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1.
In order to identify soybean cultivars with higher biological N2 fixation capacities, North American and Brazilian soybean [Glycine max (L.) Merrill] cultivars, belonging to maturity groups VI–VIII, were evaluated for nodulation parameters and N2 fixation rates. The symbiotic performance of 152 cultivars was evaluated in pots containing 4 kg soil with an established
population of the three Bradyrhizobium elkanii strains [29w (SEMIA 5019):SEMIA 566 : SEMIA 587, 22%:36%:34%] which are established in most Brazilian soils cultivated with
soybean. Differences were verified among cultivars, with some accumulating up to twice as much nodule dry weight and N in
tissues as others. The variability among cultivars was also confirmed when six of them were used in a field experiment, resulting
in differences in nodulation, yield and total N accumulated in grains. The analysis of nodule occupancy in 12 cultivars grown
either under sterile conditions and receiving a double inoculum and N-free nutrient solution, or in pots containing soil with
an established population of bradyrhizobia, showed the preference of cultivars for specific strains.
Received: 7 December 1998 相似文献
2.
M. Hungria L. H. Boddey M. A. Santos M. A. T. Vargas 《Biology and Fertility of Soils》1998,27(4):393-399
In a previous study soybean Bradyrhizobium strains, used in Brazilian studies and inoculants over the last 30 years, and strains adapted to the Brazilian Cerrados, a
region frequently submitted to environmental and nutritional stresses, were analyzed for 32 morphological and physiological
parameters in vivo and in vitro. A cluster analysis allowed the subdivision of these strains into species Bradyrhizobium japonicum, Bradyrhizobium elkanii and a mixed genotype. In this study, the bacteria were analyzed for nodulation, N2 fixation capacity, nodule occupancy and the ability to increase yield. The goal was to find a relationship between the strain
groups and the symbiotic performance. Two strains of Brazilian B. japonicum showed higher rates of N2 fixation and nodule efficiency (mg of N mg–1 of nodules) under axenic conditions. These strains also showed greater yield increases in field experiments when compared
to B. elkanii strains. However, no differences were detected between B. japonicum and B. elkanii strains when comparing nodule occupancy capacity. The adapted strains belonging to the serogroup B. elkanii SEMIA 566, most clustered in a mixed genotype, were more competitive than the parental strain, and some showed a higher capacity
of N2 fixation. Some of the adapted strains, such as S-370 and S-372, have shown similar N2 fixation rates and nodulation competitiveness to two Brazilian strains of B. japonicum. This similarity demonstrates the possibility of enhancing N2 fixing ability, after local adaptation, even within B. elkanii species. Differences in the DNA profiles were also detected between the parental SEMIA 566 and the adapted strains by analyses
with the ERIC and REP-PCR techniques. Consequently, genetic, morphological and physiological changes can be a result of adaptation
of rhizobia to the soil. This variability can be used to select strains capable of increasing the contribution of N2 fixation to soybean nutrition.
Received: 28 May 1997 相似文献
3.
4.
A bradyrhizobial-fungal biofilm (i.e. Bradyrhizobium elkanii SEMIA 5019-Penicillium spp.) developed in vitro was assayed for its nitrogenase activity and was evaluated for N2-fixing symbiosis with soybean under greenhouse conditions. The biofilm showed nitrogenase activity, but the bradyrhizobial strain alone did not. Shoot and root growth, nodulation and N accumulation of soybean increased significantly with an inoculum developed from the biofilm. This study concludes that such biofilmed inoculants can improve N2-fixing symbiosis in legumes, and can also directly contribute to soil N fertility in the long term. Further studies should be conducted to investigate the performance of these inoculants under field conditions. 相似文献
5.
A study on the diversity, phylogeny, and host specificity of soybean (Glycine max L.) and peanut (Arachis hypogaea L.) bradyrhizobia was conducted based on the 16S ribosomal RNA (rRNA) restriction fragment length polymorphisms (RFLPs),
16S rRNA sequencing, and 16S–23S rRNA intergenetic spacer (IGS) RFLP assays. Based on 16S rRNA RFLP assay, tested bradyrhizobia
were divided into five genotypes, which could be further clustered into five groups by IGS RFLP assays. According to the 16S
rRNA sequencing, strains of IGS-II, IV, and V were phylogenetically related to Bradyrhizobium liaoningense, Bradyrhizobium japonicum, and Bradyrhizobium elkanii, while strains of IGS-Ic and IGS-III related to Bradyrhizobium yuanmingense and Bradyrhizobium canariense, respectively. All isolates could crossly nodulate Phaseolus vulgaris, forming small white nodules. Strains of IGS-II originally isolated from peanut could efficiently nodulate Glycine soja, and two strains isolated from soybean could also nodulate peanut. 相似文献
6.
H.S. Jayasinghearachchi 《Soil biology & biochemistry》2006,38(2):405-408
Biosolubilization of rock phosphate (RP) using a Penicillium spp., an Aspergillus spp., Pleurotus ostreatus, Bradyrhizobium elkanii SEMIA 5019 and their fungal-rhizobial biofilms was investigated. Eppawala Rock Phosphate (ERP, total P concentration 17.6%), a RP from a deposit in Sri Lanka was used. Penicillium spp.-B elkanii SEMIA 5019 biofilm released the highest amount of P from the ERP with the highest P release-to-P uptake ratio. The P release of Penicillium spp. alone was significantly lower than that of its biofilm. Similarly, P. ostreatus-B. elkanii SEMIA 5019 biofilm showed a higher P release than P. ostreatus alone. However, P. ostreatus alone or its biofilm showed lower P release-to-P uptake ratios indicating relatively higher P uptake compared to the P release. The Aspergillus spp., showed a moderate P release. Large bradyrhizobial cell clusters attached to the mycelial mat of Penicillium spp. and P. ostreatus were observed under light microscope after 12 and 25 days of incubation, respectively. The present study, identified an effective method of fungal-rhizobial biofilm mediated solubilization of RP. 相似文献
7.
The competition with established soil populations of Bradyrhizobium able to nodulate soybean has been one of the major constraints to the introduction of more efficient strains in Cerrados soils. The effects of nodulation establishment and persistence of four serologically distinct strains of Bradyrhizobium japonicum (CPAC 15 and CPAC 7, belonging to serogroups USDA 123 and CB 1,809) and B. elkanii (29 W and SEMIA 587, belonging to serogroups 29 W and 587) were examined. These strains were introduced in a dark-red oxisol, without indigenous populations of soybean bradyrhizobia, and were evaluated for 6 years. The experimental design was a completely randomized block with four replicates. In the first year, besides the inoculation treatments, there was also an uninoculated control. In the second year, the main plots were split into three sub-plots and treatments consisted of an uninoculated control, CPAC 7 and CPAC 15. In the third year, the entire area was inoculated with CPAC 7. In the fourth and sixth years, the plots were planted with soybean without inoculation, and in the fifth year the plots were left fallow. The strains introduced in the first year influenced nodule occupancy by strain CPAC 7 until the third successive growing season. By the fourth and sixth years, as a consequence of the dispersal of strains serologically related to serocluster 123 in the entire experimental area, this serogroup dominated the nodulation, occurring, on average, in more than 50% of the nodules of the treatments where it had never been inoculated. 相似文献
8.
Bradyrhizobium japonicum strain CB 1809 was recently chosen to replace strain WB 1 in commercial soybean [Glycine max (L.) Merr.] inoculants in South Africa, the selection criterion being N2-fixing effectiveness. Nodulation competitiveness is an additional characteristic required of inoculants and was determined
for CB 1809 and WB 1 as well as two other strains, USDA 110 and a Brazilian strain 965, using the gusA marker gene to identify strains. Initial experiments with plants grown in sterile sand showed that the competitive index
of strain WB 1 was less than that of the other strains. Further comparisons used plants grown in five soils containing established
populations of B. japonicum. When strains were applied in peat inoculum to seed at a rate of 1,000 cells per seed in a soil containing 300 rhizobia g–1, significant differences in nodule occupancy were detected and strains ranked in the order 965>CB 1809>USDA 110>WB 1. The
remaining four soils each contained about 106 rhizobia g–1 and 5×106 cells were applied per seed. Nodule occupancy by inoculant strains ranged from 22% to 81% between soils. In this experiment,
WB 1 was consistently the poorest performer and its competitiveness was significantly less than CB 1809. The competition results
supported the recent decision to replace WB 1 with CB 1809 in commercial inoculants. Although WB 1 had been used in inoculants
over a period of 19 years, this strain was detected in only one soil, where it comprised 8% of isolates. In contrast, a substantial
proportion (32–78%) of isolates from the soils corresponded serologically to a former inoculant strain WB 66, which had been
discontinued in 1966. This illustrates the difficulty of replacing a resident population with an introduced strain. The effect
of naturalized populations on the establishment of CB 1809 in South African soils will need monitoring
Received: 23 November 1999 相似文献
9.
Shoichiro Akao 《Soil Science and Plant Nutrition》2013,59(4):517-525
In order to select appropriate Bradyrhizobium USDA reference strains for primary grouping of indigenous soybean bradyrhizobia, we systematically constructed phylogenetic trees of 20 USDA strains based on DNA sequence analysis and PCR-restriction fragment length polymorphism (RFLP) targeted to 16S rDNA and the internal transcribed spacer (ITS) region between 16S and 23S rDNAs. The phylogenetic trees of 16S rDNA showed 3 major groups, cluster USDA 110 (USDA 62, 110, 122, 125, and 129), cluster USDA 6 (USDA 4, 6T, 38, 115, 123, 127, 135, and 3622T) and cluster B. elkanii (USDA 31, 46, 61, 76T, 94, and 130), as well as the phylogenetically independent strain USDA 124. The topology of the ITS trees was almost similar to that of 16S rDNA, although the positions of two extra-slow-growing strains, USDA 135 and USDA 3622T were variable among the ITS sequences, PCR-RFLP of the ITS region and 16S rDNA. Only two strains, USDA 110 and USDA 122, harbored hup genes and they fell into the USDA 110 cluster. These results suggest that PCR-RFLP analysis of 16S rDNA and the 16S-23S rDNA ITS region may be useful for the grouping of bradyrhizobia and for the first screening of hup-positive strains. Based on the above results, we propose a minimum set of USDA strains reflecting Bradyrhizobium diversity that includes B. japonicum USDA 6T, B. japonicum USDA 110, B. japonicum USDA 124, and B. elkanii USDA 76T. In addition, an extra-slow-growing strain with the serotype USDA 135 might be necessary for genomic diversity analysis of bradyrhizobia, because their phylogenetic positions were variable. 相似文献
10.
The genome of Bradyrhizobium japonicum and B. elkanii contains multiple copies of the repeated DNA sequence RSα. A collection of 18 B. japonicum, 4 B. elkanii and 72 other bacterial strains was screened by polymerase chain reaction (PCR) using a pair of primers specific for RSα.
Only strains of B. japonicum and B. elkanii gave the predicted amplification product. Restriction analysis of PCR products obtained from different strains of B. japonicum showed that the RSα sequence was generally conserved. The usefulness of RSα as a specific probe for Bradyrhizobium strains capable of nodulating soybean was also demonstrated.
Received: 11 May 1995 相似文献
11.
《Soil Science and Plant Nutrition》2013,59(4):418-426
Abstract Genetic diversity and distribution of indigenous soybean-nodulating bradyrhizobia in Japan were investigated based on restriction fragment length polymorphism analysis of PCR product (PCR-RFLP) analysis of the 16S?23S rDNA internal transcribed spacer (ITS) region using Bradyrhizobium USDA strains as reference strains. Soil samples were collected from five field sites in Hokkaido, Fukushima, Kyoto, Miyazaki and Okinawa in Japan. A total of 300 isolates were derived from three Rj-genotype soybean cultivars, Akishirome (non-Rj), CNS (Rj 2 Rj 3) and Fukuyutaka (Rj 4), and five field site combinations. The PCR products of the ITS region were digested with HaeIII, HhaI, MspI and XspI. Electrophoresed patterns were analyzed for phylogenetic relationship using Bradyrhizobium reference strains. Results revealed 22 RFLP patterns and 11 clusters. The RFLP patterns of the seven clusters were similar or identical to Bradyrhizobium japonicum USDA 6, 38, 110, 115, 123 and Bradyrhizobium elkanii USDA 76 and 94. Four minor clusters were independent from the clusters of the reference strains. The isolation ratio revealed the major clusters at each field site. These results suggested that major clusters of indigenous bradyrhizobia might be in the order Bj123, Bj38, Bj110, Bj6 and Be76 from the northern to southern regions in Japan. 相似文献
12.
The competitiveness of two Bradyrhizobium japonicum strains was determined under controlled conditions. The relationship between the ratio of the nodules formed by the two bradyrhizobial strains and the ratio of the two strains in the inoculum was established and used as an internal standard to evaluate the equilibrium ratio between populations of the two strains in the soil. The fluorescent antibody (FA) technique was also used for counting the bradyrhizobial populations directly in the soil. Results with the FA technique were analysed and compared with the estimate obtained through nodule occupancy. The initial ratio of the two bradyrhizobial strains in populations introduced simultaneously into the soil changed during incubation time and the two strains reached the same equilibrium levels after 53 days. Never-theless, the strain introduced into the soil as an overpopulation remained clearly dominant for the nodule occupancy. We conclude that direct counts with the FA approach are selective and these counts could be mainly of the unattached bacteria. 相似文献
13.
《Applied soil ecology》2007,35(1):57-67
Soils of many potential soybean fields in Africa are characterized by low levels of biological nitrogen fixation (BNF) activities and often cannot support high soybean yields without addition of inorganic N fertilizers or external application of soybean rhizobia. The most probable number (MPN) technique was used to determine the bradyrhizobial populations that nodulate TGx soybean genotypes (a cross between nonpromiscuous North American soybean genotypes and promiscuous Asian soybean genotypes), cowpea or North American soybean cv. Clark IV, in soils from 65 sites in 9 African countries. The symbiotic effectiveness of isolates from these soils was compared to that of Bradyrhizobium japonicum strain USDA110. The bradyrhizobial population sizes ranged from 0 to 104 cells g−1 soil. Bradyrhizobium sp. (TGx) populations were detected in 72% and B. japonicum (Clark) in 37% of the soil samples. Bradyrhizobium sp. (TGx) populations were generally low, and significantly less than that of the cowpea bradyrhizobial populations in 57% of the samples. Population sizes of less than 10 cells g−1 soil were common as these were detected in at least 43% of the soil samples. B. japonicum (Clark) occurred in higher population densities in research sites compared to farmers’ fields. Bradyrhizobium sp. (TGx) populations were highly correlated with biotic but not abiotic factors. The frequent incidence of low Bradyrhizobium sp. (TGx) populations is unlikely to support optimum BNF enough for high soybean yields while the presence of B. japonicum (Clark) in research fields has the potential to compromise the selection pressure anticipated from the indigenous Bradyrhizobium spp. (Vigna) populations. Bradyrhizobium isolates could be placed in four symbiotic phenotype groups based on their effectiveness on a TGx soybean genotype and the North American cultivar Clark IV. Symbiotic phenotype group II isolates were as effective as B. japonicum strain USDA110 on both soybean genotypes while isolates of group IV were effective on the TGx soybean genotype but not on the Clark IV. The group IV isolates represent a unique subgroup of indigenous bradyrhizobia that can sustain high soybean yields when available in sufficient population densities. 相似文献
14.
Maria de Fátima Loureiro Glaciela Kaschuk Odair Alberton Mariangela Hungria 《Biology and Fertility of Soils》2007,43(6):665-674
In this study, soybean nodules were collected from 12 sites in the State of Mato Grosso, in the Brazilian Cerrados, where
both exotic soybean [Glycine max (L.) Merrill] and bradyrhizobial strains have been introduced from 1 to 18 years before. All soils were originally devoid
of rhizobia capable of effectively nodulating soybean and varied in terms of chemical and physical properties, inoculation
procedures, and cropping systems. Rhizobial genetic diversity was assessed on 240 isolates by rep-PCR fingerprinting with BOX primer, and indices of diversity (abundance-based coverage estimator and traditional and modified
Shannon indices) were applied to the profiles obtained. The genetic diversity was much greater than expected, as after the
introduction of a maximum of four strains, up to 13 profiles were identified, some sharing many similar bands with the inoculant
strains, but others quite distinct from the putative parental genotypes. The increase in the number of rep-PCR profiles could be attributed to genetic variability due to the stressful tropical environmental conditions, but also
might indicate that indigenous rhizobia become capable of nodulating the host legume. After the third year of cropping with
the host legume, inoculation did not affect rhizobial diversity. A high content of clay decreased diversity in comparison
with that seen in a sandy soil, probably due to reduced aeration. Diversity was higher under the no-tillage system when compared
to the conventional tillage management, highlighting the importance of maintaining crop residues in tropical soils. Understanding
the ecology of exotic rhizobia after being introduced into new cropping areas represents a first step towards the establishment
of better strategies of inoculation, which in turn may result in sustainability and higher plant yields. 相似文献
15.
This study investigates the role played by a Bradyrhizobium japonicum SEMIA 5019-Penicillium spp. biofilm in terms of soil fertility, when it is free-living in a soil. The biofilm increased N and P mineralizations of the soil and showed a high nitrogenase activity even under a very high NO3− concentration in the soil, compared to its member microbes. It maintained a low SO42− concentration in the soil, which was conducive to the high nitrogenase activity. The application of this microbial association as a biofilmed inoculum is important for sustaining soil fertility as well as survival of such rhizobia in the soil in the absence of their hosts. Further studies are needed to evaluate the performance of the biofilm in terms of soil fertility in the ecosystems. 相似文献
16.
Chinnaswamy Appunu Narayanasamy Sasirekha Vaiyapuri Ramalingam Prabavathy Sudha Nair 《Biology and Fertility of Soils》2009,46(1):57-63
The diversity among 269 rhizobia isolated from naturally occurring root nodules of soybean collected from two different agro-ecological
regions of India, based on RFLP and sequences of the intergenic spacer (IGS) between the 16S and 23S rRNA genes, growth rate,
and indole acetic acid production, revealed their significant, site-dependent genomic diversity. Among these bacteria, nine
IGS genotypes were identified with two endonucleases. They were distributed into five divergent lineages by sequence analysis
of each IGS representative strain, i.e., (1) comprising IGS genotypes I, II, III, and reference Bradyrhizobium yuanmingense; (2) with genotype IV and strains of unclassified bradyrhizobia genomic species; (3) including genotypes V, VI, and Bradyrhizobium liaoningense; (4) with IGS genotype VII and Bradyrhizobium elkanii strains; and (5) comprising IGS genotypes VIII, IX, and different Ensifer genus bacteria. Host-specificity test revealed that all rhizobia-nodulated soybean and cowpea and only part of them formed
nodules on Arachis hypogeae and Cajanus cajan. The great diversity of soybean nodulators observed in this study emphasises that Indian soil is an important reservoir of
nitrogen-fixing rhizobia. 相似文献
17.
A group of Bradyrhizobium strains isolated from soybean plants in Thailand did not correspond to any known DNA homology groups of Bradyrhizobium japonicum and Bradyrhizobium elkanii reported by Hollis et al. (J. Gen. Microbiol., 123, 215–222, 1981). To clarify the phenotypic characteristics of the group, serological properties and intrinsic antibiotic resistance (IAR) profile of 94 Thai strains were compared with those of USDA and Japanese strains. Indirect ELISA tests for each Thai strain were performed agaiIl.st polyclonal antisera prepared against 15 USDA standard serotype strains of B. japonicum and B. elkanii. Among the 94 Thai strains tested, 36 which were previously identified as B. elkanii, with the exception of one strain, were strongly responsive to an antiserum prepared against USDA 31. The remaining 58 strains, with the exception of two strains, showed multiple cross reactions which were peculiar to the Thai strains. These serological reaction patterns did not correspond to any known serogroups labeled as B. japonicum and B. elkanii. In the IAR test, the taxonomically unknown Thai soybean bradyrhizobia exhibited a high level of resistance to neomycin (50 µg/mL), polymyxin (50 µg/mL), nalidixic acid (15 µg/mL), and kanamycin (15 µg/mL). Kanamycin could thus be useful in combination with neomycine and nalidixic acid for distinguishing between the unknown Thai strains and strains of B. japonicum and B. elkanii. Our results demonstrated that the unknown Thai strains were serologically and IAR-phenotypically remote from both B. japonicum and B. elkanii. 相似文献
18.
Summary Bacteria isolated from the root zones of field-grown soybean plants [Glycine max (L.) Merr.] were examined in a series of glasshouse experiments for an ability to affect nodulation competition among three strains of Bradyrhizobium japonicum (USDA 31, USDA 110, and USDA 123). Inocula applied at planting contained competing strains of B. japonicum with or without one of eleven isolates of rhizosphere bacteria. Tap-root nodules were harvested 28 days after planting, and nodule occupancies were determined for the bradyrhizobia strains originally applied. Under conditions of low iron availability, five isolates (four Pseudomonas spp. plus one Serratia sp.) caused significant changes in nodule occupancy relative to the corresponding control which was not inoculated with rhizosphere bacteria. During subsequent glasshouse experiments designed to verify and further characterize these effects, three fluorescent Pseudomonas spp. consistently altered nodulation competition among certain combinations of bradyrhizobia strains when the rooting medium did not contain added iron. This alteration typically reflected enhanced nodulation by USDA 110. Two of these isolates produced similar, although less pronounced, effects when ferric hydroxide was added to the rooting medium. The results suggest that certain rhizosphere bacteria, particularly fluorescent Pseudomonas spp., can affect nodulation competition among strains of R. japonicum. An additional implication is that iron availability may be an important factor modifying interactions involving the soybean plant, B. japonicum, and associated microorganisms in the host rhizosphere.Paper No. 10648 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7601, USA 相似文献
19.
Field experiments were conducted to investigate the performance of three soybean cultivars with five foreign bradyrhizobia
strains in different regions. The experiments at the two sites were designed with soybean (Glycine max L.) cultivars as the main factor and bradyrhizobia strains (USDA 136, TAL 122, USDA 6, TAL 377 and TAL 102) as the sub-factor.
The experiments were arranged in randomised complete block design with four replications. Results show that nodule number,
nodule dry weight and shoot dry weight, total N and seed yield were significantly increased when soybean cultivars were inoculated
with foreign bradyrhizobia in two locations in the south east of Nigeria. At 63 days after planting the percentage increase
in nodule number and dry weight after inoculation of soybean cultivars with bradyrhizobia strains ranged from 71 to 486% and
from 0 to 200%, respectively. The percentage increase in shoot dry matter, %N and total N after bradyrhizobia inoculation
ranged between 2–130%, 18–62% and 35–191%, respectively at Awka, and at the Igbariam site the percentage increase in shoot
dry weight, %N and total N ranged between 3–76%, 0–43% and 19–125%, respectively. Seed yields after bradyrhizobia inoculation
of soybean cultivar TGX 1485–1D at Igbariam ranged between 1.20 and 2.18 t ha–1 against the uninoculated plants, which had seed yields of 1.05 t ha–1. The poorest yield response after inoculation with bradyrhizobia strains was observed in soybean cultivar M-351, with a seed
yield ranging from 0.60 to 0.98 t ha–1. The fact that foreign bradyrhizobia strains were more effective than the indigenous strains for all the parameters studied
suggests that there is a need to use bradyrhizobia inoculants for increased soybean production in Nigeria. The variations
in the strain performance with the different soybean cultivars at the two sites, emphasises the need for careful Bradyrhizobium spp. strain selection. The fact that inoculation response was cultivar- and site-specific suggests that strategies for improving
inoculation response in soybean cultivars should also consider the soil environment where the soybean is to be produced.
Received: 25 May 1999 相似文献
20.
Mio Yoshida 《Soil Science and Plant Nutrition》2013,59(3):501-505
Abstract The identification of rhizobial strains is a major problem in studies for the evaluation of the symbiotic effectiveness of specific strains in soils containing native rhizobia. Bradyrhizobium japonicum which includes most strains of soybean-nodulating bacteria is known to display a wide range of genetic diversity (Miyashita 1987). It is, therefore, necessary to develop a reliable taxonomic system based on the genetic traits, which would enable to differentiate and identify of the strains. 相似文献