Expression of wild rice Porteresia coarctata PcNHX1 antiporter gene (PcNHX1) in tobacco controlled by PcNHX1 promoter (PcNHX1p) confers Na(+)-specific hypocotyl elongation and stem-specific Na(+) accumulation in transgenic tobacco.

Soil salinization is a major abiotic stress condition that affects about half of global agricultural lands. Salinity leads to osmotic shock, ionic imbalance and/or toxicity and build-up of reactive oxygen species. Na⁺/H⁺ antiporters (NHXs) are integral membrane transporters that catalyze the electro-neutral exchange of K⁺/Na⁺ for H⁺ and are implicated in cell expansion, development, pH/ion homeostasis and salt tolerance. Porteresia coarctata is a salt secreting halophytic wild rice that thrives in the coastal-riverine interface. P. coarctata NHX1 (PcNHXI) expression is induced by salinity in P. coarctata roots and shows high sequence identity to Oryza sativa NHX1. PcNHX1 confers hygromycin and Li+ sensitivity and Na+ tolerance transport in a yeast strain lacking sodium transport systems. Additionally, transgenic PcNHX1 expressing tobacco seedlings (PcNHX1 promoter) show significant growth advantage under increasing concentrations of NaCl and MS salts. Etiolated PcNHX1 seedlings also exhibit significantly elongated hypocotyl lengths in 100 mM NaCl. PcNHX1 expression in transgenic tobacco roots increases under salinity, similar to expression in P. coarctata roots. Under incremental salinity, transgenic lines show reduction in leaf Na+, stem specific accumulation of Na+ and K+ (unaltered Na+/K+ ratios). PcNHX1 transgenic plants also show enhanced chlorophyll content and reduced malondialdehyde (MDA) production in leaves under salinity. The above data suggests that PcNHX1 overexpression (controlled by PcNHX1p) enhances stem specific accumulation of Na+, thereby protecting leaf tissues from salt induced injury.

Jegadeeson V ，Kumari K ，Pulipati S ，Parida A ，Venkataraman G ... -  《-》

A vacuolar antiporter is differentially regulated in leaves and roots of the halophytic wild rice Porteresia coarctata (Roxb.) Tateoka.

Kizhakkedath P ，Jegadeeson V ，Venkataraman G ，Parida A ... -  《-》

The SbSOS1 gene from the extreme halophyte Salicornia brachiata enhances Na(+) loading in xylem and confers salt tolerance in transgenic tobacco.

Yadav NS ，Shukla PS ，Jha A ，Agarwal PK ，Jha B ... -  《-》

Overexpression of PbrNHX2 gene, a Na(+)/H(+) antiporter gene isolated from Pyrus betulaefolia, confers enhanced tolerance to salt stress via modulating ROS levels.

Intracellular Na+/H+ antiporters (NHXs) play important roles in plant tolerance to salt stress. However, plant NHXs functioning in salt tolerance and the underlying physiological mechanisms remain poorly understood. In this report, we report the identification and functional characterization of PbrNHX2 isolated from Pyrus betulaefolia. PbrNHX2 expression levels were induced by salt, and dehydration, but was unaffected by cold. PbrNHX2 was localized in the tonoplast. Overexpression of PbrNHX2 in tobacco and Pyrus ussuriensis conferred enhanced tolerance to salt tolerance, whereas down-regulation of PbrNHX2 in Pyrus betulaefolia by virus-induced gene silencing (VIGS) resulted in elevated salt sensitivity. The transgenic lines contained lower levels of Na+, higher levels of K+, and higher K/Na ratio, whereas they were changed in an opposite way when PbrNHX2 was silenced. In addition, the transgenic plants accumulated lower levels of reactive oxygen species compared with wild type, accompanied by higher activities of three antioxidant enzymes. Taken together, the data demonstrate that PbrNHX2 plays a positive role in salt tolerance and that it holds a great potential for engineering salt tolerance in crops.

Dong H ，Wang C ，Xing C ，Yang T ，Yan J ，Gao J ，Li D ，Wang R ，Blumwald E ，Zhang S ，Huang X ... -  《-》

A novel tonoplast Na(+)/H(+) antiporter gene from date palm (PdNHX6) confers enhanced salt tolerance response in Arabidopsis.

Al-Harrasi I ，Jana GA ，Patankar HV ，Al-Yahyai R ，Rajappa S ，Kumar PP ，Yaish MW ... -  《-》