Expression of an exogenous 1-aminocyclopropane-1-carboxylate deaminase gene in Mesorhizobium spp. reduces the negative effects of salt stress in chickpea

Authors

  • Clarisse Brígido,

    1. Laboratório de Microbiologia do Solo, ICAAM, Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Universidade de Évora, Núcleo da Mitra, Évora, Portugal
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  • Francisco X. Nascimento,

    1. Laboratório de Microbiologia do Solo, ICAAM, Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Universidade de Évora, Núcleo da Mitra, Évora, Portugal
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  • Jin Duan,

    1. Department of Biology, University of Waterloo, Waterloo, ON, Canada
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  • Bernard R. Glick,

    1. Department of Biology, University of Waterloo, Waterloo, ON, Canada
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  • Solange Oliveira

    Corresponding author
    1. Laboratório de Microbiologia do Solo, ICAAM, Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Universidade de Évora, Núcleo da Mitra, Évora, Portugal
    • Correspondence: Solange Oliveira, Departamento de Biologia, Universidade de Évora, Apartado 94, 7002-554 Évora, Portugal. Tel.: 351266760878;

      fax: 351266760913; e-mail: ismo@uevora.pt

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Abstract

Our goal was to study the symbiotic performance of two Mesorhizobium ciceri strains, transformed with an exogenous 1-aminocyclopropane-1-carboxylate deaminase gene (acdS), in chickpea plants under salinity stress. The EE-7 (salt-sensitive) and G-55 (salt-tolerant) M. ciceri strains were transformed with an acdS gene present on plasmid pRKACC. Salinity significantly reduced the overall growth of plants inoculated with either wild-type strains. Although the growth of plants inoculated with either salt-sensitive or salt-tolerant strain was reduced under salinity, the salt-tolerant strain showed a higher ability to nodulate chickpea under salt stress compared with the salt-sensitive strain. The shoot dry weight was significantly higher in plants inoculated with the acdS-transformed salt-sensitive strain compared with the plants inoculated with the native strain in the presence of salt. The negative effects of salt stress were also reduced in nodulation when using acdS-transformed strains in comparison with the wild-type strains. Interestingly, by expressing the exogenous acdS gene, the salt-sensitive strain was able to induce nodules in the same extent as the salt-tolerant strain. Although preliminary, these results suggest that genetic modification of a Mesorhizobium strain can improve its symbiotic performance under salt stress and indicate that ACC deaminase can play an important role in facilitating plant–rhizobium interaction under salinity conditions.

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