Plants can vary in their mating systems from completely inbreeding to completely outcrossing, with intermediate forms referred to as mixed mating systems. Arabidopsis lyrata is a strongly outcrossing perennial due to a sporophytic self incompatibility (SI) system. The species occurs in temperate regions of the Northern hemisphere where in Europe its SI system is fully working but around the Great Lakes of North America some populations of A. lyrata show a breakdown in SI. Consequently these North American populations are inbreeding or have a mixed mating system next to outcrossing populations with a working SI system. In this thesis I used North American A. lyrata to investigate the evolutionary consequences involving variation in mating systems. First of all I was interested in the time that populations had been isolated from each other in the past that could explain differences in mating systems. In order to determine whether populations experienced a breakdown of SI independently or whether this originated from a single event I used chloroplast DNA (cpDNA) markers to reveal deep phylogeny and microsatellite markers to determine recent population genetic patterns. The results showed a loss of SI in populations from all three detected cpDNA haplotypes. Microsatellite data showed that predominantly inbreeding populations sharing one of these haplotypes showed high levels of homozygosity and that in all three haplotype lineages self-compatible individuals always had reduced heterozygosity compared to self-incompatible individuals. The data further showed that there had likely been at least two independent postglacial colonization routes to the north of the great lakes. This was consistent with phylogeographic studies of other organisms with limited dispersal such as reptiles and amphibians. The next question was the role of inbreeding depression in the loss of SI. Inbreeding depression is defined as the decline of fitness after an inbreeding event. Inbreeding causes an increase in homozygosity that exposes recessive deleterious mutations, which would normally be sheltered in a heterozygous state, and causes a fitness decline. Individuals experiencing a loss of SI will have higher inbreeding levels and can result in inbreeding depression, which is thought to maintain the SI system. To gain more insight into the role of inbreeding depression in the shift from self-incompatibility to self-compatibility, I conducted an experiment in which I created outcrossed and selfed offspring from self-compatible and self-incompatible mothers from populations with different outcrossing histories. I monitored the offspring for early- and late acting fitness traits like germination rate, growth and time to flowering. I found inbreeding depression in only one late acting fitness trait, the increase in leaves 5 weeks after germination, to be significantly higher for self-incompatible than self-compatible individuals. I also conducted a regression analysis where relative fitness (the ratio of the fitness trait values of selfed and outcrossed offspring) per mother was regressed against population heterozygosity and found a significantly negative regression. This result suggested that individuals from a population with a relatively high heterozygosity suffered more from inbreeding depression than individuals from populations with a relatively low heterozygosity. This indicated that the history of outcrossing of a population, or purging, played an important role in the shift from outcrossing to inbreeding. The detection of inbreeding depression could not be evident by only looking at life history traits under greenhouse conditions. But stressful environmental conditions like a pathogen infection could magnify inbreeding depression. I would expect that predominantly outcrossing populations would have a higher heterozygosity than predominantly inbreeding populations and therefore be able to show a higher fitness when exposed to a pathogen. To test this hypothesis I used four outcrossing and four inbreeding populations, which I infected with the crucifer pathogen Albugo candida and measured relative growth rates (RGR) and monitored resistance rates. The results showed that there were three infection phenotypes: resistant (no signs of infection), partially resistant (only the initially infected parts showed symptoms) and susceptible (symptoms present on the whole plant). The inbreeding populations showed a bimodal distribution of resistance as two populations showed a high rate of resistance and two showed a low rate of resistance. The outcrossing populations showed a much more uniform distribution of resistant individuals with a higher rate of partially infected individuals across populations than inbreeding populations. Resistant and partially resistant individuals did not differ significantly in their RGR from each other but both had a significantly lower RGR than the untreated control group and a significantly higher RGR than the susceptible individuals. This suggested a cost of resistance that was lower than a cost of being susceptible in the presence of a pathogen. There was no effect of mating system on RGR, which was primarily caused by the fact that two inbreeding populations contained a high amount of resistant individuals and an outcrossing population that showed a very low amount of partially resistant and resistant individuals. The difference in resistance to A. candida in A. lyrata differed much more between inbreeding than between outcrossing populations. This suggested that alleles responsible for resistance were concentrated in homozygous form in inbreeding populations and both homozygous and heterozygous form in outcrossing populations. This would mean that mating system plays a role in susceptibility, as resistance genes would be concentrated in certain individuals in inbreeding populations as opposed to a more modal distribution in outcrossing populations. A shift in mating system often has an effect on floral traits, as there is a lack of necessity to attract pollinators. I wanted to test whether these changes were apparent in A. lyrata by comparing pollinator attractants and sexual floral traits between strongly outcrossing and strongly inbreeding populations. I hypothesized that individuals depending on pollinators for outcrossing would show a higher emission of volatiles and floral traits that had evolved to optimize pollen transmission to conspecifics. Autonomously selfing individuals would be independent of pollinators so should show a reduced volatile emission pattern, a floral trait composition that evolved to transmit pollen to their own stigma, and a reduction in floral display compared to outcrossers. My results showed a somewhat contradicting pattern as self-compatible individuals showed higher volatile emission than self-incompatible individuals but self-incompatible individuals showed larger petal size than self-compatible individuals. Pistil height and stamen length were strongly correlated but petal size seemed to co-vary relatively independent from pistil and stamen length. I found no effect of mating system on the evolvement of floral traits to optimize pollen to the stigma and contradicting patterns for pollinator attractant traits. Due to low sample sizes this study turned out to be a pilot study for further research so the results in this study were not conclusive at this stage. Finally I conclude that SI has been lost independently several times and the low observed genetic load in the North American populations compared to the European populations could be responsible for that. There have probably been two independent colonization routes to the North of the Great Lakes following the last glaciation in which a Northern distributed cpDNA haplotype lineage seems to have a lower frequency of SC individuals than a southern cpDNA haplotype lineage.

Stress causes crops to grow below their potential and this affects the vitality and physiological functioning of the plants at all levels leading to reduction in yield. Remote sensing of vegetation is regarded as a valuable tool for the detection and discrimination of stress, especially over large or sensitive regions. The main aim of the research carried out is to assess the potential of remote sensing to detect CO2 leakage from CCS repositories. Further to this, the capability of remote sensing to discriminate between stresses with similar mode of action is explored. Two stress factors were selected for study: (1) elevated concentrations of soil CO2 in the plant root zone and; (2) herbicide, applied at sub-lethal levels. To understand the effects of soil CO2 and herbicide stress on vegetation reflectance, field experiments were carried out on maize (2009) and barley (2010) to investigate the effects of elevated soil CO2 concentrations and of different levels of herbicide treatments on vegetation growth and canopy reflectance using hyperspectral remote sensing techniques. The findings from this study shows that the average canopy reflectance response of maize and barley to CO2 and herbicide stress were increased reflectance in the visible and decrease in near infra-red region as well as changes in the position and shape of the red-edge. The red-edge first-derivative for barley treated with CO2 were composed of maximum peaks between 716 and 730nm and smaller peaks at 699 and 759nm, the control had peaks at 727 and 730 nm, with similar smaller peaks. Barley treated with herbicide had early peaks (a day after treatment) at 697, 715 and 717nm with a shoulder at 759nm, as the experiment progressed (16 days after treatment) the stress became apparent and the peak remained stationary at 730nm, the magnitude decreased to 712nm at late treatment period (35 days after treatment). The control had single peak at 726nm. CO2 treated maize had double peaks at 718 and 730nm, with secondary peaks at 707 and 794nm. Maize treated with herbicide had maximum peaks at 716 and 723nm, with the shoulder at 759 nm; the peaks were similar with the control plots but decreased in magnitude. The main differences between the treatments were in the shape and positions of the peaks that identify the red-edge. The canopy reflectances of the plants were further analysed using the blue (400-550nm) and red (550-750nm). In these regions the main feature of concern is chlorophyll content. The analysis showed that the band depths of controls plants were deeper compared to the stressed plants which is dependent on the stress and crop type. Other vegetation indices used in this study were the Chlorophyll Normalized Difference Index (Chl NDI), the Pigment Specific Simple Ratio for chlorophyll a and b (PSSRa and PSSRb) and the Physiological Reflectance Index (PRI). The results show that they were promising indicators of early stress detection, some indices performed better than others depending on the stress type, species and duration of stress. Chl NDI was sensitive to high soil CO2 concentration in maize and barley, sub-lethal herbicide treatment at 10% - 40% level in barley and was insensitive to both low CO2 in the barley and maize as well as 10% herbicide treatment in maize. PSSRa was a good indicator of early CO2 stress in maize and high CO2 in barley as well as 10- 40% herbicide treatments. PSSRb could detect high CO2 level in maize and barley and all levels (5-40%) of herbicide treatments. PRI was insensitive to 5% herbicide treatment in barley but sensitive to high CO2 in maize at early stage of the experiment. This study has demonstrated that remote sensing approach could be deployed for discriminating between different stressors using their red-edge first-derivative peaks, band depths and vegetation indices.

Marianne North was a major figure within the history of nineteenth-century botanical illustration. She produced a substantial body of botanical paintings as the result of extensive travels to many different parts of the world and was responsible for the founding of a major purpose-built gallery containing a representative collection of her work which still stands today in the Royal Botanical Gardens at Kew. Despite North's percieved importance as a botanical painter, relatively little of any critical/analytical substance has been written about her life and work from an art-historical or scientific perspective. North's place within nineteenth-century visual culture is arguably a contested one, despite having been a major contributor to nineteenth-century botanical painting. North's work therefore remains problematic to both botanists and art historians because it does not conform wholly to the established nineteenth century conventions of either scientific-botanical illustration or art. This thesis will explore the uncertain positioning of North's painting through a close analysis of its relationship to nineteenth and twentieth-century visual practices. In light of this analysis, it will be argued that North's painting does not successfully combine artistic and scientific perspectives, as some have argued, but instead presents an unidentifiable mode of visual representation that shifts uncertainly between art and science, thereby deconstructing any categorical distinction between the two.

The root system is the plant’s principal organ for water and mineral nutrient supply. Root growth follows an endogenous, developmental programme. Yet, this programme can be modulated by external cues which makes root system architecture (RSA), the spatial configuration of all root parts, a highly plastic trait. Presence or absence of nutrients such as nitrate (N), phosphate (P), potassium (K) and sulphate (S) serve as environmental signals to which a plant responds with targeted proliferation or restriction of main or lateral root growth. In turn, RSA serves as a quantitative reporter system of nutrient starvation responses and can therefore be used to study nutrient sensing and signalling mechanisms. In this study, I have analysed root architectural responses of various Arabidopsis thaliana genotypes (wildtype, mutants and natural accessions) to single and multiple nutrient deficiency treatments. A comprehensive analysis of combinatorial N, P, K an S supply allowed me to dissect the effect of individual nutrients on individual root parameters. It also highlighted the existence of interactive effects arising from simultaneous environmental stimuli. Quantification of appropriate RSA parameters allowed for targeted testing of known regulatory genes in specific nutritional settings. This revealed, for example, a novel role for CIPK23, AKT1 and NRT1.1 in integrating K and N effects on higher order lateral root branching and main root angle. A significant contribution to phenotypic variation also arose from P*K interactions. I could show that the iron (Fe) concentration in the external medium is an important driving force of RSA responses to low-P and low-K. In fact, P and K deprivation caused Fe accumulation in distinct parts of the root system, as demonstrated by Fe staining and synchrotron X-Ray fluorescence. Again, selected K, P and Fe transport and signalling mutants were tested for aberrant low-K and/or low-P phenotypes. Most notably, the two paralogous ER-localised multicopper oxidases LPR1 and LPR2 emerged as important signalling components of P and K deprivation, potentially integrating Fe homeostasis with meristematic activity under these conditions. In addition to the targeted characterisation of specific genotype-environment interactions, I investigated novel RSA responses to low-K via a non-targeted approach based on natural variation. A morphological gradient spanned the entire genotype set, linking two extreme strategies of low-K responses. Strategy I accessions responded to low-K with a moderate reduction of main root growth but a severe restriction of lateral root elongation. In contrast, strategy II genotypes ceded main root growth in favour of lateral root proliferation. The genetic basis of these low-K responses was then subsequently mapped onto the A. thaliana genome via quantitative trait loci (QTL) analysis using recombinant inbred lines derived from parental accessions that either adopt strategy I (Col-0) or II (Ct-1). In sum, this study addresses the question how plants incorporate environmental signals to modulate developmental programmes that underly RSA formation. I present evidence for novel phenotypic responses to nutrient deprivation and for novel genetic regulators involved in nutrient signalling and crosstalk.

A novel configuration of vertical downflow constructed wetland was used to treat up to 75 m3 per day of sugar beet processing wastewaters. The 403 m2, two-stage pilot system included planted and unplanted cells of a variety of sand depths (0.15 - 0.4 m) and sand particle size distributions (d10 = 0.07 - 1.2 mm). The hydraulic regime of each bed was also manipulated. Typical beet processing wastewaters contained 235 mg BOD l-1, 45 mg NH4-N l-1, 0.03 mg PO4-P l-1, 16 mg TSS l-1, at pH 8.2 and 29 °C. Overall performance of the pilot system, with respect to BOD, NH4-N, and TSS removal, was similar to, or better than, comparable two-stage vertical flow wetland systems. In vertical flow systems, influent BOD concentrations >600 mg l-1 were coincident with reduced rates of nitrification. Mean BOD removal rate in the pilot system was 38.8 g BOD m-2 d-1, with a mean loading rate of 40.4 g BOD m-2 d-1. The first-order reaction rate for BOD removal was calculated to be 0.369 m d-1 over the whole system. High rates of oxygen transfer and efficient removal of organic solids were seen as the most important factors enhancing BOD removal. Mean NH4-N removal rate in the pilot system was 5.6 g NH4-N m-2 d-1, with a mean loading rate of 7.3 g NH4-N m-2 d-1. The temperature corrected first-order reaction rate for NH4-N removal was calculated to be 0.23 m d-1 over the whole system. Nitrification accounted for between 85% and 99% of TKN removal. Evidence is presented which supports the hypothesis that cycles of assimilation/adsorption and release of NH4-N may play an important role in nitrification mechanisms in vertical flow constructed wetlands. In bed 1, removal of BOD and NH4-N were at their most efficient in the vegetated cell with the deepest (0.21 m), coarsest (d10 = 1.2 mm) sand layer. TSS removal was highest in an unvegetated cell with shallower (0.15 m), finer (d10 = 0.56 mm) sand. In bed 2, removal of BOD, NH4-N, and TSS were all at there most efficient in the vegetated cell with the deepest (0.4 m), coarsest (d10 = 0.1 mm) sand layer. Low influent phosphate concentrations may have limited nitrification rates in the pilot system. The surface area available for biofilm attachment, and media depth, both provided good models of NH4-N removal, whilst cell surface area was more important in solids removal. Media hydraulic conductivity at the beginning of the dosing cycle was five times higher in vegetated cells than in unvegetated cells. After 12 hours of dosing, media particle size distribution became the dominant factor determining media hydraulic conductivity. High influent BOD concentration was more closely associated with cell logging than hydraulic loading, TSS concentration, or BOD or TSS loading. Growth of one provenance of Phragmites australis was limited by phosphate availability. However, populations of nitrifying bacteria were highest in samples of media and roots taken from plots containing this provenance. No correlation was demonstrated between nitrifying bacteria population and root biomass. Water stress caused by high media hydraulic conductivity and inadequate influent distribution resulted in sub-optimal conditions for reed growth in bed 1. The study concludes with details of the proposed design of a full scale system designed to treat up to 1000 m3 d-1 of beet processing effluents.

The protein bodies of the endosperm of the seeds of the castor oil plant Ricinus cannon is contain a variety of storage proteins, along with two lectins, ricin and Ricinus communis agglutinin. Ricin is a heterodimer consisting of an A chain which is toxic to cell-free translation systems, and a B chain which has galactose-binding activity; the whole molecule is toxic to cells and animals by virtue of the ability of the A chain to enzymatically inactivate ribosomes after it crosses the cell membrane, this latter being achieved after binding of the molecule to cell surfaces by the B chain. The agglutinin consists of two ricin-like species linked non-covalently, is divalent, and is not significantly toxic to cells. Previous work on the synthesis of the lectins indicated diet each subunit had its own precursor, each being co-translationally segregated and glycosylated, and assembly of the lectins was thought to occur after transport to the protein bodies. However, the putative B chain precursor was far larger than the mature B chains, and further protein-based evidence Indicated that It contains both A and B chain sequences. The former A chain precursor was Identified as an albumin which contaminated lectin preparations used for raising antisera. The work reported here confirms that the putative B chain precursor contains A and B chain sequences, by means of the cloning of cDNA complementary to lectin-specific mRNA. Clones of nearly full length have been obtained and sequenced, and the precursor is shown to have an N-terminal signal sequence, which is followed by the A chain sequence, and then by the B chain sequence. A linker of 12 amino acids is shown to be present between the two chains. Sequences corresponding to both lectins are reported, and the similarities and differences between them are discussed. The sequences are placed into context by comparison with other plant nucleotide and protein sequences. Literature on the castor bean lectins is reviewed, and the uses of the clones are discussed, with special reference to their possible use in immunotoxins for cancer therapy.

Crop wild relatives are important for agriculture due to the genetic richness they possess. They have been used in plant breeding to develop high yielding varieties; varieties with improved resistance to biotic and abiotic stresses, and enhanced nutritional content. Securing their conservation in the long-term is critical to enable the continuous development of crops’ varieties able to respond to future challenges. The work presented in this thesis is a contribution to the effort of understanding the ex situ conservation gaps of crop wild relatives, their expected response to climate change and their needs for conservation. Methods used in this thesis include species distribution modelling, gap analyses, a case study assessing the preliminary IUCN Red List categories, species distribution projections onto future climate change scenarios, and an estimation of the global value of crop wild relatives based on their likelihood of being used in plant breeding, and the contributions of their associated crops to human diets and agricultural production systems. The methods used here can be applied to more crop genepools for global conservation planning, and can also be adapted for analysis at the regional and national level. The results presented here are being used to improve the conservation of the wild relatives of 29 crops.

DNA topology is dependent on axis proteins during eukaryotic cellular processes. Chromosome axis organization is complex during meiosis, when DNA repair needs to be coordinated with homology searching and synapsis. Although roles for the axis component Topoisomerase II (TOPII) and the post-translational modification (PTM) of ASY1 homologues during meiosis have previously been reported, few studies have been performed in plants. The aim of this thesis is to investigate the effects of these proteins on meiotic DNA topology and axis morphology, and their implications for homologous recombination (HR) in Arabidopsis thaliana. Using a combination of cytogenetic and molecular techniques, we show the role of PTM of ASY1 differs from that of its budding yeast orthologue. Phosphorylation of a plant specific set of residues in ASY1 affected chiasmata distribution. Analysis of the first TOPII mutants described in plants also revealed a link with HR. Chromosome replication, condensation and segregation phenotypes were consistent with previous studies of TOPII in other organisms. For the first time, we report that TOPII and chromosome movement collaborate in interlock resolution during meiosis, confirming predictions from decades ago. Overall, these investigations have revealed new roles for the axis in plant meiosis, which could have potential for crop breeding.

The limited range of commercial timber species in Great Britain has led the forestry sector to consider wider planting of other species. This research addresses wood properties, particularly relevant to structural timber, of noble fir, Norway spruce, western red cedar and western hemlock in Great Britain. Sampling covered three regions to get a representative sample for the country. Bending stiffness, bending strength, density and twist distortion from drying were assessed. The results showed high yields of C16 for all these species, with Norway spruce and western hemlock performing comparatively well to typical British-grown Sitka spruce. Within this dataset, variation of mechanical properties within trees was more important than differences between species. Strength and stiffness increased with age, whereas density followed different trends in the inner and outerwood. The three properties were modelled based on ring number. The use of acoustic techniques to assess the mechanical properties of wood (in particular stiffness), was investigated in clears, sawn timber, logs and trees. The best results were found combining density with acoustic velocity in sawn timber. The use of acoustic techniques in standing trees was more reliable measuring distances of two or three metres, rather than the commonly used one metre; most likely due to a change in the wave propagation. Tree architecture was studied for timber production and quality. Noble fir described the highest merchantable taper profile. Branchiness varied importantly with height in the stem, and models were built for number, diameter and angle of branches. Western red cedar and western hemlock had fewer but thicker branches compared to noble fir and Norway spruce. Future work should produce grading machine settings and address the variation of timber quality and merchantability under different silvicultural regimes. This thesis concludes that the four species investigated can contribute to diversity the timber industry in Great Britain.

Global change is happening at a staggering pace and the impact that change is having in the loss of plant biodiversity is unprecedented. The latest reports on the state of the world’s plants indicate that they face intensifying threats and biodiversity loss on a global scale. However, this rapid global change is also bringing extraordinary technological developments to all scientific fields. Earth Observation by Remote Sensing is undergoing a fast expansion and its capacity to monitor and analyse global environmental changes and their impact in biodiversity is ever growing. This research analyses the current and potential role of Earth Observation in the conservation of plant diversity, identifying the latest technological developments with the greatest potential use in this field. Looking into a plant conservation organisation and through a series of case studies covering a range of spatial and temporal scales, this research brings the latest Remote Sensing technology to the plant conservation community. From collecting and processing very high resolution data for local conservation projects to help determine conservation status of a country’s unique ecosystem to tracking and reporting on global plant conservation targets this research demonstrates that Remote Sensing is instrumental for addressing the observation needs of the plant conservation community.