The symbiotic matching for nodulation of Bradyrhizobium japonicum strains is a synergy of multi-proteins and plays a key role in symbiotic nitrogen fixation in nature. Studies on mechanism of symbiotic matching are si...The symbiotic matching for nodulation of Bradyrhizobium japonicum strains is a synergy of multi-proteins and plays a key role in symbiotic nitrogen fixation in nature. Studies on mechanism of symbiotic matching are significant in both theory and practice. In this paper, B. japonicum USDA110-A with high symbiotic matching with high-oil content soybean cultivar Suinong 20 and B. japonicum 2178 with low symbiotic matching were selected for proteomic to reveal mechanism of different symbiotic nodulation. The results showed that the amount and categories of proteins identified in this test were different when the two strains were treated by symbiotic nodulation. There were 10 up-regulated proteins and 5 down-regulated proteins with significant difference for B. japonicum USDA110-A. Proteins associated with nodulation and metabolism of energy and material, which were propitious to symbiotic nodulation, were all up-regulated, such as PHDPS synthase, metal-dependent phosphohydrolase, glycosyl transferase family. In contrast, only 5 up-regulated and 7 down-regulated differential proteins were detected in B. japonicum 2178. Molecular chaperones and defensive proteins, which influence the folding of nascent polypeptide chains and the active of azotase were down-regulated. To a certain extent, the different responses of B. japonicum to daidzein were one of the most important reasons that cause varieties in symbiotic matching ability.展开更多
Competitiveness for nodulation of Bradyrhizobium japonicum strains plays a key role in symbiotic nitrogen fixation. In order to reveal the difference in competitiveness, B. japonicum 4534 with high competitiveness and...Competitiveness for nodulation of Bradyrhizobium japonicum strains plays a key role in symbiotic nitrogen fixation. In order to reveal the difference in competitiveness, B. japonicum 4534 with high competitiveness and B. japonicum 4222 with low competitiveness for nodulation were analyzed by proteomic technique. The results showed that differential proteins were fewer when two strains were treated with just daidzein. Only 24 and 10 differential proteins were detected with an up-regulated rate of 58 and 40% in B. japonicum 4534 and B. japonicum 4222, respectively. However, more differential proteins were detected upon treatment with daidzein and mutual extracellular materials simultaneously. There were 78 differential proteins detected in B. japonicum 4534 with 43 being up-regulated and 35 being down-regulated. These differential proteins, such as metabolism-related proteins, transporters, transcription-related proteins, translation-related proteins, and flagellin, were found to be associated with nodulation process. 25 up-regulated and 22 down-regulated proteins were detected in B. japonicum 4222. Some of these proteins were not related to nodulation. More differential proteins associated with nodulation in B. japonicum 4534 may be the reason for its high competitiveness. The results can provide a guide to the selection and inoculation of effective strains and are significant to biological nitrogen fixation.展开更多
The current study describes the molecular characterization of a clone which can restore the ability of bdh A mutant strains NGRPA2 and Rm11107 to utilize 3-hydroxybutyrate as a sole carbon source (Hbu+ ). This clone w...The current study describes the molecular characterization of a clone which can restore the ability of bdh A mutant strains NGRPA2 and Rm11107 to utilize 3-hydroxybutyrate as a sole carbon source (Hbu+ ). This clone was screened out by complementation experiment from Bradyrhizobium japonicum US-DAI 10 genomic library, and the presence of bdhA gene in the clone was verified by Bdh assay and Southern blot analysis. Furthermore, the entire sequence of bdhA. gene was sequenced and the sequence was deposited in GenBank database under the accession number AY077581. bdhA gene comprises 789 base pairs and encodes Bdh with 262 amino acid of MW 27.59 kDa. Interposon JlKm was inserted into the bdhA ORF at EcoR I site and the bdhA mutant was constructed in B .japonicum by homologous recombination. Plant assay result did not show obvious effects of mutation of bdhA gene on nodulation and nitrogen-fixation.展开更多
Bacterial strain RV9 recovered from greengram nodules tolerated 2400 μg/mL of hexaconazole and was identified by 16 S rDNA sequence analysis as Bradyrhizobium japonicum(KY940048). Strain RV9 produced IAA(61.6 μg/mL)...Bacterial strain RV9 recovered from greengram nodules tolerated 2400 μg/mL of hexaconazole and was identified by 16 S rDNA sequence analysis as Bradyrhizobium japonicum(KY940048). Strain RV9 produced IAA(61.6 μg/mL), ACC deaminase(51.7 mg/(protein·hr)), solubilized TCP(105 μg/mL), secreted 337.6 μg/mL EPS, and produced SA(52.2 μg/mL) and 2,3-DHBA(28.3 μg/mL). Exopolysaccharides produced by strain RV9 was quantified and characterized by SEM, AFM, EDX and FTIR. Beyond tolerance limit,hexaconazole caused cellular impairment and reduced the viability of strain RV9 revealed by SEM and CLSM. Hexaconazole distorted the root tips and altered nodule structure leading thereby to reduction in the performance of greengram. Also, the level of antioxidant enzymes, proline, TBARS, ROS and cell death was increased in hexaconazole treated plants.CLSM images revealed a concentration dependent increase in the characteristic green and blue fluorescence of hexaconazole treated roots. The application of B. japonicum strain RV9 alleviated the fungicide toxicity and improved the measured plant characteristics. Also,rhizobial cells were localized inside tissues as revealed by CLSM. Colonization of B.japonicum strain RV9 decreased the levels of CAT, POD, APX, GPX and TBARS by 80%, 5%,13%, 13% and 19%, respectively over plants grown at 80 μg/(hexaconazole·kg) soil. The ability to detoxify hexaconazole, colonize plant tissues, secrete PGP bioactive molecules even under fungicide pressure and its unique ability to diminish oxidative stress make B.japonicum an attractive choice for remediation of fungicide polluted soils and to concurrently enhance greengram production under stressed environment.展开更多
The effect of pH on the nodulation of Sinorhizobium fredii and Bradyrhizobium japonicum was examined by analy- zing the indigent soybean rhizobia,predominant indigent rhizobia,and specific rhizobia,respectively.The re...The effect of pH on the nodulation of Sinorhizobium fredii and Bradyrhizobium japonicum was examined by analy- zing the indigent soybean rhizobia,predominant indigent rhizobia,and specific rhizobia,respectively.The results showed that very acid and very alkaline environment could retard the nodulation and inhibit the growth of the rhizobia.Sinorhizohium fredii could endure environment more strongly than Bradyrhizobium japonicum,and had a high competitive nodulation capacity.Bradyhizobium japonicum could endure acid environment more strongly than Sinorhizobium fredii.In very acid and very alkaline environment,the nodulation capacity of S.fredii and B.japonicum was mainly determined by their physiological characteristics.展开更多
基金supported by the National 863 Program of China (2010AA10A203)the Basic Scientific and Business Fund and Central Public Research Project, China (202-10)the Special Fund for Establishment of Modern Agri-cultural R&D System, Ministry of Agriculture, China(nycytx-004)
文摘The symbiotic matching for nodulation of Bradyrhizobium japonicum strains is a synergy of multi-proteins and plays a key role in symbiotic nitrogen fixation in nature. Studies on mechanism of symbiotic matching are significant in both theory and practice. In this paper, B. japonicum USDA110-A with high symbiotic matching with high-oil content soybean cultivar Suinong 20 and B. japonicum 2178 with low symbiotic matching were selected for proteomic to reveal mechanism of different symbiotic nodulation. The results showed that the amount and categories of proteins identified in this test were different when the two strains were treated by symbiotic nodulation. There were 10 up-regulated proteins and 5 down-regulated proteins with significant difference for B. japonicum USDA110-A. Proteins associated with nodulation and metabolism of energy and material, which were propitious to symbiotic nodulation, were all up-regulated, such as PHDPS synthase, metal-dependent phosphohydrolase, glycosyl transferase family. In contrast, only 5 up-regulated and 7 down-regulated differential proteins were detected in B. japonicum 2178. Molecular chaperones and defensive proteins, which influence the folding of nascent polypeptide chains and the active of azotase were down-regulated. To a certain extent, the different responses of B. japonicum to daidzein were one of the most important reasons that cause varieties in symbiotic matching ability.
基金supported by the National High-Tech R&D Program of China (2010AA10A203)the Basic Scientific Research Special Fund of Public Research Institutions of Central Government, China (2010-12 and 2010-34)the Special Fund for Establishment of Modern Agricultural R&D System, Ministry of Finance and Ministry of Agriculture, China (nycytx-004)
文摘Competitiveness for nodulation of Bradyrhizobium japonicum strains plays a key role in symbiotic nitrogen fixation. In order to reveal the difference in competitiveness, B. japonicum 4534 with high competitiveness and B. japonicum 4222 with low competitiveness for nodulation were analyzed by proteomic technique. The results showed that differential proteins were fewer when two strains were treated with just daidzein. Only 24 and 10 differential proteins were detected with an up-regulated rate of 58 and 40% in B. japonicum 4534 and B. japonicum 4222, respectively. However, more differential proteins were detected upon treatment with daidzein and mutual extracellular materials simultaneously. There were 78 differential proteins detected in B. japonicum 4534 with 43 being up-regulated and 35 being down-regulated. These differential proteins, such as metabolism-related proteins, transporters, transcription-related proteins, translation-related proteins, and flagellin, were found to be associated with nodulation process. 25 up-regulated and 22 down-regulated proteins were detected in B. japonicum 4222. Some of these proteins were not related to nodulation. More differential proteins associated with nodulation in B. japonicum 4534 may be the reason for its high competitiveness. The results can provide a guide to the selection and inoculation of effective strains and are significant to biological nitrogen fixation.
文摘The current study describes the molecular characterization of a clone which can restore the ability of bdh A mutant strains NGRPA2 and Rm11107 to utilize 3-hydroxybutyrate as a sole carbon source (Hbu+ ). This clone was screened out by complementation experiment from Bradyrhizobium japonicum US-DAI 10 genomic library, and the presence of bdhA gene in the clone was verified by Bdh assay and Southern blot analysis. Furthermore, the entire sequence of bdhA. gene was sequenced and the sequence was deposited in GenBank database under the accession number AY077581. bdhA gene comprises 789 base pairs and encodes Bdh with 262 amino acid of MW 27.59 kDa. Interposon JlKm was inserted into the bdhA ORF at EcoR I site and the bdhA mutant was constructed in B .japonicum by homologous recombination. Plant assay result did not show obvious effects of mutation of bdhA gene on nodulation and nitrogen-fixation.
基金the financial support received in the form of UGC NonNET fellowship granted by University Grants Commission (D. O.No.F.1993/2006 (CU) dated 01.02.2007), New Delhi
文摘Bacterial strain RV9 recovered from greengram nodules tolerated 2400 μg/mL of hexaconazole and was identified by 16 S rDNA sequence analysis as Bradyrhizobium japonicum(KY940048). Strain RV9 produced IAA(61.6 μg/mL), ACC deaminase(51.7 mg/(protein·hr)), solubilized TCP(105 μg/mL), secreted 337.6 μg/mL EPS, and produced SA(52.2 μg/mL) and 2,3-DHBA(28.3 μg/mL). Exopolysaccharides produced by strain RV9 was quantified and characterized by SEM, AFM, EDX and FTIR. Beyond tolerance limit,hexaconazole caused cellular impairment and reduced the viability of strain RV9 revealed by SEM and CLSM. Hexaconazole distorted the root tips and altered nodule structure leading thereby to reduction in the performance of greengram. Also, the level of antioxidant enzymes, proline, TBARS, ROS and cell death was increased in hexaconazole treated plants.CLSM images revealed a concentration dependent increase in the characteristic green and blue fluorescence of hexaconazole treated roots. The application of B. japonicum strain RV9 alleviated the fungicide toxicity and improved the measured plant characteristics. Also,rhizobial cells were localized inside tissues as revealed by CLSM. Colonization of B.japonicum strain RV9 decreased the levels of CAT, POD, APX, GPX and TBARS by 80%, 5%,13%, 13% and 19%, respectively over plants grown at 80 μg/(hexaconazole·kg) soil. The ability to detoxify hexaconazole, colonize plant tissues, secrete PGP bioactive molecules even under fungicide pressure and its unique ability to diminish oxidative stress make B.japonicum an attractive choice for remediation of fungicide polluted soils and to concurrently enhance greengram production under stressed environment.
文摘The effect of pH on the nodulation of Sinorhizobium fredii and Bradyrhizobium japonicum was examined by analy- zing the indigent soybean rhizobia,predominant indigent rhizobia,and specific rhizobia,respectively.The results showed that very acid and very alkaline environment could retard the nodulation and inhibit the growth of the rhizobia.Sinorhizohium fredii could endure environment more strongly than Bradyrhizobium japonicum,and had a high competitive nodulation capacity.Bradyhizobium japonicum could endure acid environment more strongly than Sinorhizobium fredii.In very acid and very alkaline environment,the nodulation capacity of S.fredii and B.japonicum was mainly determined by their physiological characteristics.
