Ian Toth

The Bacteriology Group at the Institute is led by Nicola Holden and I, with a focus on human/animal and plant enterobacterial pathogens, respectively. The plant pathogens team includes Sonia Humphris (post doc), Emma Campbell and Lauren Watts who, along with a variety of students and visitors, do most of the work.

Within the family Enterobacteriaceae, a wide range of bacteria cause disease on humans, animals and plants. Human and animal pathogens include E. coli and Salmonella species, while plant pathogens include species of Pectobacterium, Dickeya and Pantoea. In the plant pathogens team we work on all of these pathogens. However, our main research focus is on the pathogenesis and control of Pectobacterium species (including P. brasiliense and P. wasabiae but mainly the potato pathogen P. atrosepticum [Pba]), and Dickeya species (including D. dianthicola and D. solani).  Much of our research is funded by the Scottish Government’s Rural and Environmental Sciences and Analytical Services (RESAS) and the Agriculture and Horticulture Development Board (AHDB).

Pectobacterium and Dickeya: The soft rot pathogens Pectobacterium and Dickeya spp. cause disease on a number of crops and ornamentals worldwide, including blackleg diseases of potatoes in the field and soft rots of tubers in storage. It is particularly important to reduce or prevent the incidences of such diseases, which  is particularly important in Scotland due to the high health status of its potato seed industry. We undertake strategic research to identify potential methods of control both through epidemiological and genomics-based studies.  

In 2004 we published the genome sequence of Pba in collaboration with the Sanger Institute in Cambridge (Bell et al. PNAS 2004). This was the first enterobacterial plant pathogen to be sequenced, although a number of others have been sequenced since (Pritchard et al. 2013), and with the development of a powerful new comparative genomics visualisation tool – GenomeDiagram  (Pritchard et al 2005), microarrays and many great collaborations we have discovered new insights into the genome structure and function (Pritchard et al. 2009; Vanga et al. 2015), regulation (Lin et al. 2010; Liu et al 2008; Yang et al. 2009) lifestyle (Toth et al. 2006), and especially the pathogenicity (Cubitt et al. 2013; McNally et al 2012; Monson et al. 2013; Tan et al. 2014; Wang et al. 2016) of this important group of bacteria. The genomics work has also been instrumental in redefining the taxonomy of Pectobacterium and Dickeya species (Pritchard et al. 2016) and in the development new a genome-based molecular diagnostic method for bacteria in general (Pritchard 2013).  

In parallel to the genomics work we also work closely with the potato industry and other scientists to identify ways to control Pectobacterium and Dickeya spp. through a better understanding of the aetiology and epidemiology of disease, on-farm monitoring, field and glasshouse trials, the use of our new typing and detection methods, and novel modelling strategies (Parkinson et al. 2015; Skelsey et al. 2016).    

Pantoea ananatis: Pantoea ananatis, a pathogen of several crops including onion, maize and eucalyptus, is also being investigated as part of ongoing collaboration with Prof. Teresa Coutinho and colleagues at the University of Pretoria in South Africa, where I have an honorary Professorship.  This has included publishing the P. ananatis genome sequence, which was the first bacterial phytopathogen to be sequenced in Africa (De Maayer et al. 2010, 2014), and we have gone on to investigate aspects of pathogenesis in this species (Shyntum et al. 2014, 2015; Weller-Stuart et al. 2016).  

E. coli and Salmonella: Our research on the above plant pathogens, particularly through a comparative genomics study of these and the human / animal enteric pathogens (Toth et al. 2006), ties in closely with the work of Nicola Holden, who is investigating the interactions between the human/animal enterobacterial pathogens Salmonella spp. and E. coli and plants. This has led to a collaboration to investigate the interaction of human and plant pathogens with plant cell walls (Crozier et al. 2016; Holden et al. 2015; Rossez et al. 2014; Wright et al. 2013).    

Other areas of interest: Other smaller but no less interesting areas of research and collaboration include the use of elicitors to control bacterial diseases of horticultural crops (Holden et al. 2012) and Streptomyces scabies secretion systems (Fyans et al. 2013).

Key collaborators:

• Jiaqin Fan (Nanjing Agricultural University, China)
• George Sundin (Michigan State University, USA)
• Ching-Hong Yang (University of Wisconsin Milwaukee, USA)
• Teresa Coutinho (University of Pretoria, South Africa) 
• Andrew Pitman (Institute for Plant & Food Research, New Zealand)
• George Salmond (University of Cambridge, UK)
• John Elphinstone (Fera, UK)
• Gerry Saddler (SASA, UK)
• Stuart Wale (SRUC, UK) 

Related publication

• The Erwinia Manual (SCRI, 2002) (516 KB)