You are not currently logged in.
Access your personal account or get JSTOR access through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Rhizobium Nod Gene Inducers Exuded Naturally from Roots of Common Bean (Phaseolus vulgaris L.)
Mariangela Hungria, Cecillia M. Joseph and Donald A. Phillips
Vol. 97, No. 2 (Oct., 1991), pp. 759-764
Published by: American Society of Plant Biologists (ASPB)
Stable URL: http://www.jstor.org/stable/4273899
Page Count: 6
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
Four compounds exuded from young roots of a black-seeded bean (Phaseolus vulgaris L., cv PI165426CS) induce transcription of nod genes in Rhizobium leguminosarum biovar phaseoli. The three most active nod gene inducers were identified by spectroscopic methods (ultraviolet/visible absorbance, proton nuclear magnetic resonance, and mass spectrometry) as being eriodictyol (5,7,3′,4′-tetrahydroxyflavanone), naringenin (5,7,4′-trihydroxyflavanone), and a 7-O-glycoside of genistein (5,7,4′-trihydroxyisoflavone). Comparisons with authentic standards verified the chemical structures of the aglycones and their capacity to induce β-galactosidase activity in R. leguminosarum strains containing nodA-lacZ or nodC-lacZ fusions controlled by R. leguminosarum biovar phaseoli nodD genes. Roots of 9-day-old seedlings released 42, 281, and 337 nanomoles per plant per day of genistein, eriodictyol, and naringenin, respectively. Genistein and naringenin induced higher maximum β-galactosidase activities and required lower concentrations for half-maximum induction than eriodictyol. Comparing the nod gene-inducing activity of seed rinses with root exudate from PI165426CS bean showed that root flavonoids were released at about 6% the rate of those from seeds on a molar basis, but on average the individual compounds from roots were approximately three times more active than nod gene inducers from seeds.
Plant Physiology © 1991 American Society of Plant Biologists (ASPB)