Natural reedbed habitat in the UK has suffered severe declines in the last few centuries. With only 5,000 ha remaining and much of what remains is highly fragmented and degraded. The loss and fragmentation of reedbed habitat in the UK has had a profound effect on the species associated with it. Constructed reedbeds are artificial wetlands dominated by Phragmites australis designed to treat wastewater. They have been widespread in the UK because they are perceived to be a green solution, but their conservation value has never been assessed. This project aims to determine how they contribute to biodiversity. This study surveyed 24 sites, 12 constructed sites paired to 12 natural sites, for small mammals, moths and stem-dwelling invertebrates. Results show that there is no difference between constructed and natural sites. The indication is that constructed reedbeds, despite their small size, young age and contamination, are just as diverse as natural reedbeds. The implications of this for reedbed and wetland conservation are potentially substantial. There are over 1,000 constructed reedbeds in the UK that are just as diverse as their natural equivalents, which could provide connectivity across unsuitable agricultural and urban landscapes.

The aquatic macrophyte Crassula helmsii is a non-native species and classed as 'invasive' in the UK. This study was carried out in an attempt to provide empirical evidence as to whether the establishment and growth of Crassula helmsii has a measurable impact on the ecology of invaded sites. Dispersal and distribution patterns across England were explored using databases and GIS interpretation. Ecological impact was measured by comparing invaded sites with uninvaded control sites on a range of habitats and waterbody types across Kent and East Sussex. The analysis of spread patterns provided evidence that the plant is likely to have been dispersed due to the horticultural trade, as well as natural vectors into neighbouring habitats. Macrophyte analysis showed that species losses did not occur when C. helmsii was present. Changes to species composition did occur, with rarer plant species being associated with the presence of C. helmsii. Freshwater macroinvertebrates showed no change in either species number or species rarity. The seed banks of invaded and control sites showed no difference, but active management was shown to reduce the total number of seeds in the soil significantly. The water chemistry of invaded and uninvaded sites showed a relationship between the presence of C. helmsii and reduced total organic nitrogen. The results of this study show that the expected species loss associated with non-native species may not be occurring with C. helmsii. Active management may be impacting the ability of native species to recolonise. Further work on other habitats and waterbodies across a wider geographic range are required to explore whether this is a localised effect.

Ladybird beetles produce a range of alkaloid compounds which are found a high concentration in the haemolymph and released in response to perceived threat. These alkaloids are thought to function as agents of chemical defence and a small number have been shown to antagonise the nicotinic acetylcholine receptor. As intraguild predators, the chemical defence may be under selective pressure from other predatory insects, the alkaloids may therefore have evolved to target insects predominantly. To discover if other ladybird alkaloids show activity at nAChRs and investigate mode of action, alkaloids were extracted from 7-spot, 10-spot, 14-spot, cream spot, pine, orange and harlequin ladybird beetles and purified with acid-base separation. These species are each known to produce a different subset of alkaloids. Their action on nicotinic acetylcholine receptors was investigated by constructing concentration-inhibition plots by co-applying alkaloid extracts with acetylcholine to human embryonic muscle-type of TE671 cells and locust neuronal nAChRs. Peak current, net-charge and late (1 s) current were measured with whole-cell patch-clamp at VH = -75 mV. All alkaloid extracts antagonised the ACh responses of both cell types but potency and selectivity varied. The late current was the most strongly affected current parameter and the most potent antagonists of locust 1 s currents were alkaloids produced by 10-spot, 7-spot, pine and harlequin ladybird with IC50s ranging from 0.29–0.76 μg/mL. The 14-spot, cream spot and orange ladybird alkaloids had higher IC50s, ranging from 1.6-4.9 μg/mL. The IC50 values calculated for all species with, the exception of harlequin and orange ladybirds were significantly lower for locust than human nAChRs and these ranged from 1.3–47.8 μg/mL. The alkaloid extract that showed the highest selectivity for locust nAChRs was that of the 7-spot ladybird, with an IC50 value 58.4 fold lower. The alkaloids of the 10-spot, 14-spot, cream spot and pine ladybird also showed significantly higher potency for locust nAChRs over human nAChRs with IC50s 10.3–35 fold lower. Orange and harlequin ladybird alkaloids did not show higher potency for locust nAChRs. Harlequin ladybird alkaloids were highly potent to the nAChRs of both cell types whereas orange ladybird alkaloids showed low activity. The differences in potency correspond with differences in ecology, with the species that showed highest insect potency often found in close association with other predatory ladybird species. Those that showed low insect potency are arboreal specialists that are less likely to encounter insect predators. To investigate mode of action, ACh concentration-response curves in the presence and absence of harlequin ladybird alkaloid extract were constructed using TE671 cells. Increasing ACh concentrations were unable to overcome the inhibition caused by this alkaloid extract, indicating non-competitive action. Fitting the Woodhull equation to IC50 values calculated at holding potentials of 50, -50, -75, -100 and -120 mV revealed that the antagonism caused by this alkaloid extract was voltagedependent (P = 0.012), with late current IC50s of 23.1, 15.5 and 6 μg/mL at holding potentials of +50, -50 and -120 mV respectively. These data indicate that the active alkaloid(s) within this extract bind at an allosteric site and the strong voltagedependence of inhibition suggests mode of action is open-channel block rather than enhancement of desensitisation. The alkaloid harmonine was separated from other components of the alkaloid extract by thin-layer chromatography and the inhibitory activity tested against both human and locust nAChRs at VH = -75 mV. Both fractions were found to be active and displayed similar inhibitory activity towards human nAChRs with IC50s of 1.68 μg/mL for harmonine and 4.77 μg/mL for other alkaloid compounds. Harmonine was found to be significantly more potent towards locust nAChRs with an IC50 of 0.072 μg/mL as opposed to 3.23 μg/mL. This could indicate that harlequin ladybirds produce several alkaloids with different functions; harmonine may act as a chemical defence compound targeted towards insect predators. The alkaloid extract of the 10-spot ladybird was found to show significantly higher potency towards locust nAChRs than human. One of two alkaloids produced by this species is (-)-adaline. Synthetic (-)-adaline displayed identical inhibitory activity towards both cell types as the alkaloid extract of the 10-spot ladybird. Potency was significantly higher towards locust nAChRs than human, with IC50s of 10.26–45.83 μM against human and 0.55–2.97 μM against locust nAChRs. ACh concentration-response curves showed that (-)-adaline acts non-competitively and IC50 values at different holding potentials reveal that it is strongly voltage-dependent (P = 0.003 in human and P = 0.007 in locust nAChRs) and inactive at positive holding potentials. As with the alkaloid extract of the harlequin ladybird, this alkaloid acts as a non-competitive negative allosteric modulator which shows higher potency for locust over human nAChRs and strong voltage-dependence of inhibition, consistent with open-channel block. A structurally diverse range of ladybird alkaloids displayed inhibitory activity towards both human and insect nAChRs. This inhibition was non-competitive and voltage-dependent for both harlequin ladybird alkaloid extract and adaline, indicating that these alkaloids act as negative allosteric modulators, possibly open-channel blockers. The majority of ladybird alkaloid extracts tested were significantly more potent towards insect than human nAChRs. It remains to be seen whether the activity of these compounds is restricted to the nAChRs, or whether they act as non-selective pore blockers. Ladybird alkaloids appear to represent a library of novel nAChR antagonists, some of which could be further investigated as potential insecticide leads.

Plants can be characterised by a range of attributes, and measuring these attributes accurately and reliably is a major challenge for the horticulture industry. The measurement of those plant characteristics that are most relevant to a grower has previously been tackled almost exclusively by a combination of manual measurement and visual inspection. The purpose of this work is to propose an automated image analysis approach in order to provide an objective measure of plant attributes to remove subjective factors from assessment and to reduce labour requirements in the glasshouse. This thesis describes a stereopsis approach for estimating plant height, since height information cannot be easily determined from a single image. The stereopsis algorithm proposed in this thesis is efficient in terms of the running time, and is more accurate when compared with other algorithms. The estimated geometry, together with colour information from the image, are then used to build a statistical plant surface model, which represents all the information from the visible spectrum. A self-organising map approach can be adopted to model plant surface attributes, but the model can be improved by using a probabilistic model such as a mixture model formulated in a Bayesian framework. Details of both methods are discussed in this thesis. A Kalman filter is developed to track the plant model over time, extending the model to the time dimension, which enables smoothing of the noisy measurements to produce a development trend for a crop. The outcome of this work could lead to a number of potentially important applications in horticulture.

Watercress (Rorippa nasturtium-aquaticum) is a member of the Brassicaceae family. Increasing interest in healthy diets has turned the focus to watercress since it is known to contain one of the highest concentrations of the beneficial antioxidant phenethyl isothiocyanate (PEITC). This has exciting possibilities to breed a higher quality crop with increased concentrations of this key antioxidant providing a meachanism to aid in the prevention of cancer. Dwarfism is another desirable characteristic for many agricultural crops. A crop with a reduced stem length produces a stable increased yield and is easier to harvest as well as package. Dwarf mutants have been extensively characterized in many plant species and endogenous phytochrome Gibberellin (GA) is one of the several genes associated with the dwarf phenotype. The three candidate genes of particular interest are: GA2ox, GA3ox and GA20ox. GA20ox and GA3ox are involved in GA biosynthesis whilst GA2ox is involved in GA catabolism. The aim of my research was to establish a collection of watercress from around the world and breed watercress that not only has a reduced stem length but is also nutritionally beneficial therefore breed an ‘ideal’ watercress cultivar. Initial screening of the germplasm shows significant variability in stem length (ranging from 7-17cm), stem diameter (ranging from 1.58-3.18mm) and antioxidant concentrations (ranging from 80-140 mmol Fe2+ equivalent per gram fresh weight). The antioxidant concentrations were assessed using an adapted antioxidant assay Ferric Reducing Ability of Plasma (FRAP) which revealed a ranking order for the watercress lines. Two lines with high FRAP values, Wx_0033 (143.84 mmol Fe2+ equivalent per gram fresh weight) and Wx_0011 (126.44 mmol Fe2+ equivalent per gram fresh weight), and one line with a low FRAP value, Wx_0038 (87.49 mmol Fe2+ equivalent per gram fresh weight), and also a control line Wx_0001 (130.66 mmol Fe2+ equivalent per gram fresh weight) was taken forward for further glucosinolate and isothiocyanate analysis. The lines did indeed vary in the concentration of glucosinolate and isothiocyanate. Wx_0001 had both the highest concentration of phenethyl glucosinolate, 19.35 μmoles per gram weight and phenethyl isothiocyanate, 0.20mg/ml phenethyl isothiocyanate. The genetic diversity of the watercress lines held within the collection were assessed using the Amplified Fragment Length Polymorphism (AFLP) technique revealing a higher level of variation within (76%) each line than between (24%). Variation in gene expression was analysed using microarrays and verified using real time PCR. From the various data collected and recorded from the watercress germplasm collection this has lead to a breeding programme successfully being initiated at the University of Southampton.

Liriomyza bryoniae is an economically important pest of vegetable and ornamental crops in European glasshouse agriculture. Diglyphus isaea is a parasitoid of Liriomyza leaf miners and is commercially available as a biological control agent. Anecdotal reports made to commercial producers of the parasitoid suggest that the efficacy of D. isaea varies between crops. This study examines the tritrophic interactions between crop plant, L. bryoniae and D. isaea. Host plant was found to influence the abundance of L. bryoniae and D. isaea with larger populations establishing in the culturing host than in the novel host, tomato. Individual size of L. bryoniae also varies with host plant. These patterns are consistent in L. bryoniae across three generations of rearing on tomato. Habituation of L. bryoniae to tomato does not affect D. isaea efficacy nor does the natal plant host of D. isaea. Both L. bryoniae and D. isaea are affected by plant host ontogenetic stage, becoming most numerous on juvenile plants. The D. isaea natal insect-plant complex showed no effect on D. isaea olfactory preferences. Diglyphus isaea demonstrated greater thermal tolerance than its host. These results are discussed in relation to biological control and also in terms of their wider ecological implications.

In this study, the effects of different plant growth regulators on regeneration responses of various lentil explants through direct and indirect organogenesis and through somatic embryogenesis from calli and cell suspension cultures were investigated. Shoot regeneration was obtained in low frequencies from longitudinal embryonic axis explants and nodal buds of epicotyls, however whole plant regeneration was unsuccessful. Conditions provided for indirect organogenesis resulted only in swelling of hypocotyls and root directed ends of internodes and weak callus formation on leaves which were followed by tissue browning and necrosis. In somatic embryogenesis studies, the explants longitudinal embryonic axis and cotyledonary petioles produced soft and friable calli on MS media with Gamborg&rsquo / s vitamins supplemented with 0.75mg/L 2,4-D+0.5mg/L BA. The highest average number of embryos per explant, 12.36 was observed on media containing 0.75mg/L BA +0.5mg/L 2,4-D for cotyledonary petiole explants, whereas 3mg/L BA+1mg/L NAA was the only hormone combination that allowed embryo development to some extent, in both explants. Somatic callus failed to regenerate despite globular embryo formation and embryo development to some extent. Combination of sonication treatment with Agrobacterium transformation of three lentil explants / cotyledonary nodes, half cotyledons and cotyledonary nodes with intact shoots, had no effect on the improvement of transient gus gene expression on explants. Sonication treatment was also unable to form localized wounds on the petiole axils. The best gus gene expression on the axil region was obtained when cotyledonary nodes and KYRT1 strain were used in combination with vacuum infiltration and scalpel wounding of the axils. Gradual selection and repeated removal of regenerated shoots between selection cycles increased the number of gus expressing shoots significantly. The regenerated shoots were grafted on root stocks and whole plant regeneration was achieved in greenhouse conditions. By the use of the optimized Agrobacterium-mediated transformation protocol, 4 independent lines were obtained with 2.3% transformation efficiency. Southern blot analysis confirmed the integration of the gus gene into the genome of lentil plants. T0 plants were fertile and all plants showed Mendelian segregation of the gus gene in 3:1 ratio to their progenies except one line which carries three copies of the gene. Reverse transcription PCR has confirmed the expression of the genes in T0 and T1 generations. T0 plants and the following three generations strongly expressed gus gene uniformly in their tissues and the PCR amplifications of both gus and npt-II genes was successful through generations.

The objective of this study was to optimize tissue culture, transformation and regeneration parameters of mature embryo based culture of Triticum durum cv. Mirzabey 2000 and Triticum aestivum cv. Y&uuml / regir 89. The effects of auxin type of hormone at different concentrations and dark incubation periods on regeneration capacity were evaluated. Two different hormone types 2,4- dichlorophenoxyacetic acid and picloram were used at three different concentrations 2, 4 and 8 mg/l. Mature embryo derived calli were incubated in 6 different induction media at dark for 4 and 6 weeks for initiation of primary callus induction. After dark incubation periods, average callus fresh weight and primary callus induction rate were determined. The primary callus induction rates for 4 weeks and 6 weeks old dark adapted Mirzabey calli incubated was found to be 91 % and 93.25 % respectively. Y&uuml / regir primary callus induction rate was 92.5 % for 6 weeks old calli in 6W2D medium and 86.75 % for 4 weeks old calli in 4W8P medium. The primary calli were transferred to embryogenic callus induction medium. The embryogenic callus formation was 94.88 in 6W2D medium for Mirzabey cultivar. The necrosis was observed at high concentration of 2,4-D for both of cultivars. After embryogenic callus induction, embryogenic calli were transferred into hormone free regeneration medium. The maximum regeneration rate (62.31 %) and culture efficiency (44.13 %) were observed in 4W2D medium for Mirzabey. However, the low regeneration rate was observed for Y&uuml / regir (5 %) in 6W2D medium. The transformation studies were performed by using Obitek Biolab Gene Transfer System. The old and the modified loading units were used for optimization of bombardment pressure and distance for mature embryo based calli transformation. After bombardment of pAHC25 coated gold particles, histochemical GUS assay was performed and blue spots were counted. The transformation efficiency increased to 0.65 fold for 30 bar bombardment pressure and 5.5 fold for 35 bar bombardment by the modified loading unit. The modified loading unit could be used for further transformation studies.

Ethylene (C2H4) is a very simple molecule, a gas, and has numerous effects on the growth, development and storage life of many fruits, vegetables and ornamental crops. In higher plants, ethylene is produced from L-methionine in essentially all tissues and ACC Synthase and ACC Oxidase are the two key enzymes in the biosynthesis of ethylene. The objective of the present study was to transform tobacco (Nicotiana tabacum L. cv. Samsun) plant with partial sequence of torenia acc oxidase gene in antisense and sense orientations via Agrobacterium-mediated gene transfer system, and to analyze its effect on ethylene production in transgenic plants. Six antisense and seven sense T0 putative transgenic lines were obtained and were further analyzed with several assays. Leaf disc assay and chlorophenol red assay under selection (75 mg/L kanamycin) revealed positive results compared to the non-transformed plant. T1 generations were obtained from all putative transgenic lines. PCR analysis and Northern Blot Hybridization results confirmed the transgenic nature of T1 progeny. Furthermore, ethylene amount produced by flowers were measured with gas chromatography, which resulted in an average of 77% reduction in S7 line and 72% reduction in A1 line compared with the control flowers. These results indicated that, transgenic tobacco plants carrying torenia acc oxidase transgene both in antisense and sense orientations showed reduced ethylene production thus a possibility of flower life extension.

No description available.