Submitted to: Journal of Sugarbeet Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 6, 2007
Publication Date: February 8, 2008
Citation: Kuykendall, L.D., Hunter, W.J. 2008. Necrosis, carbohydrate release and ethane formation from inoculated potato slices correlate with the pathogenicity of erwinia betavasculorum strains responsible for sugar beet root rot. Journal of Sugarbeet Research. 56:128-133.
Interpretive Summary: Research on diseases of sugar beet roots, for example root rot necrosis caused by the soil bacterium "Pectobacterium betavasculorum", also known as "Erwinia," is hampered by the long incubation time currently required for the analysis of the disease-producing ability of pathogens. Investigators in ARS have now developed a simple 2-day assay that can be reliably used to examine the disease-producing ability of bacterial pathogens. The release of simple sugars caused by the bacteriums' enzymes that rapidly digest the complex structural carbohydrates holding together the plant cell walls within potato slices is monitored in the lab by a color reaction in a test tube. This new assay for disease-causing ability will help sugar beet pathologists determine the factors limiting the disease severity of pathogens and develop effective disease control measures.
The marked difference in pathogenicity exhibited by the two colony-type derivatives of Erwinia betavasculorum seemed ideal for developing a rapid pathogenicity test. Also, the pathogenic strain EB4 gave rise to a motile, nonpathogenic derivative that we term EB4Mot+. The use of these strains for the inoculation of potato slices was established as a rapid bioassay for the virulence of E. betavasculorum strains. The release of carbohydrates from inoculated potato slices correlated with pathogenicity in forming root necrosis on sugar beet. Ethane release was similarly positively correlated with pathogenicity.