OsNHAD is a chloroplast membrane-located transporter required for resistance to salt stress in rice (Oryza sativa)

In this study, we functionally identified an uncharacterized sodium ion transporter named OsNHAD which encodes a putative Na+ ⁄ H+ antiporter in rice. Homology search shows its close relation to the Arabidopsis Na+/H+ antiporter AtNHD1 with 72.74% identity of amino acids. OsNHAD transcripts mainly express in leaves and are induced by Na+ stress. Confocal laser scanning microscopy analysis of OsNHAD::GFP fusion in tobacco leaves shows that OsNHAD resides in the chloroplast envelop. Knock-down of OsNHAD by RNA interference led to increased rice sensitivity to Na+, manifested by stunted plant growth, enhanced cellular damage, reduced PSII activity and changed chloroplast morphology. Mutation of OsNHAD also resulted in accumulation of more Na+ in chloroplasts as well as shoots, suggesting that OsNHAD is involved in mediating efflux and detoxification of Na+ but does not affect K+ accumulation in plant cells and in tissues. Complementation test reveals that OsNHAD was able to functionally restore the Arabidopsis mutant atnhd1-1 growth phenotype. These results suggest that OsNHAD possibly mediates homeostasis of sodium ions in the subcellular compartments and tissues of the plants when challenged to salt stress.
Source: Plant Science - Category: Biology Source Type: research