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Title: Imaging and analysis of the uptake and activity of azoxystrobin in plant and fungal cells
Author: Swift, Samuel R.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2003
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Fungicide/fungus interactions were analysed on the wheat leaf surface using single 0.2 μl droplet of azoxystrobin and the pathogens Blumeria graminis and Puccinia recondita. Although no observable activity was observed on established colonies of P. recondita, azoxystrobin was shown to have potent curative and preventative activity on B. graminis over distances of up to 7 mm within 24 h. Micro-phosphorimaging of wheat leaves showed that azoxystrobin translocated up to 9 cm after 24 h. Wax stripping of leaves indicated that the majority of movement occurred acropetally. These results indicated that azoxystrobin diffusion through wax and epidermal cells was responsible for preventative and curative activity over short time periods (within 7 h of treatment). Quantitative analysis of radiolabelled fungicide uptake using combustion analysis and scintillation counting showed that approximately 9% of applied azoxystrobin from 0.2 μl fungicide droplets (125 g/L azoxystrobin) was taken into the leaf within 24 h. Live-cell imaging techniques were developed to study the biology and physiology of mitochondria in hyphae of Neurospora crassa, Aspergillus nidulans and Botrytis cinerea. The vital fluorescent probes DASPMI, Mitotracker Green, Rhodamine 123, FM4-64 and FMI-43, and GFP targeted to mitochondria were assessed for this purpose. On the basis of these data an assay for mitochondrial activity was developed using the potentiometric marker Rhodamine 123. Mitochondria were shown to be more tightly packed at the tips of growing hyphae than in sub-apical regions. Inhibitor studies (with azoxystrobin and FCCP) demonstrated that mitochondrial morphology was significantly altered during inhibition (mitochondria became spherical and retracted from the hyphal tip as growth rate decreased) and that membrane potential was significantly reduced. Fungicide uptake experiments supported the conclusion that the main uptake pathway for strobilurin fungicides is by diffusion.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available