TY - JOUR
T1 - Assessing the role of root plasma membrane and tonoplast Na+/H+ exchangers in salinity tolerance in wheat
T2 - In planta quantification methods
AU - Cuin, Tracey A.
AU - Bose, Jayakumar
AU - Stefano, Giovanni
AU - Jha, Deepa
AU - Tester, Mark
AU - Mancuso, Stefano
AU - Shabala, Sergey
PY - 2011/6
Y1 - 2011/6
N2 - This work investigates the role of cytosolic Na+ exclusion in roots as a means of salinity tolerance in wheat, and offers in planta methods for the functional assessment of major transporters contributing to this trait. An electrophysiological protocol was developed to quantify the activity of plasma membrane Na+ efflux systems in roots, using the microelectrode ion flux estimation (MIFE) technique. We show that active efflux of Na+ from wheat root epidermal cells is mediated by a SOS1-like homolog, energized by the plasma membrane H+-ATPase. SOS1-like efflux activity was highest in Kharchia 65, a salt-tolerant bread wheat cultivar. Kharchia 65 also had an enhanced ability to sequester large quantities of Na+ into the vacuoles of root cells, as revealed by confocal microscopy using Sodium Green. These findings were consistent with the highest level of expression of both SOS1 and NHX1 transcripts in plant roots in this variety. In the sensitive wheat varieties, a greater proportion of Na+ was located in the root cell cytosol. Overall, our findings suggest a critical role of cytosolic Na+ exclusion for salinity tolerance in wheat and offer convenient protocols to quantify the contribution of the major transporters conferring this trait, to screen plants for salinity tolerance.
AB - This work investigates the role of cytosolic Na+ exclusion in roots as a means of salinity tolerance in wheat, and offers in planta methods for the functional assessment of major transporters contributing to this trait. An electrophysiological protocol was developed to quantify the activity of plasma membrane Na+ efflux systems in roots, using the microelectrode ion flux estimation (MIFE) technique. We show that active efflux of Na+ from wheat root epidermal cells is mediated by a SOS1-like homolog, energized by the plasma membrane H+-ATPase. SOS1-like efflux activity was highest in Kharchia 65, a salt-tolerant bread wheat cultivar. Kharchia 65 also had an enhanced ability to sequester large quantities of Na+ into the vacuoles of root cells, as revealed by confocal microscopy using Sodium Green. These findings were consistent with the highest level of expression of both SOS1 and NHX1 transcripts in plant roots in this variety. In the sensitive wheat varieties, a greater proportion of Na+ was located in the root cell cytosol. Overall, our findings suggest a critical role of cytosolic Na+ exclusion for salinity tolerance in wheat and offer convenient protocols to quantify the contribution of the major transporters conferring this trait, to screen plants for salinity tolerance.
KW - Cytosol
KW - Salinity tolerance
KW - Sodium
KW - Vacuolar sequestration
UR - http://www.scopus.com/inward/record.url?scp=79955721892&partnerID=8YFLogxK
U2 - 10.1111/j.1365-3040.2011.02296.x
DO - 10.1111/j.1365-3040.2011.02296.x
M3 - Article
C2 - 21342209
AN - SCOPUS:79955721892
SN - 0140-7791
VL - 34
SP - 947
EP - 961
JO - Plant, Cell and Environment
JF - Plant, Cell and Environment
IS - 6
ER -