Strains Of Rhizobium Japonicum Research Articles

Soybean (Glycine max L) Genotype and Environment Interaction Effect on Yield and Other Related Traits

Aims: To evaluate genetic variability of five soybean genotypes, and assess genotype × environment effect on seed yield and yield related traits. Study Design: Split-plot, replicated three times. Genotypes were fixed effect while plots (main 60 m2 and subplot 12 m2) were random effects. The sub-plot consists of 4 rows 5 m long with 60 cm and 10 cm inter and intra-row spacing. Place and Duration: El Gantra, Range and Pasture Farm in Sennar State of the Sudan during 2009 and 2010 cropping season. Methodology: Five soybean genotypes NA 5009 RG; TGx 1904-6F, TGx 1740-2F, TGx 1937-1F and Soja were evaluated. A strain of Rhizobium japonicum was used for inoculation at a rate of 10 g per kg of soybean seed using a sugary solution in 2009. Inoculation was not carried out due to the assumption that the field had the remnant of inoculum effect in 2010. All the recommended soybean agronomic practices were equally applied. Number of days to 50% flowering was recorded on plot basis when almost half of the sub-plot flowers. Ten plants were randomly selected on plot basis to quantify these traits: Plant height was measured as from ground surface to the base of meri-stem of the mother plant. Number of branches was computed as an average count of branches per plant. Leaf area was computed using Iamauti [12] empirical relationship. The first pod height was measured at full bloom. Number of seeds per pod was counted at physiological Research Article American Journal of Experimental Agriculture, 3(4): 977-987, 2013 978 maturity of the crop. 100-seed weight was determined randomly from a seed bulk using a digital weighing machine. Seed yield was quantified after harvest and converted into kg/hectare. Results: The effect of genotype (G), environment (E) and G × E interactions on pod number per plant; plant height, first pod height, number of branches per plant, leaf area, number of days to 50% flowering and seed yield were found significant at P=0.05. The highest mean seed yield was obtained from TGx 1937-1F (0.98 t/ha). Beside TGx 1740-2F, TGx 1904-6F and Soja were significantly higher than NA 5009 RG in all environments for seed yield. TGx 1937-1F was an intermediate maturing and best in terms of number of pods per plant, number of branches per plant, and leaf area. Correlation coefficient for seed yield showed significant association with days to 50% flowering and leaf area. Conclusion: The best genotype for seed yield across the environments was TGx 1937-1F and TGx 1740-2F, TGx1904-6F and Soja were intermediate and NA 5009 RG was the least. Thus, partitioning G × E into adaptability and phenotypic stability will positively address the information gap on association of traits to yield.

DEĞİŞİK DOZLARDAKİ NİTROJENLİ GÜBRELEMENİN VE Rhizobium japonicum KÜLTÜRLERİ İLE AŞILAMANIN, ERZURUM TARLA KOŞULLARINDA, BAZI SOYA ÇEŞİTLERİNİN ÜRÜN VERİMİ, PROTEİN VE YAĞ İÇERİĞİNE ETKİSİ

OZET Bu denemenin amaci, 0-3-6-9-12 kg Nida dozlarinda nitrojenli gubrelemenin ve Rhizobium japonicum (So 1809, 383 ve So 11) suslari ile asilamanin soya (Glycine max) Merril ve F-66-62 cesitlerinin urun verimine, protein ye yag iceriklerine etkilerini karsilastirarak mikrobiyal gubrelemenin hangi dozdaki nitrojenli gubrelemeye esdeger oldugunu tespit etmektir. Bu amacla tarla denemesi, Faktoriyel Duzenleme ve Sans Bloklari planina uygun olarak iki asamada gerceklesmistir: 1. Soya cesitlerinin M. japonicum So 1809 suslarryla tohumlari, R 383 ve R So 11 suslari ile sulama suyu asilanmistir. //. Asisiz parseller 0, 3, 6, 9, 12 kg N/da (NH4)2SO4'la gubrelenmistir. Yillarin birlikte degerlendirilmesiyle elde edilen sonuclar asagidaki gibidir: 1) Denemede nodul olusumu sadece asili bitkilerin koklerinde izlenmistir. 2) Asilamanin soya cesitlerinin urun verimine etkisi 6-12 kg Nida (NH^)2S04 gubresine, protein icerigine etkisi ise 12 kg N/da (Nli^iSO4 gubresine esdeger olmustur. 3) Asilamanin ve nitrojenli gubrelemenin soya cesitlerinin yag icerigine etkisi denetlere onemli olmamistir.. 4) R.japonieum suslari ile degisik asilama islemlerinin birbirlerine ustunlugunun olmadigi gorulmustur. THE EFFECT OF NITROGEN FERTILIZATION AT VARIOUS RATES AND INOCULATION WITH Rhizobium japonicum STRAINS ON YIELD PRODUCTION, PROTEIN AND OIL CONTENT OF SOME SOYBEAN CULTIVARS UNDER FIELD CONDITIONS IN ERZURUM SUMMARY The aim of this research work may be summarized as to find otu the effects of nitrogen fertilization at five rates (0, 3, 6, 9 and 12 kg Nida) and inoculation with three Rhizobium japonicum strains (So 1809, 383 and So 11) on nodulation, yield production, protein and oil content of two soybean (Glycine max ) cultivars (Merrit and F-66-62). As a result it is hoped to discover which of the N-fertilization raie residted equal effect with the microbial fertilization. For this purpose, the field trials were carried out according to Factorial Experiment and Randomized Blocks at two steps: (I). Seeds of selected soybean cultivars have been inoculated with R So 1809 strain and o tuy the irrigated water has been inoculated vAth R 383 and R So 11 strains . (II). Half of the experimental plots with no seed and irrigated water inoculation were fertilized with five rates of (NH4)2804. The results as the avarage values for two - year period were asfollows: 1) The noduleformation could be detected only on roots of the inoculated plants. 2) The effect of the inoculation on yield production of soybean cultivars was eguivalent to, 6-12 kg N/da (NH4)2S04 and on protein content ofthem was equivaient to 12 kg N/da (NH4)2S04. 3) inoculation with R. japonicum strains and N-fertilization had no significant effect on tha oil content of the soybean cultivars compared to control treatments. 4) There was not difference among various inoculations of R.japonicum strains.

Interaction studies of copper fungicides with biological environment of soil

Fungicides are one of the essential inputs in the improved technology for increasing crop production through crop protection. Copper fungicides Blitox and Fungimar are used widely as foliar sprays for control of many plant diseases. As major portion of fungicides applied to economically important crops eventually finds its way to soil, may disrupt the activities of microorganisms in the soil and thereby altering the biological equilibrium of soil. It is therefore planned to study the biological health of the soil with the help of viable counts of nine strains of Rhizobium japonicum after 21, 30 and 45 days intervals at 100 to 500 ppm concentrations of the two copper Fungicides. Results reveal that Blitox is more compatible than Fungimar to R. japonicum.

Effect ofRhizobium inoculation and the application of phosphate on the growth, yield and nitrogen fixation of soybeans

Application of phosphate at 60, 90 and 120 kg P ha−1 to the ‘Bragg’ variety of soybeans inoculated with a mixture of three strains ofRhizobium japonicum (TAL 102 + TAL 377 + TAL 379) and grown in silty loam soil in a pot experiments, significantly improved the number of nodules per plant and increased production of shoots and roots by 65, 36 and 17%, the yield of pods by 38, 12 and 3% and N2-fixing capacity by 57, 29 and 20%, respectively. Rhizobium inoculation alone with the test strains caused a positive but poor nodulation of the crop and increased its dry-matter production of shoots and roots by 22%, pods yield by 7% and N2-fixing capacity by 6%. Soybean plants from uninoculated treatments were without nodules indicating that indigenous rhizobia associated with this crop are absent in the test soil. Phosphate concentration in the total dry matter of mature crop exhibited an increasing tendency as a result of all the applied levels of phosphorus.

The Glycine–Glomus–Rhizobium symbiosis. IV. Interactions between the mycorrhizal and nitrogen‐fixing endophytes

Abstract Soybean (Glycine max (L.) Men) plants were grown under controlled conditions in an experiment designed as a 4 × 4 factorial. The factors were N or P nutrition, with different strains of Rhizobium japonicum or N‐fertilization as levels of the first factor and different species of vesicular‐arbuscular mycorrhizal (VAM) fungi or P fertilization as levels of the other. Organisms used were R. japonicum strains USDA 110, USDA 136, and 61A118, and the VAM fungi Glomus versiforme (Karst.) Berch, Glomus fasciculatum (Thaxt. sensu Gerd.) Gerd. and Trappe, and Glomus mosseae (Nicol. & Gerd.) Gerd. and Trappe. There were 16 treatments: nine Rhizobium + Glomus combinations, three Rhizobium + V and three Glomus+ N combinations, and one non‐symbiotic set of plants supplied with N + P. The tripartite symbioses were evaluated by analysis of variance against the Rhizobium + P and Glomus + N comparison treatments for effects on root and leaf dry mass, root N and P content, nodule mass and activity, and VAM colinization. Significant to highly significant main effects and interactions were found in virtually all evaluations due to both Rhizobium strain and VAM–fungal species. We conclude that different endophyte isolates affect not only the host plant, but also the development and function of their co‐endophytes. These findings establish the existence of inter‐endophyte compatibility, an important consideration when selecting or engineering for desirable endophyte traits.

Glycine-Glomus-Rhizobium Symbiosis

Soybean (Glycine max [L.] Merr. cv Hobbit) plants were grown in a growth chamber for 56 days in a phosphorus- and nitrogen-deficient soil and were colonized by the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus mosseae (Nicol. & Gerd) Gerd. and Trappe and Rhizobium japonicum strain USDA 136, or by either organism alone, or by neither. Non-VAM plants received supplemental phosphorus and nonnodulated plants supplemental nitrogen to achieve the same rate of growth in all treatments. Plants of all four treatments had the same (P > 0.05) dry weights at harvest, but VAM plants had higher rates of CO(2) exchange (CER, P < 0.05) and lower leaf P concentrations (P < 0.01). Leaf nitrogen concentrations were lower in nodulated than in nitrogen-supplemented plants (P < 0.01) while starch concentrations were higher (P < 0.01). There was a significant negative relationship between nitrogen and starch (r = -0.989). Statistical evaluation of the data showed that some parameters (CER, leaf area and phosphorus content) were associated with phosphorus nutrition (or the presence of the VAM fungus), others (leaf fresh weight and root dry weight) with nitrogen nutrition (or the presence of Rhizobium), and some (leaf nitrogen and starch content) by both factors. The development of microsymbiont structures and nodule activity were significantly lower in the tripartite association than in plants colonized by one endophyte only. The findings suggest that endophyte effects go beyond those of simple nutrition and associated source-sink relationships.

Effect of combined nitrogen on nitrogen fixation of soybean (Glycine max L. Merill.) as affected by cultivar and rhizobial strain

Nine strains ofRhizobium japonicum (Bradyrhizobium japonicum) were screened for nitrogen fixation in combination with two cultivars of soybean, Chippewa and Dunadja at two levels of nitrogen fertilization,i.e. 20 kg N ha−1 and 100 kg N ha−1 using15N isotope dilution method. Plant dry weight, nitrogen yield, percent N derived from atmosphere (% Ndfa) and total amount of N2 fixed were strongly influenced by the specific combination of host-genotype and rhizobial strain. The interaction between the host and microsymbiont were so specific that accurate prediction of symbiotic performance of either partner in relation to a particular host or strain of Rhizobium appears impossible. The sensitivity of nitrogen fixation to combined nitrogen was furthermore dependent upon both the rhizobial strain and host-Rhizobium association. It is therefore, inadvisable to describe a certain bacterium as being fully effective/ineffective or sensitive/tolerant to combined nitrogen, except in relation to a particular host-genotype. There is scope for obtaining promising host-Rhizobium associations tolerant to combined nitrogen through exploiting the interactive effects between the host-genotypes and strains of Rhizobium.

Population dynamics of Rhizobium japonicum strains used to inoculate three successive crops of soybean

Three closely related strains of Rhizobium japonicum, equally effective in N2 fixation, were used to inoculate each of three successive crops of soybeans [Glycine rnax (L.) Merr. cv. Bragg] grown on the same block of land. The soil was a vertisol previously free of R. japonicum, and inoculant was applied at different rates by spraying a suspension of peat culture into the seed bed at time of sowing the seed. The populations of rhizobia that developed in rhizosphere and soil were counted at intervals during crop growth and in the fallow period between crops. There was usually a substantial decline in recovery of inoculant strains immediately after sowing. In soil initially devoid of R. japonicum, populations in the rhizospheres of young seedlings were related to rates of inoculation, but differences disappeared as the plants aged. Shortly after harvest, the soil contained large populations of rhizobia which increased up to 200 times during the fallow period between crops, probably due to release of bacteria from disintegrating nodules. The size of these populations was maintained up to the time of sowing the following crop. Although strains used for second- and third-year crops were dominated by already established rhizobia in rhizosphere colonization and nodule formation, the magnitude of the domination could be reduced by increased rates of inoculation. In soil already containing R. japonicum, the proportion of nodules formed by inoculant strains was greater than the relative number of inoculant rhizobia in the soil or the rhizosphere; this was ascribed to an advantage of specific placement of the inocula in that zone of the soil where infection foci first formed. The results are explicable in numerical terms and are discussed in relation to an inoculation strategy for maximum nodulation by applied inoculant in competition with rhizobia already established in soil.

Effect of supplemental NO3 on plant growth and components of photosynthetic carbon metabolism in soybean (Glycine max)

The effect of supplied N (5, 10, or 20 mM[Formula: see text]) on plant growth and components of photosynthetic carbon metabolism was determined in soybean plants (Glycine max (L.) Merr. cv. Ransom) inoculated with Rhizobium japonicum strain USDA 110. The N treatments were started at 14 days after transplanting and plants were sampled at 10, 17, 23 and 43 days after initiation of the treatments. Total dry weight, shoot/root ratio and mean relative growth rate all increased one- to two-fold in response to supplied N. Carbon dioxide exchange rate, assimilate export rate, sucrose phosphate synthase activity, leaf sucrose concentration and leaf starch mobilization increased in response to supplied N at the first two sample dates, whereas starch accumulation rate was affected to a lesser degree. The response of these parameters to supplied N was diminished at the later two sample dates. Plant age and partial alleviation of the nitrogen stress that occurred during early nodule development were factors associated with the decreased treatment response at the later sampling dates. Assimilate export rate was correlated positively with carbon exchange rate (r = 0.84), sucrose phosphate synthase activity (r = 0.71) and leaf sucrose concentration (r = 0.83). This suggested that the enzymatic capacity for sucrose formation as well as net carbon fixation and leaf sucrose concentration are related to the rate of assimilate export. The results illustrated the interdependence of photosynthetic carbon metabolism and N nutrition and emphasized that certain photosynthetic components are more sensitive to changes in N nutrition than others.

The Role of Dark Carbon Dioxide Fixation in Root Nodules of Soybean

The magnitude and role of dark CO(2) fixation were examined in nodules of intact soybean plants (Harosoy 63 x Rhizobium japonicum strain USDA 16). The estimated rate of nodule dark CO(2) fixation, based on a 2 minute pulse-feed with (14)CO(2) under saturating conditions, was 102 micromoles per gram dry weight per hour. This was equivalent to 14% of net nodule respiration. Only 18% of this CO(2) fixation was estimated to be required for organic and amino acid synthesis for growth and export processes. The major portion (75-92%) of fixed label was released as CO(2) within 60 minutes. The labeling pattern during pulse-chase experiments was consistent with CO(2) fixation by phosphoenolpyruvate carboxylase. During the chase, the greatest loss of label occurred in organic acids. Exposure of nodulated roots to Ar:O(2) (80:20) did not affect dark CO(2) fixation, while exposure to O(2):CO(2) (95:5) resulted in 54% inhibition. From these results, it was concluded that at least 66% of dark CO(2) fixation in soybean may be involved with the production of organic acids, which when oxidized would be capable of providing at least 48% of the requirement for ATP equivalents to support nitrogenase activity.

Isolation and characterization of a soybean lectin having 4-O-methylglucuronic acid specificity.

A new lectin from soybeans having specificity toward the extracellular 4-O-methyl-D-glucurono-L-rhamnans produced by certain strains of Rhizobium japonicum has been purified and characterized. Isolation was accomplished initially by isoelectric precipitation of contaminating globulins and subsequently by affinity chromatography on partially hydrolyzed glucuronorhamnan covalently coupled to amino-hexylagarose. Residual globulins were removed by adsorption of the lectin on concanavalin A-agarose and elution with methyl alpha-mannoside. The lectin is a glycoprotein (3-5% carbohydrate) with a molecular weight of approximately 175 000. It is a tetramer with subunit molecular weights of 45 000 when dissociated with sodium dodecyl sulfate. Reverse-phase high-pressure liquid chromatography analysis indicates the presence of two types of subunits, both having equivalent molecular weights. According to amino acid analyses, the lectin is rich in acidic but low in sulfur-containing amino acids. The carbohydrate portion of the lectin contains mannose; no hexosamines could be detected. Chemical modification of the lectin indicated that neither sulfhydryl groups nor amino groups participate in binding. Quantitative binding studies of the lectin with various carbohydrate haptens showed that specificity was directed toward 4-O-methyl-D-glucuronic acid, D-glucuronic acid, and their methyl glycosides with 4-O-methyl-D-glucuronic acid 3-4-fold more effective. In each instance, the methyl glycoside is a more effective hapten.

Enzymes of Ammonia Assimilation and Ureide Biosynthesis in Soybean Nodules: Effect of Nitrate

The effect of nitrate on N(2) fixation and the assimilation of fixed N(2) in legume nodules was investigated by supplying nitrate to well established soybean (Glycine max L. Merr. cv Bragg)-Rhizobium japonicum (strain 3I1b110) symbioses. Three different techniques, acetylene reduction, (15)N(2) fixation and relative abundance of ureides ([ureides/(ureides + nitrate + alpha-amino nitrogen)] x 100) in xylem exudate, gave similar results for the effect of nitrate on N(2) fixation by nodulated roots. After 2 days of treatment with 10 millimolar nitrate, acetylene reduction by nodulated roots was inhibited by 48% but there was no effect on either acetylene reduction by isolated bacteroids or in vitro activity of nodule cytoplasmic glutamine synthetase, glutamine oxoglutarate aminotransferase, xanthine dehydrogenase, uricase, or allantoinase. After 7 days, acetylene reduction by isolated bacteroids was almost completely inhibited but, except for glutamine oxoglutarate aminotransferase, there was still no effect on the nodule cytoplasmic enzymes. It was concluded that, when nitrate is supplied to an established symbiosis, inhibition of nodulated root N(2) fixation precedes the loss of the potential of bacteroids to fix N(2). This in turn precedes the loss of the potential of nodules to assimilate fixed N(2).

Analysis of the Behavior of Rhizobium Inoculum Using Marked Strain in the Rhizosphere of Soybeans

The behavior of the inoculum, Rhizobium japonicum strain A-1016 str+ used as a marker strain, in the rhizosphere of soybean (Glycine max, cv. Enrei) was examined and the effect of the inoculation in Andosols from Japan was evaluated using the acetylene reduction technique and by comparing the number of nodules formed by the inoculum strain under greenhouse conditions. The survival rate of the inoculum strain in the two soils was also studied in the laboratory. The results of this experiment indicated the beneficial effect of inoculation with R. japonicum A-1016 str+ in Soil A (from paddy field) which is considered to contain a low population of native rhizobia able to nodulate soybean as reflected by the seed yield, level of accumulated nitrogen, acetylene reduction activities, and high recovery percentage of inoculated rhizobia. Also, a high survival rate of the inoculum strain was observed in this soil. On the other hand, the absence of the beneficial effect associated with the inoculation was demonstra...

Nutrient and growth interactions in soybeans colonized withGlomus fasciculatum andRhizobium japonicum

Glycine max (L. Merr. cv. Amsoy 71) plants were grown in a greenhouse in a sand/perlite medium low in plant-available N and P. Plants were either inoculated with a vesicular-arbuscular mycorrhizal (VAM) fungus alone, a strain ofRhizobium japonicum alone, both endophytes together or were left non-inoculated to serve as a control. All combinations received a N-and P-free nutrient solution. Nodulated plants contained 4 to 5 times the phytomass of non-inoculated controls, and plants colonized with both the VAM fungus and Rhizobium were 18% greater in dry weight than nodulated, non-VAM plants due to a positive VAM times Rhizobium interaction. Nitrogen fixation, calculated from C2H4 and H2 data, was significantly higher in the tripartite symbiosis, with 80% of the increase attributable to increased nodule mass and 20% due to increases in specific nodule activity. Colonization by the VAM fungus and the development of vesicles increased significantly following nodulation. The synergistic interactions between the microsymbionts suggests that the response of the host to dual colonization is complex and depends on a balance between the three members of the symbiosis.

Expression of nodule-specific uricase in soybean callus tissue is regulated by oxygen

In soybean root nodules the enzyme uricase is expressed concomitantly with nodule development. The initial expression of this protein does not depend on active nitrogen fixation, as demonstrated by analysis of uricase activity in effective and ineffective root nodules. However, the maximal level of uricase activity is determined by the infecting Rhizobium japonicum strain. Sterile root cultures and callus tissue, devoid of the microsymbiont, were incubated at varying oxygen concentrations and analyzed for uricase activity. The specific activity of uricase was increased by lowering the oxygen concentration, with the highest activity obtained around 4-5% oxygen. The increase in uricase activity was due to increased uricase synthesis, as demonstrated by in vivo labelling of callus culture followed by immunoprecipitation with antibodies raised against highly purified nodule uricase.

Symbiotic mutants of USDA191, a fast-growing Rhizobium that nodulates soybeans

Symbiotic and auxotrophic mutants of Rhizobium japonicum strain USDA191 were isolated using Tn5 mutagenesis and techniques that cause plasmid deletions and plasmid curing. Characterization of several mutants that are unable to nodulate (Nod-) or unable to fix nitrogen (Fix_) showed that nod and nif genes are located within one regions of a 200 MD plasmid (pSym191). Blot hybridization analysis of plasmids in other fast-growing R. japonicum strains showed that nod as well as nif sequences are located on plasmids in eight strains but are apparently carried in the chromosome in two strains.

Glycine-Glomus-Rhizobium Symbiosis

Soybean (Glycine max [L.] Merr.) plants grown in pot cultures were inoculated with the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus mosseae (Nicol. & Gerd.) Gerd. and Trappe and Rhizobium japonicum strain 61A118 at planting (G(1)R(1)) or at 20 days (G(20)R(20)), or with one of the endophytes after the other has colonized the host root (G(1)R(20), G(20)R(1)). Nodulated (PR(1)) and VAM (G(1)N) dipartite associations, or nonsymbiotic plants (PN) using nutrient solutions with N, P, or N + P concentrations providing endophyte-equivalent nutrient inputs were used as controls. The delayed tripartite associations received the appropriate N, P, or N + P amendment while one or both endophytes were absent during the first 20 days of growth. Prior inoculation with one endophyte significantly inhibited development of the other. Root hexose sugar concentrations were negatively correlated with VAM colonization (r = -0.89), nodule activity (r = -0.91), and root P content (r = -0.93). Nodule (r = 0.97) and root (r = 0.96) P content correlated positively with VAM colonization. Nodule weight or VAM-fungal biomass were significantly greater in associations grown with only one endophyte. Dry weights of the PN, G(1)N, PR(1), and G(20)R(20) plants were significantly greater than those of tripartite plants inoculated at planting with either or both endophytes. Interendophyte inhibition is attributed to competition for root carbohydrates, and this effect apparently also affects overall plant productivity. The objective of the study was to determine if the timing of endophyte introduction and establishment affected the development of the other symbiotic partners.

Accumulation of alpha,alpha-trehalose by Rhizobium bacteria and bacteroids.

Four strains of Rhizobium japonicum (61A76 and USDA 110, 123, and 138) were grown in eight different defined media. Regardless of the carbon or nitrogen source supplied, alpha, alpha-trehalose was the major carbohydrate (among mono- and disaccharides) accumulated by all four strains. After 7 to 9 days of growth, trehalose generally accounted for 90 to 100% of the mono- and disaccharides detected. None of the four strains would grow with trehalose as a carbon source, but the utilization of endogenous trehalose was demonstrated under carbon starvation conditions in water culture or when the carbon supply in a defined medium was exhausted. Under these conditions, a small amount of trehalose was lost from cells to the medium. In a survey of most of the serogroups of R. japonicum and several strains of other Rhizobium species, all strains tested were found to accumulate some trehalose. Trehalose concentrations varied widely; the highest concentration recorded was 41 micrograms/mg of dry weight. In all but six strains trehalose accounted for greater than 80% of the mono- and disaccharides in cells. Fast-growing strains of R. japonicum also accumulated small amounts trehalose. R. japonicum bacteroids also synthesized trehalose; the quantity in nodules varied in approximate correspondence to accumulation of trehalose by cultured bacteria. In young soybean nodules (29 days after planting), 45 to 80% of the trehalose was recovered in the cytosol. There were differences among R. japonicum strains in the retention of trehalose, and the proportion of trehalose retained by bacteroids increased with increasing plant age for all strains.

Isolation and Characterization of RNA Polymerase from Vegetative and Symbiotic Forms of Rhizobium japonicum

Summary: RNA polymerase was purified from both vegetative and symbiotic forms of Rhizobium japonicum strain 3I 1b 110 and the physical and transcriptional properties of the enzyme were compared. The subunit composition of the enzyme from both sources appeared similar when analysed by SDS-polyacrylamide gel electrophoresis. Removal of an 82 kDal protein from the purified enzyme from either source, using procedures developed for isolation of the sigma factor from Escherichia coli RNA polymerase, resulted in a decreased ability of the enzyme to utilize phage T4 DNA as a template in vitro. These results indicate that the 82 kDal protein may act as a sigma-like factor for the RNA polymerase of R. japonicum. The transcriptional specificity of the enzyme from both sources was similar using a variety of exogenous DNA templates. There were no apparent differences in the kinetic properties of the enzyme from both sources, or in the specificity of promoter utilization when phage T7 DNA was used as a template. This would indicate that a novel form of RNA polymerase may not be responsible for the transcription of nif genes in the symbiotic state.

Soybean Response to Rhizobium japonicumStrain, Row Orientation, and Irrigation1

AbstractStresses or environmental differences associated with soybean [Glycine max(L.) Merr.] row configuration and drought could affect selection and symbiotic performance of Rhizobium japonicumstrains and subsequent growth and yield of soybean. The present field studies were conducted in 1981, 1982, and 1983 to assess the response of soybean nodulation, growth, and yield to R. japonicumstrains, row orientation, and irrigation. Strains USDA3I1b110 (110), NC1004 (04), and B587 (587) of R. japonicumwere compared to indigenous populations in a Norfolk loamy sand (fine loamy, siliceous, thermic, Typic Paleudult). Soybean cultivars ‘Davis,’ ‘Braxton,’ and ‘Coker 338’ were grown with and without irrigation, with east/west and north/south row orientations, and with inoculation variables. The seasonal weather was different for air temperature, rainfall, and solar radiation; and soil temperatures were generally 1 to 5 °C lower for north/south‐oriented than east/west‐oriented rows at depths of 5 and 15 cm. Nodular occupancies of inoculated strains were increased by inoculation in 1981 and 1982, but not in 1983. No significant differences in N concentration or total N of soybean shoots were found in any year. Yet, a strain ✕ row orientation interaction occurred for seed yield in all 3 yr, and a strain by irrigation interaction occurred in 1983. Seed yield of soybean inoculated with strain 04 or 110 were significantly different for row orientation; differences ranged from 0.24 to 0.43 Mg ha−1for irrigated soybean. Soybean inoculated with 587 was not significantly different in seed yield for row orientation. It was concluded that environmental differences induced by row orientation influence some R. juponicumstrains in soybean more than others, particularly under irrigated conditions.