title: Expression of an exogenous 1-aminocyclopropane-1-carboxylate deaminase gene in Mesorhizobium spp. reduces the negative effects of salt stress in chickpea.
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.
authors.affiliation: Laboratório de Microbiologia do Solo, ICAAM, Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Universidade de Évora, Núcleo da Mitra, Évora, Portugal.
authors.forename: Clarisse
authors.initials: C
authors.lastname: Brígido
authors.forename: Francisco X
authors.initials: FX
authors.lastname: Nascimento
authors.forename: Jin
authors.initials: J
authors.lastname: Duan
authors.forename: Bernard R
authors.initials: BR
authors.lastname: Glick
authors.forename: Solange
authors.initials: S
authors.lastname: Oliveira
mesh_terms: D019755:Carbon-Carbon Lyases / Q000235:genetics*; D029863:Cicer / Q000187:drug effects* / Q000254:growth & development / Q000382:microbiology*; D015964:Gene Expression Regulation, Bacterial; D059128:Mesorhizobium / Q000235:genetics*; D012492:Salts / Q000633:toxicity*; D013312:Stress, Physiological
chemical_list: D012492:Salts; C033634:1-aminocyclopropane-1-carboxylate deaminase; D019755:Carbon-Carbon Lyases
keywords: ACC deaminase; mesorhizobia; salinity; stress tolerance; symbiosis