Title : Biochemical and molecular characterization of ion transporter channels in salt sensitive versus tolerant indica rice cultivars in aspect of salt tolerance
Salt stress mediates a higher concentration of Na+ in plants through root epidermal-cortex that negatively affects plant growth and crop production. Primary transporter; proton pumping ATPase and secondary transporter (antiporter); NHX’s and SOS1 play a crucial role to manage the low concentration of Na+ under high salt concentration. The ion transport activity of secondary antiporter is facilitated by proton motif force (ΔH+) generated by primary transporter; PM H+ATPase, Vacuolar H+ATPase. Recent works highlighted the regulation of all these ion channels activities that occurred by phosphorylation. The current study was designed to investigate the defense response under salt stress for ion channels for two salt-tolerant landraces indica rice cultivars Nona Bokra and Pokkali versus two sensitive IR-64 and IR-29. Higher enzymatic activity for PM H+ATPase especially in salt treated root tissue of salt-tolerant rice cultivar seedlings can be correlated with its Thr-phosphorylation status out of its total protein. This study also highlighted the total protein level of SOS1 which is found much higher in roots than shoots in rice seedlings while NHX 1 (vacuolar antiporter) has been found constitutively expressed in shoot tissue but down-regulated in salt treated root tissue. The total Na ion accumulation data highlights that salt tolerant rice cultivar maintains high content of Na ion in root tissue versus salt sensitive species, vice versa is true in aspect of shoot for salt tolerant versus sensitive cultivar.