A proteomics approach to study the molecular basis of enhanced salt tolerance in barley (Hordeum vulgare L.) conferred by the root mutualistic fungus Piriformospora indica

Abstract

Piriformospora indica is a root-interacting mutualistic fungus capable of enhancing plant growth, increasing plant resistance to a wide variety of pathogens, and improving plant stress tolerance under extreme environmental conditions. Understanding the molecular mechanisms by which P. indica can improve plant tolerance to stresses will pave the way to identifying the major mechanisms underlying plant adaptability to environmental stresses. We conducted greenhouse experiments at three different salt levels (0, 100 and 300 mM NaCl) on barley (Hordeum vulgare L.) cultivar "Pallas" inoculated with P. indica. Based on the analysis of variance, P. indica had a significant impact on the barley growth and shoot biomass under normal and salt stress conditions. P. indica modulated ion accumulation in colonized plants by increasing the foliar potassium (K(+))/sodium (Na(+)) ratio, as it is considered a reliable indicator of salt stress tolerance. P. indica induced calcium (Ca(2+)) accumulation and likely influenced the stress signal transduction. Subsequently, proteomic analysis of the barley leaf sheath using two-dimensional electrophoresis resulted in detection of 968 protein spots. Of these detected spots, the abundance of 72 protein spots changed significantly in response to salt treatment and P. indica-root colonization. Mass spectrometry analysis of responsive proteins led to the identification of 51 proteins. These proteins belonged to different functional categories including photosynthesis, cell antioxidant defense, protein translation and degradation, energy production, signal transduction and cell wall arrangement. Our results showed that P. indica induced a systemic response to salt stress by altering the physiological and proteome responses of the plant host.

The proteome response of “Hordeum marinum” to long-term salinity stress

“…Also, enhanced expression in all ribosomal proteins was observed during salinity in genotypes of cultivated barley (Fatehi et al 2012a). An increase in the expression of ribosomal protein P1 was reported in H. vulgare cultivar "Pallas" under severe salt treatment as well (Alikhani et al 2013).…”

The endophytic fungus Piriformospora indica protects wheat from fusarium crown rot disease in simulated UK autumn conditions

“…Also in tomato, P. indica reduced the concentration of Pepino mosaic virus in shoots (Fakhro et al ., ) . Piriformospora indica also increased plant tolerance to abiotic stresses including salt stress in barley (Baltruschat et al ., ; Alikhani et al ., ), wheat (Zarea et al ., ) and tomato (Cruz et al ., ). The fungus conferred drought tolerance in Chinese cabbage and enhanced seed production and grain yield (Sun et al ., ; Michal Johnson et al ., ).…”

Sustained exposure to abscisic acid enhances the colonization potential of the mutualist fungus Piriformospora indica on Arabidopsis thaliana roots

“…The ability of P. indica to improve plant tolerance to abiotic stress has been reported for several plant species (Waller et al, 2005;Baltruschat et al, 2008;Sherameti et al, 2008a;Sun et al, 2010;Alikhani et al, 2013;Ghabooli et al, 2013); however, the basis of this phenomenon is not clear. In all previous studies, plants have been exposed to stress after being precultivated with P. indica for several weeks and probably have acquired benefits from mutualism before stress treatment.…”