Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 147-160). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Chicago, Dept. of Ecology and Evolution, December 2002. / Includes bibliographical references. Also available on the Internet.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 95-100). Also available in electronic version.

Typescript, etc. / Digitized by Kansas State University Libraries

<p> Terrestrial and oceanic biomass carbon sinks help reduce anthropogenic CO₂ emissions and mitigate the long-term effect of increasing atmospheric CO₂. Woody plants have large carbon pools because of their long residence time, however N availability can negatively impact tree responses to elevated CO₂. Seasonal cycling of internal N in trees is a component that contributes to fitness especially in N limited environments. It involves resorption from senescing leaves of deciduous trees and storage as vegetative storage proteins (VSP) in perennial organs. <i>Populus </i> is a model organism for tree biology that efficiently recycles N. Bark storage proteins (BSP) are the most abundant VSP that serves as seasonal N reserves. Here I show how poplar growth is influenced by N availability and how growth is influenced by shoot competition for stored N reserves. I also provide data that indicates that auxin mediates BSP catabolism during renewed shoot growth. Understanding the components of N accumulation, remobilization and utilization can provide insights leading to increasing N use efficiency (NUE) of perennial plants.</p>

The purpose of this work was to provide an integrated solution to the problem of optimising plant production flow while also optimising allergen control. That is, to improve process flows, improve equipment utilisation, reduce work-in-process (WIP) inventory, and reduce unnecessary movement of stock while also optimising allergen control in the area under investigation. Process improvement introduced to the plant during the project resulted in a 7% savings on labour cost, reduction in plant variability, reduced allergen cross contamination risk, reduced WIP, reduction of consumables, and increased equipment utilisation. Discrete event simulation software has been used to determine the preferred strategy for implementing allergen control in a food producing FMCG plant. Three preferred allergen control strategies were identified by the Company, which were then modelled and analysed for impact on labour cost. Furthermore, a study was done on the effect of plant layout on labour cost.

Three different aspects of plant adaptations to ecological interactions are examined. The first one is in the area of plant breeding systems. The adaptations investigated in this study involved interactions between male gametes competing for fertilizations on the plant Phormium tenax, an agavoid of New Zealand. In this system I discovered a new type of self incompatibility that depends on the levels of competition among self- and cross-pollinated fruits. This mechanism is parallel to cryptic self-incompatibility in which individual self-pollen grains are not as successful as cross-pollen when competing in the same pistil. The competition-dependent abscission of self-pollinations considered here, however, operates at the level of whole flowers. This form of self-incompatibility may allow a high level of outcrossing to be achieved while it assures seed set when pollinations are scarce. The second case focuses on the interaction between a plant of the genus Bursera and its herbivorous crysomelid beetle Blepharida. This Bursera produces terpenes that are stored in networks of canals that run throughout the leaves and the cortex of the stem. When damaged, there is often an abundant release of resins. Blepharida larvae have developed the behavioral adaptations to overcome the secretive canals of Bursera. Before feeding on the leaves they cut the leaf-veins, interrupting the flow of terpenes. By documenting the growth and survival costs of being on plants of different response strength I was able to show that canals can effectively decrease herbivory even against this specialized vein-cutting insect. The handling time involved in blocking the canals slows down larval growth, delays pupation and increases the risk of predation. Chapter III examines a more complex interaction among plants that produce extrafloral nectaries, ants, and homopterans. An alternative model to explain the function of extrafloral nectaries is proposed. According to this hypothesis, the function of these glands is not to attract ants for defense, but to distract them from tending homopterans by giving them a free source of sugar. Different sources of evidence that support this model are discussed.

Nectria haematococca mating population (MP) VI has a cytochrome P450 which confers tolerance to the pea phytoalexin pisatin. This enzyme, termed pisatin demethylase (PDA), detoxifies pisatin and is a virulence factor on pea. PDA is on a 1.6 Mb conditionally dispensable chromosome, and PDA is in a cluster of three other genes involved in pea pathogenicity. Analysis of the PEP cluster suggests it may have been acquired by horizontal gene transfer (HGT). Isolates lacking PDA are still more tolerant of pisatin than other closely related fungi and a "nondegradative" tolerance mechanism was demonstrated previously that might be responsible for this tolerance.ABC transporter, NhABC1, was identified as the gene responsible for this tolerance, fulfilling the major goal of this dissertation. NhABC1 is induced by pisatin and NhABC1 mutants are reduced in virulence on pea to a similar degree as PDA mutants. However, isolates lacking both PDA and NhABC1 are essentially non-pathogenic on pea and are more sensitive to pisatin than either single mutant, demonstrating these two proteins are the major mechanisms responsible for pisatin tolerance. A second ABC transporter in N. haematococca (NhADP1) was also shown to be involved in virulence on pea, however its function in planta remains unknown. The final part of this dissertation concerns a partial analysis of the genome sequence of N. haematococca MPVI. The genome encodes 68 ABC transporters, some of which were in multiple copies when compared to other fungal genomes. This finding led to a whole genome approach to identify extra copies of genes, which are in single copies in the most closely related sequenced fungus, Gibberella zeae. When a comparison between the orthologs found in both genomes and the unique genes found in N. haematococca was made, the results suggest HGT may have shaped the genome of N. haematococca. Several lines of evidence supports this: the large genome size of N. haematococca, the unexpected phylogenetic relationship of the extra copies of genes, the enrichment of the unique genes on dispensable portions of the genome, and a difference between codon usage and GC content of the orthologs versus the unique genes.

During maize endosperm development, cells switch from mitotic into endoreduplication cell cycles, concomitant with the differentiation of starchy endosperm cells. The identity and role of cyclins and cyclin-dependent kinases (CDKs) that control these cell cycles are poorly understood. I identified and characterized maize cyclins of the D- (CYCD2;1 and CYCD5;1) and A1-types (CYCA1;3) that are expressed in endosperm. CYCA1;3 RNA decreased sharply as the endosperm transitioned from the mitotic to the endoreduplication stage, whereas CYCD2;1 and CYCD5;1 transcripts declined gradually. Polyclonal antibodies against CYCA1;3, CYCD5;1, and CYCD2;1 and a B-type homologue, CYCB1;3, were used to characterize cyclin protein accumulation, the associated CDK activity, and spatial localization of cyclins in endosperm. Except for CYCA1;3, cyclin protein levels were nearly constant or decreased slightly throughout development. CDK activity associated with CYCA1;3 was most abundant 7 days after pollination (DAP), while that associated with CYCB1;3, CYCD2;1 and CYCD5;1 peaked at 11 DAP. CYCA1;3 appeared to be most abundant in the cytoplasm of non-endoreduplicating cells. CYCB1;3 and CYCD2;1 were found throughout the endosperm, while CYCD5;1 was mostly localized in aleurone and subaleurone cells. Stability assays using in vitro-synthesized cyclins showed that CYCA1;3, CYCB1;3, CYCD2;1 and CYCD5;1 were degraded to a large extent via the proteasome in mitotic but not in endoreduplicating endosperm extracts. The results suggest that cyclin proteolysis may not play a major role in controlling endoreduplication cell cycles in maize endosperm. I identified and characterized maize CDKs of the A- (CDKA;3) and B- (CDKB1;1 and CDKB2;1) types that are expressed in developing endosperm. Their transcripts were more abundant during the mitotic than the endoreduplication stage of development. Polyclonal antibodies that specifically recognized CDKA;3 and CDKA;1, and CDKB1;1, were obtained. A-type CDK protein levels were nearly constant, while those of CDKB1;1 decreased abruptly during endosperm development. CDKB1;1 extracted from 9-DAP endosperm bound p13suc1 in vitro, suggesting that CDKB1;1 contributes to mitotic CDK activity at early stages of endosperm development. In co-expression experiments in Drosophila S2 cells, CDKA;1 and CDKA;1 formed catalytically active complexes with CYCD2;1 and inactive complexes with CYCB1;3 and CYCD5;1.

No description available.