Showing papers on "Sesbania rostrata published in 1998"
TL;DR: The specific and transient transcript accumulation together with the lipochitooligosaccharide degradation activity of the recombinant protein hint at a role of Srchi13 in normal nodule ontogeny by limiting the action of Nod factors.
Abstract: On the tropical legume Sesbania rostrata, stem-borne nodules develop after inoculation of adventitious root primordia with the microsymbiont Azorhizobium caulinodans. A cDNA clone, Srchi13, with homology to acidic class III chitinase genes, corresponds to an early nodulin gene with transiently induced expression during nodule ontogeny. Srchi13 transcripts accumulated strongly 2 days after inoculation, decreased from day 7 onward, and disappeared in mature nodules. Induction was dependent on Nod factor-producing bacteria. Srchi13 was expressed around infection pockets, in infection centra, around the developing nodule and its vascular bundles, and in uninfected cells of the central tissue. The specific and transient transcript accumulation together with the lipochitooligosaccharide degradation activity of the recombinant protein hint at a role of Srchi13 in normal nodule ontogeny by limiting the action of Nod factors.
98 citations
TL;DR: In situ hybridizations with molecular markers for plant cell division, as well as the patterns of bacterial nod and nif gene expression, confirmed the indeterminate nature of 30-day-old functional root nodules and provided evidence that the switch in nodule type is mediated by the plant hormone ethylene.
Abstract: Leguminous plants in symbiosis with rhizobia form either indeterminate nodules with a persistent meristem or determinate nodules with a transient meristematic region. Sesbania rostrata was thought to possess determinate stem and root nodules. However, the nature of nodule development is hybrid, and the early stages resemble those of indeterminate nodules. Here we show that, depending on the environmental conditions, mature root nodules can be of the indeterminate type. In situ hybridizations with molecular markers for plant cell division, as well as the patterns of bacterial nod and nif gene expression, confirmed the indeterminate nature of 30-day-old functional root nodules. Experimental data provide evidence that the switch in nodule type is mediated by the plant hormone ethylene.
95 citations
TL;DR: To identify bacterial functions that are required for this infection process, two mutants defective in nodulation were studied and, in mixed inoculations with both mutants, functional nodules were formed, the central tissue of which was occupied by the nodA mutant.
Abstract: In the symbiotic interaction between Azorhizobium caulinodans and Sesbania rostrata root and stem-borne nodules are formed. The bacteria enter the host via intercellular spaces at lateral or advent...
94 citations
TL;DR: In situ hybridization showed that SrENOD40-1 transcripts, present around the central vascular bundle of the uninfected root primordia, were strongly enhanced upon induction of nodule development.
Abstract: At the base of adventitious root primordia, located on the stem of the tropical legume Sesbania rostrata, nitrogen-fixing nodules are formed upon inoculation with the microsymbiont Azorhizobium caulinodans. This pattern of nodule development presents features of indeterminate and determinate nodules in early and later stages, respectively. A S. rostrata cDNA clone homologous to early nodulin ENOD40 genes was isolated from a cDNA library of developing stem nodules. SrENOD40-1 contained the conserved regions I and II of other ENOD40 genes. By reverse transcriptase PCR, enhanced SrENOD40-1 expression was observed in the adventitious root primordia between 4 and 8 h after inoculation with A. caulinodans. In situ hybridization showed that SrENOD40-1 transcripts, present around the central vascular bundle of the uninfected root primordia, were strongly enhanced upon induction of nodule development. De novo SrENOD40-1 expression was observed in the initiating and growing nodule primordia and around vascular bundles. When cell type specification sets in, the expression became pronounced in cells derived from the meristematic regions. In other parts of the plant, weak SrENOD40-1 expression was associated with vascular bundles and was observed in leaf and stipule primordia.
48 citations
TL;DR: NrfA restores the defect in rpoS translation to an Escherichia coli hfq mutant, indicating that HF‐I and NrfA have similar activities in both A. caulinodans and E. coli.
Abstract: Azorhizobium caulinodans ORS571 isolated from the stem nodules of the tropical legume Sesbania rostrata has the remarkable property to fix nitrogen symbiotically in both roots and stem nodules and to grow in the free living state using dinitrogen. Nitrogen fixation genes (nif and fix) are regulated by a cascade of regulators in response to two environmental signals: oxygen and ammonia. As in other αβγ proteobacteria, nif and fixABCX genes are under NifA control. The expression of nifA is regulated by oxygen via FixLJ and K (Kaminski, Elmerich 1991; Kaminski et al. 1991) and by ammonia (Ratet et al. 1989). The nitrogen control of nif A expression involves two bicomponent regulatory systems: NtrBC and YX (Pawlowski et al. 1987; 1991) and by σ54F (Loroch et al. 1995).
34 citations
TL;DR: It is suggested that the addition of organic manure to soils increased C turnover, N availability and microbial activity which in turn led to greater enzyme synthesis and accumulation in the soil matrix.
Abstract: A fertilizer management study involving incorporation of poultry manure, farm yard manure, sesbania and gliricidia into soils of a rice-rice system was initiated in May 1993. In order to determine the effects of organic manure incorporation on soil microbial biomass and enzyme activity, soils were collected from the respective plots at the end of the second rice crop in February 1996. and were incubated with and without the respective organic manure at the rate of 15 Mg ha−1 at 25°C, under submergence. The total viable microbial counts, bacteria, actinomycetes, N flush, biomass C and activities of urease, amidase, acid and alkaline phosphatase, dehydrogenase and L-glutaminase were determined after 60 days of incubation.
Soils freshly amended and soils previously amended with organic manures registered significantly greater microbial biomass and enzyme activity than the unamended control. The microbial biomass and enzyme activity, however, varied with the type of organic manure incorporated into the soil. Except for acid phosphatase, which showed slight inhibition, all the other enzymes were activated to different degrees by organic manure incorporation. A significant and positive relationship of enzyme activity with organic C and total N suggested that the addition of organic manure to soils increased C turnover, N availability and microbial activity which in turn led to greater enzyme synthesis and accumulation in the soil matrix.
32 citations
01 Jan 1998
31 citations
TL;DR: Investigation showed that also in some ines from root nodules of pea and faba bean and from amide-exporting legumes the nodules are enriched in stem nodule of Sesbania rostrata and Azorhizobium) located in root or stem nodules.
Abstract: and Azorhizobium) located in root or stem nodules. Isotopic fractionation of 15N/14N during nitrogen fixation The natural 15N abundance (d15N value) in acetylpropyl by leguminous plants was small (’0.2 to ’2‰) when derivatives of amino acids and in ethyloxycarbonyl whole plant N was considered ( Yoneyama et al., 1986). derivatives of polyamines was determined using a However, the analysis of natural 15N abundance in the gas chromatography/combustion/mass spectrometer diVerent tissues of leguminous plants has revealed that (GC/C/MS). d15N values determined for 12 amino acids nodules, in some instances, had very high d15N values, and five polyamines by GC/C/MS were identical to while other plant tissues only showed diVerences of about those obtained by a direct combustion method using 2‰ (Shearer et al., 1982; Yoneyama et al., 1986; Unkovich an automatic nitrogen and carbon analysis (ANCA) et al., 1994). This 15N enrichment in nodules was first mass spectrometer, the difference being less than recognized in legumes which export fixed N as ureides ±1.0‰ in most cases. The GC/C/MS method was used from the nodules to host plants (Shearer et al., 1982). to analyse d15N values in the amino acids and polyam- However, further investigation showed that also in some ines from root nodules of pea and faba bean and from amide-exporting legumes the nodules are enriched in stem nodules of Sesbania rostrata. The analysis of 15N compared to other plant tissues ( Yoneyama, 1988; d15N values revealed that homospermidine had high Unkovich et al., 1994). In the ureide-exporting nodules, d15N values, as much as +40‰, while the amino the bacteroids were the most 15N-enriched N fraction, acids investigated had d15N values between ’3 and while the cytosol fraction was more 15N-enriched +6‰, putrescine between +2 and +8‰, cadaverine than the bacteroids in the amide-exporting nodules between +1 and +7‰, spermidine between ’2 and ( Yoneyama, 1988; Yoneyama et al., 1991a). Of the chem+4‰, and spermine between 0 and +6‰. The ical fractions investigated, the polyamine-containing fracmechanism of 15N enrichment in homospermidine is tion, which was eluted by 2‐6 N HCl solution from a discussed.
29 citations
TL;DR: Evidence is given that infecting bacteria follow a ‘crack entry’ invasion at sites where developing tumors have emerged through the root cortex and epidermis and establish with high cell numbers inside intercellular spaces of cortical and meristematic spaces.
Abstract: Gramineous crops such as wheat (triticum oestivum), maize (zea mays), and rice (oryza sativa) develop tumorous structures (para-nodules) along primary and secondary roots when treated with low concentrations of various auxins. Rice forms additional tumors along its hypocotyle. Histologically, auxin-induced tumors appear as cancerous grown out root meristems and thus are comparable in origin and structure to stem nodules of the legume sesbania rostrata. Auxin-affected root meristems do not recover and develop further to large nodule-like organs. Introduced diazotrophs (Azospirillum spp., Azorhizobium caulinodans, Rhizobium spp.) potentially inhabit tissues of both stem and root tumors with the central meristem as a major colonization niche. Evidence is given that infecting bacteria follow a ‘crack entry’ invasion at sites where developing tumors have emerged through the root cortex and epidermis. Bacteria are shown to establish with high cell numbers inside intercellular spaces of cortical and meristematic...
25 citations
TL;DR: A mixture of native weeds and GM legume is likely to prevent build-up of soil NO 3--N and allow BNF while limiting total N accumulation in the DTW vegetation for use as GM.
Abstract: In tropical rice lowlands, vegetation during the dry-to-wet season transition (DTW) facilitates in situ recycling of N from soil or legume biological nitrogen fixation (BNF) to wet-season flooded rice. As little is known, we examined the fates of soil N and BNF N in DTW vegetation in a 2-yr study on a Philippine Tropudalf using 15 N-labeled residues produced and soil-incorporated in situ. During DTW, Sesbania rostrata (Bremek. & Oberm.), mungbean [Vigna radiata (L.) R. Wilczek var. radiata], weeds, and a weed-free fallow were subplots in dry-season main plots of weedy, weed-free, and frequently tilled fallows. Rice yield and N uptake were not influenced by dry-season fallows, which did influence soil N and BNF N in DTW vegetation and, therefore, the amount of soil N lost, removed in a product or recycled. Build-up and decline of soil NH4-N occurred within 5 wk of residue incorporation, before significant N uptake by rice. Rice yield and N uptake responded to greater recycled DTW N; N uptake averaged 103 kg ha -1 with 208 kg S. rostrata N ha -1 , 79 kg ha -1 with 62 kg mungbean N ha -1 , 61 kg ha -1 with 41 kg weed N ha -1 , and 44 kg ha -1 with no residue N. Nitrogen-15 estimates of N recovery by rice (20% of S. rostrata N, 27% of mungbean N, 16% of weed N) were lower than the actual increase in rice N uptake due to residues. High proportions of residue N remained in soil, but N loss of 32% was estimated for S. rostrata N. As green manure (GM) N is ineffective beyond the first few weeks of incorporation, incorporating much legume N to flooded rice wastes valuable BNF N. Unmet rice N demand beyond early crop stage is better supplied with fertilizer N synchronized with rice N demand. A mixture of native weeds and GM legume is likely to prevent build-up of soil NO 3--N and allow BNF while limiting total N accumulation in the DTW vegetation for use as GM.
25 citations
TL;DR: A novel use of the 15N dilution technique is reported to detail the translocation of amino compounds in the legume Sesbania rostrata, demonstrating that a small fraction was derived from outside the nodules, and significant cycling of N through the root system was revealed by measurements of 15N distribution and amino acid concentrations.
Abstract: We report a novel use of the 15N dilution technique to detail the translocation of amino compounds in the legume Sesbania rostrata. The conventional 15N dilution technique follows the dilution of 15N within a labelled plant, as 14N2 is fixed by symbiotic bacteria. In our experiments, stem-nodulated Sesbania rostrata were enriched by feeding with 15N ammonium nitrate for 2 weeks, followed by a 1 week period where the only N available to the plants was via nitrogen fixation of atmospheric N2. We measured the composition, concentration and 15N enrichment of amino compounds in various plant tissues, both above and below the stem nodules, using GC-MS and isotopic abundance mass spectrometry techniques. Approximately 28% of the total N in the stem nodules was derived from internal plant sources. The ureides allantoic acid and allantoin were not abundant in xylem, leaf or nodule tissues. The amides asparagine and glutamine were the major export products from stem nodules although a wide range of other amino compounds are also synthesized. Amino acids within the nodules had a low level of enrichment, demonstrating that a small fraction (≈ 11%) was derived from outside the nodules, and significant cycling of N (28% of xylem N) through the root system was revealed by measurements of 15N distribution and amino acid concentrations.
TL;DR: Biological nitrogen fixation, the enzymatic reduction of atmospheric dinitrogen to ammonia, is carried out by a limited number of prokaryotic organisms as mentioned in this paper, which all possess an oxygen-sensitive nitrogenase enzyme complex that functions at ambient temperature and pressure and requires high ATP consumption to drive electron transport to N2.
Abstract: Biological nitrogen fixation, the enzymatic reduction of atmospheric dinitrogen to ammonia, is carried out by a limited number of prokaryotic organisms They all possess an oxygen-sensitive nitrogenase enzyme complex that functions at ambient temperature and pressure and requires high ATP consumption to drive electron transport to N2
Journal Article•
TL;DR: An exploratory field experiment was conducted to study the effective combination of organic and inorganic N on the availability and uptake of N and yield of rice in a black clayey soil with a long duration variety CRl009 as mentioned in this paper.
Abstract: An exploratory field experiment was conducted to study the effective combination of organic and inorganic N on the availability and uptake of N and yield of rice in a black clayey soil with a long duration variety CRl009. Application of 25 per cent organic N as basal and 75 per cent inorganic N as top dressing enhanced the availability of N in soil, thereby, induced the N uptake and augmented higher rice yield. Among the organic sources, easily degradable green manures Sesbania rostrata and Sesbania aculeata were found to be the best choice to improve crop productivity and soil health in the said combination. Ipomea cornea, a non-conventional green manure, can also be thought of as an alternative for the above green manures owing to its easy availability and cheap cost.
TL;DR: In this article, the ENOD2 gene was expressed in the nodule parenchyma and in outer cortical cells during nodule development on stems of Sesbania rostrata.
Abstract: During nodule development on stems of Sesbania rostrata, the ENOD2 gene was expressed in the nodule parenchyma and in outer cortical cells. The latter; novel expression pattern was low in uninfected nodulation sites, strongly enhanced 1 day after infection, and correlated with young peridermal cells at later stages. The induction of both ENOD2 transcript accumulation patterns was dependent on Nod factor-producing bacteria.
TL;DR: In this article, a long-term incubation study was conducted to determine the nitrogen (N) mineralization rates and kinetics in soils freshly amended with some commonly used green manures such as Sesbania rostrata.
Abstract: Long term incubation studies to determine the nitrogen (N) mineralization rates and kinetics in soils freshly amended with some commonly used green manures such as Sesbania rostrata. Gliricidia maculata. Leucaena leucocephala and Azolla pinnata are scarce. A long term aerobic study was, therefore, conducted by incubating soils freshly amended with the above-mentioned green manures in PVC columns at 35 ± 1 C and with 0.01 Mpa moisture content. The soils were then leached at periodic intervals for up to 36 weeks.
The N-mineralization rates were greatest during the first week and decreased with time in all soils. The green manure amended soils leached 247 mg kg−1 more NO3+ NO2– N than the unamended control. In general, the total N mineralized (mean 61%) was almost twice that of net N mineralized (mean 30%) in the amended soils. The percent N mineralized (total and net), however, varied with the nature of green manure incorporated into the soil. It was greatest in the soil amended with sesbania and lowest in the soil amended with azolla. The kinetic parameters derived using the double exponential model indicated that green manure amended soils possessed significantly higher N-mineralization potentials and rate constants compared to the unamended control. The kinetic parameters also varied with the nature of green manure incorporated into the soil. Among the various parameters lignin content, lignin to N ratio and lignin + polyphenol to N ratio of the green manures were the key factors governing the rate of decomposition and subsequent N mineralization from the amended soils.
TL;DR: The mere presence of the d-arabinosyl group at the reducing end of the lipo-chitooligosaccharides resulted in a higher number of nodules on roots of Sesbania rostrata, whereas the presence or absence of l-fucose had no effect.
Abstract: The Nod factors of Azorhizobium caulinodans ORS571 are lipo-chitooligosaccharides that at the reducing end can be unsubstituted, substituted with a l-fucosyl group, with a d-arabinose, or with both groups at the same time. These lipo-chitooligosaccharides are the compounds produced by the bacteria during the signal exchange with their host plant at the onset of the nodulation process. By the use of wild-type and mutant strains, the role of the different Nod factor glycosylations on the nodulation behavior was checked. The mere presence of the d-arabinosyl group at the reducing end of the lipo-chitooligosaccharides resulted in a higher number of nodules on roots of Sesbania rostrata, whereas the presence or absence of l-fucose had no effect. The situation is the opposite in other tropical legumes that respond to A. caulinodans ORS571: the l-fucose is the major determinant of nodulation, whereas the presence of d-arabinose is less significant. By the use of a β-glucuronidase reporter fusion, A. caulinodans ORS571 was shown to colonize nodules or nodule-like tissues induced on cowpea and bean, respectively.
TL;DR: S. rostrata is moderately salt tolerant and may be utilized as forage crop and green manure on saline land and higher K+/Na+ ratios in plant tissues compared to those in the root medium were found under different salinities.
Abstract: Growth of Sesbania rostrata was decreased gradually with increase in root medium salinity (mixed salts or NaCl alone). Soil moisture or anoxia did not affect plant growth significantly. Higher K+/Na+ ratios in plant tissues compared to those in the root medium were found under different salinities. This indicated a high K+-Na+ selectivity, a characteristic generally considered unique to halophytes. S. rostrata is moderately salt tolerant and may be utilized as forage crop and green manure on saline land.
01 Jan 1998
TL;DR: A role for Nod factors in bacterial entry via intercellular infection is demonstrated and demonstrated in the symbiosis between Sesbania rostrata and Azorhizobium caulinodans strain ORS571.
Abstract: In the symbiosis between Sesbania rostrata and Azorhizobium caulinodans strain ORS571, nitrogen-fixing nodules are formed on roots and stems by intercellular infection at the basis of lateral roots and adventitious root primordia. The nodule development depends on bacterial Nod factors, the lipo-chitin Oligosaccharide signals that are produced as a consequence of nod gene expression (Long, 1996). The bacterial surface Polysaccharides as well are important for nodulation. This is illustrated by the present work, which also demonstrates a role for Nod factors in bacterial entry via intercellular infection.
01 Jan 1998
TL;DR: After activation of rhizobial nodABC genes, rhizobia release Nod factors which induce nodule meristems in the plant host, and the significance of the fact that rhizOBial invasion pathways differ so greatly is unclear.
Abstract: After activation of rhizobial nodABC genes, rhizobia release Nod factors which induce nodule meristems in the plant host. The nodABC genes play an essential role in the early stages of invasion by Rhizobium meliloti, which invades alfalfa via the root hair curling pathway (Denarie et al. 1992). Azorhizobium caulinodans ORS571 contains genes showing some homology to the nodABC genes of R. meliloti (Goethals et al. 1989), but invades its host, the tropical legume Sesbania rostrata, by entering the naturally occurring cracks which form around emergent lateral roots. The significance of the fact that rhizobial invasion pathways differ so greatly is unclear.
01 Jan 1998
TL;DR: A. caulinodans is able to fix nitrogen at the free-living state and in symbiosis with the tropical legume Sesbania rostrata.
Abstract: A. caulinodans is able to fix nitrogen at the free-living state and in symbiosis with the tropical legume Sesbania rostrata. This bacterium accumulates the polymer poly-s-hydroxybutyrate (PHB) in both conditions (Stam et al., 1986).