Abstract
The isoflavones, daidzein and genistein, have been isolated and identified as the major inducers of nod genes of Bradyrhizobium japonicum. The common nod genes of rhizobia are in turn responsible for stimulating root hair curling and cortical root cell division, the earliest steps in the host response. This study evaluated whether there was a relationship between root isoflavonoid production and the hypernodulation phenotype of selected soybean (Glycine max [L.] Merr.) mutants. Three independently selected hypernodulating soybean mutants (NOD1-3, NOD2-4, and NOD3-7) and a nonnodulating mutant (NN5) were compared with the Williams parent for isoflavonoid concentrations. High performance liquid chromatographic analyses of soybean root extracts showed that all lines increased in daidzein, genistein, and coumestrol concentrations throughout the 12-day growth period after transplanting of both inoculated and noninoculated plants; transplanting and inoculation were done 6 days after planting. No significant differences were detected in the concentration of these compounds among the three noninoculated hypernodulating mutants and the Williams parent. In response to inoculation, the three hypernodulating mutants had higher isoflavonoid concentrations than did the Williams control at 9 to 12 days after inoculation when grown at 0 millimolar N level. However, the inoculated nonnodulating mutant also had higher isoflavonoid concentrations than did Williams. N application [urea, (NH4)2SO4 and NO3−] decreased the concentration of all three isoflavonoid compounds in all soybean lines. Application of NO3− was most inhibitory to isoflavonoid concentrations, and inhibition by NO3− was concentration dependent. These results are consistent with a conclusion that differential NO3− inhibition of nodulation may be partially due to changes in isoflavonoid levels, although the similar response of the nonnodulating mutant brings this conclusion into question. Alternatively, the nodulation control in the NN5 mutant may be due to factors totally unrelated to isoflavonoids, leaving open the possibility that isoflavonoids play a role in differential nodulation of lines genetically competent to nodulate.
Full text
PDF







Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Carroll B. J., McNeil D. L., Gresshoff P. M. A Supernodulation and Nitrate-Tolerant Symbiotic (nts) Soybean Mutant. Plant Physiol. 1985 May;78(1):34–40. doi: 10.1104/pp.78.1.34. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Delves A. C., Mathews A., Day D. A., Carter A. S., Carroll B. J., Gresshoff P. M. Regulation of the soybean-Rhizobium nodule symbiosis by shoot and root factors. Plant Physiol. 1986 Oct;82(2):588–590. doi: 10.1104/pp.82.2.588. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Djordjevic M. A., Redmond J. W., Batley M., Rolfe B. G. Clovers secrete specific phenolic compounds which either stimulate or repress nod gene expression in Rhizobium trifolii. EMBO J. 1987 May;6(5):1173–1179. doi: 10.1002/j.1460-2075.1987.tb02351.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gremaud M. F., Harper J. E. Selection and initial characterization of partially nitrate tolerant nodulation mutants of soybean. Plant Physiol. 1989 Jan;89(1):169–173. doi: 10.1104/pp.89.1.169. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kapulnik Y., Joseph C. M., Phillips D. A. Flavone limitations to root nodulation and symbiotic nitrogen fixation in alfalfa. Plant Physiol. 1987 Aug;84(4):1193–1196. doi: 10.1104/pp.84.4.1193. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kosslak R. M., Bohlool B. B. Suppression of nodule development of one side of a split-root system of soybeans caused by prior inoculation of the other side. Plant Physiol. 1984 May;75(1):125–130. doi: 10.1104/pp.75.1.125. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kosslak R. M., Bookland R., Barkei J., Paaren H. E., Appelbaum E. R. Induction of Bradyrhizobium japonicum common nod genes by isoflavones isolated from Glycine max. Proc Natl Acad Sci U S A. 1987 Nov;84(21):7428–7432. doi: 10.1073/pnas.84.21.7428. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McNeil D. L. Variations in Ability of Rhizobium japonicum Strains To Nodulate Soybeans and Maintain Fixation in the Presence of Nitrate. Appl Environ Microbiol. 1982 Sep;44(3):647–652. doi: 10.1128/aem.44.3.647-652.1982. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Peters N. K., Frost J. W., Long S. R. A plant flavone, luteolin, induces expression of Rhizobium meliloti nodulation genes. Science. 1986 Aug 29;233(4767):977–980. doi: 10.1126/science.3738520. [DOI] [PubMed] [Google Scholar]
- Pierce M., Bauer W. D. A rapid regulatory response governing nodulation in soybean. Plant Physiol. 1983 Oct;73(2):286–290. doi: 10.1104/pp.73.2.286. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rossen L., Johnston A. W., Downie J. A. DNA sequence of the Rhizobium leguminosarum nodulation genes nodAB and C required for root hair curling. Nucleic Acids Res. 1984 Dec 21;12(24):9497–9508. doi: 10.1093/nar/12.24.9497. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rossen L., Shearman C. A., Johnston A. W., Downie J. A. The nodD gene of Rhizobium leguminosarum is autoregulatory and in the presence of plant exudate induces the nodA,B,C genes. EMBO J. 1985 Dec 16;4(13A):3369–3373. doi: 10.1002/j.1460-2075.1985.tb04092.x. [DOI] [PMC free article] [PubMed] [Google Scholar]