A field test with transgenic alfalfa and recombinant Sinorhizobium meliloti was performed in 1995/96 in Corvallis, Oregon. Two additional years of monitoring the fate of S. meliloti occurred after the aflalfa plants were sprayed. Parental and two transgenic lines (alpha amylase or lignin peroxidase producing) of alfalfa were either not inoculated or inoculated with parental S. meliloti strain RMBPC, antibiotic-resistant strain RMB7201, or antibiotic-resistant and enhanced nitrogen-fixing strain RMBPC-2. Over two growing seasons, plant and bulk soil samples were obtained from triplicate plots of the 12 treatments. Selective plating, colony hybridization, and PCR methodologies were used to identify recombinant inocula recovered from the field. During the first year, only inoculated rows tested positive for recombinant S. meliloti with counts up to 5.6 x 10(sup 4) CFU/g dry wt soil(gdws). In the second year, counts increased in inoculated rows by about an order of magnitude to up to 8.7 x 10(sup 5) CFU/gdws. After unusual flooding of the plot in the winter of 1996, the recominant S. meliloti also became detectable in the bulk soil surrounding uninoculated alfalfa plants across the field plot.

"EPA/600/A-99/002." "September 1998." Includes bibliographical references. Microfiche.