized as follows: 1. Observation capability: The tactile sense was the important medium by which primary school students explore the world, with leaf texture in the highest observational record. Visually, students had better observation capabilities for characteristics of larger-scale forms. 2. Classification model: The standards that students most commonly used were ¡§color,¡¨ ¡§vein,¡¨ ¡§margin,¡¨ and ¡§shape.¡¨ The results of classification were more consistent with the last three standards, and the results of classification in groups were especially similar when proper morphological terms were used to express classified items. It was thus clear that morphological terminology can help students to classify plants. 3. Plant key: When devising the plant key suited to primary school students, it was better to use the polyclave method in one searching stage to show different characteristics in the same region, and to use the dichotomous method to show similar characteristics that are difficult to distinguish. When expressing options using clip art and proper terms simultaneously, students exhibited the best comprehension. 4. Studying attitude According to the quantitative data, activity-based courses only raised students¡¦ learning interest a little. However, interviews and sharing of study experiences revealed that learning by doing can improve their observational capabilities and learning memories. In addition, students would be more concerned for the relationship between human beings and the environment.

Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 197-236). Also available in electronic version. Access restricted to campus users.

The propagation of wild-type virus and a transgenic viral vector was examined in cultured plant cells to identify factors affecting viral infection of and accumulation in cultured cells and to determine if viral vectors could be used to facilitate the expression of heterologous proteins in vitro. Tobacco mosaic virus (TMV) accumulation was examined in Nicotiana tabacum and N. benthamiana suspension and hairy root cultures. TMV accumulation was superior in N. benthamiana hairy roots. Hairy roots were infected by adding TMV to the liquid culture medium at the same time as root inoculation. Hairy root growth was unaffected by virus infection. The distribution of virus within root mats from shake-flask grown cultures was non-uniform and the concentration of virus accumulated in replicate cultures was variable. When N. benthamiana hairy roots were infected using 1.5 μg mL-1 TMV, the average maximum concentration of virus accumulated in the biomass was 1.6 ?? 0.25 mg g-1 dry weight, or 15-fold lower than in TMV infected N. tabacum leaves. Virus coat protein accumulated to a level of (26 ?? 10)% total soluble protein in the hairy roots. Inoculum virus concentration and the medium in which infection was performed affected the virus yield and the percentage of inoculated cultures that accumulated virus. When cultures were inoculated using 9.0 μg mL-1 TMV, virus accumulated in the biomass to 4.2 ?? 0.60 mg g-1 dry weight. Proportional scale-up of hairy root infection in shake flasks did not result in constant virus concentrations in the scaled cultures. TMV accumulation in bioreactor-infected and -grown hairy roots was poor. N. benthamiana hairy roots were infected with a TMV-based vector (30B-GFPC3) that encoded Cycle 3 green fluorescent protein (GFP). TMV-GFPC3 was (260 ?? 140)-fold less infectious than TMV as measured by local lesion assays. Propagation of TMV-GFPC3 could not be confirmed using mass balance. GFP was not detected in the infected hairy roots or the culture medium. Hairy roots represent a potentially viable culture-based system for the in vitro production of virus and virus products when field-grown agricultural systems do not adequately address issues of containment or product safety.