Using in planta assays to elucidate the impact of a unique iron acquisition system on the virulence of a potato pathogen, Pectobacterium atrosepticum
This is one of the funded projects for our 2025 Undergraduate vacation bursary, click here to return to the list of 15 projects.
| This project is going to be… | Experimental (lab/field based) |
| Institute | The James Hutton Institute |
| Project supervisor | Dr. Ashleigh Holmes |
| Title of Project | Using in planta assays to elucidate the impact of a unique iron acquisition system on the virulence of a potato pathogen, Pectobacterium atrosepticum |
| Date of Project Commencement | 26 May 2025 |
| Duration (weeks) | 8 |
| Brief Description of Project | Iron is an essential nutrient with limited bioavailability and is sequestered by the host during bacterial infections. Gram negative bacteria utilise specialised outer membrane receptors to import iron compounds, such as siderophores, or iron-containing proteins into the cell. Ferredoxin is a highly abundant, small iron-sulphur cluster protein which plays an important role in electron transfer for plant photosynthesis.The Ferredoxin uptake system (FusBACD), found in the genus Pectobacterium, is a unique iron acquisition system as it hijacks the entire ferredoxin protein from its plant host. Ferredoxin is recognised at the cell surface by FusA, transported into the periplasm by TonB-like protein FusB and processed by FusC to release the iron-sulphur cluster for iron-acquisition by Pectobacterium (Wojnowska & Walker (2020)). Pectobacterium atrosepticum (Pba), is an economically important pathogen of potatoes worldwide, as it is the causative agent of blackleg in the field crop and soft rot of tubers. Under iron limited conditions, plant ferredoxins have been shown to enhance pectobacterial growth, indicating that FusBACD constitutes a prominent virulence factor.This 8-week interdisciplinary project aims to investigate the role of FusBACD in the virulence of P. atrosepticum by testing defined Fus gene knockouts in potato stem and tuber infection assays. We will also compare the ferredoxin uptake efficiency of a panel of Pectobacterium strains by monitoring bacterial growth in media supplemented with purified ferredoxins and plant tissue extracts, from host (potato – Pba; chinese cabbage – P. versatile) and non-host (spinach) plants. The project will be lab-based at the James Hutton Institute under the supervision of Dr Ashleigh Holmes in collaboration with Dr Marta Wojnowska (University of Cambridge), who functionally characterised the ferredoxin-import protein FusB. This project offers the student key skills in the context of plant pathology and microbiology, including plant tissue culture, plant propagation, pathogenicity tests and molecular biology with aspects of biochemistry (protein handling).Recommended reading for the project Wojnowska & Walker (2020) FusB energizes import across the outer membrane through direct interactions with its ferredoxin substrate. mBio 11:10.1128/mbio.02081-20Barber & Elde (2015) Buried Treasure: Evolutionary perspectives on microbial iron piracy. Trends in Genetics 31:627-636 Grinter et al (2012) Ferredoxin containing bacteriocins suggest a novel mechanism of iron uptake in Pectobacterium spp. PLoS ONE 7:e33033Grinter et al (2016) Structure of the bacterial plant-ferredoxin receptor FusA. Nature Communications 7:13308 |
