Strains of P. parmentieri are Gram-negative, rod-shaped necrotrophs which destroy plant tissue components through the activity of plant cell wall-degrading enzymes such as pectinases, cellulases and proteases secreted via Type I or II secretion systems (Chatterjee et al., 1995;Liu et al., 1999;Charkowski et al., 2012) but lack the Type III secretion system (Kim et al., 2009). Pectinases (pectate and pectine lyases, polygalacturonases, methyl- and acyl-) and cellulases play a major role in the virulence of soft-rotting pathogens as they degrade the primary cell walls of infected plants. Proteases are also mentioned as they disrupt host plant protoplasts via degradation of transmembrane proteins (Marits et al., 1999). Effective spread of the pathogen through the plant's vascular system, often referred to as motility of the strain, is essential for the development of disease symptoms (Toth et al., 2003). The efficient production of iron scavenging molecules, siderophores, provides cofactors involved in almost all life-supporting processes (Ishimaru and Loper, 1992).
Related invasive species
- Pectobacterium parmentieri
Related Farm Practice
- Motility
- Activity
- Production
- Development
- Systems
- Host plants
Pectobacterium parmentieri is a bacterial pathogen of potato present in Europe since the 1960s. The bacterium was earlier classified as Pectobacterium carotovorum. After reclassification of P. carotovorum subsp. carotovorum SCC3193 to P. wasabiae and later on to P. parmentieri, several studies devoted to identification of pectinolytic bacteria in international collections and identification of the strains isolated from infected potato plants have indicated that this bacteria commonly occurs in several regions of Europe, Canada, USA, New Zealand and South Africa. P. parmentieri can cause symptoms of blackleg and soft rot on potato tubers. These diseases are usually a consequence of latent infection of seed potatoes. In the majority of countries pre-basic and basic seed tuber potatoes intended for the production of seed tuber crops should be free of Pectobacterium spp. and Dickeya spp. P. parmentieri is not present on any international or national alert lists.
Symptoms only appear on potato plants. Latent infection is common on potato tubers.
Potato blackleg mainly occurs from plants derived from latently infected seed potatoes. It is more severe when host resistance is impaired. Pathogenesis of P. parmentieri is also temperature dependent. Potato stem diseases generally develop under wet and partially aerobic conditions. Blackleg develops as a consequence of pathogen multiplication in rotting (or latently infected) mother tubers. Infection of seed tubers or stem invasion by P. parmentieri soon after emergence can result in blanking (rotting and death of the whole plant). Stunting, chlorosis and wilting symptoms, caused by restriction of water flow in the xylem vessels following infection, tend to develop at that stage under dry conditions (Pérombelon, 2002).
Potato soft rot during storage is usually a consequence of latent infection of potato crops. The bacteria are sited intracellularly, in lenticels and in wounds, typically beyond the phylloderm layer. Symptoms of soft rot exhibit as tissue maceration with intact skin of potato. A characteristic odor occurs when additional bacteria are present in infected tissue (Perombelon and Kelman, 1980;Pérombelon, 2000).