A multidisciplinary investigation of the relationship between 'Pseudomonas syringae' and 'Aesculus hippocastanum' bleeding canker

Alhamd, Omar A. Ahmed

Abstract

Bleeding canker of Aesculus hippocastanum is caused by Pseudomonas syringae pathovar aesculi. The disease has rapidly spread through many countries, yet little is known about this potentially fatal disease. Climate change affects plant diseases directly, and abiotic and biotic stress adds to the pressure. In turn, the plant produces pathogen-induced defence responses at the genetic or proteomic level which are not well understood.
In this study, the transcriptome of A. hippocastanum phloem was sequenced using Illumina RNA-Seq technology. Many genes were identified, some of them known to have a relationship with wound stress in plants such as C86B1 which is involved in the stimulation of wound suberization. Some genes were up-regulated in infected trees, such as BGLl7, but their functions are still unknown. Further studies are required to determine the roles of these genes in host defence.
An experimental investigation was conducted to explore the effect of selected environmental factors and nanoparticles on the bacteria and plants. Different levels of damage and drought stress have been studied. Some positive results were observed in reducing infection and activity of bacteria with low levels of drought stress (75% soil field capacity). The thermal shock was also applied to bacteria, which showed susceptibility to the rise in temperature.
The effects of four nanoparticles (NPs) at different concentrations were investigated in vitro and in vivo. Silver and cerium oxide NPs were synthesised and characterised usmg transmission electron microscopy and inductively coupled plasma optical emission spectrometry. NPs were applied to bacteria strains, A. hippocastanum and two model plants (Phaseolus vulgaris and Lycopersicon esculentum). Titanium oxide and silver NPs showed significant antibacterial activity against several pathogenic strains of Pseudomonas. It was found that titanium NPs can have either a negative or a positive impact on bacterial and plant growth, according to concentration and species of plant.

Citation

Alhamd, O. A. A. A multidisciplinary investigation of the relationship between 'Pseudomonas syringae' and 'Aesculus hippocastanum' bleeding canker. (Thesis). Keele University. https://keele-repository.worktribe.com/output/421792

• Thesis Type: Thesis
• Publicly Available Date: Jan 2, 2025
• Public URL: https://keele-repository.worktribe.com/output/421792
• Additional Information: Embargo on electronic copy access until 1 January 2025 - The thesis is due for publication, or the author is actively seeking to publish this material.
• Award Date: 2020-03