The plasma membrane transport systems and adaptation to salinity

Regulation of Na+ and K+ homeostasis in plants: towards improved salt stress tolerance in crop plants

“…The proton motive force created by P-ATPases is largely responsible for a negative potential across the plasma membrane, which is essential for root nutrient uptake, stomatal aperture, phloem loading, and cell growth (Blumwald et al , 2000; Gaxiola et al , 2007; Mansour, 2014). Besides regulation of many physiological processes, the P-ATPases have a critical role in plant adaptation to salt stress conditions.…”

“…Higher P-ATPases activity under salt stress conditions repolarizes the NaCl-induced depolarization of PM. This response has been strongly associated with salt stress tolerance (Mansour, 2014). The maintenance of the PM potential under salt stress through P-ATPases activity has a great effect on reduction of Na + influx via depolarization-activated NSCCs and K + efflux via KORs and NSCCs, which help to restore higher K + /Na + levels (Sun et al , 2009).…”

“…The higher P-ATPases activity under salt stress also energizes the active transport that exclude Na + from root cells, a process dependent of the SOS1 Na + /H + antiporter (Gaxiola et al , 2007). Furthermore, it was reported that higher activation of P-ATPases is often found in halophytes and salt tolerant genotypes, which may correlate with salt stress tolerance (Mansour, 2014). For instance, in rice callus lines, a higher activation of P-ATPases occurred in salt-tolerant lines as compared to less tolerant ones (Pons et al , 2011).…”

“…The salt-dependent activation of PM H + -pump is associated with increased levels of gene expression as well as post-translational modifications of the enzyme present in a preexisting pool (Gaxiola et al , 2007; Mansour, 2014). However, it is likely that regulation of the pump activity occurs mostly at post-translational level (Gaxiola et al , 2007; Fuglsang et al , 2010).…”

Sodium efflux in plant roots: What do we really know?

“…This is not to say that SOS1 does not transport a significant amount of Na + out of certain cell types, however, or that this transporter function is not related to the protective properties of SOS1 against salt stress; both of these ideas appear to be well substantiated (e.g., Qiu et al, 2002;Cuin et al, 2011).However, it is important to consider here the root-expression patterns of SOS1, in particular that itappears to be highly expressed only in two regions of the root: the xylem parenchyma, and the root tip . Xylem parenchyma cells appear to be involved in the translocation of Na + to the shoot, or its retrieval (depending on the intensity of salt stress; Yadav et al, 2012;Mansour, 2014;Katschnig et al, 2015), but not in efflux to the cortical apoplast or external medium. On the other hand, the function of root-tiplocalized SOS1 appears to be important for the protection of cells in the root apical meristem, which are neither vacuolated nor connected to vascular tissue and therefore cannot, like other root cells, engage in transport to the vacuole or to the stele for the maintenance of a low cytosolic [Na + ] Chinnusamy et al, 2005;Maathuis et al, 2014).…”