Effect of manganese toxicity on growth and N2 fixation in groundnut, Arachis hypogaea

The development of manganese (Mn) toxicity symptoms and its effects on the growth, nodulation, and nitrogen fixation of groundnut genotypes were examined using a quartz-sand/solution culture system. The 11 genotypes tested all accumulated considerable concentrations of manganese (1.04–3.07 mg g-1dry matter) when supplied with 15 μg Mn ml-1of nutrient solution daily. Toxicity symptoms differed between genotypes: some showed no visual effects, some produced marginal leaf spots, and others developed marginal leaf spots coupled with an inward rolling of the margins of the younger leaves. The growth of one genotype (ICG 5394) grown with inorganic nitrogen as its source of N was more severely affected by Mn toxicity than when dependent on symbiotic fixation for its nitrogen

Competition among strains of bradyrhizobium and vesicular-arbuscular mycorrhizae for groundnut (Arachis hypogaea L.) root infection and their effect on plant growth and yield

Strains of Bradyrhizobium influenced root colonization of groundnuts by a species of vesicular-arbuscular mycorrhizae (VAM), and species of VAM influenced root nodulation by strains of Bradyrhizobium in pot experiments. In a field experiment, the effects of VAM on competition amongst inoculated bradyrhizobia were less evident, but inoculation with Bradyrhizobium strains increased root colonization by VAM. Certain VAM/Bradyrhizobium inoculum strain combinations produced higher nodule numbers. Plants grown without Bradyrhizobium and VAM but supplied with ammonium nitrate (300 micro g/ml) and potassium phosphate (16 micro g/ml) produced higher DM yields than those inoculated with both symbionts in the pot experiment. Inoculation with either symbiont in the field did not result in higher pod and haulm yields at harves

Enumeration of rhizobia by enzyme-linked immunosorbent assay (ELISA

The use of the enzyme-linked immunosorbent assay (ELISA) to enumerate rhizobia in peat carrier and in soil has been investigated. The ELISA technique takes less time than the conventional plant infection technique often used to enumerate rhizobia present in the presence of other micro-organisms. A minimum of 102–103 cells are required for a detectable ELISA reaction, limiting the use of this technique when the number of rhizobia is low

Enumeration of rhizobia by enzyme-linked immunosorbent assay (ELISA)

The use of the enzyme-linked immunosorbent assay (ELISA) to enumerate rhizobia in peat carrier and in soil has been investigated. The ELISA technique takes less time than the conventional plant infection technique often used to enumerate rhizobia present in the presence of other micro-organisms. A minimum of 102–103 cells are required for a detectable ELISA reaction, limiting the use of this technique when the number of rhizobia is low

Studies on competition, persistence, and methods of application of a peanut rhizobium strain NC 92

In field trials at Patancheru, Andhra Pradesh in 1981-3, the competitive ability of native soil Rhizobium (10²-104 cells/g dry soil) with the inoculant strain NC 92 for groundnut nodulation was studied. Strain NC 92 was detected in 25-40% of the nodules formed although this was reduced when NC 92 was mixed with other strains. When seeds were treated with fungicides, soil application of Rhizobium in a peat carrier was more effective than seed inoculation. An inoculation rate >104 cells/seed was required for successful nodulation by NC 92. The inoculated strain survived in the soil for the following seaso

Factors affecting competition of three strains of rhizobia nodulating groundnut, Arachis hypogaea

The nitrogen (N2) fixing ability of three strains of rhizobia (NC 92, NC 43.3, and TAL 176) was compared in groundnut cv. Robut 33–1. The competitiveness of these strains in pot culture in a sand-vermiculite medium and with native rhizobia in the field was also investigated. In pot culture, NC 43.3 formed more nodules than TAL 176 and NC 92. Nodules formed by NC 43.3 and NC 92 fixed more N2 (as measured by total N content in the plants at 42 days after sowing) than nodules formed by TAL 176. TAL 176 was a poor competitor compared with NC 92, NC 43.3, or with native rhizobia in the field. NC 92 when mixed with NC 43.3 (106 cells seed-1 of each strain) formed only 21% of the nodules, but when independently inoculated in the soil containing native rhizobia, the two-strains formed similar percentages of nodules. Thirty percent of the nodules in two strain combinations of NC 43.3 and NC 92 showed double occupancy. Strain NC 43.3 formed nodules earlier than NC 92 and TAL 176 and this may be one of the factors responsible for its better N2-fixation and competitiveness. Nodules formed earlier by one strain (NC 92 or TAL 176) were found to have no effect on the subsequent nodulation by the other (TAL 176 or NC 92) strain. Although NC 92 and NC 43.3 were equally competitive with native rhizobia in the field and NC 43.3 fixed more N2 than NC 92 in pot culture, earlier experiments indicated that only inoculation with NC 92 increased pod yield in field trials

Effects of mineral nitrogen and Bradyrhizobium inoculation on growth and iron nutrition of groundnut

Experiments were conducted in a glasshouse to determine the effects of the mineral N supplied as ammonium nitrate andBradyrhizobium inoculation on the growth and iron nutrition of nodulating and non-nodulating groundnut (Arachis hypogaea L.) lines. In a sterilized sand-vermiculite medium supplied with N-free nutrient solution (pH 7.0), inoculation of nodulating groundnut withBradyrhizobium strain NC 43.3 enhanced dry matter production and O-phenanthroline extractable iron and N contents of the plants. The supply of mineral N at a rate of 100 mg N L–1 (as NH4NO3) through deionized water (pH 8.5) induced iron chlorosis symptoms in the nodulating groundnuts grown in Vertisols, but these symptoms were not observed at higher N levels (200–400 mg N L–1). The induced chlorosis was only partially corrected by inoculation withBradyrhizobium strains NC 92 and NC 43.3. The iron deficiency chlorosis was, however, corrected by application of higher rates of ammonium nitrate

Potential of Enzyme-linked Immunosorbent Assay for Detecting Viruses, Fungi, Bacteria, Mycoplasma-like Organisms, Mycotoxins, and Hormones

Enz-vme-linked immunosorbent assay (ELlSA) is one of the most widely employed serological tests. For example, the double antibody sandwich (DAS-ELlSA) technique has been successfully employed for the detection of various rhizobia, to assess the quality of inoculum, and to assess the establishment of the inoculated rhizobial strains in soil. This technique can also distinguish bet ween different strains o fR hi~obiumE. LISA has successfully been adapted to direct antigen coating (DAC-ELISA) and protein A coating (PAC) procedures for the detection and assay of fveralpeanut viruses. DAC-ELlSA is a simple and useful tool for virus detection in field surveys hd in seed samples. Both DA C- and PA C- ELISA are more convenient to use lbr the detection of large numbers of antigens than DAS-EL ISA. More recently, a competitive ELISA procedure has been developed to detect up to 2 ng aflatoxin B, in goundnut seed samples

An effective method for cloning of partial MADS-box genes related to flower development in groundnut

Based on the most conserved region of the MADS box, a pair of degenerate primers were designed and used to amplify the genomic DNA of groundnut (cv. JL 24). The results indicate that an amplified fragment, related to flower development, showed a high homology to the MADS-box protein of Arabidopsis thaliana. This study laid the foundation for obtaining the full length of the MADS-box gene in groundnu

Genomic analysis and temperature-dependent transcriptome profiles of the rhizosphere originating strain Pseudomonas aeruginosa M18

<p>Abstract</p> <p>Background</p> <p>Our previously published reports have described an effective biocontrol agent named <it>Pseudomonas </it>sp. M18 as its 16S rDNA sequence and several regulator genes share homologous sequences with those of <it>P. aeruginosa</it>, but there are several unusual phenotypic features. This study aims to explore its strain specific genomic features and gene expression patterns at different temperatures.</p> <p>Results</p> <p>The complete M18 genome is composed of a single chromosome of 6,327,754 base pairs containing 5684 open reading frames. Seven genomic islands, including two novel prophages and five specific non-phage islands were identified besides the conserved <it>P. aeruginosa </it>core genome. Each prophage contains a putative chitinase coding gene, and the prophage II contains a <it>capB </it>gene encoding a putative cold stress protein. The non-phage genomic islands contain genes responsible for pyoluteorin biosynthesis, environmental substance degradation and type I and III restriction-modification systems. Compared with other <it>P. aeruginosa </it>strains, the fewest number (3) of insertion sequences and the most number (3) of clustered regularly interspaced short palindromic repeats in M18 genome may contribute to the relative genome stability. Although the M18 genome is most closely related to that of <it>P. aeruginosa </it>strain LESB58, the strain M18 is more susceptible to several antimicrobial agents and easier to be erased in a mouse acute lung infection model than the strain LESB58. The whole M18 transcriptomic analysis indicated that 10.6% of the expressed genes are temperature-dependent, with 22 genes up-regulated at 28°C in three non-phage genomic islands and one prophage but none at 37°C.</p> <p>Conclusions</p> <p>The <it>P. aeruginosa </it>strain M18 has evolved its specific genomic structures and temperature dependent expression patterns to meet the requirement of its fitness and competitiveness under selective pressures imposed on the strain in rhizosphere niche.</p