| Abstract: | Extracts of nematodes of the Raleigh, North Carolina (RNC), Waynesville, N. C. (WNC), and onion populations of Ditylenchus dipsaci were examined for pectolytic activity. RNC nematodes contained a NaCl-stimulated endo-polymethylgalacturonase with optimal pH for activity of 6.0, whereas nematodes of the WNC and onion populations possessed a NaCl-stimulated endo-polygalacturonase with pH optimum of 4.0. Nematodes of each population also contained a CaCl₂-activated endo-pectin methyl-trans-eliminase with optimal pH of 9.0. Nematode extracts containing 0.5 M NaCl macerated potato discs. RNC and onion nematodes induced gall formation in Wando pea seedlings, but WNC nematodes induced a resistant, hypersensitive response. Thus pectolytic activity was not correlated with pathogenicity of D. dipsaci on Wando pea. |
