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Iturralde ET, Stocco MC, Faura A, Mónaco CI, Cordo C, Pérez-Giménez J, Lodeiro AR. Coinoculation of soybean plants with Bradyrhizobium japonicum and Trichoderma harzianum: Coexistence of both microbes and relief of nitrate inhibition of nodulation. ACTA ACUST UNITED AC 2020; 26:e00461. [PMID: 32420051 PMCID: PMC7218258 DOI: 10.1016/j.btre.2020.e00461] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 04/15/2020] [Accepted: 04/22/2020] [Indexed: 12/18/2022]
Abstract
Bradyrhizobium japonicum and Trichoderma harzianum coexisted in soybean rhizosphere. Soybean inoculated with both microbes nodulated with high nitrate concentrations. T. harzianum produced auxins in culture medium. Auxins applied with B. japonicum alone relieved nitrate inhibition of nodulation.
Coinoculation of plants with mixtures of beneficial microbes sometimes produces synergistic effects. In this study, the effect of soybean coinoculation with the N2-fixing Bradyrhizobium japonicum E109 and the biocontrol fungus Trichoderma harzianum Th5cc was analyzed. Nodulation by E109 was not hampered by Th5cc, which antagonized five out of seven soybean pathogens tested. Furthermore, Th5cc relieved nitrate-inhibition of nodulation, enabling the formation of nodules containing infected cells with bacteroids in the presence of the otherwise inhibitory 10 mM KNO3. Th5cc released micromolar amounts of auxin, and addition of 11 μM indoleacetic acid to soybean plants inoculated with E109 in the absence of Th5cc also induced nodulation in the presence of 10 mM KNO3. Thus, Th5cc may release auxins into the soybean rhizosphere, which hormones might participate in overcoming the nitrate-inhibition of nodulation. Our results suggest that soybean plants coinoculated with these microorganisms might benefit from biocontrol while contributing to soil-nitrogen preservation.
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Key Words
- AG, arabinose-gluconate medium
- Bradyrhizobium
- CFU, colony-forming units
- CR, Congo Red
- Coinoculation
- DAI, days after inoculation
- IAA, indoleacetic acid
- LPCB, lactophenol cotton blue
- MFS, modified Fåhræus solution
- Nitrate
- PDA, potato-dextrose agar
- PGPM, plant-growth promoting microbe
- Soybean
- Trichoderma
- YM, yeast-extract mannitol medium
- YMA, YM with 1.5 % (w/v) agar
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Affiliation(s)
- Esteban Tomás Iturralde
- Laboratorio de Interacciones entre Rizobios y Soja (Lirys), IBBM CCT-La Plata CONICET and Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115 (1900), La Plata, Argentina
| | - Marina Celeste Stocco
- CIDEFI, CIC-PBA and Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata, Calles 60 y 119 (1900), La Plata, Argentina
| | - Andrés Faura
- Rizobacter Argentina SA, Avda. Dr. Arturo Frondizi 1150, Parque Industrial (2700), Pergamino, Argentina
| | - Cecilia Inés Mónaco
- CIDEFI, CIC-PBA and Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata, Calles 60 y 119 (1900), La Plata, Argentina
| | - Cristina Cordo
- CIDEFI, CIC-PBA and Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata, Calles 60 y 119 (1900), La Plata, Argentina
| | - Julieta Pérez-Giménez
- Laboratorio de Interacciones entre Rizobios y Soja (Lirys), IBBM CCT-La Plata CONICET and Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115 (1900), La Plata, Argentina
| | - Aníbal Roberto Lodeiro
- Laboratorio de Interacciones entre Rizobios y Soja (Lirys), IBBM CCT-La Plata CONICET and Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115 (1900), La Plata, Argentina.,Laboratorio de Genética, Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata, Calles 60 y 119 (1900), La Plata, Argentina
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