TY - JOUR
T1 - Mapping of HKT1;5 gene in barley using gwas approach and its implication in salt tolerance mechanism
AU - Hazzouri, Khaled M.
AU - Khraiwesh, Basel
AU - Amiri, Khaled M.A.
AU - Pauli, Duke
AU - Blake, Tom
AU - Shahid, Mohammad
AU - Mullath, Sangeeta K.
AU - Nelson, David
AU - Mansour, Alain L.
AU - Salehi-Ashtiani, Kourosh
AU - Purugganan, Michael
AU - Masmoudi, Khaled
N1 - Funding Information:
This research work was supported by funding from the United Arab Emirates University to KM under grant number 31F096. We are grateful to the International Center for Biosaline Agriculture team for phenotyping the barley USDA core collection in their field experimental station and evaluation of the salinity tolerance.
Publisher Copyright:
© 2018 Hazzouri, Khraiwesh, Amiri, Pauli, Blake, Shahid, Mullath, Nelson, Mansour, Salehi-Ashtiani, Purugganan and Masmoudi.
PY - 2018/2/19
Y1 - 2018/2/19
N2 - Sodium (Na+) accumulation in the cytosol will result in ion homeostasis imbalance and toxicity of transpiring leaves. Studies of salinity tolerance in the diploid wheat ancestor Triticum monococcum showed that HKT1;5-like gene was a major gene in the QTL for salt tolerance, named Nax2. In the present study, we were interested in investigating the molecular mechanisms underpinning the role of the HKT1;5 gene in salt tolerance in barley (Hordeum vulgare). A USDA mini-core collection of 2,671 barley lines, part of a field trial was screened for salinity tolerance, and a Genome Wide Association Study (GWAS) was performed. Our results showed important SNPs that are correlated with salt tolerance that mapped to a region where HKT1;5 ion transporter locatedon chromosome four. Furthermore, sodium (Na+) and potassium (K+) content analysis revealed that tolerant lines accumulate more sodium in roots and leaf sheaths, than in the sensitive ones. In contrast, sodium concentration was reduced in leaf blades of the tolerant lines under salt stress. In the absence of NaCl, the concentration of Na+ andK+ were the same in the roots, leaf sheaths and leaf blades between the tolerant and the sensitive lines. In order to study the molecular mechanismbehind that, alleles of the HKT1;5 gene fromfive tolerant and five sensitive barley lines were cloned and sequenced. Sequence analysis did not show the presence of any polymorphism that distinguishes between the tolerant and sensitive alleles. Our real-time RT-PCR experiments, showed that the expression of HKT1;5 gene in roots of the tolerant line was significantly induced after challenging the plants with salt stress. In contrast, in leaf sheaths the expression was decreased after salt treatment. In sensitive lines, there was no difference in the expression of HKT1;5 gene in leaf sheath under control and saline conditions, while a slight increase in the expression was observed in roots after salt treatment. These results provide stronger evidence that HKT1;5 gene in barley play a key role in withdrawing Na+ from the xylem and therefore reducing its transport to leaves. Given all that, these data support the hypothesis that HKT1;5 gene is responsible for Na+ unloading to the xylemand controlling its distribution in the shoots, which provide new insight into the understanding of this QTL for salinity tolerance in barley.
AB - Sodium (Na+) accumulation in the cytosol will result in ion homeostasis imbalance and toxicity of transpiring leaves. Studies of salinity tolerance in the diploid wheat ancestor Triticum monococcum showed that HKT1;5-like gene was a major gene in the QTL for salt tolerance, named Nax2. In the present study, we were interested in investigating the molecular mechanisms underpinning the role of the HKT1;5 gene in salt tolerance in barley (Hordeum vulgare). A USDA mini-core collection of 2,671 barley lines, part of a field trial was screened for salinity tolerance, and a Genome Wide Association Study (GWAS) was performed. Our results showed important SNPs that are correlated with salt tolerance that mapped to a region where HKT1;5 ion transporter locatedon chromosome four. Furthermore, sodium (Na+) and potassium (K+) content analysis revealed that tolerant lines accumulate more sodium in roots and leaf sheaths, than in the sensitive ones. In contrast, sodium concentration was reduced in leaf blades of the tolerant lines under salt stress. In the absence of NaCl, the concentration of Na+ andK+ were the same in the roots, leaf sheaths and leaf blades between the tolerant and the sensitive lines. In order to study the molecular mechanismbehind that, alleles of the HKT1;5 gene fromfive tolerant and five sensitive barley lines were cloned and sequenced. Sequence analysis did not show the presence of any polymorphism that distinguishes between the tolerant and sensitive alleles. Our real-time RT-PCR experiments, showed that the expression of HKT1;5 gene in roots of the tolerant line was significantly induced after challenging the plants with salt stress. In contrast, in leaf sheaths the expression was decreased after salt treatment. In sensitive lines, there was no difference in the expression of HKT1;5 gene in leaf sheath under control and saline conditions, while a slight increase in the expression was observed in roots after salt treatment. These results provide stronger evidence that HKT1;5 gene in barley play a key role in withdrawing Na+ from the xylem and therefore reducing its transport to leaves. Given all that, these data support the hypothesis that HKT1;5 gene is responsible for Na+ unloading to the xylemand controlling its distribution in the shoots, which provide new insight into the understanding of this QTL for salinity tolerance in barley.
KW - 5 gene
KW - Barley
KW - GWAS
KW - HKT1
KW - Salinity tolerance
KW - Sodium transport
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U2 - 10.3389/fpls.2018.00156
DO - 10.3389/fpls.2018.00156
M3 - Article
AN - SCOPUS:85043386289
SN - 1664-462X
VL - 9
JO - Frontiers in Plant Science
JF - Frontiers in Plant Science
M1 - 156
ER -