Trigonelline and Stachydrine Released from Alfalfa Seeds Activate NodD2 Protein in Rhizobium meliloti.

Spectroscopic data (nuclear magnetic resonance, mass spectrometry, ultraviolet-visible) in this study identify trigonelline and stachydrine as major components of alfalfa (Medicago sativa L.) seed rinse. Moreover, biological assays show that these natural products induce nodulation (nod) gene transcription in Rhizobium meliloti by activating the regulatory protein NodD2, but not the homologous NodD1 protein. These findings contrast with the fact that the only previously identified NodD2 activator, 4,4' -dihydroxy-2' -methoxychalcone (MCh), also activates NodD1 protein. Trigonelline and stachydrine induce nod genes only at much higher concentrations than MCh, but they are released from seeds in correspondingly greater amounts. The existence of these amphoteric, nonflavonoid nod gene inducers broadens our understanding of the biochemical processes and ecological mechanisms that a legume host uses to regulate its microbial symbiont.

[1]  Y. Kapulnik,et al.  Flavone limitations to root nodulation and symbiotic nitrogen fixation in alfalfa. , 1987, Plant physiology.

[2]  T. Egelhoff,et al.  Specific binding of proteins from Rhizobium meliloti cell-free extracts containing NodD to DNA sequences upstream of inducible nodulation genes. , 1988, Genes & development.

[3]  S. Ghosal,et al.  Alkaloids of Abrus precatorius , 1971 .

[4]  N. Garg,et al.  Naringenin enhanced efficiency ofRhizobium meliloti-alfalfa symbiosis , 1990, World journal of microbiology & biotechnology.

[5]  Jeffrey H. Miller.  Experiments in molecular genetics , 1972 .

[6]  T. Egelhoff,et al.  Physical and genetic map of a Rhizobium meliloti nodulation gene region and nucleotide sequence of nodC , 1985, Journal of bacteriology.

[7]  E. Ciancaglini,et al.  A survey of trigonelline concentrations in dry seeds of the dicotyledoneae , 1986 .

[8]  Susan E. Brown,et al.  Physical and genetic characterization of symbiotic and auxotrophic mutants of Rhizobium meliloti induced by transposon Tn5 mutagenesis , 1982, Journal of bacteriology.

[9]  J. W. Frost,et al.  A plant flavone, luteolin, induces expression of Rhizobium meliloti nodulation genes. , 1986, Science.

[10]  F. Ausubel,et al.  Rhizobium meliloti has three functional copies of the nodD symbiotic regulatory gene. , 1987, Proceedings of the National Academy of Sciences of the United States of America.

[11]  E. Kondorosi,et al.  Diverse signal sensitivity of NodD protein homologs from narrow and broad host range rhizobia , 1991 .

[12]  S. Long,et al.  Induction of Rhizobium meliloti nodC expression by plant exudate requires nodD. , 1985, Proceedings of the National Academy of Sciences of the United States of America.

[13]  M. Piattelli,et al.  Onium Compounds from the Red Alga Pterocladia capillacea , 1988 .

[14]  D. Tepfer,et al.  Betaine use by rhizosphere bacteria: genes essential for trigonelline, stachydrine, and carnitine catabolism in Rhizobium meliloti are located on pSym in the symbiotic region. , 1991, Molecular plant-microbe interactions : MPMI.

[15]  C. Maxwell,et al.  Chrysoeriol and Luteolin Released from Alfalfa Seeds Induce nod Genes in Rhizobium meliloti. , 1990, Plant physiology.

[16]  J. Schell,et al.  Expression of the nodulation gene nodA in Rhizobium meliloti and localization of the gene product in the cytosol. , 1986, Proceedings of the National Academy of Sciences of the United States of America.

[17]  Marc Van Montagu,et al.  Identification of the signal molecules produced by wounded plant cells that activate T-DNA transfer in Agrobacterium tumefaciens , 1985, Nature.

[18]  D. Phillips,et al.  Flavonoids Released Naturally from Alfalfa Seeds Enhance Growth Rate of Rhizobium meliloti. , 1991, Plant physiology.

[19]  C M Joseph,et al.  Effects of alfalfa nod gene-inducing flavonoids on nodABC transcription in Rhizobium meliloti strains containing different nodD genes , 1990, Journal of bacteriology.

[20]  L. Paleg,et al.  Estimates of Solutes Accumulating in Plants by 1H Nuclear Magnetic Resonance Spectroscopy , 1986 .

[21]  P Putnoky,et al.  At least two nodD genes are necessary for efficient nodulation of alfalfa by Rhizobium meliloti. , 1986, Journal of molecular biology.

[22]  D. Dolphin,et al.  Pisum sativum stress metabolites: Two cinnamylphenols and a 2′-methoxychalcone , 1982 .

[23]  H. Steenbock.  ISOLATION AND IDENTIFICATION OF STACHYDRIN FROM ALFALFA HAY , 1918 .

[24]  D. Phillips.  Flavonoids: Plant Signals to Soil Microbes , 1992 .

[25]  F. Ausubel,et al.  Rhizobium meliloti nodD genes mediate host-specific activation of nodABC , 1990, Journal of bacteriology.

[26]  H. Rapoport,et al.  Reaction of O-methyl-N,N'-diisopropylisourea with amino acids and amines. , 1977, The Journal of organic chemistry.

[27]  G. M. Smith,et al.  Identification of N,N-dimethylproline as the N-terminal blocking group of Crithidia oncopelti cytochrome c557. , 1980, European journal of biochemistry.

[28]  C M Joseph,et al.  A Chalcone and Two Related Flavonoids Released from Alfalfa Roots Induce nod Genes of Rhizobium meliloti. , 1989, Plant physiology.