Effect of salt and osmotic stresses on the expression of genes for the vacuolar H+-pyrophosphatase, H+-ATPase subunit A, and Na+/H+ antiporter from barley.

Two cDNA clones encoding vacuolar H+-inorganic pyrophosphatase (HVP1 and HVP10), one clone encoding the catalytic subunit (68 kDa) of vacuolar H+-ATPase (HvVHA-A), and one clone encoding vacuolar Na+/H+ antiporter (HvNHX1) were isolated from barley (Hordeum vulgare), a salt-tolerant crop. Salt stress increased the transcript levels of HVP1, HVP10, HvVHA-A, and HvNHX1, and osmotic stress also increased the transcript levels of HVP1 and HvNHX1 in barley roots. The transcription of HVP1 in response to salt stress was regulated differently from that of HVP10. In addition, the HVP1 expression changed in a pattern similar to that of HvNHX1 expression. These results indicate that the expression of HVP1 is co-ordinated with that of HvNHX1 in barley roots in response to salt and osmotic stresses.