How does arbuscular mycorrhizal symbiosis regulate root hydraulic properties and plasma membrane aquaporins in Phaseolus vulgaris under drought, cold or salinity stresses? New Phytol

Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, C/Profesor Alabareda 1, 18008, Granada, Spain.
New Phytologist (Impact Factor: 7.67). 02/2007; 173(4):808-16. DOI: 10.1111/j.1469-8137.2006.01961.x
Source: PubMed


Here, we evaluated how the arbuscular mycorrhizal (AM) symbiosis regulates root hydraulic properties and root plasma membrane aquaporins (PIP) under different stresses sharing a common osmotic component. Phaseolus vulgaris plants were inoculated or not with the AM fungus Glomus intraradices, and subjected to drought, cold or salinity. Stress effects on root hydraulic conductance (L), PIP gene expression and protein abundance were evaluated. Under control conditions, L in AM plants was about half that in nonAM plants. However, L was decreased as a result of the three stresses in nonAM plants, while it was almost unchanged in AM plants. At the same time, PIP2 protein abundance and phosphorylation state presented the same trend as L. Finally, the expression of each PIP gene responded differently to each stress and was dependent on the AM fungal presence. Differential expression of the PIP genes studied under each stress depending on the AM fungal presence may indicate a specific function and regulation by the AM symbiosis of each gene under the specific conditions of each stress tested.

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Available from: Juan Manuel Ruiz-Lozano, Oct 29, 2014
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    • "In general, plants supply associated AM fungi with carbohydrates, and in return, fungi provide soil phosphorus (P) and possibly nitrogen (N) to their host plants (Hodge et al., 2010; Selosse and Rousset, 2011). Mycorrhizal symbioses can also provide plants with other benefits such as protection against root pathogens (Lewandowski et al., 2013) and several types of abiotic stress (Aroca et al., 2007). Furthermore, increasing evidence shows that mycorrhizas influence the structure of plant communities (Klironomos et al., 2011; Yang et al., 2014), the rhizosphere microbiome (Vestergård et al., 2008; Veresoglou et al., 2012), soil structure (van der Heijden et al., 2006; Leifheit et al., 2015), and nutrient cycles (Cheng et al., 2012; Bender et al., 2015). "
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    ABSTRACT: Understanding the underlying mechanisms driving responses of belowground communities to increasing soil fertility will facilitate predictions of ecosystem responses to anthropogenic eutrophication of terrestrial systems. We studied the impact of fertilization of an alpine meadow on arbuscular mycorrhizal (AM) fungi, a group of root-associated microorganisms that are important in maintaining sustainable ecosystems. Species and phylogenetic composition of AM fungal communities in soils were compared across a soil fertility gradient generated by 8 years of combined nitrogen and phosphorus fertilization. Phylogenetic patterns were used to infer the ecological processes structuring the fungal communities. We identified 37 AM fungal virtual taxa, mostly in the genus Glomus. High fertilizer treatments caused a dramatic loss of Glomus species, but a significant increase in genus richness and a shift towards dominance of the lineage of Diversispora. AM fungal communities were phylogenetically clustered in unfertilized soil, random in the low fertilizer treatment and over-dispersed in the high fertilizer treatments, suggesting that the primary ecological process structuring communities shifted from environmental filtering (selection by host plants and fungal niches) to a stochastic process and finally to competitive exclusion across the fertilization gradient. Our findings elucidate the community shifts associated with increased soil fertility, and suggest that high fertilizer inputs may change the dominant ecological processes responsible for the assembly of AM fungal communities towards increased competition as photosynthate from host plants becomes an increasingly limited resource.
    Soil Biology and Biochemistry 10/2015; 89:196-205. DOI:10.1016/j.soilbio.2015.07.007 · 3.93 Impact Factor
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    • "This decrease is proposed to be attributed to either lowered PIP aquaporin activity or reduced abundance (Bhardwaj et al., 2013; Martinez-Ballest and Carvajal, 2014). In agreement with the aquaporin role in salt tolerance is the finding that mycorrhizal plants showed alleviated salt deleterious effects (Aroca et al., 2007; Evlin et al., 2009). Enhancement of tolerance to salinity in mycorrhizal plants was linked to root aquaporin upregulation in response to salt stress. "

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    • "The remaining three groups were subjected to the following treatments: (1) 24 °C and 60 % field capacity for 1 week (drought stress), (2) 4 °C for 72 h (cold stress), and (3) 24 °C and soil irrigated with 200 mM NaCl for 2 weeks (salt stress). The duration and levels of stress imposed were based on bibliographical references to these stresses (Pedranzani et al. 2005; Aroca et al. 2007; Di Giambatista et al. 2010; Garbero et al. 2010, 2012). "
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    ABSTRACT: This study evaluates antioxidant responses and jasmonate regulation in Digitaria eriantha cv. Sudafricana plants inoculated (AM) and non-inoculated (non-AM) with Rhizophagus irregularis and subjected to drought, cold, or salinity. Stomatal conductance, photosynthetic efficiency, biomass production, hydrogen peroxide accumulation, lipid peroxidation, antioxidants enzymes activities, and jasmonate levels were determined. Stomatal conductance and photosynthetic efficiency decreased in AM and non-AM plants under all stress conditions. However, AM plants subjected to drought, salinity, or non-stress conditions showed significantly higher stomatal conductance values. AM plants subjected to drought or non-stress conditions increased their shoot/root biomass ratios, whereas salinity and cold caused a decrease in these ratios. Hydrogen peroxide accumulation, which was high in non-AM plant roots under all treatments, increased significantly in non-AM plant shoots under cold stress and in AM plants under non-stress and drought conditions. Lipid peroxidation increased in the roots of all plants under drought conditions. In shoots, although lipid peroxidation decreased in AM plants under non-stress and cold conditions, it increased under drought and salinity. AM plants consistently showed high catalase (CAT) and ascorbate peroxidase (APX) activity under all treatments. By contrast, the glutathione reductase (GR) and superoxide dismutase (SOD) activity of AM roots was lower than that of non-AM plants and increased in shoots. The endogenous levels of cis-12-oxophytodienoc acid (OPDA), jasmonic acid (JA), and 12-OH-JA showed a significant increase in AM plants as compared to non-AM plants. 11-OH-JA content only increased in AM plants subjected to drought. Results show that D. eriantha is sensitive to drought, salinity, and cold stresses and that inoculation with AM fungi regulates its physiology and performance under such conditions, with antioxidants and jasmonates being involved in this process.
    Mycorrhiza 07/2015; DOI:10.1007/s00572-015-0653-4 · 3.46 Impact Factor
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