AGGLUTINATION, ADHERENCE, AND ROOT COLONIZATION BY FLUORESCENT PSEUDOMONADS

Two fractions of agglutination activity towards fluorescent pseudomona ds were detected in root washes of potato, tomato, wheat, and bean. Hi gh-molecular-mass (>10(6) Da) components in crude root washes agglutin ated only particular saprophytic, fluorescent Pseudomonas isolates. Io n-exchange treatment of the crude root washes resulted in preparations of lower-molecular-mass (10(5) to 10(6) Da) fractions which agglutina ted almost all Pseudomonas isolates examined. Also, components able to suppress agglutination reactions of pseudomonads with the lower-molec ular-mass root components were detected in crude root washes of all cr ops studied. Pseudomonas isolates were differentially agglutinated by both types of root components. The involvement of these two types of r oot components in short-term adherence and in colonization was studied in potato, tomato, and grass, using Pseudomonas isolates from these c rops. Short-term adherence of isolates to roots was independent of the ir agglutination with either type of root components. With agglutinati on negative mutants, the high-molecular-mass components seemed to be i nvolved in adherence of Pseudomonas putida Corvallis to roots of all c rops studied. Short-term adherence to roots of four Pseudomonas isolat es could be influenced by addition of both crude and ion-exchange-trea ted root washes, depending on their agglutination phenotype with these root wash preparations. Potato root colonization by 10 different isol ates from this crop, over a period of 7 days, was not correlated with their agglutination phenotype. Agg(-) mutants of P. putida Corvallis w ere not impaired in root colonization. It is concluded that the root a gglutinins studied can be involved in short-term adherence of pseudomo nads to roots but do not play a decisive role in their root colonizati on.