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2. Ensifer meliloti denitrification is involved in infection effectiveness and N2O emissions from alfalfa root nodules

Author

European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Pacheco, Pedro J., Bedmar, Eulogio J., Mesa, Socorro, Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Pacheco, Pedro J., Bedmar, Eulogio J., Mesa, Socorro, Tortosa Muñoz, Germán, and Delgado Igeño, María Jesús

Abstract

Purpose: Alfalfa is one of the most valuable forage crops in temperate climate zones. Ensifer meliloti, the endosymbiont of alfalfa, contains all the denitrification genes but the capacity of alfalfa root nodules to produce nitrous oxide (NO) is not known. In this work, NO emissions as well as the influence of bacteroidal denitrification on nodulation competitiveness and NO release from alfalfa nodules has been investigated. Methods: Medicago sativa cv. Victoria plants were inoculated with E. meliloti 1021, a periplasmic nitrate reductase (Nap) defective mutant, a Nap overexpressing strain and a nitrous oxide reductase defective mutant. Plants were grown in the presence of different nitrate and copper treatments and subjected to flooding during one week before harvesting. NO production by the nodules was analysed by using gas chromatography. Methyl viologen-dependent nitrate reductase (MV-NR), nitrite reductase (MV-NIR) and nitrous oxide reductase (NOR) enzymatic activities were measured in isolated bacteroids. Results: Alfalfa root nodules produce NO in response to nitrate and flooding. Overexpression of Nap improved nodulation competitiveness and induced NO emissions from nodules. Copper is required for an effective symbiosis as well as triggered a reduction of NO production due to the induction of the NOR and a reduction of NIR activities in the bacteroids. Conclusion: Alfalfa root nodules emit NO. Nap is involved in nodulation competitiveness and in NO emissions by the nodules. Bacteroidal NOR and NIR activities are modulated by Cu and may be considered as effective targets for the mitigation strategies of NO emissions derived from alfalfa crops.

Published
2023

3. “Alperujo” compost improves nodulation and symbiotic nitrogen fixation of soybean inoculated with Bradyrhizobium diazoefficiens

Author

Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Ministerio de Agricultura y Desarrollo Rural (Colombia), Tortosa Muñoz, Germán, Mesa, Socorro, Delgado Igeño, María Jesús, Amaya-Gómez, Carol V., Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Ministerio de Agricultura y Desarrollo Rural (Colombia), Tortosa Muñoz, Germán, Mesa, Socorro, Delgado Igeño, María Jesús, and Amaya-Gómez, Carol V.

Abstract

The utilization of compost to enhance plant productivity and symbiotic nitrogen fixation (SNF) has been recognized as an effective alternative to synthetic nitrogen fertilizers. This environmentally sustainable method is readily accessible to farmers. This study investigated the effect of olive pomace (“alperujo”, AL) compost on the nodulation and SNF of soybeans (Glycine max L.) and their natural symbiont (Bradyrhizobium diazoefficiens). For that, soybean plants were subjected to several doses of AL compost under controlled greenhouse conditions. At the end of the experiment, the dry weight of plant biomass (aerial part and roots), the number and fresh weight of nodules, and nitrogen and leghaemoglobin contents were analyzed. The application of AL compost significantly improved soybean growth, as demonstrated by an increase in both plant biomass and height. Furthermore, nodular leghaemoglobin content and nitrogen content were found to be enhanced by the addition of AL compost (7 and 40%, respectively), indicating an increase in nodule effectiveness and symbiotic efficiency. Our results provide clear evidence of the synergetic effect of AL compost on the soybean-B. diazoefficiens association, probably due to AL-compost improved soybean roots development, and rhizospheric organic matter and nutrients assimilation by rhizobia.

Published
2023

4. Nitrous oxide emissions from legume root nodules

Author

Hidalgo-García, Alba, Pérez González, S., Torres Porras, María Jesús, Tortosa Muñoz, Germán, Girard, Lourdes, Delgado Igeño, María Jesús, Hidalgo-García, Alba, Pérez González, S., Torres Porras, María Jesús, Tortosa Muñoz, Germán, Girard, Lourdes, and Delgado Igeño, María Jesús

Published
2023

5. Pleiotropic effects of phar regulator in Bradyrhizobium diazoefficiens metabolism

Author

European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Díaz-Peña, R., Cabrera Rodríguez, Juan José, Nashmias, M., Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, Mongiardini, E., Müller-Santos, M., Pettinari, J., Mesa, Socorro, Quelas, Juan I., European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Díaz-Peña, R., Cabrera Rodríguez, Juan José, Nashmias, M., Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, Mongiardini, E., Müller-Santos, M., Pettinari, J., Mesa, Socorro, and Quelas, Juan I.

Published
2023

6. Pathways and regulatory factors involved in NO and N2O emissions by nitrogen-fixing endosymbiotic bacteria

Author

Delgado Igeño, María Jesús, Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Tortosa Muñoz, Germán, Hidalgo-García, Alba, Pacheco, Pedro J., Juárez, Raquel A., Bedmar, Eulogio J., Mesa, Socorro, Delgado Igeño, María Jesús, Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Tortosa Muñoz, Germán, Hidalgo-García, Alba, Pacheco, Pedro J., Juárez, Raquel A., Bedmar, Eulogio J., and Mesa, Socorro

Published
2023

7. Novel symbiotic microbiota on several legumes at the MBG-CSIC (Spain)

Author

Rodiño Míguez, Ana Paula, Abelleira, Adela, Aguín, Olga, Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, De Ron, Antonio M., Rodiño Míguez, Ana Paula, Abelleira, Adela, Aguín, Olga, Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, and De Ron, Antonio M.

Published
2023

9. Rhizobium etli is able to emit nitrous oxide by connecting assimilatory nitrate reduction with nitrite respiration in the bacteroids of common bean nodules

Author

European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Hidalgo-García, Alba, Tortosa Muñoz, Germán, Pacheco, Pedro J., Gates, A.J., Richardson, D.J., Bedmar, Eulogio J., Girard, Lourdes, Torres Porras, María Jesús, Delgado Igeño, María Jesús, European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Hidalgo-García, Alba, Tortosa Muñoz, Germán, Pacheco, Pedro J., Gates, A.J., Richardson, D.J., Bedmar, Eulogio J., Girard, Lourdes, Torres Porras, María Jesús, and Delgado Igeño, María Jesús

Abstract

Legumes can contribute to emissions of the potent greenhouse gas nitrous oxide (NO) directly by some rhizobia species that are able to denitrify under free-living conditions and in symbiotic association with the plant. In this study, the capacity of Phaseolus vulgaris-Rhizobium etli symbiosis to emit NO in response to nitrate (NO) has been demonstrated for the first time. We found that bacteroidal assimilatory nitrate reductase (NarB) as well as nitrite reductase (NirK) and nitric oxide reductase (cNor) denitrifying enzymes contribute to nitric oxide (NO) and NO formation in nodules. We also show that R. etli NarK is involved in NO extrusion and links NO reduction by NarB in the cytoplasm with NirK and cNor denitrification activities in the periplasm. The knowledge generated in this work will be instrumental for exploring strategies and sustainable practices in agricultural soil management to increase legume crop yield and mitigate greenhouse gas emissions.

Published
2023

10. The copper-responsive regulator CsoR is indirectly involved in Bradyrhizobium diazoefficiens denitrification

Author

European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Ministerio de Universidades (España), Pacheco, Pedro J., Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Torres Porras, María Jesús, Gates, A.J., Bedmar, Eulogio J., Richardson, D.J., Mesa, Socorro, Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Ministerio de Universidades (España), Pacheco, Pedro J., Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Torres Porras, María Jesús, Gates, A.J., Bedmar, Eulogio J., Richardson, D.J., Mesa, Socorro, Tortosa Muñoz, Germán, and Delgado Igeño, María Jesús

Abstract

The soybean endosymbiont Bradyrhizobium diazoefficiens harbours the complete denitrification pathway that is catalysed by a periplasmic nitrate reductase (Nap), a copper (Cu)-containing nitrite reductase (NirK), a c-type nitric oxide reductase (cNor), and a nitrous oxide reductase (Nos), encoded by the napEDABC, nirK, norCBQD, and nosRZDFYLX genes, respectively. Induction of denitrification genes requires low oxygen and nitric oxide, both signals integrated into a complex regulatory network comprised by two interconnected cascades, FixLJ-FixK2-NnrR and RegSR-NifA. Copper is a cofactor of NirK and Nos, but it has also a role in denitrification gene expression and protein synthesis. In fact, Cu limitation triggers a substantial down-regulation of nirK, norCBQD, and nosRZDFYLX gene expression under denitrifying conditions. Bradyrhizobium diazoefficiens genome possesses a gene predicted to encode a Cu-responsive repressor of the CsoR family, which is located adjacent to copA, a gene encoding a putative Cu+-ATPase transporter. To investigate the role of CsoR in the control of denitrification gene expression in response to Cu, a csoR deletion mutant was constructed in this work. Mutation of csoR did not affect the capacity of B. diazoefficiens to grow under denitrifying conditions. However, by using qRT-PCR analyses, we showed that nirK and norCBQD expression was much lower in the csoR mutant compared to wild-type levels under Cu-limiting denitrifying conditions. On the contrary, copA expression was significantly increased in the csoR mutant. The results obtained suggest that CsoR acts as a repressor of copA. Under Cu limitation, CsoR has also an indirect role in the expression of nirK and norCBQD genes.

Published
2023

12. Heme is involved in the NO-mediated regulation by Bradyrhizobium diazoefficiens NnrR transcription factor

Author

Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Torres Porras, María Jesús, Richardson, D.J., Bedmar, Eulogio J., Gates, Andrew J., Delgado Igeño, María Jesús, Mesa, Socorro, Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Torres Porras, María Jesús, Richardson, D.J., Bedmar, Eulogio J., Gates, Andrew J., Delgado Igeño, María Jesús, and Mesa, Socorro

Published
2023

13. El sistema de dos componentes RegSR reprime la expresión de los genes norCBQD en respuesta a microoxia en la bacteria Bradyrhizobium diazoefficiens

Author

Juárez, Raquel A., Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Bedmar, Eulogio J., Mesa, Socorro, Delgado Igeño, María Jesús, Ministerio de Economía y Competitividad (España), European Commission, and Junta de Andalucía

Abstract

Resumen de la comunicación oral presentada en: I Jornada de Juventud Investigadora Estación Experimental del Zaidín. EEZ Granada; 20 noviembre (2022), Se agradece el apoyo económico de los proyectos AGL2017-85676-R y PID2020-114330GB-100 (cofinanciados por el Ministerio de Economía y Competitividad y FEDER) y el proyecto P18-RT-1401 (Junta de Andalucía)].

Published
2022

14. Distinctive phehotypes of Bradyrhizobium diazoefficiens transcriptional regulator (phaR) mutants grown on different carbon sources

Author

Díaz-Peña, R., Cabrera Rodríguez, Juan José, Nashmías, M.E., Zubimendi, J.P., Parejo, Sergio, Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, Mongiardini, E.J., Müller-Santos, M., Pettinari, M.J., and Mesa, Socorro

Abstract

Resumen del poster presentado en: XVII Congreso Argentino de Microbiología General (SAMIGE). Córdoba, Argentina, 25-28 octubre 2022.

Published
2022

15. Novel enzymes involved in N2O emission by Rhizobium etli - common bean symbiosis

Author

Hidalgo-García, Alba, Torres Porras, María Jesús, Tortosa Muñoz, Germán, Pacheco, Pedro J., Gates, Andrew J., Bedmar, Eulogio J., Girard, L., Delgado Igeño, María Jesús, European Commission, Ministerio de Ciencia e Innovación (España), and Junta de Andalucía

Abstract

Resumen del poster presentado en: I Spanish-Portuguese Congress on Beneficial Plant-Microbe Interactions (BeMiPlant) and XVIII National Meeting of the Spanish Society of Nitrogen Fixation (XVIII SEFIN). Oeiras, Portugal, 17-19 octubre (2022), This work was supported by Fondo Europeo de Desarrollo Regional (FEDER)-co-financed grants AGL2017-85676-R from the Ministerio de Ciencia e Innovación (Spain) and grant P18-RT-1401 from the Junta de Andalucía.

Published
2022

16. Control of nitrous oxide emissions by legume-associated endosymbiotic bacteria

Author

Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Pacheco, Pedro J., Juárez, R.A., Bedmar, Eulogio J., Mesa, Socorro, Delgado Igeño, María Jesús, Ministerio de Ciencia e Innovación (España), European Commission, and Junta de Andalucía

Abstract

Conferencia invitada presentada en: 25th Nitrogen Cycle Meeting. Roma 28-20 septiembre (2022), This research has been funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”, AGL2017-85676-R, and PID2020-114330GB-100 grants and also by Junta de Andalucía P18-RT1401 grant. PJP was supported by a FPU fellowship from MCIU (formerly MECD).

Published
2022

17. Análisis transcriptómico de la respuesta de Bradyrhizobium diazoefficiens a la limitación de cobre en condiciones desnitrificantes

Author

Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Pacheco, Pedro J., Juárez, R.A., Bedmar, Eulogio J., Mesa, Socorro, Delgado Igeño, María Jesús, Ministerio de Economía y Competitividad (España), European Commission, and Junta de Andalucía

Abstract

Resumen del poster presentado en: XIII Reunión del Grupo de Microbiología Molecular de La SEM. Granada, 7-9 septiembre (2022), Se agradece el apoyo económico de los proyectos AGL2017-85676-R y PID2020-114330GB-100 (cofinanciados por el Ministerio de Economía y Competitividad y FEDER) y el proyecto P18-RT-1401 (Junta de Andalucía).

Published
2022

18. The carbon regulator PhaR exerts a pleiotropic control in Bradyrhizobium diazoefficiens

Author

Díaz-Peña, R, Cabrera Rodríguez, Juan José, Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, Mongiardini, E., Müller-Santos, M., Pettinari, J., Mesa, Socorro, Quelas, J.I., European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, and Consejo Superior de Investigaciones Científicas (España)

Abstract

Resumen del poster presentado en: XIII Reunión del Grupo de Microbiología Molecular de La SEM. Granada, 7-9 septiembre (2022), This work was supported by Programme of Scientific Cooperation for Development i-COOP, CSIC, Spain (COOPB20505), Ministerio de Ciencia e Innovación, Spain (PID2020-114330GB-100), and Junta de Andalucía, Spain (P18-RT-1401).

Published
2022

19. Molecular mechanism of the Bradyrhizobium diazoefficiens NnrR transcription factor: Influence of heme in NO sensing

Author

Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Torres Porras, María Jesús, Richardson, D.J., Bedmar, Eulogio J., Gates, Andrew J., Delgado Igeño, María Jesús, Mesa, Socorro, European Commission, Ministerio de Ciencia e Innovación (España), and Junta de Andalucía

Abstract

Resumen del poster presentado en: XIII Reunión del Grupo de Microbiología Molecular de La SEM. Granada, 7-9 septiembre (2022), This research was funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”, grants AGL2017-85676-R, AGL2015-63651-P, and PID2020-114330GB-100 and also by PAIDI2020 from Junta de Andalucía, grant P18-RT-1401.

Published
2022

20. Control de la enzima óxido nítrico reductasa de Bradyrhizobium diazoefficiens por el sistema de dos componentes RegSR en respuesta a microoxia

Author

Juárez, R.A., Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Bedmar, Eulogio J., Mesa, Socorro, Delgado Igeño, María Jesús, Ministerio de Economía y Competitividad (España), Junta de Andalucía, and Consejo Superior de Investigaciones Científicas (España)

Abstract

Resumen de la presentación Oral presentada en: 44º Congreso de la Sociedad Española de Bioquímica y Biología Molecular. Málaga, 6-9 Septiembre (2022), Se agradece el apoyo económico de los proyectos AGL2017-85676-R y PID2020-114330GB-100 (cofinanciados por el Ministerio de Economía y Competitividad y FEDER) y el proyecto P18-RT-1401 (Junta de Andalucía). Raquel A Juárez agradece al CSIC la beca JAE-INTRO.

Published
2022

21. Novel enzymes involved in N2O emission by Rhizobium etli - common bean symbiosis

Author

European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Hidalgo-García, Alba, Torres Porras, María Jesús, Tortosa Muñoz, Germán, Pacheco, Pedro J., Gates, Andrew J., Bedmar, Eulogio J., Girard, Lourdes, Delgado Igeño, María Jesús, European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Hidalgo-García, Alba, Torres Porras, María Jesús, Tortosa Muñoz, Germán, Pacheco, Pedro J., Gates, Andrew J., Bedmar, Eulogio J., Girard, Lourdes, and Delgado Igeño, María Jesús

Published
2022

22. El sistema de dos componentes RegSR reprime la expresión de los genes norCBQD en respuesta a microoxia en la bacteria Bradyrhizobium diazoefficiens

Author

Ministerio de Economía y Competitividad (España), European Commission, Junta de Andalucía, Juárez, Raquel A., Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Bedmar, Eulogio J., Mesa, Socorro, Delgado Igeño, María Jesús, Ministerio de Economía y Competitividad (España), European Commission, Junta de Andalucía, Juárez, Raquel A., Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Bedmar, Eulogio J., Mesa, Socorro, and Delgado Igeño, María Jesús

Published
2022

23. Control de la enzima óxido nítrico reductasa de Bradyrhizobium diazoefficiens por el sistema de dos componentes RegSR en respuesta a microoxia.

Author

Ministerio de Economía y Competitividad (España), Junta de Andalucía, Consejo Superior de Investigaciones Científicas (España), Juárez, R.A., Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Bedmar, Eulogio J., Mesa, Socorro, Delgado Igeño, María Jesús, Ministerio de Economía y Competitividad (España), Junta de Andalucía, Consejo Superior de Investigaciones Científicas (España), Juárez, R.A., Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Bedmar, Eulogio J., Mesa, Socorro, and Delgado Igeño, María Jesús

Published
2022

24. Control of nitrous oxide emissions by legume-associated endosymbiotic bacteria

Author

Ministerio de Ciencia e Innovación (España), European Commission, Junta de Andalucía, Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Pacheco, Pedro J., Juárez, R.A., Bedmar, Eulogio J., Mesa, Socorro, Delgado Igeño, María Jesús, Ministerio de Ciencia e Innovación (España), European Commission, Junta de Andalucía, Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Pacheco, Pedro J., Juárez, R.A., Bedmar, Eulogio J., Mesa, Socorro, and Delgado Igeño, María Jesús

Published
2022

25. Efecto del compost de alperujo sobre la nodulación de la simbiosis Soja-Bradyrhizobium diazoefficiens

Author

Tortosa Muñoz, Germán, Amaya-Gómez, Carol V., Jiménez-López, José Carlos, Curaqueo, G., Caro, J., Mesa, Socorro, Delgado Igeño, María Jesús, Bedmar, Eulogio J., Tortosa Muñoz, Germán, Amaya-Gómez, Carol V., Jiménez-López, José Carlos, Curaqueo, G., Caro, J., Mesa, Socorro, Delgado Igeño, María Jesús, and Bedmar, Eulogio J.

Abstract

En este trabajo se estudió el efecto del compost de alperujo sobre la nodulación en la simbiosis leguminosa-rizobio, concretamente entre plantas de soja (Glycine maxL.) y su simbionte natural (Bradyrhizobium diazoefficiens). Para eso, se añadieron varias dosis de compost de alperujo, el principal residuo orgánico de la industria extractiva del aceite de oliva, a plantas de soja cultivadas en condiciones controladas de invernadero durante 4 semanas. Al finalizar el experimento se determinó el peso seco de la biomasa vegetal (parte aérea y raíz), el número y peso fresco de los nódulos aparecidos, así como el contenido en leghemoglobina de los mismos. Los resultados obtenidos sugieren que el compost de alperujo mejora significativamente el crecimiento de las plantas al mejorar la eficiencia simbiótica de la asociación leguminosa-rizobio

Published
2022

26. Application of biostimulant products and biological control agents in sustainable viticulture: A review

Author

Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brasil), Junta de Andalucía, Ministerio de Ciencia e Innovación (España), Jindo, K., Goron, T.L., Pizarro-Tobías, Paloma, Sánchez-Monedero, Miguel Ángel, Audette, Y., Deolu-Ajayi, A.O., van der Werf, A., Goitom Teklu, M., Shenker, M., Pombo Sudré, C., Busato, J.G., Ochoa-Hueso, Raúl, Nocentini, Marco, Rippen, J., Aroca, Ricardo, Mesa, Socorro, Delgado Igeño, María Jesús, Tortosa Muñoz, Germán, Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brasil), Junta de Andalucía, Ministerio de Ciencia e Innovación (España), Jindo, K., Goron, T.L., Pizarro-Tobías, Paloma, Sánchez-Monedero, Miguel Ángel, Audette, Y., Deolu-Ajayi, A.O., van der Werf, A., Goitom Teklu, M., Shenker, M., Pombo Sudré, C., Busato, J.G., Ochoa-Hueso, Raúl, Nocentini, Marco, Rippen, J., Aroca, Ricardo, Mesa, Socorro, Delgado Igeño, María Jesús, and Tortosa Muñoz, Germán

Abstract

Current and continuing climate change in the Anthropocene epoch requires sustainable agricultural practices. Additionally, due to changing consumer preferences, organic approaches to cultivation are gaining popularity. The global market for organic grapes, grape products, and wine is growing. Biostimulant and biocontrol products are often applied in organic vineyards and can reduce the synthetic fertilizer, pesticide, and fungicide requirements of a vineyard. Plant growth promotion following application is also observed under a variety of challenging conditions associated with global warming. This paper reviews different groups of biostimulants and their effects on viticulture, including microorganisms, protein hydrolysates, humic acids, pyrogenic materials, and seaweed extracts. Of special interest are biostimulants with utility in protecting plants against the effects of climate change, including drought and heat stress. While many beneficial effects have been reported following the application of these materials, most studies lack a mechanistic explanation, and important parameters are often undefined (e.g., soil characteristics and nutrient availability). We recommend an increased study of the underlying mechanisms of these products to enable the selection of proper biostimulants, application methods, and dosage in viticulture. A detailed understanding of processes dictating beneficial effects in vineyards following application may allow for biostimulants with increased efficacy, uptake, and sustainability.

Published
2022

27. Molecular mechanism of the Bradyrhizobium diazoefficiens NnrR transcription factor: Influence of heme in NO sensing

Author

European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Torres Porras, María Jesús, Richardson, D.J., Bedmar, Eulogio J., Gates, Andrew J., Delgado Igeño, María Jesús, Mesa, Socorro, European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Torres Porras, María Jesús, Richardson, D.J., Bedmar, Eulogio J., Gates, Andrew J., Delgado Igeño, María Jesús, and Mesa, Socorro

Published
2022

28. Nuevas proteínas implicadas en la producción de NO y N2O por la simbiosis Rhizobium etli-judía

Author

Ministerio de Ciencia e Innovación (España), European Commission, Junta de Andalucía, Hidalgo-García, Alba, Torres Porras, María Jesús, Tortosa Muñoz, Germán, Pacheco, Pedro J., Gates, A., Bedmar, Eulogio J., Girard, Lourdes, Delgado Igeño, María Jesús, Ministerio de Ciencia e Innovación (España), European Commission, Junta de Andalucía, Hidalgo-García, Alba, Torres Porras, María Jesús, Tortosa Muñoz, Germán, Pacheco, Pedro J., Gates, A., Bedmar, Eulogio J., Girard, Lourdes, and Delgado Igeño, María Jesús

Published
2022

29. Efecto del cobre (Cu) en la expresión de genes y proteínas funcionales asociados a la desnitrificación en Bradyrhizobium diazoefficiens

Author

Ministerio de Ciencia e Innovación (España), European Commission, Junta de Andalucía, Pacheco, Pedro J., Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Bedmar, Eulogio J., Mesa, Socorro, Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, Ministerio de Ciencia e Innovación (España), European Commission, Junta de Andalucía, Pacheco, Pedro J., Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Bedmar, Eulogio J., Mesa, Socorro, Tortosa Muñoz, Germán, and Delgado Igeño, María Jesús

Published
2022

30. Análisis transcriptómico de la respuesta de Bradyrhizobium diazoefficiens a la limitación de cobre en condiciones desnitrificantes

Author

Ministerio de Economía y Competitividad (España), European Commission, Junta de Andalucía, Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Pacheco, Pedro J., Juárez, R.A., Bedmar, Eulogio J., Mesa, Socorro, Delgado Igeño, María Jesús, Ministerio de Economía y Competitividad (España), European Commission, Junta de Andalucía, Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Pacheco, Pedro J., Juárez, R.A., Bedmar, Eulogio J., Mesa, Socorro, and Delgado Igeño, María Jesús

Published
2022

31. Determinantes moleculares de la interacción FixK2-ADN implicados en la adaptación de Bradyrhizobium diazoefficiens a sus diferentes modus viven

Author

Ministerio de Economía y Competitividad (España), European Commission, Junta de Andalucía, Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Tomás-Gallardo, Laura, Parejo, Sergio, Juárez, Raquel A., Casado, Sara, Torres Porras, María Jesús, Bedmar, Eulogio J., Delgado Igeño, María Jesús, Mesa, Socorro, Ministerio de Economía y Competitividad (España), European Commission, Junta de Andalucía, Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Tomás-Gallardo, Laura, Parejo, Sergio, Juárez, Raquel A., Casado, Sara, Torres Porras, María Jesús, Bedmar, Eulogio J., Delgado Igeño, María Jesús, and Mesa, Socorro

Published
2022

32. Regulation of the emissions of the greenhouse gas nitrous oxide by the soybean endosymbiont Bradyrhizobium diazoefficiens

Author

Ministerio de Ciencia e Innovación (España), European Commission, Junta de Andalucía, Bueno Romero, Emilio, Mania, D., Mesa, Socorro, Bedmar, Eulogio J., Frostegård, Åsa, Bakken, Lars Reier, Delgado Igeño, María Jesús, Ministerio de Ciencia e Innovación (España), European Commission, Junta de Andalucía, Bueno Romero, Emilio, Mania, D., Mesa, Socorro, Bedmar, Eulogio J., Frostegård, Åsa, Bakken, Lars Reier, and Delgado Igeño, María Jesús

Abstract

The greenhouse gas nitrous oxide (N2O) has strong potential to drive climate change. Soils are a major source of N2O, with microbial nitrification and denitrification being the primary processes involved in such emissions. The soybean endosymbiont Bradyrhizobium diazoefficiens is a model microorganism to study denitrification, a process that depends on a set of reductases, encoded by the napEDABC, nirK, norCBQD, and nosRZDYFLX genes, which sequentially reduce nitrate (NO3) to nitrite (NO2), nitric oxide (NO), N2O, and dinitrogen (N2). In this bacterium, the regulatory network and environmental cues governing the expression of denitrification genes rely on the FixK2 and NnrR transcriptional regulators. To understand the role of FixK2 and NnrR proteins in N2O turnover, we monitored real-time kinetics of NO3, NO2, NO, N2O, N2, and oxygen (O2) in a fixK2 and nnrR mutant using a robotized incubation system. We confirmed that FixK2 and NnrR are regulatory determinants essential for NO3 respiration and N2O reduction. Furthermore, we demonstrated that N2O reduction by B. diazoefficiens is independent of canonical inducers of denitrification, such as the nitrogen oxide NO3, and it is negatively affected by acidic and alkaline conditions. These findings advance the understanding of how specific environmental conditions and two single regulators modulate N2O turnover in B. diazoefficiens.

Published
2022

33. Effect of copper on expression of functional genes and proteins associated with Bradyrhizobium diazoefficiens denitrification

Author

CSIC - Unidad de Recursos de Información Científica para la Investigación (URICI), Pacheco, Pedro J., Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Bedmar, Eulogio J., Mesa, Socorro, Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, CSIC - Unidad de Recursos de Información Científica para la Investigación (URICI), Pacheco, Pedro J., Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Bedmar, Eulogio J., Mesa, Socorro, Tortosa Muñoz, Germán, and Delgado Igeño, María Jesús

Abstract

Nitrous oxide (NO) is a powerful greenhouse gas that contributes to climate change. Denitrification is one of the largest sources of NO in soils. The soybean endosymbiont Bradyrhizobium diazoefficiens is a model for rhizobial denitrification studies since, in addition to fixing N, it has the ability to grow anaerobically under free-living conditions by reducing nitrate from the medium through the complete denitrification pathway. This bacterium contains a periplasmic nitrate reductase (Nap), a copper (Cu)-containing nitrite reductase (NirK), a c-type nitric oxide reductase (cNor), and a Cu-dependent nitrous oxide reductase (Nos) encoded by the napEDABC, nirK, norCBQD and nosRZDFYLX genes, respectively. In this work, an integrated study of the role of Cu in B. diazoefficiens denitrification has been performed. A notable reduction in nirK, nor, and nos gene expression observed under Cu limitation was correlated with a significant decrease in NirK, NorC and NosZ protein levels and activities. Meanwhile, nap expression was not affected by Cu, but a remarkable depletion in Nap activity was found, presumably due to an inhibitory effect of nitrite accumulated under Cu-limiting conditions. Interestingly, a post-transcriptional regulation by increasing Nap and NirK activities, as well as NorC and NosZ protein levels, was observed in response to high Cu. Our results demonstrate, for the first time, the role of Cu in transcriptional and post-transcriptional control of B. diazoefficiens denitrification. Thus, this study will contribute by proposing useful strategies for reducing NO emissions from agricultural soils.

Published
2022

34. The carbon regulator PhaR exerts a pleiotropic control in Bradyrhizobium diazoefficiens

Author

European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Consejo Superior de Investigaciones Científicas (España), Díaz-Peña, R., Cabrera Rodríguez, Juan José, Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, Mongiardini, E., Müller-Santos, M., Pettinari, J., Mesa, Socorro, Quelas, J.I., European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Consejo Superior de Investigaciones Científicas (España), Díaz-Peña, R., Cabrera Rodríguez, Juan José, Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, Mongiardini, E., Müller-Santos, M., Pettinari, J., Mesa, Socorro, and Quelas, J.I.

Published
2022

35. Nuevas proteínas implicadas en la producción de NO y N2O por la simbiosis Rhizobium etli-judía

Author

Hidalgo-García, Alba, Torres Porras, María Jesús, Tortosa, Germán, Pacheco, Pedro J., Gates, A., Bedmar, Eulogio J., Girard, Lourdes, Delgado Igeño, María Jesús, Ministerio de Ciencia e Innovación (España), European Commission, and Junta de Andalucía

Abstract

Este trabajo ha sido financiado por el proyecto AGL2017-85676-R, del MCIN/AEI/10.13039/501100011033 y “ERDF A way of making Europe” y el Proyecto P18-RT-1401 de la Junta de Andalucia.

Published
2022

36. Determinantes moleculares de la interacción FixK2-ADN implicados en la adaptación de Bradyrhizobium diazoefficiens a sus diferentes modus viven

Author

Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Tomás-Gallardo, Laura, Parejo, Sergio, Juárez, Raquel, Casado, Sara, Torres Porras, María Jesús, Bedmar, Eulogio J., Delgado Igeño, María Jesús, Mesa, Socorro, Ministerio de Economía y Competitividad (España), European Commission, and Junta de Andalucía

Abstract

Resumen del poster presentado en: XV Reunión Nacional del Metabolismo del Nitrógeno. Córdoba, 2-4 febrero (2022), Se agradece el apoyo económico de los proyectos AGL2017-85676-R y PID2020-114330GB100 (cofinanciados por el Ministerio de Economía y Competitividad y FEDER) y los proyectos P12-AGR-1968 y P18-RT-1401 (Junta de Andalucía).

Published
2022

37. Efecto del cobre (Cu) en la expresión de genes y proteínas funcionales asociados a la desnitrificación en Bradyrhizobium diazoefficiens

Author

Pacheco, Pedro J., Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Bedmar, Eulogio J., Mesa, Socorro, Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, Ministerio de Ciencia e Innovación (España), European Commission, and Junta de Andalucía

Abstract

Resumen de la comunicación oral presentada en: XV Reunión Nacional del Metabolismo del Nitrógeno. Córdoba, 2-4 febrero (2022), Este trabajo ha sido financiado por los proyectos AGL2017-85676-R, AGL2015- 63651-P y PID2020-114330GB-100 del MCIN/AEI/ 10.13039/501100011033 y “ERDF A way of making Europe”, y el Proyecto P18-RT-1401 de la Junta de Andalucía. P.J.P es beneficiario de un contrato FPU del Ministerio de Universidades(MIU).

Published
2022

38. Copper involvement in Bradyrhizobium diazoefficiens denitrification

Author

Pacheco, Pedro J., Cabrera, Juan J., Mesa, Socorro, Bedmar, Eulogio J., Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, European Commission, Ministerio de Ciencia e Innovación (España), and Junta de Andalucía

Abstract

Resumen del poster presentado en: The 14th European Nitrogen Fixation Conference. Aarhus University, Dinamarca del 22 septiembre al 22 Octubre (2021), This work was funded by ERDF co-financed grants AGL2O1 7-85676-R and AGL2OI 5-6365 1 -P from Ministerio de Ciencia e Innovación and P18-RT-1401 from Junta de Andalucía. PJP is supported by a FPU fellowship from MCIU (formerly MECD).

Published
2021

39. Identification of new Rhizobium etli enzymes involved in nitric oxide (NO) and nitrous oxide (N2O) emission by common bean nodules

Author

Hidalgo-García, Alba, Torres, M.J., Tortosa Muñoz, Germán, Pacheco, Pedro J., Bedmar, Eulogio J., Girard, L., Delgado Igeño, María Jesús, European Commission, Ministerio de Ciencia e Innovación (España), and Junta de Andalucía

Abstract

Resumen de la comunicación oral presentada en: 8th Plant Nitric Oxide International Meeting. Celebrado en Hungria Szeged. 7-9 Julio 2021, This work was supported by Fondo Europeo de Desarrollo Regional (FEDER)-co-financed grant AGL2017-85676-R from the Ministerio de Ciencia e Innovación (Spain). Grant P18-RT-1401 from the Junta de Andalucía is also acknowledged.

Published
2021

40. Bacterial nitric oxide metabolism: Recent insights in rhizobia

Author

European Commission, Ministerio de Economía y Competitividad (España), Junta de Andalucía, Salas Huertas, Ana, Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Mesa, Socorro, Bedmar, Eulogio J., Richardson, E.J., Gates, E.J., Delgado Igeño, María Jesús, European Commission, Ministerio de Economía y Competitividad (España), Junta de Andalucía, Salas Huertas, Ana, Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Mesa, Socorro, Bedmar, Eulogio J., Richardson, E.J., Gates, E.J., and Delgado Igeño, María Jesús

Published
2021

41. Identification of new Rhizobium etli enzymes involved in nitric oxide (NO) and nitrous oxide (N2O) emission by common bean nodules.

Author

European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Hidalgo-García, Alba, Torres, M.J., Tortosa Muñoz, Germán, Pacheco, Pedro J., Bedmar, Eulogio J., Girard, Lourdes, Delgado Igeño, María Jesús, European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Hidalgo-García, Alba, Torres, M.J., Tortosa Muñoz, Germán, Pacheco, Pedro J., Bedmar, Eulogio J., Girard, Lourdes, and Delgado Igeño, María Jesús

Published
2021

42. Dissection of fixk2 protein-DNA interaction unveils new insights into Bradyrhizobium diazoefficiens lifestyles control

Author

European Commission, Ministerio de Economía y Competitividad (España), Junta de Andalucía, Cabrera, Juan J., Jiménez-Leiva, Andrea, Tomás-Gallardo, Laura, Parejo, Sergio, Casado, Sara, Torres Porras, María Jesús, Bedmar, Eulogio J., Delgado Igeño, María Jesús, Mesa, Socorro, European Commission, Ministerio de Economía y Competitividad (España), Junta de Andalucía, Cabrera, Juan J., Jiménez-Leiva, Andrea, Tomás-Gallardo, Laura, Parejo, Sergio, Casado, Sara, Torres Porras, María Jesús, Bedmar, Eulogio J., Delgado Igeño, María Jesús, and Mesa, Socorro

Published
2021

43. Copper involvement in Bradyrhizobium diazoefficiens denitrification

Author

European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Pacheco, Pedro J., Cabrera, Juan J., Mesa, Socorro, Bedmar, Eulogio J., Tortosa Muñoz, Germán, Delgado Igeño, María Jesús, European Commission, Ministerio de Ciencia e Innovación (España), Junta de Andalucía, Pacheco, Pedro J., Cabrera, Juan J., Mesa, Socorro, Bedmar, Eulogio J., Tortosa Muñoz, Germán, and Delgado Igeño, María Jesús

Published
2021

44. Reduction of N2O emissions through modulation of activity of the Bradyrhizobium diazoefficiens NnrR regulator

Author

Ministerio de Economía y Competitividad (España), European Commission, Biotechnology and Biological Sciences Research Council (UK), Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Richardson, David J., Bedmar, Eulogio J., Delgado Igeño, María Jesús, Mesa, Socorro, Gates, Andrew J., Ministerio de Economía y Competitividad (España), European Commission, Biotechnology and Biological Sciences Research Council (UK), Cabrera Rodríguez, Juan José, Jiménez-Leiva, Andrea, Richardson, David J., Bedmar, Eulogio J., Delgado Igeño, María Jesús, Mesa, Socorro, and Gates, Andrew J.

Published
2021

45. Molecular mechanism of NO sensing by the Bradyrhizobium diazoefficiens NnrR transcriptional regulator

Author

European Commission, Ministerio de Economía y Competitividad (España), Junta de Andalucía, Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Torres Porras, María Jesús, Richardson, D.J., Bedmar, Eulogio J., Gates, Andrew J., Delgado Igeño, María Jesús, Mesa, Socorro, European Commission, Ministerio de Economía y Competitividad (España), Junta de Andalucía, Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Torres Porras, María Jesús, Richardson, D.J., Bedmar, Eulogio J., Gates, Andrew J., Delgado Igeño, María Jesús, and Mesa, Socorro

Published
2021

47. The Hemoglobin Bjgb From Bradyrhizobium diazoefficiens Controls NO Homeostasis in Soybean Nodules to Protect Symbiotic Nitrogen Fixation

Author

European Commission, Ministerio de Economía y Competitividad (España), Junta de Andalucía, Ministerio de Educación, Cultura y Deporte (España), Ministerio de Ciencia e Innovación (España), Delgado Huertas, Antonio [0000-0002-7240-1570], Salas Huertas, Ana, Tortosa Muñoz, Germán, Hidalgo-García, Alba, Delgado Huertas, Antonio, Bedmar, Eulogio J., Richardson, David J., Gates, Andrew J., Delgado Igeño, María Jesús, European Commission, Ministerio de Economía y Competitividad (España), Junta de Andalucía, Ministerio de Educación, Cultura y Deporte (España), Ministerio de Ciencia e Innovación (España), Delgado Huertas, Antonio [0000-0002-7240-1570], Salas Huertas, Ana, Tortosa Muñoz, Germán, Hidalgo-García, Alba, Delgado Huertas, Antonio, Bedmar, Eulogio J., Richardson, David J., Gates, Andrew J., and Delgado Igeño, María Jesús

Abstract

Legume-rhizobia symbiotic associations have beneficial effects on food security and nutrition, health and climate change. Hypoxia induced by flooding produces nitric oxide (NO) in nodules from soybean plants cultivated in nitrate-containing soils. As NO is a strong inhibitor of nitrogenase expression and activity, this negatively impacts symbiotic nitrogen fixation in soybean and limits crop production. In Bradyrhizobium diazoefficiens, denitrification is the main process involved in NO formation by soybean flooded nodules. In addition to denitrification, nitrate assimilation is another source of NO in free-living B. diazoefficiens cells and a single domain hemoglobin (Bjgb) has been shown to have a role in NO detoxification during nitrate-dependent growth. However, the involvement of Bjgb in protecting nitrogenase against NO in soybean nodules remains unclear. In this work, we have investigated the effect of inoculation of soybean plants with a bjgb mutant on biological nitrogen fixation. By analyzing the proportion of N in shoots derived from N2-fixation using the 15N isotope dilution technique, we found that plants inoculated with the bjgb mutant strain had higher tolerance to flooding than those inoculated with the parental strain. Similarly, reduction of nitrogenase activity and nifH expression by flooding was less pronounced in bjgb than in WT nodules. These beneficial effects are probably due to the reduction of NO accumulation in bjgb flooded nodules compared to the wild-type nodules. This decrease is caused by an induction of expression and activity of the denitrifying NO reductase enzyme in bjgb bacteroids. As bjgb deficiency promotes NO-tolerance, the negative effect of NO on nitrogenase is partially prevented and thus demonstrates that inoculation of soybean plants with the B. diazoefficiens bjgb mutant confers protection of symbiotic nitrogen fixation during flooding.

Published
2020

48. Bradyrhizobium diazoefficiens; NtrYX two component regulatory system; Soybean nodulation; Nitrogen fixation; Cytochrome cbb3 oxidase

Author

López, M. F., Hegel, V.A., Torres Porras, María Jesús, Hidalgo-García, Alba, Delgado Igeño, María Jesús, López-García, S. L., Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina), Ministerio de Economía y Competitividad (España), Junta de Andalucía, European Commission, and Universidad Nacional de Mar del Plata

Subjects
Nitrogen fixation, NtrYX two component regulatory system, Cytochrome cbb3 oxidase, Soybean nodulation, food and beverages, Bradyrhizobiumdiazo efficiens
Abstract

Aims: Bradyrhizobium diazoefficiens is a soil bacterium capable of establishing nitrogen-fixing symbiosis with soybean plants, an important crop for food production worldwide. This interaction is under the control of several regulatory factors that affect the bacterial efficiency to nodulate legume plants and fix nitrogen within root nodules. To date, the function of the NtrYX two-component system in B. diazoefficiens remains unclear. In this work, we investigated the role of NtrY in the symbiotic interaction of B. diazoefficiens with soybean plants. Methods: We constructed a non-polar mutant of the sensor protein NtrY of the system, and then analysed the symbiosis of this mutant with soybean plants. Results: We found that the ntrY mutant was defective in plant dry weight, nitrogen content and nitrogenase activity. Haem c-staining of cbb3 oxidase components showed a clear reduction in the expression of this terminal oxidase in ntrY bacteroids with respect to wild type bacteroids. Such defect in cbb3 expression correlated with a decreased respiratory capacity of the bacteroids produced by the ntrY mutant. Conclusions: These results suggest that the role of B. diazoefficiens NtrYX in symbiotic nitrogen fixation might be a consequence of its involvement in cbb3 oxidase expression in bacteroids., This work was supported by the Agencia Nacional de Promoción de la Investigación Científica y Tecnológica (ANPCyT; project PICT 2013–2864), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Secyt-UNLP, Argentina. MJD received financial support from the European Regional Development Fund (ERDF), cofinanced grants AGL2013–45087-R and AGL2017–85676-R from the Ministerio de Economía y Competitividad (Spain) and PE2012-AGR1968 from the Junta de Andalucía. MFL was supported by fellowships from CONICETand by a travel grant from Secyt-UNLP. VAH was supported by a fellowship from CONICET. SLG is researcher at CONICET.

Published
2019

49. Expanding the regulon of the bradyrhizobium diazoefficiens NnrR transcription factor: New insights into the denitrification pathway

Author

Ministerio de Economía y Competitividad (España), Agencia Estatal de Investigación (España), Junta de Andalucía, Consejo Superior de Investigaciones Científicas (España), Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Bueno Romero, Emilio, Torres Porras, María Jesús, Salazar Iglesias, Sergio, Bedmar, Eulogio J., Delgado Igeño, María Jesús, Mesa, Socorro, Ministerio de Economía y Competitividad (España), Agencia Estatal de Investigación (España), Junta de Andalucía, Consejo Superior de Investigaciones Científicas (España), Jiménez-Leiva, Andrea, Cabrera Rodríguez, Juan José, Bueno Romero, Emilio, Torres Porras, María Jesús, Salazar Iglesias, Sergio, Bedmar, Eulogio J., Delgado Igeño, María Jesús, and Mesa, Socorro

Abstract

Denitrification in the soybean endosymbiont Bradyrhizobium diazoefficiens is controlled by a complex regulatory network composed of two hierarchical cascades, FixLJ-FixK-NnrR and RegSR-NifA. In the former cascade, the CRP/FNR-type transcription factors FixK and NnrR exert disparate control on expression of core denitrifying systems encoded by napEDABC, nirK, norCBQD, and nosRZDFYLX genes in response to microoxia and nitrogen oxides, respectively. To identify additional genes controlled by NnrR and involved in the denitrification process in B. diazoefficiens, we compared the transcriptional profile of an nnrR mutant with that of the wild type, both grown under anoxic denitrifying conditions. This approach revealed more than 170 genes were simultaneously induced in the wild type and under the positive control of NnrR. Among them, we found the cycA gene which codes for the c soluble cytochrome (CycA), previously identified as an intermediate electron donor between the bc complex and the denitrifying nitrite reductase NirK. Here, we demonstrated that CycA is also required for nitrous oxide reductase activity. However, mutation in cycA neither affected nosZ gene expression nor NosZ protein steady-state levels. Furthermore, cycA, nnrR and its proximal divergently oriented nnrS gene, are direct targets for FixK as determined by in vitro transcription activation assays. The dependence of cycA expression on FixK and NnrR in anoxic denitrifying conditions was validated at transcriptional level, determined by quantitative reverse transcription PCR, and at the level of protein by performing heme c-staining of soluble cytochromes. Thus, this study expands the regulon of NnrR and demonstrates the role of CycA in the activity of the nitrous oxide reductase, the key enzyme for nitrous oxide mitigation.

Published
2019

50. Bradyrhizobium diazoefficiens; NtrYX two component regulatory system; Soybean nodulation; Nitrogen fixation; Cytochrome cbb3 oxidase

Author

Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina), Ministerio de Economía y Competitividad (España), Junta de Andalucía, European Commission, Universidad Nacional de Mar del Plata, López, M. F., Hegel, V.A., Torres Porras, María Jesús, Hidalgo-García, Alba, Delgado Igeño, María Jesús, López-García, S. L., Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina), Ministerio de Economía y Competitividad (España), Junta de Andalucía, European Commission, Universidad Nacional de Mar del Plata, López, M. F., Hegel, V.A., Torres Porras, María Jesús, Hidalgo-García, Alba, Delgado Igeño, María Jesús, and López-García, S. L.

Abstract

Aims: Bradyrhizobium diazoefficiens is a soil bacterium capable of establishing nitrogen-fixing symbiosis with soybean plants, an important crop for food production worldwide. This interaction is under the control of several regulatory factors that affect the bacterial efficiency to nodulate legume plants and fix nitrogen within root nodules. To date, the function of the NtrYX two-component system in B. diazoefficiens remains unclear. In this work, we investigated the role of NtrY in the symbiotic interaction of B. diazoefficiens with soybean plants. Methods: We constructed a non-polar mutant of the sensor protein NtrY of the system, and then analysed the symbiosis of this mutant with soybean plants. Results: We found that the ntrY mutant was defective in plant dry weight, nitrogen content and nitrogenase activity. Haem c-staining of cbb3 oxidase components showed a clear reduction in the expression of this terminal oxidase in ntrY bacteroids with respect to wild type bacteroids. Such defect in cbb3 expression correlated with a decreased respiratory capacity of the bacteroids produced by the ntrY mutant. Conclusions: These results suggest that the role of B. diazoefficiens NtrYX in symbiotic nitrogen fixation might be a consequence of its involvement in cbb3 oxidase expression in bacteroids.

Published
2019

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