A native Glomus intraradices strain from a Mediterranean saline area exhibits salt tolerance and enhanced symbiotic effi
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A native Glomus intraradices strain from a Mediterranean saline area exhibits salt tolerance and enhanced symbiotic efficiency with maize plants under salt stress conditions Beatriz Estrada & José Miguel Barea & Ricardo Aroca & Juan Manuel Ruiz-Lozano
Received: 16 May 2012 / Accepted: 20 July 2012 / Published online: 6 September 2012 # Springer Science+Business Media B.V. 2012
Abstract Aims Arbuscular mycorrhizal (AM) fungi have been shown to occur naturally in saline environments and it has been suggested that differences in fungal behaviour and efficiency can be due to the origin and adaptation of the AM fungus. These findings invite to look out for AM fungal species isolated in saline environments and compare their salt-tolerance mechanisms with those of species living in non-saline areas. Methods A fungal strain of G. intraradices (Gi CdG) isolated from a region with serious problems of salinity and affected by desertification, has been compared with a collection strain of the same species, used as a model fungus. An in vitro experiment tested the ability of both AM fungi to grow under increasing salinity and an in vivo experiment compared their symbiotic efficiency with maize plants grown under salt stress conditions. Results The isolate Gi CdG developed better under saline conditions and induced considerably the expression of GintBIP, Gint14-3-3 and GintAQP1 genes, while it showed a lower induction of GintSOD1 gene
than the collection G. intraradices strain. The isolate Gi CdG also stimulated the growth of maize plants under two levels of salinity more than the collection strain. The higher symbiotic efficiency of Gi CdG was corroborated by the enhanced efficiency of photosystem II and stomatal conductance and the lower electrolyte leakage exhibited by maize plants under the different conditions assayed. Conclusions The higher tolerance to salinity and symbiotic efficiency exhibited by strain Gi CdG as compared to the collection G. intraradices strain may be due to a fungal adaptation to saline environments. Such adaptation may be related to the significant upregulation of genes encoding chaperones or genes encoding aquaporins. The present study remarks that AM fungi isolated from areas affected by salinity can be a powerful tool to enhance the tolerance of crops to saline stress conditions.
Responsible Editor: Hans Lambers.
Introduction
B. Estrada : J. M. Barea : R. Aroca : J. M. Ruiz-Lozano (*) Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín (CSIC), Profesor Albareda nº 1, 18008 Granada, Spain e-mail: [email protected]
Keywords Adaptation . Arbuscular mycorrhiza . Monoxenic culture . Salinity . Symbiotic efficiency
Soil salinity exists naturally on Earth, but inadequate cultivation practices, mainly due to excess irrigation (Zhu 2001; Tester and Davenport 2003; Flowers 2004) have also exacerbated growing concentration of salts in the rhizosphere (Mahajan and Tuteja 2005). This is
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a major concern in some parts of the wor
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