ROOT COLONIZATION OF DIFFERENT PLANTS BY PLANT-GROWTH-PROMOTING RHIZOBIUM-LEGUMINOSARUM BV TRIFOLII R39 STUDIED WITH MONOSPECIFIC POLYCLONAL ANTISERA

Monospecific polyclonal antisera raised against Rhizobium leguminosaru m bv. trifolii R39, a bacterium which mas isolated originally from red clover nodules, mere used to study the colonization of roots of legum inous and nonleguminous plants (Pisum sativum, Lupinus albus, Triticum aestivum, and Zea mays) after inoculation, Eight weeks after inoculat ion of soil-grown plants, between 0.1 and 1% of the total bacterial po pulation in the rhizospheres of all inoculated plants were identified as R. leguminosarum bv. trifolii R39, To characterize the associative colonization of the nonleguminous plants by R. leguminosarum bv. trifo lii R39 in more detail, a time course study was performed with inocula ted roots of Z. mays. R. leguminosarum bv. trifolii R39 was found almo st exclusively in the rhizosphere soil and on the rhizoplane 4 weeks a fter inoculation, Colonization of inner root tissues was detected only occasionally at this time, During the process of attachment of R. leg uminosarum bv. trifolii R39 to the rhizoplane, bacterial lipopolysacch arides were overexpressed, and this may be important for plant-microbe interaction, Fourteen weeks after inoculation, microcolonies of R. le guminosarum bv. trifolii R39 were detected in lysed cells of the root cortex as well as in intracellular spaces of central root cylinder cel ls, At the beginning of flowering (18 weeks after inoculation), the nu mber of R. leguminosarum bv. trifolii R39 organisms decreased in the r hizosphere soil, rhizoplane, and inner root tissue.