Petrol and ethanolic extracts of six asteraceous weeds were added to artificial diet and screened for inhibition of larval growth on variegated cutworm, Peridroma saucia (Hbn.). Petrol and ethanolic extracts of Artemisia tridentata and Chamomilla suaveolens and ethanolic extracts of Chrysothamnus nauseosus and Centaurea diffusa were highly inhibitory at five times the naturally occurring concentrations. The two C. suaveolens extracts and the ethanol extract of A. tridentata were active at the natural concentration (100%) and were further examined at 20, 40, 60, and 80% of this level. Inhibition of larval growth was directly related to concentration for each of the three extracts tested. EC₅₀'S (effective concentration to inhibit growth by 50% relative to controls) for the three extracts were 36-42% of the naturally occurring level in the plants. Nutritional indices were calculated for second instar P. saucia feeding on the active ethanolic A. tridentata extract and the petrol extract from C. suaveolens. The relative growth rate (RGR) of P. saucia larvae fed the ethanolic extract of A. tridentata in artificial diet was significantly lower than that in larvae fed diet with the petrol extract of C. suaveolens and larvae on control diet. Dietary utilization was significantly lower for larvae fed the A. tridentata extract. Results of a field trial indicated that a single treatment of A. tridentata extract at the equivalent of 0.2 g/ml could protect cabbage significantly better than the carrier solvent (30% aq ethanol) or distilled water as measured by a visual damage estimate. An insecticide standard, deltamethrin (17.9 µg/1 with 0.4% Superspred TM ), suppressed pest damage significantly better than the A. tridentata-extract treatment. A residual oviposition deterrency to Pieris rapae was found in the field results. Caged experiments in the laboratory confirmed the contact oviposition deterrency of the A. tridentata extract at 0.2 g/ml. Offspring of field-collected P. saucia larvae grew 2.5-fold heavier than larvae from the laboratory colony. However, diet with the A. tridentata extract inhibited both field-collected and laboratory reared saucia larvae equally when compared to their respective controls fed untreated diet. In summary, these results indicate the potential benefit of using specific unrefined plant extracts for growth inhibitors and oviposition deterrents against insect pests. The contribution of individual phytochemicals in the A. tridentata ethanolic extract to growth inhibition or oviposition deterrency is currently speculative. / Land and Food Systems, Faculty of / Graduate

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Tsang, Kwok On. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 147-165). / Abstracts in English and Chinese. / ACKNOWLEDGMENTS --- p.i / ABSTRACT --- p.ii / TABLE OF CONTENTS --- p.vii / LIST OF FIGURES --- p.xiv / LIST OF TABLES --- p.XX / Chapter CHAPTER 1 --- Introduction --- p.1 / Chapter 1.1 --- "Mikania micrantha, a problematic weed around the world" --- p.1 / Chapter 1.1.1 --- Current situation --- p.1 / Chapter 1.1.2 --- Properties of M micrantha --- p.2 / Chapter 1.1.3 --- Control methods of M. micrantha --- p.6 / Chapter 1.1.3.1 --- Manual removal --- p.6 / Chapter 1.1.3.2 --- Chemical control methods --- p.7 / Chapter 1.1.3.3 --- Biological control methods --- p.7 / Chapter 1.2 --- Parasitic plants --- p.10 / Chapter 1.2.1 --- Introduction --- p.10 / Chapter 1.2.2 --- Modes of parasitism --- p.10 / Chapter 1.2.3 --- Biology of Cuscula spp. --- p.13 / Chapter 1.2.3.1 --- Seed germination --- p.15 / Chapter 1.2.3.2 --- I lost detection and parasitism --- p.17 / Chapter 1.2.3.3 --- Reproduction --- p.19 / Chapter 1.2.3.4 --- Impacts on hosts --- p.21 / Chapter 1.3 --- Previous researches on the control of M. micrantha by cuscuta --- p.23 / Chapter 1.4 --- Research significance --- p.25 / Chapter 1.4.1 --- Knowledge gap --- p.25 / Chapter 1.4.2 --- Experimental objectives and significance --- p.26 / Chapter 1.4.3 --- Thesis layout --- p.28 / Chapter CHAPTER 2 --- Germination biology of Cuscuta japonica --- p.29 / Chapter 2.1 --- Introduction --- p.29 / Chapter 2.2 --- Materials and Methods --- p.34 / Chapter 2.2.1 --- "Cuscuta seeds collection, treatment and storage" --- p.34 / Chapter 2.2.2 --- Imbibition --- p.35 / Chapter 2.2.3 --- Germination --- p.35 / Chapter 2.2.4 --- Emergence --- p.36 / Chapter 2.2.5 --- Germination dynamics --- p.37 / Chapter 2.2.6 --- Statistical analysis --- p.37 / Chapter 2.3 --- Results --- p.38 / Chapter 2.3.1 --- Imbibition test --- p.38 / Chapter 2.3.2 --- Germination test --- p.40 / Chapter 2.3.3 --- Emergence test --- p.42 / Chapter 2.3.4 --- Germination dynamic --- p.43 / Chapter 2.4 --- Discussion --- p.44 / Chapter 2.4.1 --- Seed dormancy --- p.44 / Chapter 2.4.2 --- Germination requirements --- p.48 / Chapter 2.4.3 --- Emergence ability --- p.51 / Chapter 2.4.4 --- Germination dynamics --- p.52 / Chapter 2.5 --- Conclusions --- p.54 / Chapter CHAPTER 3 --- Life cycle of C. japonica --- p.55 / Chapter 3.1 --- Introduction --- p.55 / Chapter 3.2 --- Materials and Methods --- p.57 / Chapter 3.2.1 --- Site description --- p.57 / Chapter 3.2.2 --- Data collection --- p.62 / Chapter 3.3 --- Results --- p.64 / Chapter 3.4 --- Discussion --- p.71 / Chapter 3.4.1 --- Life cycle of C. japonica in Dragon's Back and its implication --- p.71 / Chapter 3.4.2 --- Life cycle of (\ japonica in Shan Tong Road and Yau King Lane --- p.74 / Chapter 3.5 --- Conclusions --- p.80 / Chapter CHAPTER 4 --- Effect of infestation by C. japonica and C. campcstris on the growth of M. micrantha --- p.82 / Chapter 4.1 --- Introduction --- p.82 / Chapter 4.2 --- Materials and Methods --- p.84 / Chapter 4.2.1 --- Sites description --- p.84 / Chapter 4.2.2 --- Plant materials --- p.85 / Chapter 4.2.3 --- Infestation --- p.86 / Chapter 4.2.4 --- Harvest of plant materials --- p.87 / Chapter 4.2.5 --- Chlorophyll extraction and concentration determination --- p.87 / Chapter 4.2.6 --- Measurements --- p.88 / Chapter 4.2.7 --- Statistical analysis --- p.89 / Chapter 4.3 --- Results --- p.89 / Chapter 4.3.1 --- "Changes in length of stem, leaf size and number of leaves" --- p.89 / Chapter 4.3.2 --- Changes in biomass of hosts and parasites --- p.94 / Chapter 4.3.3 --- Changes in the chlorophyll concentration --- p.97 / Chapter 4.4 --- Discussion --- p.99 / Chapter 4.2.1 --- Cuscuta as a strong sink to the host --- p.99 / Chapter 4.2.2 --- Growth of cuscuta and comparison of its influence on M micrantha --- p.104 / Chapter 4.5 --- Conclusions --- p.106 / Chapter CHAPTER 5 --- Effect of C. japonica infestation on the activities of anti-oxidative enzymes of M. micrantha --- p.107 / Chapter 5.1 --- Introduction --- p.107 / Chapter 5.2 --- Materials and Methods --- p.110 / Chapter 5.2.1 --- Plant materials --- p.110 / Chapter 5.2.2 --- Infestation --- p.111 / Chapter 5.2.3 --- Harvest of plant materials --- p.111 / Chapter 5.2.4 --- Measurement of enzyme activity --- p.112 / Chapter 5.2.4.1 --- Reagent preparation --- p.112 / Chapter 5.2.4.2 --- Extraction method --- p.112 / Chapter 5.2.4.3 --- Enzyme activity determination --- p.113 / Chapter 5.3 --- Results --- p.115 / Chapter 5.3.1 --- SOD activity --- p.115 / Chapter 5.3.2 --- CAT activity --- p.116 / Chapter 5.3.3 --- POD activity --- p.117 / Chapter 5.4 --- Discussion --- p.1 19 / Chapter 5.4.1 --- Changes in SOD activity --- p.120 / Chapter 5.4.2 --- Changes in CAT and POD activity --- p.122 / Chapter 5.4.3 --- Effects and implications of the changes in the activities of the anti-oxidative enzymes --- p.123 / Chapter 5.5 --- Conclusions --- p.124 / Chapter CHAPTER 6 --- Host range of C. japonica --- p.126 / Chapter 6.1 --- Introduction --- p.126 / Chapter 6.2 --- Materials and methods --- p.130 / Chapter 6.2.1 --- Field study --- p.130 / Chapter 6.2.1.1 --- Site description --- p.130 / Chapter 6.2.2.2 --- Data collection --- p.130 / Chapter 6.2.2 --- Greenhouse study --- p.131 / Chapter 6.2.2.1 --- Site description --- p.131 / Chapter 6.2.2.2 --- Plants selection --- p.131 / Chapter 6.2.2.3 --- Experimental setup --- p.132 / Chapter 6.2.2.4 --- Statistical analysis --- p.133 / Chapter 6.3 --- Results --- p.133 / Chapter 6.3.1 --- Field study --- p.133 / Chapter 6.3.2 --- Greenhouse study --- p.137 / Chapter 6.4 --- Discussion --- p.138 / Chapter 6.4.1 --- Field study --- p.138 / Chapter 6.4.2 --- Greenhouse study --- p.140 / Chapter 6.4.3 --- Implications on application --- p.141 / Chapter 6.5 --- Conclusions --- p.143 / Chapter CHAPTER 7 --- General Summary and Conclusions --- p.144 / REFERENCES --- p.147 / APPENDIX A --- p.166 / APPENDIX B --- p.173 / APPENDIX C --- p.176

Indiana University-Purdue University Indianapolis (IUPUI) / Drought and cold conditions are among the major factors affecting plant growth and crop production globally. Dehydrins are group II late embryogenesis abundant (LEA) proteins characterized by a conserved K-region (EKKGIMDKIKEKLPG consensus sequence) that accumulate in many plants during drought, low temperature, and high salinity to confer stress tolerance. While it has been demonstrated that overexpression of dehydrins improves cold tolerance in various crop plants, the mechanism leading to cold tolerance is still unclear. Previous studies reported phosphorylation of AtERD14 dehydrin by casein kinase II (CKII) led to an increase in calcium binding activity. Mass spectroscopy analysis determined that the phosphorylation was localized to a poly-serine (S) region. To further characterize the S-region, GST fused ERD14 mutants were created via site-directed mutagenesis and deletion of either the amino or carboxyl ends of ERD14 via the QuickChange® Multi Site-Directed Mutagenesis Kit. Phosphorylation of purified mutant proteins by CKII was analyzed via gel shift and direct phosphorylation assays. The effect of phosphorylation on calcium binding activity was also analyzed. Results showed the serine (S) residue at position 83 was crucial to phosphorylation-dependent molecular mass shift and Ca2+-binding activities followed by the serine residue at position 85 in importance. Mutation of serines at positions 83, 84, and 85 completely eliminated the phosphorylation-dependent gel shift and calcium binding. Examination of truncation mutants determined the N-terminal was an important region for protein structure modification and phosphorylation ability leading to Ca2+ activation. Calcium binding activity of the truncated mutants indicated the calcium binding site was localized in the region between the S-region and the K-region near the C-terminal end. To characterize the acidic dehydrins contribution to cold tolerance in vivo, three single (erd10, erd14, cor47) knockouts (KOs) were characterized. Single KOs produced no cold sensitive phenotype indicating the need for multiple dehydrin KOs in Arabidopsis in order to potentially produce a cold sensitive phenotype.