Work Package Lead: Roy Neilson (James Hutton Institute)

Objective 1.1 - Free-living nematodes as vectors and role in P. atrosepticum infection

Team: Mike MacDonald (University of Dundee); Eric Anderson (Scottish Agronomy); Roy Neilson, Kath Wright, Sonia Humphris, Dave Roberts, Jacquie Marshall, Ian Toth (James Hutton Institute)

Free-Living nematodes (FLN) are a major problem in the UK potato industry, exacerbated by removal of some nematicides (91/414/EEC) and in the long-term by expected population increases due to climate change. There are >250 economically important plant parasitic FLN species, many of which are in the UK. FLN feed on roots and root hairs through puncturing of root cells.

We have preliminary data showing that potato plants grown in the presence of Pectobacterium atrosepticum (Pba) and a mixed population of FLN leads to a 100-fold increase in Pba in plant stems compared with Pba alone. However, it is not clear whether this entry is passive via damage sites (FLN as ‘enhances’ of infection) or direct, following ingestion and vectoring by species-specific FLN. 

This objective will address these questions through use of infection assays performed in our newly developed transparent soil fluidic systems and the use and further development of our microscopy tools based on Light Sheet and Confocal Laser Scanning Microscopy (LSM and CLSM).

Objective 1.2 - Aerosol and insect transmission

Team: Greig Cahill (SASA)

While the main source of blackleg is thought to be contaminated seed tubers, preliminary studies by SASA have shown that c. 20% of seed crops grown from pathogen-free minitubers had detectable levels of Pba at harvest, while 6.5% had no detectable Pba but still developed blackleg in subsequent crops, suggesting direct environmental infection. This supports the notion that infection is occurring directly from soil and/or FLN but does not rule out the possibility that Pba may be entering crops and soil via aerosols and/or insect vectors.

This objective will establish the role of aerosols and insects in Pba transfer from diseased potato plants to the canopy, roots and tubers of healthy plants.