Disc-Electrophoretic Studies of Soluble Proteins and Enzymes of Meloidogyne incognita and M. arenaria.

Soluble-protein and eight enzyme profiles obtained by polyacrylamide-gel electrophoresis were compared between Meloidogyne incognita and M. arenaria. Esterase, malate dehydrogenase, and alpha-glycerophosphate dehydrogenase patterns were distinctly characteristic for each species. Peroxidase and alpha-glycerophosphate dehydrogenase isoenzyme patterns varied when nematodes were propagated on different host plants. Similar profiles were obtained for two populations within each species. Antigenic proteins of these two species were compared following separation by electrophoresis.

Improved method for immunoelectrophoretic research.

A rapid, semiquantitative method for immunoelectrophoretic research is described. It combines the great resolving capacity of polyacrylamide gel disc electrophoresis with rapid immunoprecipitation in a thin agar film surrounding the acrylamide gel.

Dehydrogenases, Acid and Alkaline Phosphatases, and Esterases for Chemotaxonomy of Selected Meloidogyne, Ditylenchus, Heterodera and Aphelenchus spp.

Various taxonomically useful profiles of four dehydrogenases (lactate, malate, glucose-6-phosphate, and a-glycerophosphate) and three hydrolases (acid and alkaline phosphatase and esterase) were detected in whole nematode homogenates of Meloidogynejavanica, M. hapla, M. incognita, M. arenaria, Ditylenchus dipsaci, D. triformis, Heterodera glycines, and Aphelenchus avenae. The enzyme profiles were stable in populations cultured on several different hosts. A tentative enzymically-determined phylogeny of Meloidogyne is given.

Antifungal activity of alkylxylylene-bis-isothiuronium chlorides.

Low concentrations of dodecylxylylene-bis-isothiuronium chloride, synthesized from an inexpensive detergent intermediate, inhibited members of 21 genera of fungi.

Comparative Disc-Electrophoretic Protein Analyses of Selected Meloidogyne, Ditylenchus, Heterodera and Aphelenchus spp.

Disc-electrophoretic separation of soluble proteins from whole nematode homogenates yielded band profiles useful for distinguishing selected species of Meloidogyne and Ditylenchus, and the genera Heterodera, and Aphelenchus. Certain protein bands were common to all the species of Meloidogyne, whereas other bands were specific. Meloidogyne spp. and Heterodera glycines shared some protein similarities, but other genera differed distinctly. Protein profiles of Meloidogyne spp. were not significantly altered by the host on which the nematode was cultured.

Calcium Nutrition and Resistance of Alfalfa to Ditylenchus dipsaci.

Stem nematode-susceptible 'Atlantic' and resistant 'Lahontan' alfalfa seedlings, grown in sand and watered with complete nutrient solutions containing 0.75, 1.5, 3.0, 6.0, or 12.0 mM Ca/liter, were inoculated with Ditylenchus dipsaci (the stem nematode) 5-6 days after emergence. Approximately equal numbers of nematodes entered the tissues of each variety/Ca concentration within 2 days. Penetration was reduced at 12 mM Ca/liter. Reproduction during 21 days following inoculation yielded 3-fold, or greater, nematode increases in 'Atlantic' buds at all Ca concentrations, in 'Atlantic' cotyledons at the four lower concentrations, in 'Lahontan' buds at the lowest concentration and in 'Lahontan' cotyledons at the two lowest concentrations. Reproduction was lower at the higher Ca concentrations.Increased nutrient Ca concentrations resulted in increased Ca content, decreased Na and K content, and unchanged Mg content of buds and cotyledons. Accordingly, increased nutrient Ca resulted in increased divalent/monovalent cation ratios (Ca + Mg/Na + K ). Resistance to reproduction was correlated more closely with the divalent/monovalent cation ratio than with Ca content of tissue, At the four higher nutrient Ca concentrations, 'Lahontan' buds had higher ratios than 'Atlantic,' and infected buds had higher ratios than noninfected buds. Although cation balance modifies disease expression, the basic resistance mechanism remains unknown.

Murine toxicit of Agrobacterium tumefaciens.

Eleven strains of the crown gall organism, Agrobacterium tumefaciens, tested by intraperitoneal injection into mice, were lethal within 48 hr. Five other species had some lethal strains. The lethal effect of A. tumefaciens appeared to be the result of a toxic rather than an infectious process, since histopathological anomalies were not found in mice injected with live cultures and since heat-killed cultures were lethal. The murine toxin disappeared when A. tumefaciens was grown at 36 C and reappeared when the organism was subsequently incubated below 30 C. The murine toxin itself was not inactivated by exposure to 100 C for 30 min. The toxin was associated with the cells and was not excreted into the medium. Centrifugal fractionation revealed that the toxin was associated with the smaller cells in 3-day stationary-phase cultures. These data suggested a possible relationship between toxin production and the production of the agents responsible for the initiation of plant tumors.