Activation of the nodA promoter by the nodD genes of Rhizobium galegae induced by synthetic flavonoids or Galega orientalis root exudate
| Autor: | Christophe Roos, Kristina Lindström, Leena Suominen, R. Luukkainen |
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| Rok vydání: | 2003 |
| Předmět: |
Transcriptional Activation
Exudate Galega orientalis medicine.disease_cause Plant Roots Sensitivity and Specificity Microbiology Galega Rhizobium leguminosarum Rhizobium galegae Rhizobia 03 medical and health sciences Bacterial Proteins Genetics medicine Promoter Regions Genetic Molecular Biology Phylogeny 030304 developmental biology Flavonoids 0303 health sciences Sinorhizobium meliloti biology Plant Extracts 030306 microbiology food and beverages Gene Expression Regulation Bacterial Sequence Analysis DNA biology.organism_classification Mutagenesis Insertional Rhizobium medicine.symptom Sequence Alignment Acyltransferases |
| Zdroj: | FEMS Microbiology Letters. 219:225-232 |
| ISSN: | 1574-6968 0378-1097 |
| Popis: | Rhizobial nodD genes produce transcriptional regulators that, together with appropriate inducer compounds, activate the other symbiotic nodulation (nod) genes and initiate the nodule formation process. Two nodD homologues, nodD1 and nodD2, are present in the Rhizobium galegae strain HAMBI 1174. In this work we analysed their ability to induce the nodA promoter with synthetic inducers known to activate nod genes in other rhizobia. According to phylogenetic analysis, the inducer-specific carboxy-terminal part of the R. galegae nodD protein sequence groups together with those of Rhizobium leguminosarum and Sinorhizobium meliloti. However, the respective inducer compounds for their NodD proteins are not highly effective with R. galegae nodD products. The best inducer discovered with R. galegae nodD1 was the root exudate of the host plant of R. galegae, Galega orientalis. HPLC analyses revealed the presence of many divergent flavonoid compounds in the G. orientalis root exudate. The most effective HPLC fractions induced R. galegae nodD1 up to the level obtained by intact G. orientalis root exudate while apigenin and luteolin, which were also present in the root exudate, were only moderate inducers. A UV-Vis diode array spectrum of the most active peak indicated that the main inducer present in the G. orientalis root exudate is an unidentified chalcone-type compound. In the Galega-R. galegae interaction the first recognition between the NodD protein and the flavonoid inducer secreted from the roots of Galega is specific for these organisms, and thus partly responsible of the strict host specificity of this symbiosis. |
| Databáze: | OpenAIRE |
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