Isolation and characterization of nod factors that have the ability to initiate nodulation on a restrictive Phaseolus vulgaris host. (Molecular Biology and Genetics 02:00 PM, Saturday, April 5, 2003 Brewer/Frost Science 141 Dr. Beth Berger Pritts-Presiding).

Bashore, Sarah L. ; Trese, Arthur T.

4:00

Soil bacteria in the genus Rhizobium are microsymbionts of Phaseolus vulgaris. Initiation of the symbiosis begins with the transcription of the Rhizobium nod genes that are induced by flavonoids exuded from the plant. These nod genes encode enzymes that synthesize nod factors, lipo-chitin oligosaccharides (LCO's), which are involved in signaling the plant and determining host specificity. We have isolated a spontaneous mutant of P. vulgaris that prevents nodulation. Further evaluation resulted in the isolation of 3 strains of Rhizobium that have the ability to `overcome' this mutation and nodulate the mutant plant. The three `overcoming' strains are believed to produce nod factors with a different chemical structure than the nod factors produced by the other strains, designated `restricted' within their genus and species designation. Working with both the `overcoming' and `restricted' strains, nod factor production was induced with Naringenin and LCO's were isolated using butanol extraction and high-pressure liquid chromatography (HPLC). Bioassay of the nod factors has shown that nod factors of `restricted' strains do not have the ability to initiate nodulation (root hair curling) on the mutant plant but do on the wild-type plant. `Overcoming' strain nod factors do have the ability to initiate nodulation on both the mutant plant and the wild-type. This suggests that the `overcoming' strains of bacteria have novel nod factors that allow them to nodulate the mutant P. vulgaris.

SARA. L. BASHORE [email protected] AND ARTHUR T. TRUE, DEPT OF ENVIRONMENTAL AND PLANT BIOLOGY, 317 PORTER HALL, RICHLAND AVE, OHIO UNIVERSITY, ATHENS OH 45701