Effects of temperature on competition and relative dominance of Bradyrhizobium japonicum and Bradyrhizobium elkanii in the process of soybean nodulation

Suzuki, Yuta; Adhikari, Dinesh; Itoh, Kazuhito; Suyama, Kousuke

doi:10.1007/s11104-013-1924-5

Cited by 33 publications

(24 citation statements)

References 24 publications

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“…However, rhizobia must survive often a long period of time in the soil as free-living organisms until they meet their symbiotic partner. During this period, they are exposed to the action of several environmental factors (e.g., drought, pH, temperature, salinity, nutrient limitation, heavy metals, oxidative stress) (Frey and Blum 1994;R s nen et al 2004;Soussou et al 2013;Talbi et al 2013;Suzuki et al 2014;Cazenave et al 2014;Pini et al 2014;Burchill et al 2014;Barthelemy-Delaux et al 2014;Jaszek et al 2014). Extracellular polysaccharide secreted in large amounts by rhizobial cells plays a significant protective role in their adaptation to stress conditions.…”

Section: Discussionmentioning

confidence: 99%

Genetic characterization of the Pss region and the role of PssS in exopolysaccharide production and symbiosis of Rhizobium leguminosarum bv. trifolii with clover

2015

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Background and aims In the symbiotic bacterium Rhizobium leguminosarum bv. trifolii, a majority of proteins involved in exopolysaccharide (EPS) synthesis are encoded by genes located in a large polysaccharide synthesis cluster (Pss). The aim of this study was genetic characterization of the Pss region in the Rt24.2 strain in the context of EPS production and symbiosis with red clover (Trifolium pratense). Methods The expression of genes located in the Pss cluster was determined using constructed pss-lacZ transcriptional fusions. The role of transcriptional regulator RosR in pss transcription was confirmed using a rosR mutant and the Rt24.2(pBR1) strain carrying multiple rosR copies. An EPS-deficient mutant, Rt770 was obtained using a random mutagenesis and mTn5SSgusA40 transposon. Symbiotic properties of the Rt770 strain in interaction with clover were characterized in inoculation experiments. Infection of host roots and nodule occupancy by this mutant were investigated using both light and electron microscopy. Results Transcriptional levels of particular pss genes differed significantly; the genes encoding glycosyltransferases and enzymes modifying EPS have promoters of weak activities, whereas those encoding proteins involved in EPS polymerization and export possess stronger promoters. Furthermore, RosR affected expression of some pss genes. A mutation in Rt24.2 pssS encoding glucosyltransferase totally abolished EPS synthesis, decreased motility, and increased sensitivity to some stressors. The pssS mutant Rt770 induced formation of nodules on clover roots, which were ineffective in nitrogen fixation. Conclusion EPS secreted by Rt24.2 is required for both adaptation to soil conditions and the establishment of effective symbiosis with clover plants.

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Section: Discussionmentioning

confidence: 99%

Genetic characterization of the Pss region and the role of PssS in exopolysaccharide production and symbiosis of Rhizobium leguminosarum bv. trifolii with clover

2015

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“…Alcaligenes faecalis has been shown to secrete IAA as plant growth-promoter in young lettuce seedling (Barazani and Friedman, 1999), while others have classified this strain as a salt-tolerant bacteria and a potential human pathogen (Egamberdieva et al, 2008). Bradyrhizobium and Rhizobium are two well-known bacteria in legume symbiosis, with vital roles on nodule formation and BNF (Nguyen et al, 2012;Suzuki et al, 2014;Klonowska et al, 2012).…”

Section: Ajabsmentioning

confidence: 99%

Isolation and Characterization of Rhizobia and Plant Growth-Promoting Rhizobacteria and Their Effects on Growth of Rice Seedlings

Tan

Othman

Halimi

et al. 2014

American Journal of Agricultural and Biological Sciences

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Biofertilizer is a relatively safer, environmentally friendly and cost-effective approach as an alternative to reduce chemical fertilizer usage. The selection of bacterial strains with multiple beneficial characteristics are important to maximize the effectiveness on the host plant. Due to aforementioned interest, several Plant Growth-Promoting Rhizobacterial (PGPR) and rhizobial strains were isolated from rice and legume roots, respectively, at four locations in Malaysia namely Universiti Putra Malaysia (UPM), Serdang, Selangor; Besut, Terengganu; Tunjung, Kelantan and Sik, Kedah. Bacterial isolations were undertaken to select the best isolates which exhibit multiple beneficial effects to the rice plant and a total of 205 bacterial strains were isolated and categorized as follows; 94 rhizospheric and 107 endophytic bacteria from rice roots, one rhizobial strain from soybean and three from Mimosa pudica. These isolates were screened for their abilities to fix N 2 and solubilize phosphate; 52 were positive for both tests. The selected isolates were then tested for IAA production and other biochemical tests such as potassium solubilization, hydrolyzing enzymes (cellulase and pectinase) and iron siderophore productions. Four isolates, namely UPMB19 (rhizospheric PGPR from Tunjung, Kelantan), UPMB20 (endophytic PGPR from Besut, Terengganu), UPMR30 (rhizobia from soybean) and UPMR31 (rhizobia from Mimosa) were selected for subsequent plant inoculation tests with UPMB10, a PGPR isolated from oil palm root, as the reference strain. Based on 16S rDNA gene sequencing, these bacterial strains were identified under several genera: Lysinibacillus, Alcaligenes, Bradyrhizobium, Rhizobium and Bacillus, respectively. Results of plant inoculation test indicated that UPMB19 significantly enhanced the seedling height at the early growth stage (7 days after transplanting, DAT) which could be attributed to the higher N 2 fixation rate of this strain as compared to the other strains, except UPMB20. UPMB10 and UPMR31 also showed significant effects with increased seedling height and Total Dry Weight (TDW) at the later stage (14 DAT) possibly due to the higher bacterial population and IAA produced as observed in the residual nutrient solution without addition of fertilizer-N. This study has successfully demonstrated the effectiveness of locally isolated PGPR and rhizobial strains with multiple beneficial characteristics on early growth and vigor of rice seedlings under controlled condition. The result proved to be a vital information in the development of a liquid biofertilizer for rice; thus further studies will be done to evaluate the effectiveness of these isolates under glasshouse and field conditions on growth, tillering and yield of rice.

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“…Many effective rhizobial strains have been identified and are available. However, it has been observed that rhizobial strains often perform poorly under conditions dissimilar to their original habitat (5-7) and that their effectiveness depends on environmental factors such as soil temperature (5,6,8), soil pH (9), soil texture (7), and host plant variety (10), an issue which might be especially relevant for the Okavango region with its harsh climate, heterogeneous soils, and local plant varieties. In this regard, Law et al (7) already reported that a prominent inoculant strain had no effect on cowpea and peanut grown in Botswana.…”

mentioning

confidence: 99%

Rhizobia Indigenous to the Okavango Region in Sub-Saharan Africa: Diversity, Adaptations, and Host Specificity

Grönemeyer

Kulkarni

Hölscher

et al. 2014

Appl Environ Microbiol

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The rhizobial community indigenous to the Okavango region has not yet been characterized. The isolation of indigenous rhizobia can provide a basis for the formulation of a rhizobial inoculant. Moreover, their identification and characterization contribute to the general understanding of species distribution and ecology. Isolates were obtained from nodules of local varieties of the pulses cowpea, Bambara groundnut, peanut, hyacinth bean, and common bean. Ninety-one of them were identified by BOX repetitive element PCR (BOX-PCR) and sequence analyses of the 16S-23S rRNA internally transcribed spacer (ITS) and the recA, glnII, rpoB, and nifH genes. A striking geographical distribution was observed. Bradyrhizobium pachyrhizi dominated at sampling sites in Angola which were characterized by acid soils and a semihumid climate. Isolates from the semiarid sampling sites in Namibia were more diverse, with most of them being related to Bradyrhizobium yuanmingense and Bradyrhizobium daqingense. Host plant specificity was observed only for hyacinth bean, which was nodulated by rhizobia presumably representing yet-undescribed species. Furthermore, the isolates were characterized with respect to their adaptation to high temperatures, drought, and local host plants. The adaptation experiments revealed that the Namibian isolates shared an exceptionally high temperature tolerance, but none of the isolates showed considerable adaptation to drought. Moreover, the isolates' performance on different local hosts showed variable results, with most Namibian isolates inducing better nodulation on peanut and hyacinth bean than the Angolan strains. The local predominance of distinct genotypes implies that indigenous strains may exhibit a better performance in inoculant formulations.T he catchment area of the Okavango River extends across parts of the three sub-Saharan African countries of Angola, Namibia, and Botswana and is mainly characterized by smallholder and subsistence farming. Since cultivation techniques remain underdeveloped, e.g., in terms of irrigation and the application of agrochemicals or rhizobial inoculants, local farmers are confronted with low yields and decreasing soil fertilities (1). Pulses like cowpea (Vigna unguiculata), Bambara groundnut (Vigna subterranea), peanut (Arachis hypogaea), hyacinth bean (Lablab purpureus), and common bean (Phaseolus vulgaris) are cultivated and occasionally intercropped, but natural nodulation rates are often low (2), presumably due to a seasonal reduction of the rhizobial population caused by drought and heat. Thus, nitrogen input via symbiotic N 2 fixation might be very limited.Field-grown cowpea plants in Ghana have been reported to fix more than 200 kg N/ha (89% of plant N) (3). In contrast, values of only 4 to 29 kg N-fixed/ha (15 to 56% of plant N) were observed in semiarid southwestern Zimbabwe (4). In such areas, the application of a rhizobial inoculant may thus hold the potential to increase plant nutrition and soil fertility. Many effective rhizobial strains have been identif...

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Effects of temperature on competition and relative dominance of Bradyrhizobium japonicum and Bradyrhizobium elkanii in the process of soybean nodulation

Cited by 33 publications

References 24 publications

Genetic characterization of the Pss region and the role of PssS in exopolysaccharide production and symbiosis of Rhizobium leguminosarum bv. trifolii with clover

Genetic characterization of the Pss region and the role of PssS in exopolysaccharide production and symbiosis of Rhizobium leguminosarum bv. trifolii with clover

Isolation and Characterization of Rhizobia and Plant Growth-Promoting Rhizobacteria and Their Effects on Growth of Rice Seedlings

Rhizobia Indigenous to the Okavango Region in Sub-Saharan Africa: Diversity, Adaptations, and Host Specificity

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