Soft rot

Barras, F., van Gijsegem, F. and Chatterjee, A. K. (1994). Extracellular enzymes and pathogenesis of soft-rot Erwinia. Annu Rev Phytopathol 32, 201-234. 

Among the family of Enterobacteriaceae, two species of the genus Erwinia define the soft rot group E. chrysanthemi and E. carotovora. The main characteristic of the soft rot bacteria is their ability to produce large quantities of plant cell wall degrading enzymes. The maceration of plant tissue resulting from... 

Yang Z, Cramer CL, Lacy GH (1992) Erwinia carotovora subsp. carotovora pectic enzymes In planta gene activation and roles in soft rot pathogenesis. Mol Plant-Microbe Interact 5 104-112... 

Weber J, Olsen O, Wegener C, von Wettstein D (1995) Digalacturonates mediate tissue responses against potato soft rot. In press Physiol Mol Plant Pathol. 

Soft rot symptoms produced by E. chrysanthemi consist of a disorganisation of parenchymatous tissues following the release of bacterial pectinolytic enzymes. The diverse enzymes do not contribute equally to the virulence on a given host and their implication may vary according to the host considered. For instance, inactivation of pelE, pelD, pelA or pern in strain 3937 considerably reduces the virulence on African violets while mutations in pelB or pelC remain ineffective [2]. Pectinolysis is regulated by the transcriptional repressor KdgR, inactive in the presence of pectic inducers. 

Soft rot spreading depends on the efficiency of the iron uptake pathway mediated by the siderophore chrysobactin. Biosynthesis of the ferrichrysobactin outer membrane receptor (Fct) and of the chrysobactin precursor, i.e. the activated form of 2,3-dihydroxybenzoic acid, are encoded by an operon,/cr ebsCEBA [3]. 

Does the regulatory effect of iron, observed under laboratory conditions, have a physiological significance in the soft rot disease caused by E. chrysanthemi strain 3937 on AMcan violet ... 

Regarding the prevalence of pectinolytic enzymes in the soft rot symptoms, it is noteworthy that the experimental model developed on African violets stresses the dynamic aspect of the disease and illustrates a number of points which have long been questioned. 

Rhizopus-soft rot is a threat in all postharvest situations including storage, marketing, and transport of crops. It causes soft rot of avocados, cassava, crucifers, pulses, yams, and sweet potatoes. This spoilage type is mainly caused by Rhizopus stolonifer and to a lesser extent by R. oryzae, Mucor piriformis, and Gilbertella persicaria (Dijksterhuis and Samson 2006). 

The effectiveness of bacteriocins is often a function of environmental factors such as pH, temperature, food composition, structure, and food microflora (De Vuyst and Leroy 2007). A novel bacteriocin-like substance produced by Bacillus licheniformis P40 inhibits the activity of the soft rot bacterium Envinia carotovora. This compound caused a bactericidal effect on the pathogen cells at a 30 p.g/mL concentration (Cladera-Olivera and others 2006). 

Cladera-Olivera F, Caron GR, Motta AS, Souto AA and Brandelli A. 2006. Bacteriocin-like substance inhibits potato soft rot caused by Erwinia carotovora. Can J Microbiol 52(6) 533-539. 

Liao CFI, Hung HY and Chatterjee AK. 1988. An extracellular pectate lyase is the pathogenicity factor of the soft-rotting bacterium Pseudomonas viridiflava. Mol Plant Microbe Interac 1 199-206. 

Soft magnetic spinel ferrites, 11 57 Soft oils, in toilet soap making, 22 734 Soft repulsions, 23 94 Soft rot... 

Sugar maple was reacted with propylene and butylene oxide (Rowell etal., 1982). The modulus of elasticity (MOE) and modulus of rupture (MOR), fibre stress at proportional limit, and maximum crushing strength all exhibited a reduction, compared to unmodified samples. Nilsson and Rowell (1983) reacted ponderosa pine with butylene oxide and exposed the wood in an unsterile soil decay test. At low WPGs, severe surface decay due to soft rot and tunnelling bacteria was observed. Such attack was reduced at 15 % WPG,... 

Tjeerdsma etal. (1998a) subjected thermally modified wood to soft rot decay in unsterile soil tests. Although decay resistance was enhanced by thermal treatment, it was not possible to prevent attack entirely. Treatments giving the best performance in terms of decay resistance also exhibited the highest strength losses. Viitanen etal. (1994) have also reported on some preliminary experiments on heat-treated wood in unsterile soil. 

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