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Salt stress-induced alterations in the root proteome of barley genotypes with contrasting response towards salinity.

Witzel K, Weidner A, Surabhi GK, Börner A, Mock HP - J. Exp. Bot. (2009)

Bottom Line: Multivariate analysis of the resulting protein patterns revealed cultivar-specific and salt stress-responsive protein expression.Hierarchical clustering was applied to detect similar protein expression patterns.This study emphasizes the role of proteins involved in ROS detoxification during salinity stress, and identified potential candidates for increasing salt tolerance in barley.

View Article: PubMed Central - PubMed

Affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, D-06466 Gatersleben, Germany.

ABSTRACT
In addition to drought and extreme temperatures, soil salinity represents a growing threat to crop productivity. Among the cereal crops, barley is considered as notably salt tolerant, and cultivars show considerable variation for tolerance towards salinity stress. In order to unravel the molecular mechanisms underlying salt stress tolerance and to utilize the natural genetic variation of barley accessions, a series of hydroponics-based salinity stress experiments was conducted using two genetic mapping parents, cvs Steptoe and Morex, which display contrasting levels of salinity tolerance. The proteome of roots from both genotypes was investigated as displayed by two-dimensional gel electrophoresis, and comparisons were made between plants grown under non-saline and saline conditions. Multivariate analysis of the resulting protein patterns revealed cultivar-specific and salt stress-responsive protein expression. Mass spectrometry-based identification was successful for 26 out of 39 selected protein spots. Hierarchical clustering was applied to detect similar protein expression patterns. Among those, two proteins involved in the glutathione-based detoxification of reactive oxygen species (ROS) were more abundant in the tolerant genotype, while proteins involved in iron uptake were expressed at a higher level in the sensitive one. This study emphasizes the role of proteins involved in ROS detoxification during salinity stress, and identified potential candidates for increasing salt tolerance in barley.

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The effect of NaCl on the seedling growth of cvs Morex and Steptoe. (A) Schematic diagram of salt stress application to barley seedlings using hydroponic culture. NaCl treatment started 7 d after germination in a step-wise manner until the desired concentration was reached. Plants were harvested after 13 d of stress treatment at the indicated concentrations. (B) The relative growth rate of salinity-stressed barley seedlings. Growth inhibition in both barley cultivars was already detectable at 50 mM NaCl treatment and increased with higher salt concentrations. The biomass production of the second and third leaf in cv. Morex was more advanced than in cv. Steptoe. The data represent the means of 20 plants per treatment, with the standard error shown as error bars. (C) The effect of 100 mM and 150 mM NaCl on seedling growth.
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fig1: The effect of NaCl on the seedling growth of cvs Morex and Steptoe. (A) Schematic diagram of salt stress application to barley seedlings using hydroponic culture. NaCl treatment started 7 d after germination in a step-wise manner until the desired concentration was reached. Plants were harvested after 13 d of stress treatment at the indicated concentrations. (B) The relative growth rate of salinity-stressed barley seedlings. Growth inhibition in both barley cultivars was already detectable at 50 mM NaCl treatment and increased with higher salt concentrations. The biomass production of the second and third leaf in cv. Morex was more advanced than in cv. Steptoe. The data represent the means of 20 plants per treatment, with the standard error shown as error bars. (C) The effect of 100 mM and 150 mM NaCl on seedling growth.

Mentions: The contrasting salinity stress response of cvs Steptoe and Morex was verified by the imposition of salinity stress at the seedling stage. For long-term experiments, the hydroponic culture system was used as it facilitates the controlled application of NaCl to plants via a nutrient solution and the harvest of roots as compared with soil-grown plants. In order to determine the appropriate NaCl concentration for the subsequent proteomic analysis, plants were exposed to gradual salt stress as indicated in Fig. 1A. At the harvest time point both lines suffered a delay in growth due to the imposition of salinity stress, and both root dry weight and the dry weight of the leaves were reduced (Fig. 1B and Supplementary Table S1 available at JXB online). The growth was inhibited in both cultivars, although even at the higher salt concentrations there was no sign of any leaf senescence. No change in the biomass production of the second leaf was detected for Morex, whereas the growth of the cv. Steptoe second leaf was reduced at the highest concentrations of NaCl. The development of the cv. Steptoe third leaf was compromised at 150 mM NaCl and almost completely inhibited at 200 mM NaCl. In contrast, the cv. Morex was able to develop its third leaf even at 250 mM NaCl, although there was a growth reduction of ∼90% as compared with control plants. The root biomass was also affected by salt treatment, but there was no cultivar-specific response, as the biomass was reduced by 40–50% at the highest salt concentrations tested as compared with control plants. Based on these data, the diagnostic concentrations for the proteome analysis were set at 100 mM and 150 mM NaCl, as these generate a moderate stress response in both genotypes (Fig. 1C).


Salt stress-induced alterations in the root proteome of barley genotypes with contrasting response towards salinity.

Witzel K, Weidner A, Surabhi GK, Börner A, Mock HP - J. Exp. Bot. (2009)

The effect of NaCl on the seedling growth of cvs Morex and Steptoe. (A) Schematic diagram of salt stress application to barley seedlings using hydroponic culture. NaCl treatment started 7 d after germination in a step-wise manner until the desired concentration was reached. Plants were harvested after 13 d of stress treatment at the indicated concentrations. (B) The relative growth rate of salinity-stressed barley seedlings. Growth inhibition in both barley cultivars was already detectable at 50 mM NaCl treatment and increased with higher salt concentrations. The biomass production of the second and third leaf in cv. Morex was more advanced than in cv. Steptoe. The data represent the means of 20 plants per treatment, with the standard error shown as error bars. (C) The effect of 100 mM and 150 mM NaCl on seedling growth.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2724703&req=5

fig1: The effect of NaCl on the seedling growth of cvs Morex and Steptoe. (A) Schematic diagram of salt stress application to barley seedlings using hydroponic culture. NaCl treatment started 7 d after germination in a step-wise manner until the desired concentration was reached. Plants were harvested after 13 d of stress treatment at the indicated concentrations. (B) The relative growth rate of salinity-stressed barley seedlings. Growth inhibition in both barley cultivars was already detectable at 50 mM NaCl treatment and increased with higher salt concentrations. The biomass production of the second and third leaf in cv. Morex was more advanced than in cv. Steptoe. The data represent the means of 20 plants per treatment, with the standard error shown as error bars. (C) The effect of 100 mM and 150 mM NaCl on seedling growth.
Mentions: The contrasting salinity stress response of cvs Steptoe and Morex was verified by the imposition of salinity stress at the seedling stage. For long-term experiments, the hydroponic culture system was used as it facilitates the controlled application of NaCl to plants via a nutrient solution and the harvest of roots as compared with soil-grown plants. In order to determine the appropriate NaCl concentration for the subsequent proteomic analysis, plants were exposed to gradual salt stress as indicated in Fig. 1A. At the harvest time point both lines suffered a delay in growth due to the imposition of salinity stress, and both root dry weight and the dry weight of the leaves were reduced (Fig. 1B and Supplementary Table S1 available at JXB online). The growth was inhibited in both cultivars, although even at the higher salt concentrations there was no sign of any leaf senescence. No change in the biomass production of the second leaf was detected for Morex, whereas the growth of the cv. Steptoe second leaf was reduced at the highest concentrations of NaCl. The development of the cv. Steptoe third leaf was compromised at 150 mM NaCl and almost completely inhibited at 200 mM NaCl. In contrast, the cv. Morex was able to develop its third leaf even at 250 mM NaCl, although there was a growth reduction of ∼90% as compared with control plants. The root biomass was also affected by salt treatment, but there was no cultivar-specific response, as the biomass was reduced by 40–50% at the highest salt concentrations tested as compared with control plants. Based on these data, the diagnostic concentrations for the proteome analysis were set at 100 mM and 150 mM NaCl, as these generate a moderate stress response in both genotypes (Fig. 1C).

Bottom Line: Multivariate analysis of the resulting protein patterns revealed cultivar-specific and salt stress-responsive protein expression.Hierarchical clustering was applied to detect similar protein expression patterns.This study emphasizes the role of proteins involved in ROS detoxification during salinity stress, and identified potential candidates for increasing salt tolerance in barley.

View Article: PubMed Central - PubMed

Affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, D-06466 Gatersleben, Germany.

ABSTRACT
In addition to drought and extreme temperatures, soil salinity represents a growing threat to crop productivity. Among the cereal crops, barley is considered as notably salt tolerant, and cultivars show considerable variation for tolerance towards salinity stress. In order to unravel the molecular mechanisms underlying salt stress tolerance and to utilize the natural genetic variation of barley accessions, a series of hydroponics-based salinity stress experiments was conducted using two genetic mapping parents, cvs Steptoe and Morex, which display contrasting levels of salinity tolerance. The proteome of roots from both genotypes was investigated as displayed by two-dimensional gel electrophoresis, and comparisons were made between plants grown under non-saline and saline conditions. Multivariate analysis of the resulting protein patterns revealed cultivar-specific and salt stress-responsive protein expression. Mass spectrometry-based identification was successful for 26 out of 39 selected protein spots. Hierarchical clustering was applied to detect similar protein expression patterns. Among those, two proteins involved in the glutathione-based detoxification of reactive oxygen species (ROS) were more abundant in the tolerant genotype, while proteins involved in iron uptake were expressed at a higher level in the sensitive one. This study emphasizes the role of proteins involved in ROS detoxification during salinity stress, and identified potential candidates for increasing salt tolerance in barley.

Show MeSH
Related in: MedlinePlus