Abstract
Vacuolar Na+/H+ antiporter has been investigated as the key to salt tolerance in plants. We have reported that overexpression of OsNHX1 improved the salt tolerance of transgenic rice relative to that of wild-type and that OsNHX1 had the ability to transport K+, suggesting that the antiporter plays important roles in various physiological phenomena of rice (Fukuda et al., 2004 Plant Cell Physiol., in press). In this report, we show that OsNHX1 may have an important role in the tolerance of rice to iron-deficiency stress. To begin with, we observed that iron content of transgenic rice calli overexpressing OsNHX1 was higher than that of wild-type. Next, the transcript levels of OsNHX1 increased in rice calli treated with the iron-deficiency stress. Furthermore, chlorosis of transgenic rice seedlings overexpressing OsNHX1 in iron-deficiency conditions was somewhat inhibited relative to that of wild-type. We will discuss the relationship of OsNHX1 to iron uptake of rice.
