Acid tolerance in the Rhizobium meliloti - Medicago symbiosis

1986 ◽  
Vol 37 (1) ◽  
pp. 55 ◽  
Author(s):  
JG Howieson ◽  
MA Ewing
Keyword(s):  
Rhizobium Meliloti ◽  
Acid Soil ◽  
Acid Soils ◽  
Acid Tolerance ◽  
Loamy Sand ◽  
Alkaline Soils ◽  
Regenerative Growth ◽  
Commercial Inoculant ◽  
Acid Tolerant ◽  
Second Year

Several strains of Rhizobium meliloti that originated from acid soils in Sardinia, Italy, were markedly superior in colonizing a moderately acid loamy sand (pH 5.0 in 1:5 0.01 M CaCl2) than two Australian commercial inoculant strains (U45 and CC169), and a group of strains that originated from alkaline soils in Syria and Iraq. Six Medicago hosts also varied greatly in their ability to achieve nodulation in this soil. M. polymorpha and M. murex were far superior in this respect to M. littoralis, M. truncatula and M. tornata. The most acid-tolerant strains of R. meliloti, WSM419 and WSM413, were able to nodulate a high proportion of plants of M. polymorpha and M. murex sown in the second year between 11 and 20 cm from the point of introduction of the rhizobia into the soil the previous year. It is suggested that these more saprophytically competent isolates of R. meliloti, combined with the species of Medicago more able to nodulate readily in acid soil, will extend the range of soils suitable for successful regenerative growth of these species.

Nodulation and growth of Medicago truncatula on acid soils. I. Effect of calcium carbonate and inoculation level on the nodulation of Medicago truncatula on a moderately acid soil

1970 ◽  
Vol 21 (3) ◽  
pp. 427 ◽  
Author(s):  
AD Robson ◽  
JF Loneragan
Keyword(s):  
Calcium Carbonate ◽  
Medicago Truncatula ◽  
Soil Ph ◽  
Soil Acidity ◽  
Rhizobium Meliloti ◽  
Acid Soil ◽  
Acid Soils ◽  
Acid Tolerant ◽  
Annual Medicago ◽  
Medicago Species

On a moderately acid soil (pH 4.6 in 115 suspension of soil in 0.01M calcium chloride), nodulation of Medicago truncatula cv. Cyprus responded markedly to increasing applications of calcium carbonate, which increased soil pH. Since the effect of increasing soil pH on the percentage nodulation could be replaced to a large extent by increasing the inoculation level, it appeared that nodulation was restricted by the inability of Rhizobium meliloti to survive or multiply in the acid soil. The growth of R, meliloti appeared more sensitive to soil acidity than growth of the host plant of annual Medicago species. It is suggested that more acid-tolerant strains of R. meliloti would permit annual Medicago species to be grown successfully on moderately acid soils, thus extending the range of soils suitable for the growth of these species.

Nodulation and growth of Medicago truncatula on acid soils. II. Colonization of acid soils by Rhizobium meliloti

1970 ◽  
Vol 21 (3) ◽  
pp. 435 ◽  
Author(s):  
AD Robson ◽  
JF Loneragan
Keyword(s):  
Calcium Carbonate ◽  
Medicago Truncatula ◽  
Rhizobium Meliloti ◽  
Acid Soils ◽  
Sandy Soils ◽  
Acid Tolerant ◽  
Second Year ◽  
Annual Medicago ◽  
Medicago Species ◽  
Better Than

Six strains of Rhizobium meliloti varied greatly in their ability to colonize two moderately acid sandy soils (pH 5.0-5.1 in 115 suspension of soil in 0.01M calcium chloride) in the year of sowing inoculated lime-coated seeds of Medicago truncatula. The strains also varied in their ability to nodulate M. truncatula in the year after sowing. With all rhizobial strains and on both soils, calcium carbonate applied in the year of sowing strongly promoted colonization in the year of sowing. It also greatly increased nodulation and growth of M. truncatula in the year after sowing. Apparently calcium carbonate increased second year nodulation by promoting the colonization of the acid soils by R. meliloti in the year of sowing. Differences among strains in second year nodulation appeared to be related to differences in the ability of the strains to colonize the soils in the year of sowing. Strains isolated from moderately acid sandy soils were markedly superior in both properties, and on both soils, to strain SU47 from commercial inoculum, but were generally no better than strain U45 from commercial inoculum. Even the most acid-tolerant strains colonized the acid soils relatively slowly. It is suggested that R. meliloti strains in general have a poor ability to colonize acid soils and that this property is a major factor limiting the growth and persistence of annual Medicago species on acid soils in the field.

Preferential nitrate immobilization in alkaline soils

Soil Research ◽  
1992 ◽  
Vol 30 (5) ◽  
pp. 737 ◽  
Author(s):  
IJ Rochester ◽  
GA Constable ◽  
DA Macleod
Keyword(s):  
Acid Soil ◽  
Nitrification Inhibitor ◽  
Biological Significance ◽  
Nitrate Assimilation ◽  
Acid Soils ◽  
Ammonium Assimilation ◽  
Potassium Nitrate ◽  
Alkaline Soil ◽  
Alkaline Soils ◽  
Nitrate Immobilization

The literature pertaining to N immobilization indicates that ammonium is immobilized in preference to nitrate. Our previous research in an alkaline clay soil has indicated substantial immobilization of nitrate. To verify the preference for immobilization of nitrate or ammonium by the microbial biomass in this and other soil types, the immobilization of ammonium and nitrate from applications of ammonium sulfate and potassium nitrate following the addition of cotton crop stubble was monitored in six soils. The preference for ammonium or nitrate immobilization was highly correlated with each soil's pH, C/N ratio and its nitrification capacity. Nitrate was immobilized in preference to ammonium in neutral and alkaline soils; ammonium was preferentially immobilized in acid soils. No assimilation of nitrate (or nitrification) occurred in the most acid soil. Similarly, little assimilation of ammonium occurred in the most alkaline soil. Two physiological pathways, the nitrate assimilation pathway and the ammonium assimilation pathway, appear to operate concurrently; the dominance of one pathway over the other is indicated by soil pH. The addition of a nitrification inhibitor to an alkaline soil enhanced the immobilization of ammonium. Recovery of 15N confirmed that N was not denitrified, but was biologically immobilized. The immobilization of 1 5 ~ and the apparent immobilization of N were similar in magnitude. The identification of preferential nitrate immobilization has profound biological significance for the cycling of N in alkaline soils.

Soil pH is a major determinant of the numbers of naturally occurring Rhizobium meliloti in non-cultivated soils in central New South Wales

1991 ◽  
Vol 31 (2) ◽  
pp. 211 ◽  
Author(s):  
J Brockwell ◽  
A Pilka ◽  
RA Holliday
Keyword(s):  
Soil Ph ◽  
Rhizobium Meliloti ◽  
New South ◽  
New South Wales ◽  
Acid Soils ◽  
Alkaline Soils ◽  
Naturally Occurring ◽  
South Wales ◽  
Dominant Soil ◽  
The Relationship

Measurements were made of soil pH, frequency of occurrence of annual species of Medicago (medics) and populations of Rhizobium meliloti at 84 sites on 7 dominant soil groups of the Macquarie region of central-western New South Wales. Over all sites, soil pH (0-10 cm; 1:5 soil: water) ranged from 5.26 to 8.07, medic frequency from 0 to 100% and most probable numbers of R. meliloti from undetectable to 675 000/g soil. There was a highly significant (P<0.001) relationship between soil pH and number of R. meliloti. Above pH 7.0, the mean soil population of R. meliloti was 89000/g; below pH 6.0, it was 37/g. Medics occurred most frequently on the more alkaline soils and with least frequency on the more acid soils, but the relationship between soil pH and medic frequency was weaker than between pH and R. meliloti number. Medics were more tolerant of low soil pH than their rhizobia were; at 2 sites, of pH 5.49 and 5.35, medics occurred at 100% frequency but R. meliloti was undetected. There was an indication of some acidification in these soils over a period of 35 years but this remains to be confirmed.

EFFECTS OF CaCO3 AND INOCULUM LEVEL ON NODULATION AND GROWTH OF ALFALFA IN AN ACID SOIL

1975 ◽  
Vol 55 (3) ◽  
pp. 245-250 ◽  
Author(s):  
W. A. RICE
Keyword(s):  
Rhizobium Meliloti ◽  
Acid Soil ◽  
Relative Yield ◽  
Acid Soils ◽  
Inoculum Level ◽  
Al Content ◽  
N Yield ◽  
Ineffective Nodule ◽  
Medicago Sativa L ◽  
Nodule Tissue

The effects of CaCO3 and inoculum level on nodulation and growth of alfalfa (Medicago sativa L.) in an acid soil were studied by measuring alfalfa yield, nodule numbers and nodule weights in relation to various levels of CaCO3 amendment and to the number of Rhizobium meliloti applied per seed. When sufficient CaCO3 was applied to the soil (4 mg CaCO3/g soil) to reduce soluble Al to sub-toxic levels, the relative yield (yield without N/yield with N) of alfalfa increased from 0.7 with no inoculum to 1.0 with 3 × 107 rhizobia per seed. Increasing the inoculum level from no inoculum to 3 × 107 rhizobia per seed decreased the amount of ineffective nodule tissue from 0.65 to 0.27 mg/pot without CaCO3 added, and from 0.60 to 0.06 mg/pot with the addition of 4.0 mg CaCO3/g soil. When no inoculum was applied, the amount of effective nodule tissue was increased from 0 to 0.91 mg/pot by adding 4.0 mg CaCO3/g soil. Application of inoculum increased the amount of effective nodule tissue at all levels of CaCO3. The results demonstrate the importance of liming to decrease the soluble Al content of acid soils for alfalfa production, and show that high inoculum levels can be used to improve alfalfa yields on acid soils.

Evaluasi Galur Kedelai Transgenik Toleran Aluminium pada Fasilitas Uji Terbatas

2016 ◽  
Vol 35 (2) ◽  
pp. 155 ◽  
Author(s):  
Saptowo J. Pardal ◽  
Suharsono Suharsono
Keyword(s):  
Agricultural Development ◽  
Aluminum Toxicity ◽  
Acid Soil ◽  
Acid Soils ◽  
Acid Tolerance ◽  
Al Toxicity ◽  
Nutrient Deficiencies ◽  
Al Tolerance ◽  
Phenotypic Analysis ◽  
Soil Media

Some acid soil is potential for the agricultural development. Constraints for soybean production in the acid soils are Aluminum toxicity and macro nutrient deficiencies. Breeding for soybean varieties tolerant to acid soil is needed. This could be made through genetic engineering, by inserting acid tolerance genes into a soybean genome. Thirty one soybean lines (T0) had been obtained by insertion of Al tolerance genes (MaMt2) through an Agrobacterium mediated transformation, which nine of them contained MaMt2 gene based on PCR test. Further evaluation of those lines was carried out in the Biosafety Containment, where four T1 soybean lines were carrying MaMt2 gene, namely line GM2, GM5, GM10 and GM14. The study was aimed to evaluate the degree of tolerance of T2 generation of GM2, GM5, GM10 and GM14 lines to Al toxicity. Results showed that T2 line were able to grow in hygromicin media, indicating that those T2 lines were containing hygromicin resistant gene (hptII). Phenotypic analysis of T2 lines in four acid soil media treatments indicated that all lines could survive and grow on acid soil without liming and adding compost. GM2 line grew best on the acid medium than did other lines.

Differential rhizobial colonisation of the roots of sown and volunteer annual species of Medicago in an acid soil

1994 ◽  
Vol 34 (6) ◽  
pp. 745 ◽  
Author(s):  
RM Barclay ◽  
DM Hebb ◽  
J Brockwell
Keyword(s):  
Rhizobium Meliloti ◽  
Acid Soil ◽  
Arid Environment ◽  
Plant Infection ◽  
South Wales ◽  
Large Populations ◽  
Specific Strain ◽  
Acid Tolerant ◽  
Red Earth ◽  
Annual Medics

Two annual medics, Medicago murex and M. truncatula, were inoculated with specific strains of Rhizobium meliloti, WSM540 and CC169, respectively, and sown into a mildly acid red earth in a semi-arid environment at Cobar, New South Wales. A third medic, M. laciniata, volunteered abundantly at the experimental site and large populations of its specific strain(s) of R. meliloti were naturalised in the soil. Serial dilution, plant infection tests, using 3 test plants in parallel, were employed to count the populations of each of the 3 types of R. meliloti that colonised the roots (rhizospheres) of the 3 medics. The size of the rhizosphere populations was regarded as an index of nodulation potential. Large populations of the naturalised rhizobia (about 45000lplant) developed in the rhizospheres of M. laciniata; these rhizobia also colonised the root surfaces of the sown medics but in much lower numbers (< 80/plant). Strain WSM540 colonised the rhizospheres of M. murex in sufficient numbers (1121 rhizobia/plant) to indicate that an effective nitrogen-fixing symbiosis would have established had seasonal conditions permitted. By contrast, the colonisation of M. truncatula rhizospheres by CC169 was significantly lower (64 rhizobia/plant; P<0.05) and the likelihood of nodulation was uncertain. Both WSM540 and M. murex are known to be acid tolerant whereas both CC169 and M. truncatula are acid sensitive. There was very little colonisation of the rhizospheres of the sown medics by non-specific inoculant strains. Nor was there evidence that the large naturalised population of rhizobia for M. laciniata competed with the specific inoculant strains for colonisation of the roots of the sown medics or interfered with their potential nodulation.

scholarly journals Liquid Swine Manure Can Kill Verticillium dahliae Microsclerotia in Soil by Volatile Fatty Acid, Nitrous Acid, and Ammonia Toxicity

2005 ◽  
Vol 95 (1) ◽  
pp. 28-35 ◽  
Author(s):  
Kenneth L. Conn ◽  
Mario Tenuta ◽  
George Lazarovits
Keyword(s):  
Soil Moisture ◽  
Soil Solution ◽  
Nitrous Acid ◽  
Volatile Fatty Acid ◽  
Acid Soil ◽  
Swine Manure ◽  
Acid Soils ◽  
Ammonia Toxicity ◽  
Alkaline Soils ◽  
Liquid Swine Manure

In previous studies, liquid swine manure (LSM) was sometimes shown to reduce Verticillium wilt of potato caused by Verticillium dahliae. We also observed that microsclerotia of this fungus died within 1 day, or between 3 and 6 weeks, after addition of LSM to some acid soils and within 1 week in some alkaline soils. In this study, we demonstrated that a volatile fatty acid (VFA) mixture with an identical concentration of VFAs as that found in an effective LSM reduced germination in an acid soil (pH 5.1) to the same extent as the LSM after 1 day of exposure. Germination was reduced by 45, 75, and 90% in the 10, 20, and 40% ([wt/wt] soil moisture) treatments, respectively, with the latter being equivalent to an application of 80 hl/ha. Addition to this acid soil of 19 LSMs (30% [wt/wt] soil moisture) collected from different producers resulted in complete kill of microsclerotia with 12 manures. Effective manures had a total concentration of nonionized forms of VFAs in soil solution of 2.7 mM or higher. In some acid soils (pH 5.8), addition of LSM (40% [wt/wt] soil moisture) did not kill microsclerotia until 3 to 6 weeks later. Here, a reduction in viability of microsclerotia was attributed to the accumulation of 0.06 mM nitrous acid in the soil solution at 4 weeks. When an LSM was added (40% [wt/wt] soil moisture) to an alkaline soil (pH 7.9) where VFAs are not toxic, microsclerotia germination was reduced by 80% after 1 week. Here the pH increased to 8.9 and the concentration of ammonia reached 30 mM in the soil solution. An ammonium chloride solution having an equivalent concentration of ammonium as the manure was shown to have the same spectrum of toxicity as the manure in assays ranging from pH 7 to 9, both in solutions and above the solutions. At pH 9, the concentration of ammonia reached 18 mM and 100% mortality of microsclerotia occurred. Thus, in acid soils, LSM can kill microsclerotia of V. dahliae by VFA and/or nitrous acid toxicity and in alkaline soils by ammonia toxicity. In order to take advantage of these mechanisms for disease reduction, the manure chemical composition, rate of addition, and soil characteristics need to be determined for each instance of use.

SCREENING OF SESBANIA FOR TOLERANCE TO ALUMINUM TOXICITY AND SYMBIOTIC EFFECTIVENESS WITH ACID TOLERANT RHIZOBIA STRAINS IN ACID SOIL IN WESTERN KENYA

2009 ◽  
Vol 45 (4) ◽  
pp. 417-427 ◽  
Author(s):  
S. O. GUDU ◽  
P. O. KISINYO ◽  
E. T. MAKATIANI ◽  
D. W ODEE ◽  
J. F. O. ESEGU ◽  
...  
Keyword(s):  
Acid Soil ◽  
Acid Soils ◽  
Al Toxicity ◽  
Symbiotic Effectiveness ◽  
N Content ◽  
P Deficiency ◽  
P Use Efficiency ◽  
P Content ◽  
Acid Tolerant ◽  
Use Efficiency

SUMMARYNitrogen fixation by leguminous trees such as sesbania (Sesbania sesban) in acid soils is limited by aluminium (Al) toxicity and phosphorus (P) deficiency. We screened 214 East African sesbania accessions for Al toxicity tolerance, P use efficiency and sesbania–rhizobia symbiosis. Aluminium toxicity tolerance or sensitivity was measured by the relative root elongation index. Highly Al tolerant and sensitive accessions were screened for P use efficiency. Highly P use efficient and Al sensitive accessions were assessed for symbiotic effectiveness with acid tolerant rhizobia. Eighty-eight per cent of the accessions were Al toxicity tolerant. High Al levels reduced shoot P content by 88% and total dry matter (TDM) by 83%. P addition increased shoot P content and TDM. Rhizobia inoculation increased nodulation by 28–82%, shoot N content by 28–45% and TDM by 15–34% in the low rhizobia density acid soil of Bumala, Kenya. P use efficient accessions had higher nodulation, shoot N content and TDM in the ranges 32–70, 20–52 and 22–36%, respectively, compared to sensitive genotypes. The combination of sesbania accession (SSUG10) and rhizobia strain ASs48 was superior in shoot N accumulation. Inoculation of P use efficient germplasm with acid tolerant rhizobia can improve N-rich biomass accumulation suitable for N replenishment in acid soils.

Calcium modifies pH effects on the growth of acid-tolerant and acid-sensitive Rhizobium meliloti

1992 ◽  
Vol 43 (3) ◽  
pp. 765 ◽  
Author(s):  
JG Howieson ◽  
AD Robson ◽  
LK Abbott
Keyword(s):  
Soil Acidity ◽  
Rhizobium Meliloti ◽  
Acid Soils ◽  
Defined Medium ◽  
Ph Effects ◽  
Poor Growth ◽  
Growth And Survival ◽  
Ph Values ◽  
Acid Tolerant ◽  
Selection Of

The growth of Rhizobium meliloti is sensitive to soil acidity, and its poor growth and survival limits the production from Medicago spp. on acid soils. In the selection of acid tolerant rhizobia for medics, growth in acidified laboratory media has been poorly related to persistence in acid soils. However, the Ca concentration in laboratory media may have been inadequate for growth of some rhizobial strains at low pH. Therefore, acid-tolerant and acid-sensitive strains of R. meliloti were grown in a buffered, defined medium at a range of Ca and P concentrations, and at several pH values. Growth rate was increased by increasing the Ca concentration from 200 to 2000 8M at low (5-70) and moderate (6.50) pH, but not at pH 7.30. Thus, the Ca requirement for the growth of R. meliloti under acid conditions is much higher than previously thought.

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