Aldonic Acids: A Novel Family of nod Gene Inducers of Mesorhizobium loti, Rhizobium lupini, and Sinorhizobium meliloti
Molecular signals, such as flavonoids (or nonflavonoid type), nod gene-inducers, and bacterial lipochitin oligosac-charides (LCOs) act as modulators of species specificity during early stages of infection in Rhizobium spp.-legume interactions. The fact that signaling in Lupinus albus remains to be d...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
The American Phytopathological Society
1998-10-01
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| Series: | Molecular Plant-Microbe Interactions |
| Online Access: | https://apsjournals.apsnet.org/doi/10.1094/MPMI.1998.11.10.988 |
| _version_ | 1811264515846701056 |
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| author | Hubert Gagnon Ragai K. Ibrahim |
| author_facet | Hubert Gagnon Ragai K. Ibrahim |
| author_sort | Hubert Gagnon |
| collection | DOAJ |
| description | Molecular signals, such as flavonoids (or nonflavonoid type), nod gene-inducers, and bacterial lipochitin oligosac-charides (LCOs) act as modulators of species specificity during early stages of infection in Rhizobium spp.-legume interactions. The fact that signaling in Lupinus albus remains to be determined prompted us to investigate the flavonoid signal responsible for nod gene induction in Rhizobium lupini. A screening method was used based on the measurement of β-galactosidase activity of R. lupini strains harboring nodC::lacZ fusions in the presence of (i) authentic lupin isoflavones, (ii) carbohydrate-like inducers, and (iii) high-pressure liquid chromatography (HPLC)-fractionated lupin seed effusates and root exudates, as putative nod gene inducers. The results indicate that both erythronic and tetronic acids (4-C sugar acids) led to low but significant increases in β-galactosidase activities, compared with the controls. In addition, lupi-wighteone, a monoprenylated isoflavone, exerts a synergistic effect with the carbohydrate-like inducers, compared with other isoflavone treatments. The natural occurrence of aldonic acids in L. albus root exudates and seed effusates has been demonstrated by HPLC analysis. When tested with nodC::lacZ fusions, tetronic acid resulted in nod gene induction in Sinorhizobium meliloti. In addition, a combination of luteolin and tetronic acid promotes further increases in S. meliloti nod gene expression, as shown by β-galactosidase assays. Incorporation studies with [14C]LCO precursors confirmed the inductive role of both erythronic and tetronic acids in promoting LCO biosynthesis in R. lupini cultures, and of tetronic acid in Mesorhizobium loti and S. meliloti. Hydrolysis of the LCOs with various enzymes substantiated their putative identities. These results are discussed in relation to the impact of these unusual signal molecules on our knowledge of flavonoid signaling in Rhizobium-legume symbiosis. |
| first_indexed | 2024-04-12T20:05:40Z |
| format | Article |
| id | doaj.art-61e54392c7a64a89bccab417a8cc1aab |
| institution | Directory Open Access Journal |
| issn | 0894-0282 1943-7706 |
| language | English |
| last_indexed | 2024-04-12T20:05:40Z |
| publishDate | 1998-10-01 |
| publisher | The American Phytopathological Society |
| record_format | Article |
| series | Molecular Plant-Microbe Interactions |
| spelling | doaj.art-61e54392c7a64a89bccab417a8cc1aab2022-12-22T03:18:24ZengThe American Phytopathological SocietyMolecular Plant-Microbe Interactions0894-02821943-77061998-10-01111098899810.1094/MPMI.1998.11.10.988Aldonic Acids: A Novel Family of nod Gene Inducers of Mesorhizobium loti, Rhizobium lupini, and Sinorhizobium melilotiHubert GagnonRagai K. IbrahimMolecular signals, such as flavonoids (or nonflavonoid type), nod gene-inducers, and bacterial lipochitin oligosac-charides (LCOs) act as modulators of species specificity during early stages of infection in Rhizobium spp.-legume interactions. The fact that signaling in Lupinus albus remains to be determined prompted us to investigate the flavonoid signal responsible for nod gene induction in Rhizobium lupini. A screening method was used based on the measurement of β-galactosidase activity of R. lupini strains harboring nodC::lacZ fusions in the presence of (i) authentic lupin isoflavones, (ii) carbohydrate-like inducers, and (iii) high-pressure liquid chromatography (HPLC)-fractionated lupin seed effusates and root exudates, as putative nod gene inducers. The results indicate that both erythronic and tetronic acids (4-C sugar acids) led to low but significant increases in β-galactosidase activities, compared with the controls. In addition, lupi-wighteone, a monoprenylated isoflavone, exerts a synergistic effect with the carbohydrate-like inducers, compared with other isoflavone treatments. The natural occurrence of aldonic acids in L. albus root exudates and seed effusates has been demonstrated by HPLC analysis. When tested with nodC::lacZ fusions, tetronic acid resulted in nod gene induction in Sinorhizobium meliloti. In addition, a combination of luteolin and tetronic acid promotes further increases in S. meliloti nod gene expression, as shown by β-galactosidase assays. Incorporation studies with [14C]LCO precursors confirmed the inductive role of both erythronic and tetronic acids in promoting LCO biosynthesis in R. lupini cultures, and of tetronic acid in Mesorhizobium loti and S. meliloti. Hydrolysis of the LCOs with various enzymes substantiated their putative identities. These results are discussed in relation to the impact of these unusual signal molecules on our knowledge of flavonoid signaling in Rhizobium-legume symbiosis.https://apsjournals.apsnet.org/doi/10.1094/MPMI.1998.11.10.988 |
| spellingShingle | Hubert Gagnon Ragai K. Ibrahim Aldonic Acids: A Novel Family of nod Gene Inducers of Mesorhizobium loti, Rhizobium lupini, and Sinorhizobium meliloti Molecular Plant-Microbe Interactions |
| title | Aldonic Acids: A Novel Family of nod Gene Inducers of Mesorhizobium loti, Rhizobium lupini, and Sinorhizobium meliloti |
| title_full | Aldonic Acids: A Novel Family of nod Gene Inducers of Mesorhizobium loti, Rhizobium lupini, and Sinorhizobium meliloti |
| title_fullStr | Aldonic Acids: A Novel Family of nod Gene Inducers of Mesorhizobium loti, Rhizobium lupini, and Sinorhizobium meliloti |
| title_full_unstemmed | Aldonic Acids: A Novel Family of nod Gene Inducers of Mesorhizobium loti, Rhizobium lupini, and Sinorhizobium meliloti |
| title_short | Aldonic Acids: A Novel Family of nod Gene Inducers of Mesorhizobium loti, Rhizobium lupini, and Sinorhizobium meliloti |
| title_sort | aldonic acids a novel family of nod gene inducers of mesorhizobium loti rhizobium lupini and sinorhizobium meliloti |
| url | https://apsjournals.apsnet.org/doi/10.1094/MPMI.1998.11.10.988 |
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