Skip to main content
NCBI home page
Plant Physiology logoLink to Plant Physiology
. 1987 Aug;84(4):1193–1196. doi: 10.1104/pp.84.4.1193

Flavone Limitations to Root Nodulation and Symbiotic Nitrogen Fixation in Alfalfa 1

Yoram Kapulnik 1,2, Cecillia M Joseph 1, Donald A Phillips 1
PMCID: PMC1056750  PMID: 16665583

Abstract

Transcription of the nodABC genes in Rhizobium meliloti is required for root nodule formation in alfalfa (Medicago sativa L.) and occurs when specific compounds, such as the flavone luteolin, are supplied by the host plant. Results reported here indicate how luteolin in the root and rhizosphere can affect subsequent N2 fixation and plant growth. Previous experiments with `Hairy Peruvian 32' (HP32), an alfalfa population produced from `Hairy Peruvian' (HP) by two generations of selection for increased N2 fixation and growth, found that HP32 had more root nodules and fixed more N2 than the parental HP population. In the present study, flavonoid extracts of HP32 seedling roots are shown to contain a 60% higher concentration of compounds that induce transcription of a nodABC-lacZ fusion in R. meliloti than comparable extracts of HP roots. Chromatographic data indicated that HP32 roots had a 77% higher concentration of luteolin than HP roots. Adding 10 micromolar luteolin to the rhizosphere of HP seedlings increased nodulation, N2 fixation, total N, and total dry weight but had no effect on nitrate assimilation. These data show that normal levels of flavone nodulation signals in the rhizosphere of HP alfalfa can limit root nodulation, symbiotic N2 fixation, and seedling growth and suggest that one mechanism for increasing N2 fixation can be the genetic enhancement of specific biochemical signals which induce nodulation genes in Rhizobium.

Full text

PDF
1193

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Beringer J. E. R factor transfer in Rhizobium leguminosarum. J Gen Microbiol. 1974 Sep;84(1):188–198. doi: 10.1099/00221287-84-1-188. [DOI] [PubMed] [Google Scholar]
  2. Dejong T. M., Phillips D. A. Nitrogen Stress and Apparent Photosynthesis in Symbiotically Grown Pisum sativum L. Plant Physiol. 1981 Aug;68(2):309–313. doi: 10.1104/pp.68.2.309. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Mulligan J. T., Long S. R. Induction of Rhizobium meliloti nodC expression by plant exudate requires nodD. Proc Natl Acad Sci U S A. 1985 Oct;82(19):6609–6613. doi: 10.1073/pnas.82.19.6609. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. 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]
  5. Phillips D. A., Center D. M., Jones M. B. Nitrogen Turnover and Assimilation during Regrowth in Trifolium subterraneum L. and Bromus mollis L. Plant Physiol. 1983 Mar;71(3):472–476. doi: 10.1104/pp.71.3.472. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Williams L. E., Dejong T. M., Phillips D. A. Carbon and nitrogen limitations on soybean seedling development. Plant Physiol. 1981 Nov;68(5):1206–1209. doi: 10.1104/pp.68.5.1206. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Zaat S. A., Wijffelman C. A., Spaink H. P., van Brussel A. A., Okker R. J., Lugtenberg B. J. Induction of the nodA promoter of Rhizobium leguminosarum Sym plasmid pRL1JI by plant flavanones and flavones. J Bacteriol. 1987 Jan;169(1):198–204. doi: 10.1128/jb.169.1.198-204.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Plant Physiology are provided here courtesy of Oxford University Press

RESOURCES