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Jan W. Kijne - One of the best experts on this subject based on the ideXlab platform.
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exopolysaccharide structure is not a determinant of host plant specificity in nodulation of Vicia Sativa roots
Molecular Plant-microbe Interactions, 2005Co-Authors: Marc C Laus, Anton A N Van Brussel, Jan W. KijneAbstract:Exopolysaccharide (EPS)-deficient strains of the root nodule symbiote Rhizobium leguminosarum induce formation of abortive infection threads in Vicia Sativa subsp. nigra roots. As a result, the nodule tissue remains uninfected. Formation of an infection thread can be restored by coinoculation of the EPS-deficient mutant with a Nod factor-deficient strain, which produces a similar EPS structure. This suggests that EPS contributes to host-plant specificity of nodulation. Here, a comparison was made of i) coinoculation with heterologous strains with different EPS structures, and ii) introduction of the pRL1JI Sym plasmid or a nod gene-encoding fragment in the same heterologous strains. Most strains not complementing in coinoculation experiments were able to nodulate V. Sativa roots as transconjugants. Apparently, coinoculation is a delicate approach in which differences in root colonization ability or bacterial growth rate easily affect successful infection-thread formation. Obviously, lack of infection-thread formation in coinoculation studies is not solely determined by EPS structure. Transconjugation data show that different EPS structures can allow infection-thread formation and subsequent nodulation of V. Sativa roots.
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role of cellulose fibrils and exopolysaccharides of rhizobium leguminosarum in attachment to and infection of Vicia Sativa root hairs
Molecular Plant-microbe Interactions, 2005Co-Authors: Marc C Laus, Anton A. N. Van Brussel, Jan W. KijneAbstract:Infection and subsequent nodulation of legume host plants by the root nodule symbiote Rhizobium leguminosarum usually require attachment of the bacteria to root-hair tips. Bacterial cellulose fibrils have been shown to be involved in this attachment process but appeared not to be essential for successful nodulation. Detailed analysis of Vicia Sativa root-hair infection by wild-type Rhizobium leguminosarum RBL5523 and its cellulose fibril-deficient celE mutant showed that wild-type bacteria infected elongated growing root hairs, whereas cellulose-deficient bacteria infected young emerging root hairs. Exopolysaccharide-deficient strains that retained the ability to produce cellulose fibrils could also infect elongated root hairs but infection thread colonization was defective. Cellulose-mediated agglutination of these bacteria in the root-hair curl appeared to prevent entry into the induced infection thread. Infection experiments with V. Sativa roots and an extracellular polysaccharide (EPS)- and cellulose-...
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role of cellulose fibrils and exopolysaccharides of rhizobium leguminosarum in attachment to and infection of Vicia Sativa root hairs
Molecular Plant-microbe Interactions, 2005Co-Authors: Marc C Laus, Anton A. N. Van Brussel, Jan W. KijneAbstract:Infection and subsequent nodulation of legume host plants by the root nodule symbiote Rhizobium leguminosarum usually require attachment of the bacteria to root-hair tips. Bacterial cellulose fibrils have been shown to be involved in this attachment process but appeared not to be essential for successful nodulation. Detailed analysis of Vicia Sativa root-hair infection by wild-type Rhizobium leguminosarum RBL5523 and its cellulose fibril-deficient celE mutant showed that wild-type bacteria infected elongated growing root hairs, whereas cellulose-deficient bacteria infected young emerging root hairs. Exopolysaccharide-deficient strains that retained the ability to produce cellulose fibrils could also infect elongated root hairs but infection thread colonization was defective. Cellulose-mediated agglutination of these bacteria in the root-hair curl appeared to prevent entry into the induced infection thread. Infection experiments with V. Sativa roots and an extracellular polysaccharide (EPS)- and cellulose-...
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involvement of exo5 in production of surface polysaccharides in rhizobium leguminosarum and its role in nodulation of Vicia Sativa subsp nigra
Journal of Bacteriology, 2004Co-Authors: Marc C Laus, Anton A N Van Brussel, Trudy J J Logman, Russell W Carlson, Parastoo Azadi, Muyun Gao, Jan W. KijneAbstract:Analysis of two exopolysaccharide-deficient mutants of Rhizobium leguminosarum, RBL5808 and RBL5812, revealed independent Tn5 transposon integrations in a single gene, designated exo5. As judged from structural and functional homology, this gene encodes a UDP-glucose dehydrogenase responsible for the oxidation of UDP-glucose to UDP-glucuronic acid. A mutation in exo5 affects all glucuronic acid-containing polysaccharides and, consequently, all galacturonic acid-containing polysaccharides. Exo5-deficient rhizobia do not produce extracellular polysaccharide (EPS) or capsular polysaccharide (CPS), both of which contain glucuronic acid. Carbohydrate composition analysis and nuclear magnetic resonance studies demonstrated that EPS and CPS from the parent strain have very similar structures. Lipopolysaccharide (LPS) molecules produced by the mutant strains are deficient in galacturonic acid, which is normally present in the core and lipid A portions of the LPS. The sensitivity of exo5 mutant rhizobia to hydrophobic compounds shows the involvement of the galacturonic acid residues in the outer membrane structure. Nodulation studies with Vicia Sativa subsp. nigra showed that exo5 mutant rhizobia are impaired in successful infection thread colonization. This is caused by strong agglutination of EPS-deficient bacteria in the root hair curl. Root infection could be restored by simultaneous inoculation with a Nod factor-defective strain which retained the ability to produce EPS and CPS. However, in this case colonization of the nodule tissue was impaired.
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autoregulation of root nodule formation signals of both symbiotic partners studied in a split root system of Vicia Sativa subsp nigra
Molecular Plant-microbe Interactions, 2002Co-Authors: Anton A N Van Brussel, Kees J M Boot, Teun Tak, Jan W. KijneAbstract:Inhibition of root nodule formation on leguminous plants by already induced or existing root nodules is called autoregulation of root nodule formation (AUT). Optimal conditions for AUT were determined using a split-root technique newly developed for Vicia Sativa subsp. nigra. Infection of a root A with nodulating Rhizobium leguminosarum bv. Viciae bacteria systemically inhibited nodulation of a spatially separated root B inoculated 2 days later with the same bacteria. This treatment gives complete AUT (total absence of nodules on root B). Only partial AUT of root B was obtained by incubation of root A with mitogenic nodulation (Nod) factors or with a noninfective strain producing normal mitogenic Nod factors. Nonmitogenic Nod factors did not evoke AUT. We identified two systemic plant signals induced by Rhizobium bacteria. Signal 1 (at weak buffering) was correlated with sink formation in root A and induced acidification of B-root medium. This signal is induced by treatment of root A with (i) nodulating rhizobia, (ii) mitogenic Nod factors, (iii) nonmitogenic Nod factors, or (iv) the cytokinin zeatin. Signal 2 (at strong buffering) could only be evoked by treatment with nodulating rhizobia or with mitogenic Nod factors. Most probably, this signal represents the specific AUT signal. Induction of complete AUT appears to require actively dividing nodule cells in nodule primordia, nodule meristems, or both of root A.
Ben Lugtenberg - One of the best experts on this subject based on the ideXlab platform.
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chitin oligosaccharides can induce cortical cell division in roots of Vicia Sativa when delivered by ballistic microtargeting
Development, 1997Co-Authors: Helmi R M Schlaman, Jan W. Kijne, Ben Lugtenberg, Herman P. Spaink, Andreas Gisel, Nicolette E M Quaedvlieg, Guido V Bloemberg, Ingo Potrykus, C SautterAbstract:Rhizobia, bacterial symbionts of leguminous plants, produce lipo-chitin oligosaccharide (LCO) signal molecules that can induce nodule organogenesis in the cortex of legume roots in a host-specific way. The multi-unsaturated fatty acyl and the O-acetyl moieties of the LCOs of Rhizobium leguminosarum biovar Viciae were shown to be essential for obtaining root nodule induction in Vicia Sativa plants. We have used ballistic microtargeting as a novel approach to deliver derivatives of the nodulation signal molecules inside the roots of V. Sativa. This method offers the unique ability to introduce soluble compounds into the tissue at a small area. The mitogenic effect of microtargeting of chitin oligosaccharides, including an analysis of the influence of the chain length and modifications, was tested in a qualitative assay. The role of a cell division factor from the root stele, uridine, has also been examined in these experiments. The results show that O-acetylated chitin oligosaccharides can induce root cortical cell divisions when delivered by microtargeting. For this effect it is essential that uridine is co-targeted. The foci of cortical cell division were often similar to root nodule primordia. Anatomical examination also revealed chimeric structures that share characteristics with lateral root and nodule primordia. Our data favour a model in which the oligosaccharide moiety of the rhizobial LCO induces cortical cell division and the fatty acyl moiety plays a role in transport of the LCO into the plant tissue.
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activation of flavonoid biosynthesis in roots of Vicia Sativa subsp nigra plants by inoculation with rhizobium leguminosarum biovar Viciae
Plant Molecular Biology, 1992Co-Authors: K Recourt, Ben Lugtenberg, A J Van Tunen, L A Mur, A A N Van Brussel, Jan W. KijneAbstract:Infective (nodulating) Rhizobium leguminosarum biovar Viciae (R.l. Viciae) bacteria release Nod factors which stimulate the release of nodulation gene-inducing flavanones and chalcones from roots of the host plant Vicia Sativa subsp. nigra (K. Recourt et al., Plant Mol Biol 16: 841–852; H.P. Spaink et al., Nature 354: 125–130). The hypothesis that this release results from increased synthesis of flavonoids was tested by studying the effect of inoculation of V. Sativa with infective and uninfective R.l. Viciae bacteria on (i) activity of L-phenylalanine ammonia-lyase, (ii) level of chalcone synthase mRNA, and (iii) activity of (eriodictyol) methyltransferase in roots. Consistent with the hypothesis, each of these parameters was found to increase 1.5 to 2-fold upon inoculation with infective R.l. Viciae bacteria relative to the situation for uninoculated roots and for roots inoculated with uninfective rhizobia.
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inoculation of Vicia Sativa subsp nigra roots with rhizobium leguminosarum biovar Viciae results in release of nod gene activating flavanones and chalcones
Plant Molecular Biology, 1991Co-Authors: K Recourt, Jan W. Kijne, Jan Schripsema, A A N Van Brussel, Ben LugtenbergAbstract:Flavonoids released by roots of Vicia Sativa subsp. nigra (V. Sativa) activate nodulation genes of the homologous bacterium Rhizobium leguminosarum biovar Viciae (R. l. Viciae). Inoculation of V. Sativa roots with infective R. l. Viciae bacteria largely increases the nod gene-inducing ability of V. Sativa root exudate (A.A.N. van Brussel et al., J Bact 172: 5394–5401). The present study showed that, in contrast to sterile roots and roots inoculated with R. l. Viciae cured of its Sym plasmid, roots inoculated with R. l. Viciae harboring its Sym plasmid released additional nod gene-inducing flavonoids. Using 1H-NMR, the structures of the major inducers released by inoculated roots, 6 flavanones and 2 chalcones, were elucidated. Roots extracts of (un)inoculated V. Sativa contain 4 major non-inducing, most likely glycosylated, flavonoids. Therefore, the released flavonoids may either derive from the root flavonoids or inoculation with R. l. Viciae activates de novo flavonoid biosynthesis.
Marc C Laus - One of the best experts on this subject based on the ideXlab platform.
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exopolysaccharide structure is not a determinant of host plant specificity in nodulation of Vicia Sativa roots
Molecular Plant-microbe Interactions, 2005Co-Authors: Marc C Laus, Anton A N Van Brussel, Jan W. KijneAbstract:Exopolysaccharide (EPS)-deficient strains of the root nodule symbiote Rhizobium leguminosarum induce formation of abortive infection threads in Vicia Sativa subsp. nigra roots. As a result, the nodule tissue remains uninfected. Formation of an infection thread can be restored by coinoculation of the EPS-deficient mutant with a Nod factor-deficient strain, which produces a similar EPS structure. This suggests that EPS contributes to host-plant specificity of nodulation. Here, a comparison was made of i) coinoculation with heterologous strains with different EPS structures, and ii) introduction of the pRL1JI Sym plasmid or a nod gene-encoding fragment in the same heterologous strains. Most strains not complementing in coinoculation experiments were able to nodulate V. Sativa roots as transconjugants. Apparently, coinoculation is a delicate approach in which differences in root colonization ability or bacterial growth rate easily affect successful infection-thread formation. Obviously, lack of infection-thread formation in coinoculation studies is not solely determined by EPS structure. Transconjugation data show that different EPS structures can allow infection-thread formation and subsequent nodulation of V. Sativa roots.
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role of cellulose fibrils and exopolysaccharides of rhizobium leguminosarum in attachment to and infection of Vicia Sativa root hairs
Molecular Plant-microbe Interactions, 2005Co-Authors: Marc C Laus, Anton A. N. Van Brussel, Jan W. KijneAbstract:Infection and subsequent nodulation of legume host plants by the root nodule symbiote Rhizobium leguminosarum usually require attachment of the bacteria to root-hair tips. Bacterial cellulose fibrils have been shown to be involved in this attachment process but appeared not to be essential for successful nodulation. Detailed analysis of Vicia Sativa root-hair infection by wild-type Rhizobium leguminosarum RBL5523 and its cellulose fibril-deficient celE mutant showed that wild-type bacteria infected elongated growing root hairs, whereas cellulose-deficient bacteria infected young emerging root hairs. Exopolysaccharide-deficient strains that retained the ability to produce cellulose fibrils could also infect elongated root hairs but infection thread colonization was defective. Cellulose-mediated agglutination of these bacteria in the root-hair curl appeared to prevent entry into the induced infection thread. Infection experiments with V. Sativa roots and an extracellular polysaccharide (EPS)- and cellulose-...
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role of cellulose fibrils and exopolysaccharides of rhizobium leguminosarum in attachment to and infection of Vicia Sativa root hairs
Molecular Plant-microbe Interactions, 2005Co-Authors: Marc C Laus, Anton A. N. Van Brussel, Jan W. KijneAbstract:Infection and subsequent nodulation of legume host plants by the root nodule symbiote Rhizobium leguminosarum usually require attachment of the bacteria to root-hair tips. Bacterial cellulose fibrils have been shown to be involved in this attachment process but appeared not to be essential for successful nodulation. Detailed analysis of Vicia Sativa root-hair infection by wild-type Rhizobium leguminosarum RBL5523 and its cellulose fibril-deficient celE mutant showed that wild-type bacteria infected elongated growing root hairs, whereas cellulose-deficient bacteria infected young emerging root hairs. Exopolysaccharide-deficient strains that retained the ability to produce cellulose fibrils could also infect elongated root hairs but infection thread colonization was defective. Cellulose-mediated agglutination of these bacteria in the root-hair curl appeared to prevent entry into the induced infection thread. Infection experiments with V. Sativa roots and an extracellular polysaccharide (EPS)- and cellulose-...
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involvement of exo5 in production of surface polysaccharides in rhizobium leguminosarum and its role in nodulation of Vicia Sativa subsp nigra
Journal of Bacteriology, 2004Co-Authors: Marc C Laus, Anton A N Van Brussel, Trudy J J Logman, Russell W Carlson, Parastoo Azadi, Muyun Gao, Jan W. KijneAbstract:Analysis of two exopolysaccharide-deficient mutants of Rhizobium leguminosarum, RBL5808 and RBL5812, revealed independent Tn5 transposon integrations in a single gene, designated exo5. As judged from structural and functional homology, this gene encodes a UDP-glucose dehydrogenase responsible for the oxidation of UDP-glucose to UDP-glucuronic acid. A mutation in exo5 affects all glucuronic acid-containing polysaccharides and, consequently, all galacturonic acid-containing polysaccharides. Exo5-deficient rhizobia do not produce extracellular polysaccharide (EPS) or capsular polysaccharide (CPS), both of which contain glucuronic acid. Carbohydrate composition analysis and nuclear magnetic resonance studies demonstrated that EPS and CPS from the parent strain have very similar structures. Lipopolysaccharide (LPS) molecules produced by the mutant strains are deficient in galacturonic acid, which is normally present in the core and lipid A portions of the LPS. The sensitivity of exo5 mutant rhizobia to hydrophobic compounds shows the involvement of the galacturonic acid residues in the outer membrane structure. Nodulation studies with Vicia Sativa subsp. nigra showed that exo5 mutant rhizobia are impaired in successful infection thread colonization. This is caused by strong agglutination of EPS-deficient bacteria in the root hair curl. Root infection could be restored by simultaneous inoculation with a Nod factor-defective strain which retained the ability to produce EPS and CPS. However, in this case colonization of the nodule tissue was impaired.
Anton A N Van Brussel - One of the best experts on this subject based on the ideXlab platform.
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exopolysaccharide structure is not a determinant of host plant specificity in nodulation of Vicia Sativa roots
Molecular Plant-microbe Interactions, 2005Co-Authors: Marc C Laus, Anton A N Van Brussel, Jan W. KijneAbstract:Exopolysaccharide (EPS)-deficient strains of the root nodule symbiote Rhizobium leguminosarum induce formation of abortive infection threads in Vicia Sativa subsp. nigra roots. As a result, the nodule tissue remains uninfected. Formation of an infection thread can be restored by coinoculation of the EPS-deficient mutant with a Nod factor-deficient strain, which produces a similar EPS structure. This suggests that EPS contributes to host-plant specificity of nodulation. Here, a comparison was made of i) coinoculation with heterologous strains with different EPS structures, and ii) introduction of the pRL1JI Sym plasmid or a nod gene-encoding fragment in the same heterologous strains. Most strains not complementing in coinoculation experiments were able to nodulate V. Sativa roots as transconjugants. Apparently, coinoculation is a delicate approach in which differences in root colonization ability or bacterial growth rate easily affect successful infection-thread formation. Obviously, lack of infection-thread formation in coinoculation studies is not solely determined by EPS structure. Transconjugation data show that different EPS structures can allow infection-thread formation and subsequent nodulation of V. Sativa roots.
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involvement of exo5 in production of surface polysaccharides in rhizobium leguminosarum and its role in nodulation of Vicia Sativa subsp nigra
Journal of Bacteriology, 2004Co-Authors: Marc C Laus, Anton A N Van Brussel, Trudy J J Logman, Russell W Carlson, Parastoo Azadi, Muyun Gao, Jan W. KijneAbstract:Analysis of two exopolysaccharide-deficient mutants of Rhizobium leguminosarum, RBL5808 and RBL5812, revealed independent Tn5 transposon integrations in a single gene, designated exo5. As judged from structural and functional homology, this gene encodes a UDP-glucose dehydrogenase responsible for the oxidation of UDP-glucose to UDP-glucuronic acid. A mutation in exo5 affects all glucuronic acid-containing polysaccharides and, consequently, all galacturonic acid-containing polysaccharides. Exo5-deficient rhizobia do not produce extracellular polysaccharide (EPS) or capsular polysaccharide (CPS), both of which contain glucuronic acid. Carbohydrate composition analysis and nuclear magnetic resonance studies demonstrated that EPS and CPS from the parent strain have very similar structures. Lipopolysaccharide (LPS) molecules produced by the mutant strains are deficient in galacturonic acid, which is normally present in the core and lipid A portions of the LPS. The sensitivity of exo5 mutant rhizobia to hydrophobic compounds shows the involvement of the galacturonic acid residues in the outer membrane structure. Nodulation studies with Vicia Sativa subsp. nigra showed that exo5 mutant rhizobia are impaired in successful infection thread colonization. This is caused by strong agglutination of EPS-deficient bacteria in the root hair curl. Root infection could be restored by simultaneous inoculation with a Nod factor-defective strain which retained the ability to produce EPS and CPS. However, in this case colonization of the nodule tissue was impaired.
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autoregulation of root nodule formation signals of both symbiotic partners studied in a split root system of Vicia Sativa subsp nigra
Molecular Plant-microbe Interactions, 2002Co-Authors: Anton A N Van Brussel, Kees J M Boot, Teun Tak, Jan W. KijneAbstract:Inhibition of root nodule formation on leguminous plants by already induced or existing root nodules is called autoregulation of root nodule formation (AUT). Optimal conditions for AUT were determined using a split-root technique newly developed for Vicia Sativa subsp. nigra. Infection of a root A with nodulating Rhizobium leguminosarum bv. Viciae bacteria systemically inhibited nodulation of a spatially separated root B inoculated 2 days later with the same bacteria. This treatment gives complete AUT (total absence of nodules on root B). Only partial AUT of root B was obtained by incubation of root A with mitogenic nodulation (Nod) factors or with a noninfective strain producing normal mitogenic Nod factors. Nonmitogenic Nod factors did not evoke AUT. We identified two systemic plant signals induced by Rhizobium bacteria. Signal 1 (at weak buffering) was correlated with sink formation in root A and induced acidification of B-root medium. This signal is induced by treatment of root A with (i) nodulating rhizobia, (ii) mitogenic Nod factors, (iii) nonmitogenic Nod factors, or (iv) the cytokinin zeatin. Signal 2 (at strong buffering) could only be evoked by treatment with nodulating rhizobia or with mitogenic Nod factors. Most probably, this signal represents the specific AUT signal. Induction of complete AUT appears to require actively dividing nodule cells in nodule primordia, nodule meristems, or both of root A.
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lipochitin oligosaccharides from rhizobium leguminosarum bv Viciae reduce auxin transport capacity in Vicia Sativa subsp nigra roots
Molecular Plant-microbe Interactions, 1999Co-Authors: Kees J M Boot, Anton A N Van Brussel, Herman P. Spaink, Teun Tak, Jan W. KijneAbstract:Induction of the formation of root nodule primordia in legume roots by symbiotic rhizobia is probably preceded by a change in plant hormone physiology. We used a Vicia Sativa (vetch) split root system to study the effect of inoculation with rhizobia or purified Nod factors (lipochitin oligosaccharides, LCOs) on polar auxin transport in roots. Addition of R. leguminosarum bv. Viciae, the infective symbiote of vetch, to roots of its host plant reduced polar auxin transport capacity of these roots within 24 h, in contrast to addition of non-nodulating, Sym plasmid-cured rhizobia. Addition of purified vetch-specific LCOs (NodRlv-IV/V[18:4,Ac]) caused a transient reduction in as little as 4 h after application, while after 16 h a second, stronger, and prolonged inhibition was observed that lasted at least 48 h. This reduction of auxin transport capacity was in the same order of magnitude as inhibition by N-(1-naphthyl)phthalamic acid (NPA). Purified LCOs (NodRm-IV[16:2,Ac,S]) from Sinorhizobium meliloti, the s...
K Recourt - One of the best experts on this subject based on the ideXlab platform.
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activation of flavonoid biosynthesis in roots of Vicia Sativa subsp nigra plants by inoculation with rhizobium leguminosarum biovar Viciae
Plant Molecular Biology, 1992Co-Authors: K Recourt, Ben Lugtenberg, A J Van Tunen, L A Mur, A A N Van Brussel, Jan W. KijneAbstract:Infective (nodulating) Rhizobium leguminosarum biovar Viciae (R.l. Viciae) bacteria release Nod factors which stimulate the release of nodulation gene-inducing flavanones and chalcones from roots of the host plant Vicia Sativa subsp. nigra (K. Recourt et al., Plant Mol Biol 16: 841–852; H.P. Spaink et al., Nature 354: 125–130). The hypothesis that this release results from increased synthesis of flavonoids was tested by studying the effect of inoculation of V. Sativa with infective and uninfective R.l. Viciae bacteria on (i) activity of L-phenylalanine ammonia-lyase, (ii) level of chalcone synthase mRNA, and (iii) activity of (eriodictyol) methyltransferase in roots. Consistent with the hypothesis, each of these parameters was found to increase 1.5 to 2-fold upon inoculation with infective R.l. Viciae bacteria relative to the situation for uninoculated roots and for roots inoculated with uninfective rhizobia.
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inoculation of Vicia Sativa subsp nigra roots with rhizobium leguminosarum biovar Viciae results in release of nod gene activating flavanones and chalcones
Plant Molecular Biology, 1991Co-Authors: K Recourt, Jan W. Kijne, Jan Schripsema, A A N Van Brussel, Ben LugtenbergAbstract:Flavonoids released by roots of Vicia Sativa subsp. nigra (V. Sativa) activate nodulation genes of the homologous bacterium Rhizobium leguminosarum biovar Viciae (R. l. Viciae). Inoculation of V. Sativa roots with infective R. l. Viciae bacteria largely increases the nod gene-inducing ability of V. Sativa root exudate (A.A.N. van Brussel et al., J Bact 172: 5394–5401). The present study showed that, in contrast to sterile roots and roots inoculated with R. l. Viciae cured of its Sym plasmid, roots inoculated with R. l. Viciae harboring its Sym plasmid released additional nod gene-inducing flavonoids. Using 1H-NMR, the structures of the major inducers released by inoculated roots, 6 flavanones and 2 chalcones, were elucidated. Roots extracts of (un)inoculated V. Sativa contain 4 major non-inducing, most likely glycosylated, flavonoids. Therefore, the released flavonoids may either derive from the root flavonoids or inoculation with R. l. Viciae activates de novo flavonoid biosynthesis.
